"classic car" problemssssss

oldsmobile
cutlass

#1

Our 1994 Olds cutlass supreme convertible

3.5L 24V, DOHC…leather seats…don’t get me started…

Has developed a stalling problem.

It will rev up & then almost die & again & again until the engine warms up.



Mechanic says: intake manifold is cracked in many places & needs to be replaced.

Well…finding parts for this car is becoming a problem, since GM didn’t use this engine for very long.



As a machinist, I know it is possible to weld Aluminum… & know of several places that do it.

Q: would that work?


#2

Labor is expensive,have you done the comparison of finding a intact manifold?


#3

Ahh…yesss…finding an intact manifold…ya’ see? GM didn’t make many of these engines & parts are scarce, to say the least.

I’ve been looking & learning more than I wanted to know about intake manifolds.

Most of it is: HAHAHAH You have a WHAT YEAR OLDS? With WHAT engine???

Welding is looking better & better…


#4

So has this mechanic pulled the intake and showed you all of these alleged cracks?
Just wonderin’.


#5

This is just an old car. How much are you willing to spend on it? Whether or not this is a “classic” car is too soon to tell. Personally I don’t see folks lining up to own this one in 2024.


#6

Obviously you like the car, so I would definitely pull the manifold and try to weld it, but I fear that in a year, you will be facing the same problem.

I am guessing that the engine and manifold don’t expand and contract at the same rate or in the same patterns as the engine heats and cools. Eventually the aluminum gets brittle at the stress points and starts cracking. Welding will be a temporary fix unless you can keep it from stressing in the same way - perhaps shaving it a bit and making a thicker, softer gasket? That is a crap shoot as it will change heat transfer in ways that are hard to predict.

The best solution would be a fresh new manifold if you could get one. That would likely last 15+ years before it got brittle like this one did. Cracks in GM V-6 manifolds are common, but the ones I have seen fail were plastic manifolds.


#7

It’s a 3.4L engine. And while it’s not as common as say the 3.1L OHV V6. The LQ1 did have a six year production run and found its way into many W-Body cars. Hundreds of thousands were made. I’m sure you poke around enough junk yards you’ll find a replacement manifold. You may also want to consult the good folks at http://www.60degreev6.com/ They are experts on the subject.


#8

These engines had a unique name, I can’t recall it at the moment…They looked good on paper, but in reality they were nothing but trouble…Stop beating your head against the wall. Time to move on…