engine and drivetrain squeal after warming up (vacuum leak?)

[kenped86]

Got a pretty nasty squeal that happens after warming up. It goes away at low vacuum after blipping the throttle. I removed alternator and A/C belts and squeal continued. I suspect the warm up regulator. Removed it and got full 10mm extension in my pot of boiling water but seem to get about half extension when its on the car. The carb cleaner trick causes the engine to surge whenever the stuff is sprayed in the general vicinity of the engine. I've tried to isolate a location but it seems every nook and cranny has a "leak". Here's a video for your enjoyment/my pain.

 

'72tii

 

 

 

 

Edited October 8, 2016 by kenped86

[PaulTWinterton]

It's very loud for a vacuum leak, but I guess it could be.

 

I'd listen around the engine to get an idea of where it's coming from.  I'm sure you've done that.  I'd check the distributor to make sure it was lubricated (shaft and nylon block).  I'd check the KFish belt.  I'd inspect every air hose for cuts (hey, they might whistle like a screech).

 

Not likely the WUR, but maybe a hose connected to it.

 

Carb cleaner might just be getting sucked into your aircleaner, to increase your rpm.  That's all I've got.  Good luck.

 

 

[kenped86]

Thanks Paul, I tried the hose trick to isolate the noise but no help. But alas, the stethoscope buried with my leakdown tester! After some prodding it appears to be coming from the gasket at the #1 intake runner to lower manifold. I took apart the manifold to do some cleaning a few months back (just prior to this problem starting) and found the old gaskets petrified onto the runners. I scraped off the old hardened gasket and used a new gasket but apparently did so unsuccessfully. I'll disassemble it again and report back what I find here...

 

Ken

[PaulTWinterton]

Fixing that will make a world of difference to the performance of the engine as well.  Tii's hate air leaks.

[kenped86]

Am I correct that this gasket (runner to lower manifold) is a dry, no sealant gasket?

[achman]

I had similar noise, belt dressing on alternator belt and tightening it caused it to go away permanently 

[PaulTWinterton]

2 hours ago, kenped86 said:

Am I correct that this gasket (runner to lower manifold) is a dry, no sealant gasket?

 

Correct.

[PaulTWinterton]

7 hours ago, kenped86 said:

found the old gaskets petrified onto the runners.

 

Funny, I just spent the last hour with a razor blade, shaving off old gaskets from the intake manifold on my project engine.  I can see how a corner could be missed and cause a leak.

[kenped86]

 

a little bit on there. Cleaned it further, but still squealing like a banshee. Some small nicks in the metal, would the runners/manifold possibly need machining?

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Edited October 10, 2016 by kenped86

[kenped86]

Very sad conclusion to this saga...it was the #1 intake manifold gasket, confirmed by lowering of the noise when increasing the torque on the mounting bolt, however my momentary pleasure of identifying it was immediately replaced by depression associated with the dangers of over-torquing a nut



 

Edited October 10, 2016 by kenped86

[PaulTWinterton]

Sorry to hear and see that.  The surface looked very clean.  Could it be that the gasket was compressed beyond use?  I know some people would tell you that those gaskets are only meant to be used once.

 

Hopefully you can find a replacement runner easily.

Edited October 10, 2016 by PaulTWinterton

[Simeon]

Surface was fine. Bolts hanging up?

[kenped86]

Was a new gasket and bolt was fine... sourced a replacement runner/gasket easily from 2002ad

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[PaulTWinterton]

58 minutes ago, kenped86 said:

Was a new gasket and bolt was fine

 

Hmmm, maybe that runner was already cracked? If a new runner solves your issue, then it must have been cracked.

[kenped86]

Replaced with a used (NLA from BMW) runner and new gasket. Squeal is gone. Thanks everyone for the assistance. Hopefully this helps someone in the future

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