4722 replies to this topic

[Nev]

Hmm, I've just had a thought, maybe the level of boost is the same as before, but my gauge had a leak thus meaning it indicated less than the engine was making. Now that I've had a good fiddle about with all the pipes, maybe the gauge is now reading correctly. This might explain why the last dyno thought I was making 2 bar of boost yet the gauge only showed 1.4 Bar... However, this would disagree with the the original dyno metrics that Courtenays gave me on a print out, which showed 2.4 bar of MAP. God knows, I guess next time I drive I better keep an eye on the lamda wideband output.

Edited by Nev, 03 May 2013 - 09:44 PM.

[Arno]

Perhaps cross-check/correlate the gauge value with the MAP reading from the OBD port? Would at least give you an idea if they are generally giving the same output or are wildly different. Bye, Arno.

[steveboyslim]

Hmm, I've just had a thought, maybe the level of boost is the same as before, but my gauge had a leak thus meaning it indicated less than the engine was making. Now that I've had a good fiddle about with all the pipes, maybe the gauge is now reading correctly. This might explain why the last dyno thought I was making 2 bar of boost yet the gauge only showed 1.4 Bar... However, this would disagree with the the original dyno metrics that Courtenays gave me on a print out, which showed 2.4 bar of MAP. God knows, I guess next time I drive I better keep an eye on the lamda wideband output.

 

Where is the boost gauge plumbed into the engine ?

 

Steve

[Nev]

Well, thanks to Alex (Ormes) coming round this afternoon the whole engine and gearbox is out and sitting on the floor waiting for me to strip off the ancillaries and gearbox and then open it up for a bore and piston inspection. Many thanks again to Alex, let me know if/when/how I can reciprocate Amazingly the whole operation took only 5 hours.

Edited by Nev, 12 May 2013 - 04:38 PM.

[Ormes]

No worries Nev, glad I could help

[Nev]

Well the engine is now stripped down of it's ancillaries in anticipation of Saturday when I'll drive it up to Steve Miltons for diagnostics. Steve has 86.5mm and 87mm forged pistons in stock and can machine the cylinders if necessary. Hopefully the reason for the low compression will be evident or else I will be in a quandary ! I had a quick look at the exhaust ports on the manifold and they were rather oily/sooty. Also had a look at the valve tops which didn't appear oily, so maybe the valve stem seals are fine. My guess (based on fairly even loss of compression over all 4 cylinders) is that the rings/bores have simply worn out. Steve will measure them up and let me know.

Edited by Nev, 14 May 2013 - 04:44 PM.

[cnrandall]

Out of interest, what oil are you using and how often are you changing?

 

[Nev]

Fully synth Sylkolene 15w50 I think Chris and have changed the oil at least 4 times. Twice whilst running in over the first 500 miles or so (with mineral) and then fully synth every 3500 miles or so after that. I've never run out (or low) even on the dipstick either. It's all a bit of a mystery, hopefully identifiable when then engine is opened up. I also extracted/tested the spring + plunger on the oil relief valve in the pump and that is fine too, no sign of scoring or sticking on the plunger. I did this to be sure it wasn't stuck closed (had heard of a few cases where this has happened) as it might have caused overwhelming oil pressure at high revs and when the oil was cold, which might explain the turbo 'seals'/shaft leaking. I have bought an oil pressure sender unit and gauge for installation after the oil restrictor to the turbo for when I put the engine back in. This will at least let me know what pressure the turbo is seeing.

Edited by Nev, 14 May 2013 - 07:34 PM.

[Ormes]

when I put the engine back in.

Give me a shout when the time comes if you wan't a second pair of hands

[vocky]

it's possible that the pistons will have sections missing / melted away 

Edited by vocky, 15 May 2013 - 07:58 AM.

