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Raindem
10-06-2010, 09:54 PM
Got a no-start condition on my daily driver I'm hoping someone can help with. It's a 2001 Kia Sephia. It quit suddenly while cruisin on the highway and wouldn't re-start. Towed it home and found that the timing belt was toast. I replaced it but it still won't start.

Before I replaced the belt I pulled the codes and got a P0343. My tester says that is the crankshaft position sensor but the Chilton book says it's the camshaft position sensor. So I'm thinking one of those was bad in addition to my timing belt.

Today I replaced the crankshaft position sensor and it still won't start. Before I throw more money down on a camshaft position sensor I'm wondering if there is something else that I'm missing here. Fuel pressure is good. The spark seems really weak but it's there. Battery is good.

Any ideas?

Thanks

slim83
10-06-2010, 09:58 PM
Alternator maybe?

mla2ofus
10-06-2010, 10:01 PM
I hope it didn't bend some valves.
Mike

boatbuoy
10-06-2010, 10:18 PM
that code was likely caused by the crank and cam being out of sync due to the broken belt. are you sure they were properly positioned when you installed the new belt ?

Raindem
10-06-2010, 10:30 PM
I hope it didn't bend some valves.
Mike

That's my fear as well being that it's an interference engine. I asked the wife if she heard any funny noises when it quit and she said no, but you know how that goes.

Raindem
10-06-2010, 10:35 PM
that code was likely caused by the crank and cam being out of sync due to the broken belt. are you sure they were properly positioned when you installed the new belt ?

Yes, I double and triple checked it. I even took a picture of how I had the dual cams lined up and took it into the Kia dealership. The service rep was very helpful and said the positioning was correct.

There's another clue I forgot to mention. I checked compression and all the cylinders were good but #3. It has only about 55 psi. Could low compression in just one cylinder cause a no-start condition?

dabar39
10-06-2010, 11:02 PM
Are you positively sure the crankshaft was rotated to have the #1 cylinder at top dead center? Did you set the cam gears so that the E and I were facing up at the timing marks on the head?

On thing to check to make sure the timing is right, set the crank to it's timing mark, make sure the cam gears are on their marks, then rotate the crankshaft 2 revolutions (with the belt installed). If after 2 turns the marks all line up timing is correct, if the timing marks don't line up your crank wasn't set to #1 tdc.

If that is all good and checks out properly then try to clear the codes, normally disconnecting the battery for 15 minutes or so will do it on the Kia's if I remember correctly.

Make sure all engine grounds are hooked up, car won't run without them making good contact.

And if all that fails take a look at the cam sensor, the code you stated is for the Camshaft Position Sensor Circuit High Input. Might explain the weak spark.

rlitman
10-06-2010, 11:04 PM
When the crankshaft position sensor failed on my Jeep, the engine would crank with the starter, but there was no spark AND no fuel, but that engine is distributorless.
If your engine has a distributor, and isn't sensing either the correct cam or crank position, you might have spark (I'd expect it to be weak, since you're just cranking with the battery, right?), but no fuel delivery (the computer won't send a signal to the injectors, even though you should have normal pressure at the fuel rail).

IF you have spark, but no fuel, you could try to squirt some gas, or blow a little propane into the throttle body. If that gets it to cough (or maybe even run for a few seconds), then you know that something is stopping the engine from getting fuel.

If your crankshaft position sensor is anything like mine, it came with a piece of paper stuck to the tip, to set its position. Unfortunately, the paper that came with mine was too thick, and when I first installed it, I was getting misfire codes because of missed signals (but you could get no signal entirely too). I pulled the sensor, and used two layers of blue painters tape on the tip instead (which added up to about half the gap the original paper set), and it worked like a charm.

BTW, my failing CPS left me stranded, but I never got a code from it. When it went, the engine died so fast, it never had a chance to detect an error condition.

Anyway, if the codes were from before you changed the timing belt, its possible the CPS sensor codes came from when the belt was broken. Are there any new codes?
It might be a good idea to clear the codes, and see what pops up AFTER you try cranking it again.

