4722 replies to this topic

[CocoPops]

Ah good point, I have a rattley slidey thing in my pax sill.... bring it round TAGL

[JG]

We need footage of the innards of your Milltek back box to settle the is it chambered, or not, question?

yep, could do that too.

My what a lot of fun there is to be had from a £12 usb endoscope

In other £12 random ebay purchases i bought an infrared termometer yesterday -50 to +700c. Any good ideas what we could do with that.

Perhaps combine with the endoscope for real excitment...

[siztenboots]

whats under the passenger seat finally revealed

[CocoPops]

Is that for testing your nimbus heatshield?

[Nev]

Thanks for the links into the endoscope. I vaguely remember looking some time back but for some reason I remember them being in the region of £200! I expect I will take a punt on one tonight. However, the area of damage (if there is any) will be on the ringlands (possibly partially collapsed) which will be unlikely to see, or simply worn rings which you can't see either The worry I have with simply re-installing the turbo is that that if I run it and the crank backpressure is genuinely there, then it will knacker my turbo again and I will face another £400 refurb bill. Another option is to install a small scavenger pump under the turbo to pull the oil from it and push it into the sump. The pump would thus block any positive crank case pressure, thus protecting the turbo seals. One of the side benefits of this would be that I could take the oil from the turbo and shove through an oil cooler in the left ear and thence back into the sump. My left ear is currently completely empty as the airbox was moved, so there is loads of room in there for a big cooler.

Edited by Nev, 17 April 2013 - 02:30 PM.

[steveboyslim]

Thanks for the links into the endoscope. I vaguely remember looking some time back but for some reason I remember them being in the region of £200!

I expect I will take a punt on one tonight. However, the area of damage (if there is any) will be on the ringlands (possibly partially collapsed) which will be unlikely to see, or simply worn rings which you can't see either

The worry I have with simply re-installing the turbo is that that if I run it and the crank backpressure is genuinely there, then it will knacker my turbo again and I will face another £400 refurb bill. Another option is to install a small scavenger pump under the turbo to pull the oil from it and push it into the sump. The pump would thus block any positive crank case pressure, thus protecting the turbo seals.

I would be more worried that if the piston lands are damaged that a piece breaks away and damages the turbine wheel on the turbo leading to another rebuild.
i think it could be time to put forged pistons in your engine.

Steve

[cnrandall]

Thanks for the links into the endoscope. I vaguely remember looking some time back but for some reason I remember them being in the region of £200!

I expect I will take a punt on one tonight. However, the area of damage (if there is any) will be on the ringlands (possibly partially collapsed) which will be unlikely to see, or simply worn rings which you can't see either

The worry I have with simply re-installing the turbo is that that if I run it and the crank backpressure is genuinely there, then it will knacker my turbo again and I will face another £400 refurb bill. Another option is to install a small scavenger pump under the turbo to pull the oil from it and push it into the sump. The pump would thus block any positive crank case pressure, thus protecting the turbo seals.

I would be more worried that if the piston lands are damaged that a piece breaks away and damages the turbine wheel on the turbo leading to another rebuild.
i think it could be time to put forged pistons in your engine.

Steve

What he said. + and ECU that has good knock control.

That said, best to do a leakdown on an engine that has been run at least recently so bores are oiled as normal. In my experience, on these engines, det shows itself down the sides of the piston between the bore and the first ring land so Steve has a very, very valid point.

[cnrandall]

Oh, and you really need worry less about your turbo core. They don't have seals as such... you try keeping a rubber seal intact on a turbo that's doing nearly 1000degrees!!

[Nev]

I've ordered up one of those titchy bore-scope cameras - thanks for the tips. Ideally it would be good if it shows up some deformation, as I would at least be sure there was genuine damage. It should arrive Fri or Sat at the latest, so will know a bit more then once I've shoved it into each bore and had a look.

[Nev]

I received the bore scope today, and it is surprisingly good. However, using it in the cylinder and trying to rotate it to view a full 360 degrees is not easy. What I've seen of the pistons is fine apart from a fair bit of oil on top of them. I have retested the leak down procedure and leakage is perhaps a bit worse than before, though I have my doubts about the accuracy of the tester itself. The leak has to be either the rings or the valves, the latter being far less likely. I think I am veering on the side of taking the engine out, head off, gearbox off, pistons and rods out. Then we can measure the bores and see whats what. Ideally with some proper forged pistons in there with stronger rings they may last a bit longer. Personally I think the bores will have worn a lot, based on the amount of iron debris I found on the magnetic sump plug. If this is true, then a rebore to 87mm will be likely.

