924Board.org

rockhound72 · Posted: Mon Apr 28, 2014 12:44 am Post subject: serious 924 engine issue

My original alternator finally died and I replaced it, but it is still having a difficult time starting. Unless I keep it above 1100 rpm it will die, but the whole engine sputters and shakes sounding like a Harley Davidson. I figured the timing may be off, but it isn't a one person job when you have to keep on the gas. I know it isn't off that much. Anyway this last time smoke came from the manifold somewhere and it smelled like coolant. Now I'm concerned. Been working on this little '79 for a while. Do you think the engine has finally died? Any ideas? I also replaced the coil just in case.

jason c · Joined: 13 Jan 2014 Posts: 1018 Location: Nwi

When did this problem start, before or after the alternator?
Did you leave something loose when changing the alternator?
If you think you have a head gasket problem.....
Start it when its cold & let it run for 30 seconds, open the coolant reservoir cap and listen for pressure. Pressure in the system that fast indicates a blown head gasket.

Pull the plugs (look at color, wetness & condition), check mechanical timing and do a compression test.
If all checked out....
Check condition of wires, rotor & cap.

Then start looking at vacuum leaks and fuel system

rockhound72 · Posted: Mon Apr 28, 2014 2:59 am Post subject: before the alternator

I was driving it home when it all started. It would shutter and it i let it idle , it would die. After $150 tow, I took off the alternator cause it wouldn't hold a charge. It was totally fried. Even after replacing the alternator, it kept doing this. Two of the small white vacuum lines were broken and I patched them up too. Could my vacuum sensor be messed up too? Kinda sucks not having engine codes. I don't have a ton of stuff here to work on it as far as testing things go. Don't think the head would have blown.

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

Step one of CIS diag is testing system and control pressures, and step two is testing for and correcting any vacuum leaks.
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WeiBe (1987 924S 2.5t) - 931 S3

jason c · Joined: 13 Jan 2014 Posts: 1018 Location: Nwi

You need to test for a drain to fix the battery Dying issue.
I somehow read your post thinking you were implying a head gasket issue. Anyway, I would still do the checks I posted just so you know where you're at and can rule those things out. Just start with the basics.

rockhound72 · Posted: Mon Apr 28, 2014 1:04 pm Post subject: Update.....

Bee doing a little research. The sound is JUST LIKE a blown EGR, but I can't find the dang thing! The closest thing is about 2" diameter with one white vacuum line on top and screw mounted on the bottom with an adjusting screw. Also, the intake boots AND the intake had some oil in them. NOW i'm getting more concerned. The EGR part # is 93011017300, but having a hard time finding it. This car came from Germany originally and everything on it is in German.

jason c · Joined: 13 Jan 2014 Posts: 1018 Location: Nwi

The Exhaust Gas Recirculation valve is attached to the bottom of the intake manifold. It has a line linking it to the exhaust.
Happy hunting.

larchie · Joined: 19 Jun 2003 Posts: 297

emoore924 · Joined: 13 Apr 2004 Posts: 2822

I have what appears to be a working EGR in my hand right now. PM if you're interested...

rockhound72 · Posted: Tue Apr 29, 2014 9:31 am Post subject: for viewing pleasure

I figured a better way to show my issue. Go to youtube.com and look for 1979 Porsche 924 and the first thing will be my engine bay. I posted te video on there so anyone can actually see what's going on. I figure one of you will see it and go HEY, I KNOW THAT SOUND. First, it sounds like my starter is dying too, but just watch the video and see.

Fasteddie313 · Joined: 29 Sep 2013 Posts: 2595 Location: MI

wild ass crazy guess butt...

sometimes spark plugs fail and leak compression, may sound like that whistle/squeak in the video.

I've scene plugs blow the ceramic right out of the threaded steel part.

they make millions of them, some are bound to mess up.
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80 Turbo - Slightly Modified

sciroccosteve · Joined: 16 Apr 2012 Posts: 215 Location: Rochester, NY

My car did something similar. I finally worked up the courage to trace all my wiring/grounds(several bad cracks in wires), replace all vaccuum lines and ensure that they were going to right places(they were not...i didnt even have a vacuum canister!)

AND I also did the timing belt.

long story short: everytime I thought I was timing the car using cam/distributor I was not as the crank wasnt in perfect time.

Now my car starts every time. runs absolutly mint every time, and is as reliable as a 1979 german car can be.
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1979 924
2000 V6 Passat
"Let the fools have their tar tar sauce."
C. Montgomery Burns

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

Compression/leakdown test. Does not sound right when cranking, and once it fires it sounds like it has a burned valve.
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Toofah King Bad

WeiBe (1987 924S 2.5t) - 931 S3

musicalannette · Joined: 21 Feb 2012 Posts: 413 Location: UK

doublecheck your plug leads are ok and are on in the right sequence. sounds and looks very like that, you either have a leaky injector or the timing is not quite right as when you cranck at first the engine hesitiates, this m,ight be due to plug leads being on in the wrong sequence.

if you have moved or touched any ignition, double check that too. rotor arm is on ok, distributor cap. dont move the timing if you have not moved the distributor.

if you are unsure still or want to check what is going on and which cylinders are doing something, pull 1 ht lead at a time off the distributor(it is easier on the 924 to do it at the dizzy than at the plug).

so trythis

1 crank the car get it running.
2 stop the engine.
3 pull off 1 ht lead at the dizzy.
4 crank the engine try to get it running and note is it the same or worse?
(this will tell you what cylinders are doing something or doing nothing)
if its the same then that cylinder is doing nothing,
but if it is worse or now wont start, then that cylinder is making the engine run and is probably ok for now.

5 put the plug lead back and repeat steps 1 to 4 for the next lead.

at the end you will probably have 2 leads doing something (actually stopping the engine from running) and 2 leads not doing something (making no difference). i am guessing the 2 leads not doing something need to be swapped.

hope this helps

if it does not, then check compression on each cylinder, if thats ok then check the fuel is getting into each cylinder.

engines need, fuel/air, compression and iginition. those 3 are whats not right. it should be that simple

good luck.
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I KNEW white wall tyres were invented by Americans .....just not at Boeing.... to be fitted on the 737.....

musicalannette · Joined: 21 Feb 2012 Posts: 413 Location: UK

vacume leaks tend to make the idle bad but at 2000 rpm the engine will be fine. so unless its an almighty leak i dont think its that. a leak that bad and the engine probably would not run at all.

hope this helps

utube tastic.
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I KNEW white wall tyres were invented by Americans .....just not at Boeing.... to be fitted on the 737.....