924Board.org

caswah · Joined: 21 Mar 2006 Posts: 51 Location: Uppsala, Sweden

Just fixed my distributor after many hours of struggling.

Bosch sweden sent me an exploded view of the distributor, I took it apart, cleaned it and bent the stator legs even more until there was a gap of almost .5 mm

Reinstalled, timed the engine again and then she fired up instantly.

After running smoothly for 15 minutes it died. I found a piece on the ground. It was one of the L-shaped steel legs holding the engine to the chassis.

Because of the violent vibrations, the timing belt was jammed and ripped off. Im so sick of this. There is absolutely no rust anywhere else in the car except for in that engine attachment. Ripped timing belt is, as you all know, a bit like ripping someones main artery : bad bad idea.

So from one problem to another. Are the valves screwed? The valve lifters ? Is my 924 crap?

Really dont want this

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Euro ´81 924 - Interior being restored

Slam · Posted: Tue Sep 15, 2009 2:47 am Post subject:

Take heart - the 924 is not an interference engine so no harm done, really. The 924S is a different story.
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'84 944 - kid blew motor
'83 944 - resting comfortably. For 12 years
'87 944 - sideswiped by trucker
'80 924 - gone
'78 924 - gone
'77 924 - rusting comfortably

Rich H · Posted: Tue Sep 15, 2009 3:13 am Post subject:

What he said. Just replace it, no harm done.
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1994 Lotus Esprit S4 - Work in progress...
1980 Porsche 924 S2 DITC Turbo - Original spec
1978 Homo-Sapiens - Tired spec
1953 Landrover S1 - Pensioner Spec

ideola · Joined: 01 Oct 2004 Posts: 15550 Location: Spring Lake MI

From your other thread:

Martijnus · Joined: 29 Dec 2006 Posts: 2019 Location: Netherlands

My belt lost all its teeth at 140km/h.
I only found that out when I had the engine already out, and paid literally 100 times more to rebuild the engine than just replacing the belt and roller.

Well... I actually wanted to rebuild the engine anyway... but it wasn't necessary.

So you should be back on track for a few euro's

Another reason why the 924 is the best car ever.
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"Rule: Turbo's make torque, and torque makes fun." (C. Bell)

924 "50-jahre", 1981.
MSII/extra, LPG, ITB's, 5lug.
To be turbo'ed in a while.
Killed her at the Nurburgring, Porscheless at the moment

968rz · Joined: 21 Aug 2006 Posts: 537 Location: S. E. Wisconsin

If you belt breaks rolling down the road at high speed (rpm) even a non-interference motor can bend valves, but at idle or even revving in the garage your safe.
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Rick
79 924 coupe Petrol Blue 3spd auto (wife's DD)
93 968 coupe Amazon Green 4spd Tip (my DD)

!tom · Posted: Tue Sep 15, 2009 10:24 am Post subject:

Rocco R16V · Joined: 03 May 2009 Posts: 497 Location: PNW

968rz · Joined: 21 Aug 2006 Posts: 537 Location: S. E. Wisconsin

Sh1tz moving fast at that speed (rpms), I've replaced cyl heads more that a few times when I was an auto tech because of this.
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Rick
79 924 coupe Petrol Blue 3spd auto (wife's DD)
93 968 coupe Amazon Green 4spd Tip (my DD)

!tom · Posted: Tue Sep 15, 2009 12:57 pm Post subject:

968rz · Joined: 21 Aug 2006 Posts: 537 Location: S. E. Wisconsin

I can only tell you what I've seen (several times); one customer was rolling down I-94 @ 70/80 MPH when the belt let go (non-interference motor), towed the car in I put a new belt on and it runs like crap (miss, back fire...), do a comp test and find low cyl pressure, pull head and find bent valve(s). How would you explain this? This example was a regular customer so I know the engine wasn't some POS to start.
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Rick
79 924 coupe Petrol Blue 3spd auto (wife's DD)
93 968 coupe Amazon Green 4spd Tip (my DD)

Khal · Posted: Tue Sep 15, 2009 2:46 pm Post subject:

Am I missing something here? The cam/valves/pistons/crank/etc... are all travelling at the same rate whether they're connected by the timing belt or not, right? (I mean at the instant the belt breaks, of course) As long as they don't hit each other, what possible difference could it make if the belt breaks?

EDIT: Could the pressure of the combustion stroke bend a valve if it's open and it shouldn't be, perhaps?
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'80 924 Turbo

Min · Posted: Tue Sep 15, 2009 3:09 pm Post subject:

fill the pockets in your pistons with years of carbon buildup and presto, interference motor.

Min
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Custom means it didn't come from a box.
1980 n/a with EDIS and Megasquirt II Injection. 7 different colors and counting.

daniel · Joined: 18 Jun 2009 Posts: 686 Location: Sydney, Australia

Im not getting into the debate of if its possible or not, however what difference does it make if the cars being driven or reved in the driveway ?????

...that being said I have always found carbon to be quite soft once the initial layer goes down..... to the point where anymore than 1 or two layers are blowen away by the combustion process...

Daniel
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Over the top of skyline, total brake failure.... hit the wall at over 200 kp/h at the dipper, so anyone who has to brake for the esses is a pussy.
1977.5 Race Car, CAMS Group S Spec
1989 944 Cabriolet

Duncan · Posted: Tue Sep 15, 2009 7:06 pm Post subject:

I used to carry a spare timing belt in my car toolbox