924Board.org

BWW · Joined: 21 Sep 2021 Posts: 58 Location: Idaho, USA

I was setting the timing on the 931 manually to make sure everything was in order. (The car seems like it wants to start but won't keep running.) The pictures show the positioning of the camshaft gear when the flywheel timing mark is visible. As can be seen, they're out of alignment. I know these are interference engines, so I'm concerned about the possibility of internal damage. Would this much misalignment be likely to cause something catastrophic? As always, I'm grateful for the help of the wise people here.

https://isu.box.com/s/2vl9bbz7wtj0oecffzocjmie8t3ijyi8
https://isu.box.com/s/umegx75hzynli4j8e9lq2hm7dwnm9jlm
_________________
Brent
'81 931 project car

Fasteddie313 · Joined: 29 Sep 2013 Posts: 2596 Location: MI

That is wayyy off..
Idk what timing mark you are looking at on the flywheel, but compare your cam time mark to your crank pulley time mark..

If it’s way off from that, then you could have problems..
And we will have investigating to do, like making sure the cam lobes are directly facing up, because that cam pulley can be on backwards, the flywheel can be put on in the wrong position, but the crank will be correct unless it’s key is stripped, you may also be looking at the wrong line on the flywheel..

Sooo..
Confirm your timing marks in multiple ways..
Are you looking at the 0 zero tdc mark on your flywheel?
That looks too far off to even be from looking at the wrong flywheel mark though..

I guess a quick way to check for internal damage would be to pull your valve cover and check your valve lash..
If any are huge, something is probably quite wrong inside..
_________________
80 Turbo - Slightly Modified

BWW · Joined: 21 Sep 2021 Posts: 58 Location: Idaho, USA

Ugh. Okay. I'm not sure what the timing mark is either. I spoke to the guy who rebuilt the engine and he thought the yellow mark on the flywheel was TDC, but he couldn't remember for sure. If you zoom in on the picture, you can see something stamped into it (or written on it?) that looks like maybe 21 or 23. I don't know.

I'm trying to use the crank pulley mark, but for the life of me I can't find the pointer mark. I found this picture on the forum that might have been posted by you, but I'm having a hard time figuring out what angle the picture was taken from.

Thanks for your help and your patience with a newbie to these cars.

https://isu.box.com/s/zzgussonx0mh0r5hh4ij4yu2c8ptcz10
_________________
Brent
'81 931 project car

Fasteddie313 · Joined: 29 Sep 2013 Posts: 2596 Location: MI

That view is down from the top almost looking down the timing belt..

It’s a big ole aluminum nub that sticks out there with a triangle at the end..

I recall the pic but if it was in my post I probably stole it from someone else..
_________________
80 Turbo - Slightly Modified

BWW · Joined: 21 Sep 2021 Posts: 58 Location: Idaho, USA

I still can't seem to find it, but I will keep looking. I must be blind or something. Here's a picture of what I'm looking at if it helps for reference. I did find the timing mark on the crankshaft pulley the other day, but it's not visible now. (It too had been painted yellow for ease of identification.) But the fact that it's not visible even though the camshaft gear indicator shows TDC suggests I might have some issues. One thing I noticed when I compared my picture to the one I posted before is my belt has the notches on the topside. Is this installed incorrectly? In any case, I'm going to have to fret about this for a while. We're going out of town for a few weeks from tomorrow so I won't have time to further investigate until then. It'll be rough.

In case you're wondering what those hoses are, they are coolant lines running to the turbocharger which was taken from a 944.

https://isu.box.com/s/e1gqa4pup0e865gfouvc9bgdkmda4omz
_________________
Brent
'81 931 project car

Fasteddie313 · Joined: 29 Sep 2013 Posts: 2596 Location: MI

Your timing belt is installed smooth side down on the pulleys, with the notches on the outside?

Whaaaaat?

Those notches don’t even look like a 924 timing belt..
_________________
80 Turbo - Slightly Modified

Fasteddie313 · Joined: 29 Sep 2013 Posts: 2596 Location: MI

https://m.youtube.com/shorts/dUTw-cJ3BI4

That is your crank timing mark..

How did that belt Get on your car?
Or is that the belt on your AC compressor?
_________________
80 Turbo - Slightly Modified

Fasteddie313 · Joined: 29 Sep 2013 Posts: 2596 Location: MI

Ok.. You had me for a minute..