No, low compression on one cylinder will not cause a no-start. You could easily run a four cylinder engine on three cylinders (but it sure would be rough).

Oh, and I did some quick googling, and it appears you may have a non-interference engine after all. You might want to verify that with the dealer, but from what I found (which may or may not apply to you), the cylinder face is dished, and fly cut for the valves.
One site confirms that the DOHC engines are all non-interference, and another mentioned a Kia service bulletin that says all Sephia engine are non-interference.
Unfortunately, a number of references (Gates, chilton) say the engine is an interference engine, but it appears they may be wrong.

rlitman
10-06-2010, 11:05 PM
And if all that fails take a look at the cam sensor, the code you stated is for the Camshaft Position Sensor Circuit High Input. Might explain the weak spark.

High input means that the sensor is failed, or the connection is no good.

dabar39
10-06-2010, 11:14 PM
You were typing as I was so I didn't catch your last reply, You need at least 90 lbs. of compression to fire each cylinder, so you know you have a dead cylinder, not good. My guess is that you may have a bent or broken valve and have at least some moderate damage to the cylinder head as well. I would do another compression test just to make sure the readings are correct, to see if #3 is still reading 55 lbs. If the readings are the same then at this point it would probably be best to yank the head and find out how bad the damage really is.

dabar39
10-06-2010, 11:18 PM
High input means that the sensor is failed, or the connection is no good.

That's why I suggested checking the grounds for good connections. bad grounds may show a fault code when the sensor may not really be bad.

DSW
10-06-2010, 11:26 PM
If that is all good and checks out properly then try to clear the codes, normally disconnecting the battery for 15 minutes or so will do it on the Kia's if I remember correctly.

If I remember from my friends Kia, he disconnects the battery and then turns on the radio and trys to start the engine. That drains the system completely and resets the codes.

Taiden
10-06-2010, 11:49 PM
#3 at 55 psi? It's dead man, there's a not so happy valve in there. Time to pull the head and get it to a machine shop.

Raindem
10-07-2010, 12:06 AM
Thanks for all the good info, especially dabar39 and rlitman. As to the specific suggestions...

Yes, the camshafts E and I marks were position correctly. I rotated the engine 2 full turns and everything lined up correctly. In fact, after everything was back together and I had cranked it several times with the starter I checked the timing alignment again and it was spot on.

I had disconnected the battery when replacing the timing belt and that cleared all the codes. No new codes have been tripped.

I will check the electrical connections and grounds. The camshaft position sensor was going to be my next shotgun replacement part.

My engine is distributorless also. That's a good point about the fuel injectors. I always asumed if you had pressure at the rail then everything was fine with the fuel delivery system. I've got a can of starting fluid laying around somewhere. I'll give it a squirt.

Neither the old crank sensor or the new one I got today had any paper on it.

I'm pretty sure my engine is interference. When I was replacing the belt I was trying to rotate the intake cam into position and it came in contact with something and wouldn't move. I then rotated the crank 180, and after that the cam could be moved.

That was my thought when I saw the low compression in #3, that the failed timing belt cause valve train damage. I was hoping to at least get it running again before worrying about that.

Raindem
10-09-2010, 01:15 PM
OK, I just re-checked for spark and it's definitely getting spark. I sprayed some starting fluid into the intake manifold and it didn't even come close to starting. Ironically, just before that while checking for spark it almost sounded like it wanted to start up.

So I guess the next step is getting into the head to see what's going on there. While I'm at it I can re-check the timing belt placement.

Taiden
10-09-2010, 06:13 PM
i dont mean to sound like a dick... but if you have 55 psi of compression in one cylinder, and your cam timing is correct, you've got a bunged up valve assembly in that cylinder. no way around it. I've been in similar positions and been in denial. One time a motor of mine got rod knock, and I kept sayin "no, no way, that's a tappy valve" as my aftermarket oil temp gauge slowly puts the needle off the gauge... :(

as for it stopping it from starting... it's hard to say. My uncles civic will run on two cylinder and you can still drive it around the driveway..

farmall
10-11-2010, 07:39 PM
www.kia-forums.com could be a place to ask.

