200TDI compression

IIRC it should be 19.5:1

Take care Pantelis

Correct that's the ratio, but I'm looking for a figure for the actual pressure as measured.

Niamh.

Don't you start with atmospheric pressure and work it out using the ratio above?

I am not sure, but I think you should be looking for considerably more than the compression ratio, as the air will heat during compression, increasing pressure further.

Pieter

snipped-for-privacy@otenet.gr

I cant put my hands on the figure just now, but ith the readings are pretty much all the same that is definateky a Good Thing

Richard

Should be somewhere in mid 20's

OK, so the even 16 bar is about a third down... any thoughts as to the possible cause on what is supposed to be a newly reconned engine?

Niamh.

All the usual suspects. Valve seats, piston rings (was the test done dry), wrong head gasket (too much volume). Is the guage accurate? 16 bar is only

With them all being low, could it be that the wrong head gasket has been fitted? There might not be that much difference in the thinknesses, but LR do make a point of saying that the correct one should be used. That last little bit of could make quite a difference - some sums would be needed to work this out..... The other thing would be to try a second guage - I'm a little suspicious of all four cylinders being low by the same amount, that would be unusual.

Richard

The variation from a 2 hole down to a 1hole gasket wouldn't make that much difference, as to the rest they *shouldn't* be a problem if the recon was done properly.

One assumes so, it's new; and the engine doesn't start and is gutless.

Niamh.

Umm.. your right. Done the sums now. 1 hole out only drops 0.35:1 CR

If it doesn't start what makes you think it's gutless? How much of the engine is reconditioned? Have you checked the timing? What are the tappet clearances? Something's very wrong somewhere ;(

Easystart gets it going

It's supposed to be a full recon, done for the previous owner who sold the vehicle to us as soon as the work was completed.

We'd expect lots of exhaust smoke if the valve timing was out

Not actually measured yet, but there is some.

Very, or something very stupid and silly, however the next stage of diagnostics is going to involve significant disassembly I think :(

Niamh.

Sounds suspicous? If I'd just had a recon motor I'd want my monies worth.

Good enough really

Well ah, head off first I'd say ?

take off "ospam" to mail me

His work circumstances changed and he was no longer running up & down the M4; the sale was genuine, we've known the guy for a few years, and he's going to chase up the garage who did the removal & refitting who they sent the engine to for the recon.

We're of the same mind.

Niamh.

Steady on, I agree with Richard, if all cylinders are within 10% of each other then they are either all equally worn or its something else. I have never played with a tdi engine, is there any easy way of putting a wee drop of 20/50 oil on the bores and then quickly retesting, hypodermic? If there is a dramatic increase in pressure this normally indicates a ring sealing problem.

AJH

We squirted some oil down the glow plug holes and retested, an marginal increase to 17 bar.

Niamh.

It we could have found a gauge to borrow we wouldn't have gone out and bought one. I agree that the consistency across all 4 is a further puzzle.

Niamh.

Of course the fact that it needs a squirt of easystart in the air intake to start suggests that the compression reading might well be right.

Niamh.

Do that for long and the detonation will soon round off the lands of the piston and ring edges, that's how engines get "addicted" to the stuff.

I think you were right to ask for comparative compression pressures, in the absence of knowing what any other 200 tdi gets it's hard to judge. The thing is a quick pv=rt calculation will be too low and the adiabatic equivalent pv^gamma will be too high as we don't know the losses when cold cranking.

The fact that the pressure only increased marginally when the oil sealed the bores normally means looking at valve sealing or head gasket problems.

OTOH if the pressures are average then it's likely to be valve or injection timing, or injectors themselves.

AJH