924Board.org

[MikeDanger]

DAMN!
How could this happen?:
I start the car Seems to run fine, slight missing at idle, but ok. spin it around a parking lot everything seems fine. Ok take it out on the road pulls good on boost.
Then at a stop light about 6 miles later
the car dies, it doesnt just quit, the rpms start to dropand about 3 seconds later it dies.
No sure what happened so i tried to crank it, i hear cranking but it sounds differnt, sounds high pitched. So i get the car towed.

Open the hood everything seems fine, try to crank it and the belts/cam shaft arent turning.
I cant figure it out. I have and assistant look while i crank and and he says the crank bolt is SPINNING!!
How could that be?? I could see the timing belt breaking but this??

So assuming that the crank is spinning, did i dammage and valves? I didnt hear anything.
This is an 80 turbo
How can i check if ther are any bent valves(relatively easily)?

One thing i did notice is that the pas few times i ran the car(but only drove it around the parking lot) the oil ligh would come on, at idle and dim as the rpms rose) there was plenty of oil in the engine)

This sucks.

Mike

[Paul]

Ouch! I feel your pain.

If the crank is turning and the camshaft isn't, you most likely have bent valves.

Sounds as if someone installed your crank pulley and drive gear without a key. Or if the lower pulley is turning, more than likely your belt has lost its teeth at the crank drive gear.

To test for bent valves remove the plugs and one at a time bring each piston up to top dead center, insert a air hose and listen for for air leaking at the exhaust, air cleaner, and oil cap.

Or you can check valve clearances, bent ones usually have lots of extra clearance.

[Joes924]

Is this 80 a intefernce motor,79 and below are not I dont think yours is either if so though then you prob.bend valves.I did I tore the teeth off cam belts before its because they were tightend down to much your supposed to be able to twist the belt when its tightend its prob. just the belt. You need to know if its a interference or noninterference that means the valves get in the way of the pistons if they are not moved via the cam belt..This equals benmt valves
if this happend youd know it I think because it would come to a sudden crunching stop..

_________________
JoeD. 1979 924NA
MSD6 rev control/big bore TB/P&P.head
Bursche header/Schneider cam/dialcam


[ This Message was edited by: Joes924 on 2002-08-26 11:38 ]

[MikeDanger]

The belt still has its teeth, the gear is not turning, only the bolt.
But howcould someone NOT put the pin in?
Although the pin is hollow and kind small,
But either way it worked just fine before.

I didnt hear any noise when it died, and when i cranked it since then.

Im not sure if this is an interference or not, but im thinking, this is an 80 with 7.5:1 cr and the turbo has the rescesed head, so i guess its possible.

But how do i line up the crank shaft now?
Is it still turning the oil pump?

Could that pin have sheared?

Now what do I do?

And how do i check to see what position the crank and cam shaft are in to check for compresion?

[Rick MacLaren]

Ok...this is very wierd.

You said: "One thing i did notice is that the pas few times i ran the car(but only drove it around the parking lot) the oil light would come on, at idle and dim as the rpms rose) there was plenty of oil in the engine)"

The oil light is the scariest symptom, IMHO. Bent valves can be replaced. Just pray it's not the bottom end.

It's suspicious that the RPM's dropped slowly and then died. That doesn't sound like a valve to me. Sounds like oil.

Despite having lots of oil in the car, the system can still get deprived of oil.

You know, I've seen crank pully bolts not torqued properly...and come out. Have you heard any loud BANG noises under the hood lately? As if a bolt is hitting metal?

This totally sucks. Good luck with it.

[MikeDanger]

No i didnt hear any noise, but then i was having to jam the tranny in gear with a bit of grinding.

I just read in the FAQ on the site, that the oil light comming on at idle and goining away when you hit the gas is ok.

Although the engine was running pretty hot almost to teh red when it quit because as i found the hose coming from the water pump was leaking. But i dont think that had to much to do with it.

The bolt didnt come out, but evne it if loosened it still supposed to have the pin right?

But so what do i do now? Take the crank bolt out and will the crank pulley come off with it?

Its kinda hard to time the cam shaft without knowing what position the crank is in.

Mike

[Smoothie]

You should find a small opening at the rear left top side of the engine to view timing marks on the flywheel. You might need 2 people - one to turn the crank from the front and one to watch for the timing mark at the back.

The pulley comes off when that bolt is removed. Yes, there should be a pin in there - I'm guessing in two pieces at this time.

[Rick MacLaren]

Well there's room for optimism. If the car didn't make a lot of banging, maybe it's not a busted anything! Very strange though. Can't offer up more than Smoothie here...

[MikeDanger]

stupid question: is there any position the cam shaft can be in where all the valves would be closed or near closed?
and if i did bend some valves how loud woudl it have been? AND would i hear anything as i crank the car afterwards?

Mike

[fielderd]

not really, if you want all your valves closed then loosen cam shaft holders.

[Joes924]

Just grab the nut on the cam gear and turn it overstanding on passenger side turn towards grivers side up and over to keep the nut tight..You dont have a interference motor Is my guess.

[Paul]

I hate to be the bearer of bad news, but all 931 stock motors I have worked on have been interference motors.

My guess is that the motor in its last minutes of life slipped timing to the point that it stumbled then bent valves and stopped.

At idle there is no bang, it just stops.

At this point, don't worry about lining up anything, just do one of the 2 procedures I mentioned in my post last night.



[ This Message was edited by: Paul on 2002-08-27 08:29 ]

[Joes924]

OOps I own a 924 na sorry messed up .. your valves are prob. toast..I bet its tough to get bent valves thru the guides..No on 2nd thought they prob bend inbetween the face and where they go into the guides somewhere..
easy fix if you know how.

[numbers]

yep, all 931 motors are interference motors. That doesn't mean your valves are bent. If you were lucky, maybe your engine stopped before you crashed valves. Anyway, having a head done is not all that expensive, it is just the cost of the valves that may be a problem. Pull that crank pulley and find out why it is not turning. Then, you can go from there.

[Lizard]

he has cranked his engine over though numbers and it did a few rotations if his valves werent bent his engine would stop turning as the starter wouldn't have enough power to bend a valve or push it out of the way. hate to be the bearer of the bad news but a couple of valves are fried. Sorry