1997 GT turbo Punto so an old 1,372cc 8v OHC motor 163,000 mile fairly stock no wild tuning.
well looked after regularly serviced no expense spared.
Earlier this year...........
new cylinder head
new turbo
manifold uncracked
all new gaskets
new downpipe
no dashboard warning lights on and no blink test fault codes stored
new cam carrier and cam
new timing belt and tensioner
compression is still strong
timing bang on
the 3 engine mounts are all new - checked no splits.
no components are touching the chassis anywhere - ive crawled all over the car and nothing is rubbing or rattling against the subframe or body etc.

just cannot trace a roughness to the motor which rises with revs. the roughness generates the noise at higher speeds so it become less rough but more noisy (if that makes any sense)

Ive run the car both hot and from stone cold without the aux drive belt for the water pump, PAS pump and alternator briefly and even at a stationery idle the roughness is still there. At idle its more of a vibration and while the gear stick doesnt vibrate the steering wheel does. cant feel any of this via any of the pedals.
when on a hot idle the vibration can appear randomly and then chime in and chime out. the vibration can resemble a serious engine mounting failure noise but I swear its not those.

I have just 3 remaining theories;-
1. the oil pump aux shaft bushes are worn (cannot feel any looseness on the pully) but its apparently very rare on these old Lampredi engines for the bushes to wear out.
2. the turbo engine is now coming to the end of its life at 163k and its maybe got piston slap - when cold it is possible to rock the piston crowns back and forth (so radiator to bulkhead and back direction) enough to get a knock sound but I have power aplenty, the engine runs fine and it doesnt burn oil or overheat
3. On doing a compression test I was getting a really high pitched screeching from the spark plug holes not sure if its all 4 cylinders or just 1 but it doesnt sound healthy. Screeching is inaudible when the engine is running (unless that screeching is whats giving me the noise but in a different lower pitch inside a sealed engine - would it cause vibration though?)

What do the fiat experts make of that lot!?

I have ruled out the gearbox and clutch etc. its not drive train.

I could drive it till it dies but the driving experience is spoiled by this. Had it for years and its never gone away and never got any worse but its not right.

This sort of thing can be most frustrating. It took me the best part of two years to find a rattle in my old SEAT which was only heard when on the move under moderate to hard acceleration. (And I'm supposed to be a mechanic!) It turned out to be a captive nut, hidden behind the battery, for the intercooler pipe which had worked loose in the inner wing but not on the pipe itself!

I suspect that trying to diagnose this from a distance, especially as you seem to be a " technically competent" person yourself and seem to have looked at everything already, is doomed to failure. Where are you based? If a "technically competent" forum member lives anywhere near you perhaps they could help by having a listen? (On the basis that two heads are often better than one?)

at least you replied.

the number of threads Ive seen where people are quick to moan that enough info has not been provided then you provide loads of info for a forum full of enthusiasts and you get............. one reply.

hey ho.

dukeboys said:

at least you replied.

the number of threads Ive seen where people are quick to moan that enough info has not been provided then you provide loads of info for a forum full of enthusiasts and you get............. one reply.

hey ho.

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Aye, well, there's a very true saying I learned many years ago which is :- Life's a bitch and then you die!

Anywhere near me here in Edinburgh? I'd be happy to have a listen and tell you I haven't a clue what's causing it!

Regards
Jock

have you tried leakdown test or camera down bores?

Hi would you say it was a knocking noise?
You say there is movement back and forth?
Also did you carry out the replacement of cylinder head yourself if so was there any scoring of the bores?
Sounds a strange one tbh but I'm knew to this forum bit ill try be of some help just keep us posted