[cnrandall]

Fully synth Sylkolene 15w50 I think Chris and have changed the oil at least 4 times. Twice whilst running in over the first 500 miles or so (with mineral) and then fully synth every 3500 miles or so after that. I've never run out (or low) even on the dipstick either. It's all a bit of a mystery, hopefully identifiable when then engine is opened up. I also extracted/tested the spring + plunger on the oil relief valve in the pump and that is fine too, no sign of scoring or sticking on the plunger. I did this to be sure it wasn't stuck closed (had heard of a few cases where this has happened) as it might have caused overwhelming oil pressure at high revs and when the oil was cold, which might explain the turbo 'seals'/shaft leaking. I have bought an oil pressure sender unit and gauge for installation after the oil restrictor to the turbo for when I put the engine back in. This will at least let me know what pressure the turbo is seeing.

 

It might be worth sending a bit of oil off for sample.  One of the two Europa race cars we have here has a propensity to absorb a fair bit of fuel into the oil which thins it down considerably.  We have been using the silkolene 15-50, now swapping out to Joe Gibbs to see if that works any better.

[Nev]

 

it's possible that the pistons will have sections missing / melted away 

  I am hoping it's nice and obvious like that Vocky, otherwise I won't know what to fix ! Fuel mixed into the oil and bore wash/glazing has been at the back of my mind too. Though having said that the spark plugs seem a nice brown/tan colour, I can't smell fuel in the oil and various dynos have confirmed by AFR to be around 11 to 14 depending on load. However the exhaust used to get very sooty. I think I am likely to get new fully forged pistons put in anyway, as the C20LET ones I installed were only meant to meet my initial spec of 420 BHP, but are now having to handle a lot more.

Edited by Nev, 15 May 2013 - 11:45 AM.

[Nev]

 

when I put the engine back in.

Give me a shout when the time comes if you wan't a second pair of hands

  Gosh, thats a very kind offer Alex How was your back after the extraction?

[Ormes]

How was your back after the extraction?

It held up remarkably well thanks

[Nev]

Ugg, I've just been pottering in the garage this evening amongst the debris of my engine extraction and saw the bowl of oil I drained out of the car the other day (approx. 3500 miles old, perhaps 4000 miles). I stirred it up and sniffed it and then compared it to fresh oil in the can. The used oil certainly smelled a lot different, not distinctly of petrol but certainly different and stronger and perhaps more petrol like... I think I will attempt a home made viscosity test by pouring a set amount of each oil (used and unused) down a narrow funnel and time it. If there is a marked difference in time (ie the used oil is thinner and hence flows faster) I wonder if this would be considered as evidence to oil contamination? Is that a fair test? The car does get dreadful MPG, approx. 20 MPG just driving normally, so maybe it is overfueling.

Edited by Nev, 15 May 2013 - 08:30 PM.

[jules_s]

Give me a shout and i'll pop over too Utterly useless spannering/lifting due to the obvious, but have a Pug and I'm happy to bugger off getting bits while you two graft if that helps

[Nev]

Thank you Jules, we can make it an unofficial mini-meet ! LOL

[CocoPops]

How long has the oil been sat around tho Nev? Is it not likely to have taken on contaminates from air/moisture etc in the garage? Would need to be tested straight out of the car vs new. (Apologies if it was drained just now but I'm not sure)

[jules_s]

I cold even stoke up the barbie if this weather ever improves Lot's to talk about given whats happening to mine atm too (no power just a nice chap who knows whats what in suspension geo etc) edit: I must be cold or summat

Edited by jules_s, 15 May 2013 - 08:39 PM.

[Nev]

The engine is apart now. No signs of piston disintegration, no failed rings and no detonation marks. There is some evidence of over fueling and the side skirts are worn, though some honing marks are still evident. Combine this with 2 other bits of oveidence: 1/ Fuel consumption was terrible and 2/ the oil smelt rather funny, this currently leads me to think I have suffered mild bore wash and oil contamination (with petrol). The block will be measured for wear/ovality in the next few days and we can make a decision based on that. Clearly I will have to address the over-fueling issue as well, once the engine is back in.

Edited by Nev, 28 May 2013 - 10:57 AM.