Porsche Enthusiasts Club Forum

Hello everyone!

I have engine problems, your understanding, help and support is requested...

My 1986 951 has been layed up for a couple of months after developing a horrible clackety sound that originated from the front engine area. The noise would disappear at around 2k only for it to return as revs decreased. Whilst trying to isolate the noise, the engine cut out and would not re-start. I researched the likely suspects and came to the conclusion that I'd had a timing belt and/or balance belt mishap. This was after checking and changing things like the dizzy cap and rotor and the DME as I was encouraged to at the time.

Anyway, this weekend I had some time to get a better look. I've finally removed the top engine cover and expected to see belt carnage. None was evident. In fact it all looked quite... correct, to an untrained eye. Using the timing and balance belt diagrams from Clarks garage, I identified all the belts, pulleys, rollers and tensioners. All appear in good nick and the balance belt appears to be aligned correctly with decent tension. The cambelt however, is slack, by how much I don't know but mainly around the tensioner. This is probably down to the timing belt tensioner which moves around. I'm guessing that it shouldn't move much if it all, definately not like a wooden spoon in porridge as it does now!

So...
If the tensioner was in the middle of a fail, would the original clackety clack noise be a symptom of that failure in progress?
Would a none working tensioner cause the car to stall? (The engine turns over but much faster than normal like nothing's actually engaged)
What's the liklihood of there being head damage? How can I check if this is the case without pulling the head? Plugs have been pulled and all look evenly used. I shone a flashlight (admittedly a poo flashlight) into each of the cylinders and I was able to ascertain there was a piston in each, not much else.
What should my next steps be in regard to diagnosis?

Any help appreciated!!

Cheers,
Rik

Hi Rik, you need to do a compression test as it sounds like you have no compression if the engine spins over faster than it did before. Sounds like the belt has slipped. You need to set the engine to top dead centre on the flywheel and then check to see if the cam mark is lined up, my money would be it won't. I would check the tension of the 2 bolts that hold the tensioner arm onto the body, they will probably be slack. Is the spring missing from the tensioner body?
Alasdair Cowan

Hello & welcome. Sounds from your post that your not familiar with working on your 951. The cam belt isn't rocket science but it's not the easiest to do either so if you don't know what your doing get it checked out by somebody who does! As if your engine isn't goosed already it could very well soon be! I fairly familiar with mine but trust the cam belt to a mechanic friend who does them every week. If he gets it wrong I get a new engine! Takes about half an hour which is £25. New engine = £££££'s (A new belt is less than £10!!)
Hope it's just jumped a tooth & isn't damaged.

I hope it doesn't sound like a sewing machine as a number of Pug GTi-6s do (their cambelt makes a 944 look likes child's play):
as that will mean the damange is too badly done to the head meaning it will require refurbishing.

I had a similar noise noise (in terms of revs) on my first engine, but that was more of a knock than a ticking, but the noise did die down after 3.5krpm.

Sounds like the belt is loose and the crank is turning without the cam.

Turn the crank over by hand - 24mm socket on the front pulley see if the cam pulley turns - check the mark on the cam pulley lines up with TDC.

Sounds like you have valve damage I'm afraid.

Rich

Gents,

Thanks for the responses ...

I'll try checking the timing this weekend and possibly do a compression test depending how it all goes. It has the eccentric bolt tensioner which doesn't have a spring, or does it? But regardless of type it's not right!

And it was making a similar noise to to the one in that vid (not the 205 although the sight of it brought back happy memories) What was the diagnosis of the 944 engine noise?

Whatever I discover, I suspect I'm heading for a head job!

Wish me luck!

Rik

You'd rather not know about what was wrong with my S2 TBH! All I will say is that a new engine cured the problem. The other solution was not so cheap (read getting the bore re silicated, or steel linered with new pistons...)

Basically, the engine had suffered from a seized piston in the no.2 bore. As a result, the score marks on the bore were pretty awful (as Kevin put it, it looked like a Tiger was trying the escape when he put an Endoscope on the bore and the damage was there for all to see). Initially, it didn't sound quite as bad but the more I drove the car (I drove it for 3k like that), the knocking did gradually get a little worse (That clip being the last time I drove the car with that engine in it). Kevin put it down to the engine being seriously overheated, and PCT also agreed with the diagnosis (they thought it was piston related when the parts man heard it, with my local garage thinking it was a little end gone), or that the car had seen very little use (before I bought it, the car hadn't been used for almost a year going off the MOTs, maybe it was why the car went off the road).

However, I think 951 blocks may go cheaper than S2 blocks (damn these vultures of Turbo owners wanting 3.2 power ), although as Barry at Hartech showed, maybe you could upgrade to 3.2 power a little more cost effectively than you anticipated.

Not sure where in the country you are but JM garage Bournmouth would be the guys to ask. Give John a ring & see if he has a turbo lump kicking around that you could put in for real world money. Rebuild it your looking at 5K. If your not too far away get it trailered over for a diagnosis. If you spend 1K+ on the head & new tappets. (£50 each) & it still knocks your nowhere.

That is the quote that Kevin from EMC gave me for an engine rebuild. I think he said the rebore/sleeving took around £1k of that.

They changed my engine for pretty reasonable money. Whilst I was there I got them to change the clutch, and set the cam timing up on the cams (he does the latter regardless when a cambelt change is done) whilst the cambelts and tensioners were changed.

If it wasn't for the clutch (which came to nearly £500 alone) the final bill would have been much less, but it was still done for reasonable money all things considered.

I think Porsche introduced the spring belt tensioner in 1986 so you could have either of them. It doesn't matter though if the belt is loose. I'd check the timing marks first, without cranking the engine over! If the belt is loose the belt could have jumped a tooth. If the valve and spark is slightly behind the pistons it's bound to be a bit clattery. Past that maybe a failed tappet, but that probably wouldn't stop it running.

Hi All,

FourtyFourSuperTwo - I should have realised your vid was for an S2 from your name and avatar pic, Doh! Should have kept my S2 and got the sills sorted but I got seduced by boost! Bet that S2 engine is still going strong somewhere.

JJ - I'm based on the Fylde coast so Bournemouth would be a bit of a trek although if the Porka was driveable I'd probably give it a go! I really cannot stretch to a full rebuild at the moment but a second hand lump could be possible should I need it which I hopefully wouldn't but then perhaps it would be worthwhile whilst everything is in bits.

Anyway...

I didn't get chance to do anything over the weekend but I did check the invoice from the last works carried out (by a reputable NW specialist) and it clearly shows the front of the engine was stripped to rectify an incorrectly tensioned balance belt and to correctly set the rest of the timing belt and tensioners etc. So I've mailed them and they want to investigate so I'll be checking my insurance policy for recovery cover to hopefully get it towed to the garage. I don't know why this didn't occur to me sooner but it sort of demostartes my fuzzy thinking throughout this er... 'sad' time.

Finally, is it be because I'm not a fullly fledged member that my posts need to be authorised by a moderator or is that the same for everyone? I do intend on becoming a member and joining in with the 944 community fun but with the fate of the 951 in the balance I'm gonna wait. I'd be a sad member in so many respects if I joined without a Porsche! Hopefully it's fixable within my budget and I can offer some of my experiences back into the mix, support TIPEC and get more positives from 951 ownership (which is very different indeed from my 4 years trouble free 944 S2 ownership experience!)

I'll update with progress soon!

Thanks everyone

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