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[TheBoy]

Kevin Wood had another look last night, with the LPG injector loom removed.  Noise still present 

If you can play it (I can't) noise is:

http://images.omegaowners.com/images/kevin/theboy-engine.flac

Just found some speakers and had a listen.

I might have cloth ears but all I can hear is a slightly wheezy V6 with dry cam followers. No missfire. No noise from steel exhaust manifolds.

If you were a new member I would be asking the usual questions (is there oil in the sump, when was it last changed, do you have oil pressure? have you done anything to stir up crud in the sump?)

My 200,000 mile 2.5 used to sound like that for 10-15 seconds when started in freezing weather so I switched to 5w30 oil and the lifters seemed much happier.

Oil last changed about 1.5k ago.  Oil light goes off quickly.  Oil measuring on dipstick. Can't think of anything that could have done anything in sump.

[Andy H]

Started mine a few minutes ago to move it prior to changing the rear brakes. Had a listen with the bonnet up to remind me what it sounds like from cold.
No lifter noise
A bit of wheezing
Two seconds of piston slap?
10 seconds of shrieking from a belt or idler (all being changed tomorrow)

Kevin's bore wash theory sounds quite convincing to me now but your sound recording does sound to me like a freshly assembled engine before the oil has had a chance to fill the lifters :-/

[TheBoy]

In back of my mind I was beginning to dismiss the borewash theory, as Kevin has found nothing that would cause it in the first place  :-/

But then, the compression had dropped on No1 to 6bar, and back up to 14bar once a teaspoon of oil added to pot, which would point towards borewash, or a very worn engine?


The reason I decided to proceed with LPG on this car was the fact the engine was a peach, despite its 162k, as those who saw the runway stunts at York last autumn will testify. No odd noises, hot or cold.


Short of replacing leads and putting original (and incorrect ) plugs back in, I'm out of ideas completely.

[TheBoy]

The reason I was beginning to think the borewash idea may be wrong is the noise started, iirc, immediately the car was started for the first time, not, say, 5s later.

 :-/  :-/  :-/

[hotel21]

Surely the injectors are firing before the spark ignites?  Would be trying to burn fresh air otherwise......

If injector one is overfuelling/constant running, then would that not lent credence to the borewash theory?

[Kevin Wood]

Surely the injectors are firing before the spark ignites?  Would be trying to burn fresh air otherwise......

If injector one is overfuelling/constant running, then would that not lent credence to the borewash theory?

Yep. However, I have checked the injector signals during cranking without the fuel pump running and they all behave as expected.

Next theory was high fuel pressure. Different manifold, fuel rail, injectors and FPR fitted.

Only other cause I can think of is overfuelling by ECU (but have tried it with MAF disconnected), blocked return line to tank (could we have crushed it?). Maybe I have resolved the issue and it just has dry bores still.

No other ideas at the moment.

Kevin

[Andy H]

Is fuel pressure monitored by the ECU & reported by Tech2?

[TheBoy]

Is fuel pressure monitored by the ECU & reported by Tech2?

No

[cem_devecioglu]

hoping this site will give some idea :-/

http://www.pistonslap.com/

[2woody]

back at home now - got in at 03.30 this morning.

Wednesday : Hexham - Newcastle - Oldham - Bristol
Thursday : Bristol to Kevin's & back
Yesterday : Bristol - Haslemere - Chiswick - Hexham

did London to Newcastle last night in 3 1/2 hours with stops. And didn't exceed 2500 rpm for the entire trip.

Back to the engine :-

Borewash. Don't go with that theory myself. Oil splash, even at idle would replenish the oil on the bores within 10 revolutions or so.

Bore wear. Nope - it'll hold compresion.

Overfuelling. This is possible, but you'd have to overfuel really drastically to constantly wash the bores. To the extent where you end up with a sump-full of fuel. Normally, any malfunction results in no fuel, not too much fuel.

FPR. The "toilet almost fuel" noise is absolutely typical of a FPR when the fuel pump is on. Anyway, a FPR malfunction would affect all cylinders.

Plug or lead. Well, yes it's possible, but I've never seen one make such a noise. Anyway, you can test them in isolation.

Cam follower. Yes, possible

Big end. Yes, possible. Well, actually I'd say very unlikely if I hadn't got a very similar problem in a car of mine. Noise sounded identical. Easy to check for if you put something down the bore and feel for the lost motion over TDC. Go on, just for me 

Cam belt. Yes, possible that a roller could have disintegrated - I've seen this recently, too.

[Kevin Wood]

Well, spent the afternoon on it.

Plugs and leads changed - no difference.
Looked for lost motion at TDC - feels fine to me.
Checked for collapsed lifter - 8 thou feeler gauge won't fit under any of the cam base circles on the noisy bank when closed. Other bank- intake valves visually checked for any obviously faulty lifters.

 :-/

Kevin

[damon80]

I take it you haven't checked to see whether or not the frequency of the knocking increases with revs? (Understandable, given the first instinct would be to knock the engine off!)

It's not something daft like an engine mount coming loose is it?  Yes, nothing to to do with the work you've done on the engine, but maybe a cruel coincidence?

Hopefully it's summut n nowt - fingers crossed for you Jamie 

[feeutfo]

I take it you haven't checked to see whether or not the frequency of the knocking increases with revs? (Understandable, given the first instinct would be to knock the engine off!)

It's not something daft like an engine mount coming loose is it?  Yes, nothing to to do with the work you've done on the engine, but maybe a cruel coincidence?

Hopefully it's summut n nowt - fingers crossed for you Jamie 

noise matches revs, not audible during cranking, noise comes in the momment it fires and is there to the last revolution when turned off. We've ruled out any issues with work done one by one, and moved on to none related coincidences, cant find out wrong with it.

 Although Kev added oil to drivers side bank cylinders and fired it up, quieter for a couple of seconds, just, but noise returned just the same.

We out of ideas....

[Lazydocker]

I take it you haven't checked to see whether or not the frequency of the knocking increases with revs? (Understandable, given the first instinct would be to knock the engine off!)

It's not something daft like an engine mount coming loose is it?  Yes, nothing to to do with the work you've done on the engine, but maybe a cruel coincidence?

Hopefully it's summut n nowt - fingers crossed for you Jamie 

noise matches revs, not audible during cranking, noise comes in the momment it fires and is there to the last revolution when turned off. We've ruled out any issues with work done one by one, and moved on to none related coincidences, cant find out wrong with it.

 Although Kev added oil to drivers side bank cylinders and fired it up, quieter for a couple of seconds, just, but noise returned just the same.

We out of ideas....

An unlikely source of sound but it's not something catching on a pully :-/ :-/ :-/

[edit]Must be because I'm tired... Not there when cranking, so no [/edit]

[Lazydocker]

I assume it's still no 1 cyl which is making all the noise? Just can't think what it could be any more... I was convinced it was borewash, and still think it most likely, but can't come up with a reason for it any more, unless the ecu has been upset :-/ :-/

Have you looked at live injector info with Tech 2?