'95 Volvo 940 - crack in manifold

volvo
940

#1

Thanks for the advice on the previous post. Now a mechanic reports a “hairline crack” in the exhaust manifold, and that things there (what things???) are all rusted and there might be problems removing manifold. Son’s Internet research turns up lots of cases of Volvos with broken bolts from trying to remove rusted manifold. (Of course, you only hear about the bad ones.)

Son says he does not hear any noise (popping) and he does not smell any exhaust. Can we let it go? Is there a stickum repair we could try? (I was thinking of the high temperature cement I used on furnace flue metal duct, but I suspect it would not hold the pressure of the exhaust.)


#2

Ideally you’ll want to replace it but, in a pinch, you could try filling the crack with some JBWeld. That’s a high temperature epoxy that may hold.
It is a little bit of a ‘ducktape, bailing wire and bubble gum’ approach to auto repair, tho.


#3

If this is the “free” Volvo mentioned earlier, probably not worth trying to replace the manifold. Just live with the fact that you might only get a year or two out of the car anyway. It’s a gift horse with some bad teeth. :wink:


#4

Yup, same free Volvo. Need it to last for one year. Son is making good progress. He reads the owners manual and has a Chilton’s, and will ask me questions that I pass on here if I don’t know the answer myself.

Thanks to all for your help.


#5

Can you reach the crack? That JB Weld High Temp suggestion sounds good, if you can.


#6

I’d replace the cracked exhaust manifold if you can do it for a reasonable price. Contact your local auto-recycler, get a quote from them at least. A crack in the exhaust manifold can confuse the O2 sensor, and when the ECM tries to compensate for this bogus reading, it can result in an overly rich mixture. Of course it is possible that the crack is so small at this point nothing is leaking in or out worth worrying about. And if all the O2 sensors are upsteam of the leak, that’s another mitigating factor which could rule in favor of a patch instead of replacement. Are there any DTC’s indicating a rich mixture?

If it turns out that replacing is the best bet, well, anything with the exhaust is usually a difficult project. The bolts are rusted in the first place, and heat-stuck just to enhance the aggravation. But mechanics know all the tricks as they do this every day. If all else fails a machine shop can do whatever needs to be done.