Post engine type and VIN in case that matters.

Also, it's a ten year old car so don't put much money into it.

Raindem
10-11-2010, 09:01 PM
I've pretty much given up on it. I'm looking for a replacement vehicle now. I'll tinker with it in my spare time and if I get it running again fine. Either way I'm selling it.

mla2ofus
10-11-2010, 09:24 PM
I guess it's the way they make money. You'd think the auto co's would design an engine w/ belt driven cams so they wouldn't bend valves when the belt fails.
Mike

DSW
10-11-2010, 10:34 PM
My uncles civic will run on two cylinder and you can still drive it around the driveway..

:laugh: I changed the plugs in my 71 Plymouth with a 318 and took it out for a test drive. Ran like cr@p and had no get up and go. Got it back and found I'd gotten distracted and left the left side plug wires off! Not to bad running a 3500+lb car at 35mph on 4 out of 8 cylinders.

Raindem
10-11-2010, 10:42 PM
I've no doubt there might be other issues keeping it from starting. At this point it doesn't make sense to troubleshoot the ignition further when I don't even know how messed up it is inside.

Raindem
10-30-2010, 12:28 PM
OK, it took a couple of weeks but I finally got the head off. There is no visible damage on any of the valves or piston tops. #3 cylinder head (the one with low compression) was more carboned up than the others but that's all I see. The valves seem to be sealing fine.

But of course I don't know what I'm doing, so my question is could there still be valve damage from the timing belt breakage even though it "looks" OK? Is there a way I can check without having to purchase specialized tools? I'm willing to take it to a machine shop for a professional valve job but only if there are issues beyond the normal 110k wear and tear.

Thanks

Taiden
10-30-2010, 12:40 PM
Did you get a cylinder leakdown test before you pulled the head? That would tell you where you were losing compression in #3 (intake valve, exhaust valve, rings)

mechanic416
10-30-2010, 01:18 PM
Hi, OK you have the head off, remove the cams. install the spark plugs and turn the head over and set it on blocks so it is level. Fill the head ports with ATF to cover the valves mark the level. check it in a hour and see if the ATF has run out and were intake or exhuast valves or both, this will tell you with valves are bent and not sealing.

Raindem
10-30-2010, 01:37 PM
Did you get a cylinder leakdown test before you pulled the head? That would tell you where you were losing compression in #3 (intake valve, exhaust valve, rings)

I did a compression check. Is that the same thing?

Raindem
10-30-2010, 01:38 PM
Hi, OK you have the head off, remove the cams. install the spark plugs and turn the head over and set it on blocks so it is level. Fill the head ports with ATF to cover the valves mark the level. check it in a hour and see if the ATF has run out and were intake or exhuast valves or both, this will tell you with valves are bent and not sealing.

Now that's what I'm talking about. Thanks, I'll give it a shot.

jakea
10-30-2010, 01:49 PM
it is almost certain you will have some bent valves with a timing belt failure on an interference Kia motor.

duaneb55
10-30-2010, 01:50 PM
Maybe I missed it in your replies but did you make absolutely sure the CRANKSHAFT was in proper timing to the cams as boatbouy and dabar39 referred to? Having the cams properly set to their E and I marks is only have the total timing picture.

As for one or more bent valves, if there was an altercation between any piston and its valve(s) there would be a distinct mark(s) on the piston dome as a result.

Taiden
10-30-2010, 03:32 PM
no, a compression test isn't the same.

A cylinder leakdown test... you put the cylinder to test at top dead center, then fix the crank in place (via crank pully). cam lobes should be at their lowest position (valves closed)

You then stick a thing that fits where your spark plug was and hook it to your air compressor. It pressurizes the cylinder and gives you a % leakdown rating on the supplied gauge. The % leakdown rating tells you the overall health of that cylinder.

