Ohhhh Bugger

sladey · Post by **sladey** » Wed Mar 15, 2006 11:54 pm

Frum users who followed my backdate saga may remember that when I got the car back on the road on January I was concerned about the tappets being noisy - I re-did the tappets twice and even turned the radio up but the noise was still there.

It only goes away when I really give it beans when it's somewhat muffled by the induction roar.

At the week-end I decided to drop into Zentrum - local porsche specialist (looks after Helens cars) for him to confirm it is just noisy tappets and to book the car in. Mike said straight away "sorry mate but that's not tappets". He said the sound was not deep enough for the crank but too deep for tappets.

He said the only way to find out what it was was to drop the engine and start stripping it. His guess was that I'm hearing the start of some piston slap on one cylinder. The sound appears to be only coming from one side of the engine.

I've booked the car in with him for the 10th 11th & 12th April to get it sorted out and wil be waiting with baited breath. In the meantime I've turned the radio up again.

Bleeding cars!

hot66 · Post by **hot66** » Thu Mar 16, 2006 7:34 am

look on the bright side ....you can do some engine / power upgrades at the same time

Viv_Surby · Post by **Viv_Surby** » Thu Mar 16, 2006 8:32 am

He he - yeah prob is you'll end with the 'well as the engine's out I might as well' syndrome

davidppp · Post by **davidppp** » Thu Mar 16, 2006 8:37 am

Wow.

I can honestly say I would not recognise piston slap in a 911..it must be pretty rare..

It will be sensible to make a tactful enquiry about the compressions and leakdowns on each clinder before stripping..

My money would be on valve springs or tappet feet. FWIW..

Kind regards
david

sladey · Post by **sladey** » Thu Mar 16, 2006 9:50 am

The upgrade path has occurred to me, but it'll depend on how bad it is - for example if it needed all new pistons & barrels then I'd definately go for large capacity - taking it to 3.4 - as I understand it this would be more or less a straight swap and the extra cost is about £500. However if it's just one to be replaced I'd go for keeping the bill as low as possible.

On the piston slap thing - he hasn't said it is that for sure - he's just said he's not a betting man but if he were then he'd bet on that. There is a regular tapping noise and it's coming from one side of the engine. I think it sounds worse at some times than others.

He's going to take the engine out and then start stripping from the cam covers in, checking at each stage to see what it could be. If it is valve springs or tappet feet then he should pick this up first

Barry · Post by **Barry** » Thu Mar 16, 2006 1:23 pm

I'm with David on this: make sure you get some 'before' compressions or leakdown results (I'm sure your engine man will do this anyway).

At least then, if they are all perfect, and you've got good, reliable oil pressure, it should keep the diagnoses up near the top of the engine.

Bad luck though, hope you get it sorted O.K.

steve wright · Post by **steve wright** » Thu Mar 16, 2006 1:42 pm

tapping or knocking under load at low rpm is often a sign of worn big end bearings. not something i've seen in a 911 motor but v' common on high mileage vw motors

Dyno Soar · Post by **Dyno Soar** » Thu Mar 16, 2006 6:35 pm

I hate these types of threads... they always sound expensive.

Also it makes me start to do my own sound diagnosis of the state of my own motor. It always sounds expensive.

210bhp · Post by **210bhp** » Thu Mar 16, 2006 9:44 pm

Sladey
Might be worth having a chat with Brendan (BJMullen). He has had what sounds like a similar problem for months. He told me he has done the same adjustments as you but still has the noise. Hasn't stopped him driving it though!
Regards
Mike

davidppp · Post by **davidppp** » Thu Mar 16, 2006 9:55 pm

heloo again.

It would take alot to make me tear down a running 911 engine for a noise..the labour cost is often more than a replacement engine..

Chances are good it is not at all serious, provided the pressures are OK..

This must be your first step, surely?

kind regatrds
david

Derek · Post by **Derek** » Thu Mar 16, 2006 10:18 pm

Agree with what people have said before.

You MUST get a comp & leakage test. This test can diagnose just about all the potential problems.

steve wright · Post by **steve wright** » Fri Mar 17, 2006 8:18 am

except poor oil pressure & bearings going away...

bjmullan · Post by **bjmullan** » Fri Mar 17, 2006 8:46 am

Hi sladey as Mike has already said I have a knock coming from the engine at idle and as you would expect it's worst when cold but once I put a bit of load of it seems to go away. I bought a mechanical stethoscope and tried to find where the noise was coming from without any joy. Therefore I am just going to continue driving and enjoying my car as I think it would be mad to pay to have a engine stripped and you still may not find the problem. I did a lot of reading on Pelican and you noise might even be a exhaust leak! Enjoy that beautiful new car as life is too short.

Derek · Post by **Derek** » Fri Mar 17, 2006 9:12 am

You can check for poor oil pressure without a strip down. And bearings on the way out, you would expect any expert to be able to diagnose that without a strip down.

I'm just saying engine strip is an extreme starting point IMHO.

steve wright · Post by **steve wright** » Fri Mar 17, 2006 10:08 am

agreed Derek - i was just clarifying that a leakdown and compression test won't tell you anything about oil pressure or bearing wear