Kinked coolant pipe -- what is correct geometry? (Page 2/3)
theogre FEB 14, 11:34 AM
Don't think Exhaust repair = Coolant tube repair. Many exhaust shops won't touch this for many reasons...

Exhaust repairs including welded joints doesn't matter when seams leak and often they do.
OE welds at car factory are done before most to all parts are in the car. Often done by "robots" too even many years ago likely many Spot weld bots.
But 3rd party welds and clamps often have gaps and leak some to a lot and most owners have no clue.

Most exhaust welds are on overlap parts because pipes are make for use w/ clamp on joints too. If the overlap is tight, the inner tube expand a little more when hot and can close a small leak while car is running.
OE welds are cheap and fast just to save time and money for GM. 3rd party is similar issue.
If you see clamps, Most factory exhaust clamps seal way better because made different then most clamps used by DIY and even "Pro" shops. Most aftermarket clamps don't load the joint evenly and make leaks.

I've seen many exhaust repairs leaking a little to a lot to fail but where they happen and when can mean not easy to see or hear. Even crack exhaust manifold and other pipes upstream of the cat may not make much noise and pass E-testing and/or not set Codes until crack is big. But leak there can let Air inside and F'd up O2 sensor reading causing other problems and eat more gas.

Many coolant systems can still have problems even when metal tubes overlap and welded or clamped...

Coolant leaking even a tiny drop per mile can cause a lot of problems fast and leave you stranded.
Coolant has ~ 16 psi in the system when hot vs exhaust runs < 2 psi at any time and very tiniest coolant leak w/ cold engine, like tiny and you can't see w/ cold engine, can dump faster and more when hot and tries to build up system pressure. Is also why iffy coolant hoses & seals often only leak at joints w/ hot engine and need a pressure tester tool kit to find them w/ engine cold and safe to work on.

Mismatched tube material can have different expansion rates and stress for this could crack or fail at weld points or anywhere on or near a patch. more so have more system pressure to handle too.

Worse, If you weld the coolant tube... Know that this damage is very common and next time you let any shop to do any work can quickly wreck the tube again and welded repair can break not bend.
Is common because many places use Jacks, Jack Stands, and most Lifts Wrong to lift a Fiero.
And not only the coolant tube but the plastic rocker panels and small rear panel in front of tire is damage for same reason.
Open door and look at where that small panel meet the door jam. When the panel doesn't sit tight to jam then whole area is wrecked most by jacking/lifting wrong.
If rocker is cracked/broken there often have same thing happen.
(Note that Lowered cars can see same problem.)
oneinch FEB 14, 12:07 PM
I discuss things at the weld shop. Welding is the best way to repair. As with any repair, poor work results in poor results. With welding, the material and conditions won't be the problem. Using rubber hose and clamps certainly works. It's not the route I'm choosing to go first. I don't think this repair will be a problem for a competent welder. The first problem for me to overcome is being an incompetent judge of any welder. But hey... ¯\_(ツ)_/¯
reinhart FEB 15, 11:39 PM
Regarding different metals, why not 1) attempt to straighten pipe. If works, done. If kink remains, remove pipe and just cut the pipe at the kink. Straighten ends. Now have a welder use stainless flux to weld the stainless pipe. Done
oneinch FEB 15, 11:57 PM
I just turned my pipes over to a welder today. I expect to have them back end of the week. I have high expectations. I'll post pictures of the finished job. My pipes weren't leaking, but we noticed a few minor imperfections here and there in the pipes. The welder is going to fill these spots. The pipe will be sanded down and should look next to new. We'll see.
oneinch FEB 16, 12:56 PM
I just picked up my welded and repaired coolant pipes. I'm am completely satisfied in everyway with choosing this repair method and the welding that was done. Cost was just under $350; $320 for the welding and under $30 for a repair pipe from McMaster Carr. This price is extremely competitive to the DIY repair tubes from Rodney Dickman. His pipes will 100% make the repair and would have been less expensive ($300 + shipping), but I wanted a welded solution. Sure, there are even less expensive solutions. This could be considered the high end on the repair scale.

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Stanton
'88 Formula, red on gray

Raydar FEB 16, 02:18 PM
Good show! Nice work. Very nice.
reinhart FEB 17, 02:06 AM
Glad you're happy with the result. I'm a bit confused why such a big patch was needed for just a kink. Did he give a reason why he couldn't cut at the kink and just weld once (Rather than twice) after straightening? Would have looked nearly perfect without the added turbulance of multiple changes in diameter (small, big, small).

Also $300 seems excessive for just a couple seems. The local welder I used before COV19 would give me an hour of welding for $150. This shouldn't have taken more than 15 minutes.
oneinch FEB 17, 02:54 AM
The reason for the big patch is because you have to cut out the crushed pipe. Cutting through the middle of the kink, trying to reshape the tube, and then butt welding it back together - while possible in only a perfect world - is not the way to do it. You'd never get the two pieces to match up. Four inches or so was cut out...back to round tube. The repair pipe is 1.5" OD / 1.402" ID is a little bigger and slips over the original. Hence the two welds . If there was a turbulence scale it wouldn't even register. It's now twice as good as it was, if not better. As far as price, your price may vary. I guess I hired the most expensive welder in the world. Que sera sera.

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Stanton
'88 Formula, red on gray

Will FEB 17, 09:39 AM

quote
Originally posted by oneinch:

Cutting through the middle of the kink, trying to reshape the tube, and then butt welding it back together - while possible in only a perfect world - is not the way to do it. You'd never get the two pieces to match up.



I've had exactly that done... it's not that difficult.
oneinch FEB 17, 10:00 AM
Sounds like I'm being challenged. It's the nature of the internet. Between the two methods the way I had it done is stronger and superior. I'll take best over good every time I can.

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Stanton
'88 Formula, red on gray