924Board.org

[Krgracing]

I'm new here but had my 924 about 6 months, it is giving me grief when trying to start. I've had the starter motor rebuilt by an auto electrician, also checked the alternator and replaced the battery.
Recently I've added all the earth strap upgrades and taken it to another auto electrician for a second opinion.
It appears the timing is over advancing on start up and the starter motor comes to a halt mid crank. After trying two or three times it will eventually crank normally and start.
I just replaced the dist cap and rotor and backed the timing off but this has made little improvement. Just ordered a Hayes manual too but in the meantime has anyone had a similar problem ? Any ideas?
Thanks.
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80' 924 auto
86' 944 man
94' 968 man
Current car is an 82' 924 man

[Ozzie]

I'd double check the valve timing
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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

[dpw928]

Also, make sure you don't have an injector leaking which is causing a hydrolock on one cylinder.

Dennis
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81 931 5 sp
78 928 5 sp Silver
78 928 AT Euro Black

[Ozzie]

Hydrolock is definitely a possibility.
check for coolant loss and check oil for fuel contamination.
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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

[sciroccosteve]

[Rasta Monsta]

Put it on TDC per flywheel mark, then check the mark on the cam sprocket against the pointer on the valve cover. If no mark on the cam gear, rotate the crank 360 degrees and look again (you can also look at the distributor to eliminate this step, but I HATE removing my dizzy cap).

If still unconvinced, you can pop the valve cover. . .if #1 is at TDC, #4 should be at overlap.
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Toofah King Bad

• WeiBe (1987 924S 2.5t) - 931 S3

[sciroccosteve]

[Raceboy]

It is one of the most frequent problems of 924: worn out starter motor bushings that cause the starter motor to halt during cranking. It is usually ok when engine is cold, but when the engine is hot, the starter stalls.
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'83 924 2.6 16v Turbo, 470hp
'67 911 2.4S hotrod
'90 944 S2 Cabriolet
'78 924 Carrera GT replica
'84 928 S, sold
'91 944 S2, sold
'82 924S/931 "Gulf", sold
'84 924, turbocharged, sold.
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[sciroccosteve]

[musicalannette]

It sounds from the advice that it is probably not timing thats at fault, but to be sure I would double check with a timing light when you try to start it.
It will let you know when your spark is actually firing, it will advance when you rev the engine, but to remember you have set the engine timing with the vacume advance hose disconnected (assumng you can get is started).

Whatever happens the timing should not "move" around when the engine is at a constant speed. If you can get the engine spinning freely on the starter or ticking over it should be pretty constant. If you can get it to spin or tickover then its worth a check, it will advance as rpm increases, it will advance more if the vacume advance is connected and it will advance quickly when you rev it if the vacume is connected.

All the engine timing is carried out in the dizzy IIRC, here are bob weight which give a general timing profile. perhaps a bit more retard on the dizzy to see if goes away might be a cheap shot in the dark. i would retard until it wont start, you can always turn it back. cost you nothing to try it .

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

[Krgracing]

Thanks heaps to everyone who responded!
Hydra lock is something I hadnt considered and I will double check the timing too. If the car has points I've read they may need adjusting and can cause poor starting.

I think the starter motor is to blame and I'm glad to hear its a common thing with 924's, from searching the net the starter motor never gets a mention just bad earths, and points to electronic ignition.

When did 924's go from points ignition to electronic ? I've pulled and replaced the cap and rotor but couldn't get any further. Workshop manual arrives today hopefully.

Thanks again
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80' 924 auto
86' 944 man
94' 968 man
Current car is an 82' 924 man

[Krgracing]

Just to conclude this thread.

The reason for the poor cranking and starter motor issues was the initial ignition timing was too far advanced. Every time I retarded the timing the engine would struggle to idle but what the mechanic did was play with the air / fuel mixture screw near the throttle body. This bought the idle up and leaned the mix off.

At the ideal position between too rich and too lean the mechanic advised I go half way betweeen counting the number of turns made. The central position resulted in an idle speed of 1600 rpm so unfortunatly I had to further richen the mix until the idle was around 1000 rpm.

Runs good now and starts !
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80' 924 auto
86' 944 man
94' 968 man
Current car is an 82' 924 man

[staticsan]

On the throttle body? That's the idle screw. The mixture screw is down a hole in the top of the air-mass meter assembly.

Wade.
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'82 British NA - Which I think I've been very lucky with!

[RC]

Yep, or you`ve got a vacuum leak, or some DH has screwed with the butterefly stop screw thinking it is idle adjustment.

Would also check the dizzy centrifugal advance and the total advance myself, not pay a mechanic (even a Porsche one ) who appears to be guessing.
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World`s quickest 924 2L slushbox

[Ozzie]

if the springs in the centrifugal advance are shot or missing it can cause lots of problems too.
_________________
Porsche 924 1984 (UK import) NA
Its AUTO and its BLACK
Montego Black on black/red
Engineer of Electro/Mechanical Systems Maintenance