Please help a worried (or should that be worrying? ) mind

Left my '91 S4 Auto at a friend's place over the weekend. Car was running fine when I arrived. Came back to it on Sunday evening, turned the key and it turned over for a second or so then stopped cranking/siezed with a 'clunk'.

"Uh-oh" I thought, but since I was miles from home and short of other options I tried firing it up again.. and the engine turned over (a bit slowly) but then started OK. Drove home, everything sounded/felt fine. Once I was on my driveway, I tried stopping it and starting it again when hot. Cranked nice and fast as normal, started no problem.

Could it be something as simple as a weak battery? Or something more... sinister..

Am I right that slow-to-crank/hard-to-turnover symptoms of the dreaded TBF tend to manifest themselves when engine hot rather than from cold? As I say, engine has never stalled and cranks/runs fine when hot. Apologies if I'm sounding highly paranoid, but I've read enough threads on here that I'll worry it's TBF even for a problem with the wipers and the way it 'clunked' had me worried.

 

Well, obviously it runs, so that's good.

If it were my car, just to be sure, I would pull the passenger timing belt cover and then inspect the entire belt to be sure everything looks okay. I'd also check to make sure everything is still line up properly.

If this all checks out, I would drop the lower bell-housing cover and check to see how much pre-load there is on the flex plate.

If these both check out, I'd call it good and drive the car (asuming there were no other deleterious signs of anything else being wrong).

Let me know if you needs links to write ups...

 

sounds like its time for some inspections and maintenance
Andrew s ideas are good to follow.
After that i would also clean all of the grounds.
Start at the battery .
then the hot post and 14 pin connector above it .
Then the CE panel and the grounds above it.
Also inspect the fuses and the relays for correct position and ratings.
fuse chart here www.928gt.com on page 2 under tips and links, print one off to keep in the car

 

Timing belt problems rarely heal themselves, so I would do the flexplate inspection first, and would definitely check the end play on the crankshaft. While I was doing that, I would also inspect the starter carefully for looseness and wear.

 

Thanks very much for the replies - looks like I am going to get the flexplate & cambelt checked then! :|

I don't have the space or facilities to jack my car up and get underneath it at the moment so have booked it in with specialist tomorrow AM. Actually it's the same guys who rebuilt my torque tube and checked flex plate when I bought the car back in March (he was aware of this issue as he'd seen a TBF case before).

I'm hoping it hasn't suddenly decided to ruin an otherwise great relationship

 

I'm betting on grounds, could be a relay.
TBF isn't usu associated with a cold start. When they checked the flex plate last Spring what did they find?

 

Update:

Timing belt (and timing) checked and was OK. Likewise, flex plate had practically no (under 0.5mm) pressure when released. Took the opportunity to get PKlamp on there WYAIT

Anyway, suggestion was that it could have been the starter motor siezing/jumping (to make that "clunk" that scared me) but it seems to have been well-behaved since.. *shrugs*

However I am going to check the earthing points as suggested.. and also the state of the battery as I've no of its age/condition. Presume the "CE Panel" that Mrmerlin refers to, is the main fuse board i.e. under the plank of wood in the pax footwell?

 

CE panel is under the dash /wood board.
I would remove the starter relay and open it , Inspect and clean the internal contacts and smell it for burning..
If it smells burned then it might be wise to either swap it with the horn relay or replace it.

If this relay has a bad contact inside or has seen a lot of long time cranking its quite possible that the relay has melted and this will make it shut off once in a while if not fail all together