Cracked rb20 Manifold

[colbol89]

I'm pretty sure I cracked my exhaust manifold and need to replace it but here are my car's symptoms. From a cold start it squeals until it warms up but I'm pretty sure that's from my power steering pump dying. I thought it was my belts but when I had to jump start my friend's car the squealing came back and then stopped immediately when his battery had charged up enough to start his car. The added power drain makes me think that if it was my belts, this would have been irrelevant. Continuing from a cold start, squealing aside, my car sounds fine like it should but after about 15 minutes of driving at ideal operating temp the exhaust suddenly sounds harsher, rumbly, and louder (albeit it grosser). Almost like a old muscle car.

From all I've gathered this is pretty typical symptoms of cracked exhaust manifold and I'm going to take a look at the car when I have time to jack it up and investigate it this weekend but any other suggestions as to what is causing the sound would be great.

If it is the exhaust manifold, anybody out there have a good condition rb20 stock exhaust manifold for sale? I looked at the aftermarket ones which are beastly but until I've upgraded my turbo I'd rather not spend the $300 on say an S-tec manifold. I live in the Texas area and would like to pick something up local so shoot me an email or pm if you've got something available or know where I can get one. Thanks guys

[dtowngoalie]

I've got a stock rb20det exhaust manifold for sale if you're interested.

[RustspecS13]

That doesn't really sound like a cracked turbo manifold.

A cracked manifold would give you a slower spooling turbo, it may not build full boost, it would run richer, drive like crap, and it should sound like a mack truck depending on how bad it is.

Id take some sea foam and suck it into the engine and see where it smokes from. That's awesome stuff for finding exhaust leaks.

~Alex

[colbol89]

Would sea foam be a bad idea if my car is already running incredibly rich?

[virus77]

Could be an gasket going bad... most likely the one between the turbo and manifold

[colbol89]

Ran a test earlier, turbo spools up to 10psi normally and vacuum is normal as well. Don't know how this would help on diagnosing things. I considered the gasket and if I don't see any cracks that's definitely on the list to check. Anyone know how much those bolts need to be torqued back down if I end up having to take them out?

[Cjmartz2k]

Yeah, I seriously doubt you cracked a stock RB manifold, especially with the stock turbo still being intact. You've probably got a nasty leak where a gasket should be or something.

[Yellow4g63]

cast iron exhaust manifolds do crack but I doubt that's your problem. It's 4 bolts and it might have loosen up and caused you to blow out your turbo gasket. What was your vacuum in inches? 20?

[ItzGenX]

What does this squeal sound like? Does it literally sound like belt squeal? If it does, then it could still be the belt.

At a cold start your belt may squeal because the rubber is cold and hard (possibly old) or needs to be retightened. After it warms up, the rubber softens up a little, and much like a tire, it should have somewhat increased grip. The problem is if it was already slipping while cold, after warming up the belt expands a tad (gets a hair looser), so the belt is still barely holding on in a sense.

Adding additional load to the slipping belt will cause it to break traction again. For example, if it were the a/c belt, activating the a/c will make it scream, the power steering belt will cry if you turn your wheel to full lock and hold it, and alternator will squeal if a large electrical load is suddenly given to it.

Jumping off someone else's car implies that you added extra load to the alternator, aka possibly causing the belt to break traction again. The reason it would squeal and stop is that when a belt slips, the heat of the turning pulley will warm the rubber up (like doing a burnout at the strip) and traction increases where the belt will stop slipping again. Then as it cools back off with the added load still there, it will once again break loose and squeal.

An old belt doesn't necessarily need to be cracked to be replaced. An old belt can slip due to hard worn rubber. The cheaper the belt, the easier it slips later on (don't ask how i know this lol). It is like buying an all season walmart tire for a life on the road course. I've had a cheap belt after a month that would squeak and cry all the time, no matter how tight I would readjust it, the damn thing would scream a week later from either turning on the headlights AND defroster or turning the wheel lock to lock. Inspecting the belt, it looked new still, never again with those cheapies!

As for exhaust manifold cracking, you would KNOW IT KNOW IT. Like what someone said earlier, it will sound like a Mac truck - kind of clicky clacky. If your exhaust sounds anywhere sputtery, start inspecting gaskets in the exhaust from the head all the way back with the car on - they are usually obvious then by looking for the excess carbon.

Modified by ItzGenX at 4:19 PM 12/1/2009
Modified by ItzGenX at 4:26 PM 12/1/2009

[colbol89]

Do you know what the torque specs on the bolts are so when I end up taking things off to check the gasket I can properly torque them back down.