Now you take a stethoscope or a long piece of vacuum hose with one end in your ear, and open your throttle body and stick it in. If you hear air hissing, it's your intake valve.

Stick your listening device into your exhaust, if it's hissing, it's your exhaust valve.

Open your oil cap and listen through there. If it's hissing, it's your rings.

Headgasket I'm a little foggy on, but I think that you check for the sound/sight of bubbling by your radiator cap.

you do this test with the motor assembled, warm, and the timing belt/chain installed.

Bluewelders
10-30-2010, 03:43 PM
If you bent a push rod or rocker arm , the intake valve would not open all of the way and the compression would be low.

Taiden
10-30-2010, 03:48 PM
If you bent a push rod

he drives a kia, not a dinosaur chevy. :nono:

:D

Raindem
10-30-2010, 03:59 PM
no, a compression test isn't the same.

A cylinder leakdown test... you put the cylinder to test at top dead center, then fix the crank in place (via crank pully). cam lobes should be at their lowest position (valves closed)

You then stick a thing that fits where your spark plug was and hook it to your air compressor. It pressurizes the cylinder and gives you a % leakdown rating on the supplied gauge. The % leakdown rating tells you the overall health of that cylinder.

Now you take a stethoscope or a long piece of vacuum hose with one end in your ear, and open your throttle body and stick it in. If you hear air hissing, it's your intake valve.

Stick your listening device into your exhaust, if it's hissing, it's your exhaust valve.

Open your oil cap and listen through there. If it's hissing, it's your rings.

Headgasket I'm a little foggy on, but I think that you check for the sound/sight of bubbling by your radiator cap.

you do this test with the motor assembled, warm, and the timing belt/chain installed.

Oh, no I didn't do that.

Raindem
10-30-2010, 04:06 PM
I'm as sure as I can be Duane. The E mark was lined up with the notch on the valve cover. The I mark was lined up with it's notch. #1 was at TDC as indicated by the cranshaft pulley alignment marks. If that's not in time, then I don't know what is.

I didn't see any marks or scratches on either the piston tops or the valves. I've completed the ATF fluid leak test mentioned earlier and all compression chambers are holding the fluid.

Taiden
10-30-2010, 04:35 PM
i say you put it all back together, and have a decent shop do a proper cylinder leakdown test, or do one yourself. Now would be a good time to add that to your list of tools! Plus, some performance guys will pay extra for cylinder leakdown tests because they know the difference, and a lot of shops just don't have the tool kicking around.

Bluewelders
10-30-2010, 04:37 PM
he drives a kia, not a dinosaur chevy. :nono:

:D
I wasn't dealing with the specifics of any one brand of engine.
But It's good to know that they don't make cars with push rods anymore.

Taiden
10-30-2010, 04:49 PM
I wasn't dealing with the specifics of any one brand of engine.
But It's good to know that they don't make cars with push rods anymore.

hehe, I was just being a smartass. :p

Raindem
10-30-2010, 05:12 PM
i say you put it all back together, and have a decent shop do a proper cylinder leakdown test, or do one yourself. Now would be a good time to add that to your list of tools! Plus, some performance guys will pay extra for cylinder leakdown tests because they know the difference, and a lot of shops just don't have the tool kicking around.
I think you're right, my next step should be to put it all back together and start fresh. Those leakdown testers don't sound too expensive. The head gasket looked fine but I don't know what a blown head gasket looks like so I'll install a new one on the re-assembly. And of course I'll make extra sure I got the timing belt right.

Thanks again everyone for your suggestions.

duaneb55
10-30-2010, 06:17 PM
I'm as sure as I can be Duane. The E mark was lined up with the notch on the valve cover. The I mark was lined up with it's notch. #1 was at TDC as indicated by the cranshaft pulley alignment marks. If that's not in time, then I don't know what is.

