Strange Squeal on Engine Shutdown

[LTDXTC]

Hi guys,

Recently installed the Trick Flow Track Heat top end kit on my '93 LTD (Australian, but same 302 as in 94/95 'Stangs) but I now have a mystery vacuum leak somewhere, on engine shutdown it will hiss for about 10-20 seconds after it's stopped running, and will then let out an almighty "squeal".

A short rundown of mods which may be related/help are:
Rebuilt 302
TFS top end kit
Crane Hi-6, LX92 coil
Pertronix TFI module
Ford Racing 24lb injectors (M-9593-AA302)
Aeromotive fuel system
70mm T/B
70mm MAF
MSD leads
Falcon GT ECU (factory tuned for MAF and 24lb injectors)

3.27 diff gears (yes, I want 3.7's)
T5Z manual

Here is a short Youtube clip to show the sound, you will hear it at the end when I turn the engine off:


It also bucks horribly on part throttle, even above 2000rpm, which is leading me to believe it's a vacuum leak somewhere. All the vac fittings under the intake are sealed with that non-hardening Loc-tite liquid sealer (shellac?). So I'm thinking maybe I should use Teflon tape.

Cheers!

 

[toyman]

Check the check valve at the brake booster. The video wouldn't open so this is just an off the wall guess.

 

[LTDXTC]

Check the check valve at the brake booster. The video wouldn't open so this is just an off the wall guess.

I just changed the video to public, so should work now. The noise sounds like it's coming from within the engine, but I will check the booster.

 

[divit250r]

Check your PCV valve. My cousin's did that after he re-rung it. It would scream like a tight bearing when it was running. We did everything, checked all the vacuum lines, checked for weird exhaust leaks, pulled the tranny and started it on his lift, nothing changed it. Hot or cold, didn't matter. He changed his oil three times in a week to check for metal and there wasn't any. Finally, he accidentally knocked the PCV valve out of the grommet when he was checking the hoses again and it stopped. He replaced the new valve with his old one and he hasn't had any problems since. Just a thought.

Scott

 

[LTDXTC]

Check your PCV valve. My cousin's did that after he re-rung it. It would scream like a tight bearing when it was running. We did everything, checked all the vacuum lines, checked for weird exhaust leaks, pulled the tranny and started it on his lift, nothing changed it. Hot or cold, didn't matter. He changed his oil three times in a week to check for metal and there wasn't any. Finally, he accidentally knocked the PCV valve out of the grommet when he was checking the hoses again and it stopped. He replaced the new valve with his old one and he hasn't had any problems since. Just a thought.

Scott

I had thought about the PCV, so when I got home from work today I went out to check it (factory PCV from 193,000km ago) but thought I would check the bolts one more time. So I took the two centre bolts out, and the end nuts off. Re-torqued, however the two centre bolts wouldn't torque to 20ft/lb, they got to a point and then spun. So I took the upper off, and sure enough the tops of the bolt holes thread was stripped and wrapped around the bolt threads. The gasket was soaking wet with fuel around the two middle intake ports. There were no obstructions stopping the intake from properly seating, the torque wrench was clearly set at 20ft/lb (TFS say to do 22) and the nuts/bolts were tightened in the correct sequence. It's only the two centre bolts that wouldn't tighten, so I'm going to check if the manifolds are actually flat.


Very frustrating!