The pic in your first post showing the cam pulley, your timing belt is on correct side down..

That last pic you posted must be your ac compressor belt..

It also looks like you still have your timing belt cover on..

Step1: take that timing belt cover off.. Decide later if you want to put it back on or not..

Buy this..
https://www.ebay.com/itm/165374859535?hash=item26811c190f:g:cPsAAOSwtrxiKF1K

#1 first thing to do on a 924 turbo is replace the timing belt IMMEDIATELY!

It will be waiting for you when you get home from your trip, and we will get your new belt and tensioner on there and make sure your cam is timed correctly..

Then we will check your ignition distributor position..

Meantime you can work on getting that cover off..
_________________
80 Turbo - Slightly Modified

BWW · Joined: 21 Sep 2021 Posts: 58 Location: Idaho, USA

I'm back to the land of internet access after a couple of days of travel with camping.

Okay. I will pull off the cover once I get back and see what's what with the timing belt. Sorry for the confusion I caused with the previous pictures. I *think* the belt and tensioner are already new, but I will confirm this with the guy I bought the car from. He's local so he said he'd come and take a look when I got back to town.

Many thanks for the help with this!
_________________
Brent
'81 931 project car

BWW · Joined: 21 Sep 2021 Posts: 58 Location: Idaho, USA

I'm back to the land of internet access after a couple of days of travel with camping.

Okay. I will pull off the cover once I get back and see what's what with the timing belt. Sorry for the confusion I caused with the previous pictures. I *think* the belt and tensioner are already new, but I will confirm this with the guy I bought the car from. He's local so he said he'd come and take a look when I got back to town.

Many thanks for the help with this!
_________________
Brent
'81 931 project car

BWW · Joined: 21 Sep 2021 Posts: 58 Location: Idaho, USA

Sure enough, the timing belt and tensioner are new. So I'm going to have to wait until I get home to further investigate.
_________________
Brent
'81 931 project car

BWW · Joined: 21 Sep 2021 Posts: 58 Location: Idaho, USA

I'm back from the long trip and finally got some time to do some investigating. Got the timing belt cover off, lined up the crankshaft pulley with the mark and found the dot on the outside of the camshaft gear was lined up but the one on the inside was no where to be seen. Also couldn't see anything on the flywheel for some reason. The pictures tell the story.

https://isu.box.com/s/ldygl3m3ucp380g8k2mbrw9lgnkczeit
https://isu.box.com/s/p6taj3vipn2u9z4tmb3dm4spy8t7jfxw
https://isu.box.com/s/stxmx3syzke29v8saouqsgfnozloutcl
https://isu.box.com/s/y93iajth0thlixxr8xv3c2z70xcfsld9
_________________
Brent
'81 931 project car

BWW · Joined: 21 Sep 2021 Posts: 58 Location: Idaho, USA

I don't know if anyone is still following this, but just in case I did some more checking and it looks like the mark on the inside of the camshaft gear is about (exactly) 180 degrees opposite the mark on the outside. So essentially my combustion strokes and my exhaust strokes are reversed. Might explain why it's not starting... On the upside, it also means there shouldn't be any internal damage.
_________________
Brent
'81 931 project car

Fasteddie313 · Joined: 29 Sep 2013 Posts: 2596 Location: MI

Yes, you could have been at TDC on the exhaust stroke..

You want TDC on the compression stroke..
The cam turns at half speed of the crank, so every other time the crank is at tdc it’s either on compression or exhaust stroke..

Turn the engine over again to get that dot to the top of the cam pulley, cam loves for cyl 1 should be facing up (valves closed), and that is where you want to set your ignition distributor to be landing on the contact for the #1 spark plug lead on the cap..

Make sense?
_________________
80 Turbo - Slightly Modified

BWW · Joined: 21 Sep 2021 Posts: 58 Location: Idaho, USA

Sure does. I'm going to reset it all and take it from there. I checked more closely today, and it looks like it's not quite 180 off, but a little less than than (maybe 160 from TDC going clockwise looking from the front of the car). Still seem to be compression and exhaust strokes when cranking the crankshaft pulley by hand, so I'm hopeful there's not internal damage.

Thanks for all the help. I wouldn't have figured this out without your guidance.
_________________
Brent
'81 931 project car