I didn't see any marks or scratches on either the piston tops or the valves. I've completed the ATF fluid leak test mentioned earlier and all compression chambers are holding the fluid.

Just checking as I didn't see anywhere that you confirmed positioning the crank in the proper relationship to the cams in the belt timing process.;)

cowski
11-01-2010, 12:58 AM
i know nothing about kia. but sounds like timing belt 180 degrees off. engines that i have worked on the marks line up twice .one right one 180 degrees off.if one cylinder has low compression it will not fire. but the others will. i have seen v8 run miles wih a rod sticking out the side.

DougAustinTX
11-01-2010, 01:45 AM
Ignore this. Someone already said what I was gonna say

Raindem
11-01-2010, 09:04 PM
i know nothing about kia. but sounds like timing belt 180 degrees off. engines that i have worked on the marks line up twice .one right one 180 degrees off.if one cylinder has low compression it will not fire. but the others will. i have seen v8 run miles wih a rod sticking out the side.

Could be. When I put it back together I'll take extra care with the belt.

BTW, I let the head sit all night with ATF in the chambers. Checked it the next morning and not a single drop leaked through any of the valves.

cowski
11-01-2010, 09:58 PM
if it were mine this is what i would do . since you have taken the head off,carry it to the machine shop and have a valve job done.it will cost 4 dollars a valve.if you have a bent valve they will find it.they can also check for cracks or warpage. then i would put a new head gasket on and time it correctly.you may need to get a book.

Taiden
11-01-2010, 10:12 PM
4 dollars a valve for a valve job? Holy hell, I want to live near your machine shop.

If your local machine shop is priced like that, and good, do that first. That's crazy

cowski
11-01-2010, 10:39 PM
thats funny i nearly had a stroke when he went from 2 too 4.looking over the last 3 engines we built a honda 350 a catapillar diesel and a ford v8 it was 4 dollars a valve for the valve job.what do they charge for them up north?

mechanic416
11-01-2010, 10:48 PM
Well if you let it set all night and no leaks then there are no bent or leaking valves. Your lucky I can't beleave that it broke a timing belt at highway speed and didn't bend the valves or put holes in the pistons. If that happend to me every valve would be bent and at least one cam would be broken and a few pistons would have holes in them.

Taiden
11-01-2010, 11:45 PM
To be fair, in my area, there are hardly any walk in machine shops. Most of them are military contracted and they laugh at the idea of doing valve jobs.

mrmikey
11-02-2010, 05:26 AM
Just reading thu these threads I'm leaning toward what most others are saying, it's 180 deg. out. TDC on the exhaust stroke instead of the compression. When you line up the cams make sure both valves are closed, if you're on the wrong one the exhaust will be open/ing.
Don't mean to sound like an echo LOL....Mike

Raindem
11-02-2010, 09:20 PM
Just reading thu these threads I'm leaning toward what most others are saying, it's 180 deg. out. TDC on the exhaust stroke instead of the compression. When you line up the cams make sure both valves are closed, if you're on the wrong one the exhaust will be open/ing.
Don't mean to sound like an echo LOL....Mike

TDC is TDC, right? If both cam marks are lined up and the cranshaft mark is lined up, it must be in time. If I turn it 180 deg then the marks don't line up anymore. If timing is the problem then more likely I'm a tooth or two off, not 180 deg.

mechanic416
11-02-2010, 09:49 PM
Ok TDC is when #1 piston is up and both intake and exhaust valves are closed, looking at the motor from the front is the intake cam on the left and the exhaust cam on the right

steve45
11-02-2010, 11:35 PM
Before I replaced the belt I pulled the codes and got a P0343. My tester says that is the crankshaft position sensor but the Chilton book says it's the camshaft position sensor. So I'm thinking one of those was bad in addition to my timing belt.

Today I replaced the crankshaft position sensor and it still won't start. Before I throw more money down on a camshaft position sensor I'm wondering if there is something else that I'm missing here.

