wicked squeaks, possibly TPEFI related

[Shannen Durphey]

----------
> I've got a weird one here. Every one I've asked so far has been stomped. I
> drove my '89 5.7L TPI '58 chevy truck to Atlanta last weekend, 100mph
> plus...420 miles one way from my home...so I'm perty sure it's not a
> mechanical engine noise. The following is what I know. I think it's the
EGR
> valve or diaphragm resonating.
> 
> When the engine is hot (just after getting off the highway) I get this
high
> pitch squeaking sound. Sounds like a belt but much louder. I can hear it
100
> yards off.  Changed the belt, operated the engine with the belt off, added
> many cans of belt dressing, and the engine still squeaks. 
> 
> Swapped trannys and inspected the flywheel. Flywheel a-ok, still got the
> squeaks.
> 
> Check this out, I can pull the engine oil dip stick when it's squeaking
and
> magicly, it stops. That's why I think it might be EGR related. The EGR
valve
> vacuume line is disconnected. The truck stumbles bad when it's connected.
I
> suspect the diaphram is leaking. I can't pull vacuume in it if the engine
is
> running. Pulls ok when the engine is off.
> 
> By now, I'm desperate to stop this damn squeaking so I connected a vacuume
> gage to the engine dip stick tube to see why it would affect the engine
> squeak. Here is what I found.
> 
> 9.5"    engine idle, park, no squeak
> 11.5"   engine idle, Drive, light squeak
> 13.0"   engine idle, park, Loud squeak
> 9.5"    engine idle, park, no squeak, after pulling the engine dip stick
to
> 'break vacuume'
> 
> 9.5"    engine idle, park, no squeak
> 11.5"   engine idle, Drive, light squeak
> 13.0"   engine idle, park, Loud squeak
> 9.5"    engine idle, park, no squeak, after winging the throttle and
reving
> engine to ~3,000rpm quickly
> 
> Manifold vauume was 18" - 18.5" at idle and 17" in gear. 
> 
> What ever is causing the squeak is definitly vacumme related. I checked
both
> PVC vales, clean as a wistle and free.  The evidence suggest that there
is a
> ported vacuume leak from the manifold to the crankcase and that the
vacuume
> is held untill you pull the dip stick or kill the motor. I have all but
> given up on finding the root cause of this irritating noise. If you guys
> don't give a solution, I will be forced to treat the symptom rather than
> solve the problem. I'll install a vacuume breaker that relieves crankcase
> vacuume at 10"  If it turns out that this is not EFI related, feel free to
> E-mail me personally...somebody somewhere has had this problem or is
having
> it.
> 
> thanks in advance for any solution offered,
> GMD
> 
> "Irritating sounds and actions can drive a man to do insane things"
> George M. Dailey
> gmd at tecinfo.com
> 
> 

Sounds like you're developing vacuum in your crankcase, which is a no-no. 
You said that you checked BOTH pcv valves, but the crankcase ventilation
system is designed to have ONE pcv valve and one vent tube to the filtered
side of the intake line.  Try removing one pcv valve from the valve cover
while the engine is running.  If the squeak dissappears, vent your
crankcase and remove the redundant valve.