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m8782538 · Joined: 09 Aug 2006 Posts: 41 Location: Wiltshire

I noticed that my cam/ timing belt was a bit on the loose side. I have re-tensioned the pulley and all is ok, apart from it no longer wants to start, when i do eventually get it started it is very very rough and eventually cuts out. Any idea's, Plugs and leads are fine and were fine beforehand. Everything was ok before hand. Not too sure what has gone wrong. HELP.

Lizard · Posted: Tue Nov 28, 2006 6:22 am Post subject:

model and year.
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3 928s,

Chrenan · Joined: 15 Jan 2003 Posts: 3903 Location: Canada

Did you re-tension it so much that you knocked the cam/crank alignment out? Have you checked the marks on the cam sprocket and oil pump pulley at TDC?
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1987 951 - M193 Version for Japan

Ozzie · Posted: Tue Nov 28, 2006 8:18 am Post subject:

Make sure this mark

Lines up at the same time as this mark 'D" in the pic

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Porsche 924 1984 (UK import) NA
Its AUTO and its BLACK
Montego Black on black/red
Engineer of Electro/Mechanical Systems Maintenance

m8782538 · Joined: 09 Aug 2006 Posts: 41 Location: Wiltshire

ok, i'm a novice when i comes to most jobs on cars. Literally all i did was de-tension the cam belt, and re-tension it up as it has about a inch worth of slack which is not good, it now has about 10mm and you can twist it almost 90 degrees which appears right to me. I left the large sproket/ pulley as it was but the timing was not set to TDC ( both white marks aligned) started it up and after turning for about 7 or 8 secs it fired (just), then was very very rough, almost stalled a few times and then after a couple of mins, cut out. I don't know which is the oil pulley but i cannot see any marking on any pulley bar the one at the top (cam). Please re-phase into plain language, im a bit of a muppet at the moment.

m8782538 · Joined: 09 Aug 2006 Posts: 41 Location: Wiltshire

1984 2.0 n/a 924. sorry forgot to add this.

Ozzie · Posted: Tue Nov 28, 2006 10:28 pm Post subject:

Lucky it wasn't a 931 or you'd be looking at replacing valves, head or pistons.
You'll have to remove the belt, rotate the cam pulley and crank till the marks are lined up then refit the belt making sure they stay lined up.
Retension and check the marks.
The NA flywheel has a +10, 0, -10 markings. Line up with 0.
_________________
Porsche 924 1984 (UK import) NA
Its AUTO and its BLACK
Montego Black on black/red
Engineer of Electro/Mechanical Systems Maintenance

m8782538 · Joined: 09 Aug 2006 Posts: 41 Location: Wiltshire

Slight issue. I tried that it would not even turn. I have got it starting (just) but sounds and smells like it is not fireing on all 4 cylinders. All plugs and leads are not very old so i don't suspect that is the issue. When it has started it is very rough and when you actually drive the car there is a servere lack of power and very poor idle.

When i got the car the markings never matched up, plus there is only 1 marking on the wheel, a white mark there are no others.

Chrenan · Joined: 15 Jan 2003 Posts: 3903 Location: Canada

Sounds like your timing has been knocked out of alignment by your belt adjustment. The oil pump has an arrow cast into it which points to a notch (very small) cut into the oil pump pulley (the pulley at the bottom of the timing belt) when the engine is at Top-Dead-Centre (TDC). Turn the big nut on the oil pump pulley with a large socket until the little notch on the oil pump pulley lines up with the arrow on the oil pump. Now, when this lines up, there is also a notch cut into the back of the cam sprocket (the pulley at the top of the timing belt) that will line up with an arrow cat into the cam cover on the top of the engine. If these 2 marks (oil pump pulley and cam sprocket) don't line up with their pointers at the same time, you need to play with your tension or adjust your belt (remove and replace, play with teeth spacing) until they do or your engine will never run correctly.

If your engine is covered in road grime you'll need to clean it first, especially around the oil pump, to see the marks clearly.
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1987 951 - M193 Version for Japan

m8782538 · Joined: 09 Aug 2006 Posts: 41 Location: Wiltshire

Thanks for that Chrenan. Looks like i'll have to invest in a set of axel stands and a trolley jack and get underneath, i have been working from the top of the engine, is it possible to see any of the markings from the top? if not it is going to have to wait, haven't got the money to get a trolley or stands at the mo. May have to clean the bottom end of the engine, the top is done, can of de-greaser and a hose works wonders.

Rasta Monsta · Joined: 12 Jul 2006 Posts: 11733 Location: PacNW

Yeah, sounds like your belt was so loose it skipped a tooth, probably at shutdown. If you look at the photos above, all the timing marks mentioned are visible from up top.
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Toofah King Bad

WeiBe (1987 924S 2.5t) - 931 S3

Chrenan · Joined: 15 Jan 2003 Posts: 3903 Location: Canada

Yes, all marks are visible from the top, no need to get under the car.

Please note that Ozzie's second picture shows flywheel marks on the back side of the engine. They can be used for the same purpose as the oil pump makrkings in matching the cam and crank timing, but his second picture won't match to my description.
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1987 951 - M193 Version for Japan

Ozzie · Posted: Wed Nov 29, 2006 7:06 am Post subject:

With the belt attached rotate the crank (with a socket) until the cam mark lines up.
Remove the belt, rotate the crank til the flywheel mark or the oil pulley mark lines up.
Refit belt.
Note*** the flywheel mark and the oil pulley mark should both line up at the same time unless the flywheel has not been refitted correctly. If they dont, use the oil pulley mark.
_________________
Porsche 924 1984 (UK import) NA
Its AUTO and its BLACK
Montego Black on black/red
Engineer of Electro/Mechanical Systems Maintenance

m8782538 · Joined: 09 Aug 2006 Posts: 41 Location: Wiltshire

Thanks for all the extra info, i am going to try and look at it again today, pulled a muscle in my back during the night, in a bit of pain and doing the work may take a while.

Will update and let you know how it goes.

m8782538 · Joined: 09 Aug 2006 Posts: 41 Location: Wiltshire

I know some of this is going to sound stupid but here it is. I don't have a socket big enough to turn the bottom pulley so that the marks line up. I have found the marking on the back of the top pulley but mine is a small circle, i also have a white mark on the front of the top pulley about a quarter the way around to the left from other backside marking. Plus in the second picture, there are a number of items that are not visable on my car, or are not there at all. D- Timing Mark Window and E-Serial number location. A Tad lost now, but to my understanding is as follows, get the two white marks on the bottom pulley and the two marks on the top pulley to match up, them attatch and tension the belt, all done. Can someone please confirm this for me?