View Full Version : Welding on automotive exhaust??
10-08-2004, 11:57 PM
Hello.........My question is that when welding on exhaust.........is it necessary to disconnect any or all the battery terminals??
The cars and truck that I am welding on are 1994-2004 models.
I've herd of concern about frying the computers.....but only when welding on the frame. Will exhaust welding possibly damage the computers aswell?
thanks, any help would be great.
a good rule of thumb is to always disconnect the battery when welding on vehicles, also keep in mind that you should keep the ground clamp as close to where your welding as possible. The reason being you don't want to arc out bearings in rearends, motors transmissions etc. the arc mark will cause a hard spot on the material. Yes electricity is supposed to take the shortest route- but not always.
Keep your stick on the ice.
11-02-2004, 10:38 PM
I run across something similiar to this frequently. My main job is electric fork lift repair. Elec. Forklifts, unlike cars, have a very large battery that gives of ALOT of hydrogen gas even when its not being charged. Also like cars, newer forklifts are loaded with one or more coputers. Being an electric vehicle, the welding current can travel through bearings, and brushes in the electric motors. This can feed right back into the drive cards causing all sorts of havoc.
When I weld on an electric forklift, I always disconnect the battery and will remove it (some weigh 3000lbs) if possible. Keeping it far away from the weld area. I make sure my ground is clamped on a perfectly clean area of steel as close to my work area as possible. MY work area is also finished down to clean steel. I work as fast as possible, (not rushing, but I dont dawdle) and I dont lay any more beads than I need to. Having a poor ground area or work area thats not clean can cause delays in welding, and numerous problems getting the arc going. These wil cause damage to the trucks electrical system if they become too numerous. I have even removed comonents from the truck to ensure that an $1100 board doesnt get fried.
I have seen batteries explode from errand sparks and the clean up is tremendous. ( not to mention possible injury)Its not bad on a forklift, but imagine trying to clean an acid spill from an exploded battery up in some Lexus.
As fas as exhaust, most exhaust systems are now rubber hung. And while they are bolted to the engine, the engine/trans combo is usually rubber mounted as well. Most cars/trucks have an engine ground strap. Disconnecting this (temporarily) will help ensure any ill effect are minimum. Still need to disconnect the battery and keep your ground as close as possible.
Dont run the vehicle without the engine ground strap connected. ITs ususally a computer killer.
11-03-2004, 09:32 PM
I never disconnect the batteries and doing so is no total insurance that you wont cook something from a ground loop. There are so many ground wires in harnesses on cars anymore partially due to the amount of plastic fixtures. Have seen it happen with every precaution taken and I cant see how disconnecting a battery would make any difference. Many new cars it causes lots of problems when doing so. I ground on the part I am welding on. I agree about not welding near batteries but batteries make the gas when charging. Ground right to the exhaust, its the best you can do. I have welded on hundreds of cars, never had a problem. Have heard lots of stories, never actually seen a case of it happen. I am sure it has though.
11-03-2004, 11:43 PM
I won't venture whether you should or shouldn't but it's fun to mess around with the "what ifs"..
Back in the earlier days of computers in cars, they had a lot of problems. Some caused by nothing more than hot days and static. I can see where the last guy to work on it wuld be the sucker who got blamed. Heck they even had problems with computers in the home and at work. Then came all the bonding straps from the engine, hoods, body panels and individual circuits by the jillions, new wiring schemes and most of the problems went away.
Like Sberry says, disconnecting the battery will isolate the battery and that's about it any more. A misplaced work lead sure could cook something but I don't know for sure how you could go about disconnecting enough items to prevent that. Double extra care on the work clamp (ground) is about the best you can do.
Think about this. Disconnecting the battery is going to erase not only the history codes and fault codes but any other smog/effeciency settings that have been set. Heck they have it now to where your driving habits effect the tranny shift ranges after about a hundred miles. So if you do disconnect the battery just remember that the car might run somewhat differently for a week or so till all the ranges get set again.
How about remove the exhaust?? LOL!!
11-04-2004, 02:17 AM
I've had to do alot of repairs on tractor trucks and the rule of thumb for me is to disconnect the battery and pull the plug from the brain box. I've heard some war stories of people having to spend a few bills replacing them due to grounds looping through the wrong holes.
11-04-2004, 12:46 PM
Sberry make a point that is probably key to this whole discussion - plastic vehicles! In days of yore (and around the time that the "disconnect the battery" axiom was first stated) motor vehicle parts were nearly all electricaly conductive. It may have made sense to unhook the battery then; now, so little of a vehicle can carry current that the wirng harnesses have become the size of your forearm. There are two considerations: one, nearly all the electrical components are served by two conductors - the battery and the ground, rather than just the battery with ground all over the place like before. Two, if you place the welding ground as close as possible to the weldment, there should be little opportunity for ground-loop currents.
I'd probably worry a little about older HF supplies that converted older stick welderes to TIG machines, but using modern equipment, I think the battery thing is moot.
vBulletin® v3.8.7, Copyright ©2000-2013, vBulletin Solutions, Inc.