engine and drivetrain Engine Screeches At 4000 Rpm

[ck_74tii]

Just picked up my 74tii a week ago and drove it home. Over this weekend when i dorve the car I noticed that the engine screeches at ~ 4000 rpm. This is independent of the gear I am in. The previous owner has a shop receipt that says the timing belt and water pumps were replaced in July 2013. I do not recall this scrrech sound when I drove the car last weekend. Can it be the belts? Should I try belt dressing? 

 

Is there an article descriing the different belts on the tii?

[Hans]

I'm pretty sure the injection pump belt is toothed, so unlikely that slipping. Maybe some other issue with tii belt??

 

Timing belt is actually a chain, so not that. I'd start with fan belt: was it replaced last year? Check tension, maybe remove belt, clean pulleys with Brake Klean, and take some emery paper to the pulleys to deglaze them. Make sure alt mounting bushing haven't failed and let alt. run at an angle. WHile belt is off, check alt and water pump for smooth turning.

Edited January 27, 2014 by Hans

[eurotrash]

It's the fan/water pump (singular) belt. Belt noise is usually poor tension setting or unnecessary belt drag from something failing. Water pump or alt bearings, etc.

[Hans]

check the other thread on belt screeching today.

[cosm3os]

Mine does the exact same thing.  Seemed to start when it got alittle cold out.  74tii motor, 4k rpm no matter how much throttle (the other thread was doing it at low rpm).

Edited January 27, 2014 by cosm3os

[Hans]

Audible rev limiter?

Will it do it with car at rest?

[willys]

my wife usually screeches when I get my tii above 4000rpm - I suggest checking your passenger seat

[OriginalOwner]

+1 eurotrash.

 

 

YES, the fuel injection pump belt is toothed, it will not screech.

 

my '74tii screeches because: 

 

a) cold fan belt with insufficient tension.  

a1)  the fix:  Belt Dressing and more tension.

a2)  another fix:  new belt, Belt Dressing, proper tension.

 

b.) water pump bearings.

b1)  the fix:  replace water pump.

 

So far I've been lucky:  alternator bearings have never screeched.

 

AND, something else to check is the mounting of the alternator in the alternator bracket.  The rubber bushings in the alternator tend to take a "set" over time and the alternator does not stay properly aligned to the fan belt (I don't know how else to say it).  In other words, the alternator is sitting "sideways" to the fan belt.  Obviously this will contribute to a lessening of fan belt tension.

  So open the hood and look down at the alternator:  does it sit "sideways" to the fan belt ??  If so, I'd recommend removing the alternator and installing new mounting bushings.  And to confuse the issue, you can install rubber bushings or urethane bushings.  Rubber was original equipment, urethane is aftermarket.  Urethane should theoretically last "forever" whereas rubber requires replacing after a few years.

 

Cheers,

 

Carl

Edited January 28, 2014 by OriginalOwner

[ck_74tii]

I checked and the car does screech when it is at rest at around 4k rpm. Today it got relatively cold in Houston (below 32 F) and the screeching started at 3500 rpm. From your feedback I am leaning towards the fan belt as being the culprit.I will adjust the tension and de-glaze the pulleys. 

[oh2fly]

Check the mounting bolts while you are at it. Tiis are famous for loosening them up and breaking off.

[ck_74tii]

can i simply undo the bolt on the tension adjust c-shaped arm, push out alternator as far as possible and re-tighten it wihtout messign around with the alternator mountign bolts? Any suggestions as to how to pussh out alternator to get proper tension? Thanks.

Cheenu

[John_in_VA]

Yes. Long screwdriver or prybar to push it out. Don't make the belt too tight - ~1/2" deflection, measured at the middle.

[Hans]

Just make sure your adjustment is holding - worn bushings can let it go loose again.