Edited by Nev, 19 April 2013 - 04:32 PM.

[Nev]

Jeremy (Hairy) kindly came round this evening in his VX for me to do a final comparison test of his crank case pressure to mine. We took his crank case breather rubber pipe off an let the car idle. I had my hand up against it to feel the pulses of pressure. They felt approx. half to a third less that what I felt in Nipper when I did the same test. I think I have now resolved to take the engine out tomorrow and am currently summoning up a big dose of will power with a glass of port.

Edited by Nev, 19 April 2013 - 08:05 PM.

[VXT Tim]

Fine weather tomorrow so garage door open and let the warmth in. No freezing garage has to be motivation enough

[Dally868]

good luck Nev, i went for 87mm as well. Have u actually done compression test on engine? sorry if i missed something here

Edited by Dally868, 19 April 2013 - 08:13 PM.

[Nev]

What make of piston did you use Dally? Have you found a lot of fillings on your magnetic sump plug after a few thousand miles ? I have a feeling that my C20LET piston rings have chomped my bores away rather quickly. I did try a compression test, but the guage was terribly inaccurate and varied badly, so gave up with it. Yes indeed Tim, it actually feels like a heat wave here at 15 degrees celcius !

Edited by Nev, 19 April 2013 - 09:01 PM.

[Ormes]

Good luck Nev... sorry things aren't plain sailing.

[Nev]

Thx Alex, plain sailing and eeking 2.75 BHP/Cubic CC is not compatible ! LOL. Imagine a cubic centimetre in yout minds eye and how the hell 2.75 BHP comes out of it... ! Taking the engine out and stripping it seems easy these days (a BAD sign!), just time consuming. I remember 4 years ago when it seemed daunting, but now it's just a slog of repetition !

Edited by Nev, 19 April 2013 - 10:17 PM.

[Nev]

Ooops, I meant 0.275 BHP out of a CC. I was a bit drunk when I calculated that last night!

[Dally868]

i was using pec, mahle don't do them which i would prefer. i have a bit more oil consuption with them,about a litre per 400miles. no fillings what so ever and i have changed oil each 200 miles for next 600. what i noticed with those pistons is they have quite big compression wal anl less gaps between rings they looks like wiseco to me.

[Nev]

Well, after much fannying about I think the mystery oil smoke has been identified. After sending the turbo off for a rebuild and have strapped it back on (with and additional oil restrictor this time) and driven the car for about 75 miles. Initially loads of smoke was coming out of the exhaust as there must have been puddles of oil trapped in it, but that has all stopped now. However, a second source of smoke has been identified which is the area of my bodged crank case breather pipe. I think some of the silicone pipes I stupidly used are leaking slightly and spattering traces of oil vapour onto the exhaust downpipe and exhaust manifold. I get vague whisps of smoke rising up from the area and as that pipe is the only oily thing in the area I am hoping it is that. I am bidding on a new pipe on eBay and will cut and weld it up (without silicone pipes!) as a replacement in a few days. The rebuilt turbo is now boosting up like a beast and makes me realise how knackered it must have become with that terrible air filter I had 2 years ago. I've had the balls to take it upto about 5000 RPM so far and worryingly it seems to be making a more boost than before (I saw the boost gauge go up to 25 PSI instead of its old max of 22 PSI). This might be due to some other issue, like the the wastegate not getting it's signal, or possibly I had a boost leak previously for the last 2 years! Anyway, this is something I need to check carefully or I will go out of the range of the map and risk underfueling and making way more power than I want Anyway, things are looking a little more rosy now, and at least I can drive the bloody thing, abeit gently due to the excessive boost and due to feeling like a complete newb (after barely driving it for 5 months).I am still hoping to drive up to Dave Hardwicks and getting him to use his leak down tester on my car and compare the results to other known Z20LEX's.

Edited by Nev, 03 May 2013 - 07:58 PM.

[Ormes]

Great news Nev