In answer to your original question, it's the crankshaft sensor. I just Googled it and found the Kia forum: http://www.kia-forums.com/do-yourself/33370-all-kia-trouble-codes.html

Taiden
11-02-2010, 11:59 PM
if your cam timing was off from your crank timing you could get a code like that

mrmikey
11-03-2010, 05:07 AM
TDC is TDC, right? If both cam marks are lined up and the cranshaft mark is lined up, it must be in time.
You're right, in order to be 180 deg out the marks on the camshaft would have to be on the other side of the sprocket with the crank on TDC. It's the position of the cams that determine whether if it's compression or exhaust.
Hey, I'm a weldor, not a mechanic :D LOL......Mike

Raindem
11-03-2010, 08:30 AM
I remember when installing the new belt the cams wouldn't stay lined up with their marks. There was just a slight tension (pushing on a lifter I presume) which caused them to move a degree or two in one direction or the other. I wound up having to use vise grips and clamps to lock them in place while I slipped the belt on.

Now I'm wondering if I should have just let them be in the "resting" position, even though the marks would have been slightly off.

Rick V
11-03-2010, 09:42 AM
Hi Raindem, I've been following this story of your 2001 Kia Sephia, hoping you would find a quick fix.

However 50+ posts later, this has gotten deeper technically and rather off-subject for a WeldingWeb. No offense meant to you or anyone else on this site (were all trying to help), but wouldn't you receive more directly applicable advice on repair of your vehicle on either a Kia forum or a car mechanics forum?

Taiden
11-03-2010, 09:56 AM
cam marks should be lined up, not at resting position.

although rick v has a great point, we can combine all of our chevy/ford/mopar/honda/toyota/subaru experience and the Kia's might have something quirky going on that we just have no idea about.

Raindem
11-03-2010, 09:57 AM
Possibly. I found one Kia forum that I couldn't log into because I couldn't get past their spam filter. I found another Kia forum and posted the question but never got a reply. I posted in some other car forums I frequent but Welding Web just happened to be the thread that took off.

cowski
11-03-2010, 12:37 PM
raindem go back and read dabar39 he explains it better than me.if it fires it is not the sensor .it appears to be a timing issue.go get a cheap book at autozone.

jdchmiel
11-03-2010, 04:31 PM
if cam pos sensor is dead, then pull the crank pulley and tiing pulley off and check that the keyway did not shear.

I agree that it sounds like a cams / crank out of alignment issue. Dont forget, cams run half speed of the crank and it matters that they are not 180 out.

Bluewelders
11-03-2010, 05:28 PM
Whatever the cam position,I doubt that it would effect the compression on just one cylinder.
You could try turning the engine over manually, and watch the valves to see what is going on.

joefitz
11-04-2010, 08:44 PM
I'll just throw some things out there...

My first solo timing belt job at age 14 (A Toyota Camry) I didn't get the engine connected to ground. I totally forgot to plug it in. The timing was perfect, the engine had full compression. But when cranking it over...just sputtered, never actually starting but sounding like it wanted to.

I bitched and moaned, and almost asked my grandfather for help. But I didn't I took the night off and went back to it in the morning. Found the non connected ground and she fired up and has been on the road for 11 years.

About a year ago a friend called me with a freebie Dodge Durango, 4.7L V8 (Piece of junk btw). Said it overheated and maybe needed heads. I looked at it, and it started and ran almost normally. Just some funky sounds coming from it and a tendency to stall. After removing the heads I noted that two valve seals had popped out of the heads and kept the valves from closing completely when the engine overheated. Of course the pistons struck the valves and damaged the heads blah blah blah. That said, even with bad internal damage the engine still ran... started up fine. So I'm assuming with your KIA you've got a little problem with the communications from the engines sensors to the computer.

Sorry I couldn't have jumped in sooner... before you removed the head. You can call me if you want, PM me for my number and I could walk you through some thoughts if you haven't already gotten it running. I travel a lot finding software / communications issues with engines.

Anyone with a Jeep Grand Cherokee 6cyl 4.0 made between 1996 and 1999 that has non working heat, loss of power, stalling, unable to go into overdrive... It's your ECU case. They manufactured it too small and it shorts out the computer. I've seen at least a dozen of these things go into junkyards because people have replaced everything from the pickup coil (Cam position sensor), ignition sensor, even tried flashing a junkyard ECU... of course the ECU box is the problem....

So check your sensors. MAF, TPS, O2, CPS, etc etc... Call me and I can walk you through some stuff.

Sorry about the tangent, we mathematicians tend to do that.

Raindem
11-09-2010, 11:06 PM
Time to put this thread to bed.

I put everything back together, threw it back together is a better description. Except for the timing belt, I took extra care with that. Wouldn't you know it the POS started right up! I've got some oil and coolant leaks now 'cause like I said I didn't take a lot of care in reassembly because I thought I had a dead engine. But those I can deal with.

In the end I think the problem was what most of you said it was... incorrect timing belt installation. Those timing marks, I mean they have to be lined up PERFECT. Close doesn't cut it here. I wound up having to use an assortment of clamps and vice grips to lock the cam sprockets in place while I maneuvered the belt into position.

Thanks again for everyone's help.

Spar-X
11-10-2010, 02:09 AM
You will know if is not perfect soon enough.
or drive it up a hill......

Therealmccoy
11-29-2010, 05:39 AM
Time to put this thread to bed.

I put everything back together, threw it back together is a better description. Except for the timing belt, I took extra care with that. Wouldn't you know it the POS started right up! I've got some oil and coolant leaks now 'cause like I said I didn't take a lot of care in reassembly because I thought I had a dead engine. But those I can deal with.

In the end I think the problem was what most of you said it was... incorrect timing belt installation. Those timing marks, I mean they have to be lined up PERFECT. Close doesn't cut it here. I wound up having to use an assortment of clamps and vice grips to lock the cam sprockets in place while I maneuvered the belt into position.

Thanks again for everyone's help.

oh man talk about a hard lesson learned. i noticed in the beginning when you posted all cylinders were fine except one at 55 psi. in your situation yes it could have been a bent valve but like you found out after you took the head off it wasn't. my thoughts are you had a leak in the head gasket for that cylinder before your timing belt broke.

and for compression testing and leak down testing i think of it this way, do a compression test first because its a less accurate leak down test which is easier. if you get bad results in the compression test run a leak down test to be 100 percent positive you have a leak.

Example: earlier today i was inspecting my mothers car due to some white smoke from her tail pipe. knowing white smoke is either coolant or oil i ran a compression test. i get bad results for all cylinders but they were all with in 10 psi of each other and this is what gave me the hint that somethings not accurate about this. so i ran a leak down test just to be 100 percent sure this motor is worn out and it turns out i have 10% leakage at the most in one cylinder and the rest were about 5% which is a healthy motor. NOW I"M REALLY CONFUSED AT THIS POINT... sitting there scratching my head i realize THE COMPRESSION TESTER HAS TO BE FAULTY! i go get a new compression tester and guess what all cylinders were in spec and the motor is just dandy. The white smoke was coming from a leaky valve seal. imagine if i would have gone with those original compression test results. i would be spending a ton of money on a bunch of stuff i don"t need just because i didn't double check my work..

ALWAYS DOUBLE CHECK YOUR WORK! it will save you time and money in the long run.


kinda just rambling on about this but i thought it would be informative.:sleeping:

Raindem
11-29-2010, 08:10 AM
oh man talk about a hard lesson learned. i noticed in the beginning when you posted all cylinders were fine except one at 55 psi. in your situation yes it could have been a bent valve but like you found out after you took the head off it wasn't. my thoughts are you had a leak in the head gasket for that cylinder before your timing belt broke.


Want to hear something even stranger? When I got it back together and the engine was running fine I took another compression check and all cylinders were at 120. How could that happen? Oh well, like you say lesson learned. Next time I do a leak down test.