head coming off again

[Tinus lotz]

Andre I am no engine expert .....but it might be to do with crank end float or something like that .....why is there only wear in the way the engine gets loaded by the clutch ???? And why is the pistons and rings not damiged but the sleeves are? I Really think you need to get some proper measurements done and get as many opinions ......a lot of people will speculate on this but at least you can make up your mind on what went wrong ???
I hope frans gets to have a look at it he is the guru on those engins and I will trust him to give a fair comment on what the problem could have been

[Andre Steyn]

I spoke to Frans on the day I received the bad news, and he mentioned the bore to piston clearance should be checked, its perfect in spec, 4thou. I measured that again today and its correct, the other thing he mentioned is the oil squirters that help cool the crown, but according to the engineers and sac I should have had worse piston damage if squirters where failing, unless my oil pump is finished but it checked out when we did the rebuild last time. On the one had I feel like throwing in the towel and on the other I feel now that I have to spend again I feel like seeing that I'm busy I must make this TD42T very"kwaad" and go a step up with everything! I was only boosting .5bar!! So maybe .85 ?

[Andre Steyn]

In aus they get them up to 156rear wheel kw's by only increasing the fuel pump plunger to 12mm and a bigger turbo and cooler and of course 22psi boost!!!

[Peter Connan]

Mater, jy moet skerp kyk.

The marks are all one one side, not front or back (down at the bottom you can see the crank journals).

This is not a thrust bearing issue. These marks are either made under compression (when the pistons will be pushed against the right-hand side of the bore as seen from behind) or during the power stroke (if they are on the left-hand side). Unfortunately I don't know the engine well enough to know which side I am looking at.

[Andre Steyn]

Peter the marks are all on the intake side, drivers side.

[Peter Connan]

Thus, the marks are made as the pistons move up, compressing the mixture before ignition.

I am wondering if there is a mismatch between the rings and the bores (that the rings are too hard or too soft for the bores)? I don't know if this is possible, whether there are different rings for different bores?

Andre, I am probably notorious for my views on engine mods in general and turbos in particular, but be very careful here. Some of the engines they have in Auz have much bigger crank journals etc. than most of the engines we have here, and other design features as well that are much better suited to high-boost applications.

My feeling is, if you want power, swop it for a 4.8. If you want reliabaility and feul economy, keep the boost low...

[Andre Steyn]

Hmmm, On the nissan TD42 black tops in aus. Interesting. Not sure about the ring mismatch, how to prove this? The pistons rings and sleeves were bought in a sleeve kit. Did you know the newer UD40's are powered by td42t motors, they call it mo2's. It doesn't have a intercooler though. I wonder if the fuel doesn't ignite at the wrong time on the way up? But timing would have shown other issues though?

[Tinus lotz]

Andre....stem saam piet ....los die reisies karre vir die manne wat wil sukkel.....kry die fout met jou motor en geniet hom...ry ver oor ons grense en kom weer huis toe ....daai amper 3 ton lorrie moet kan vertrou word anders maak jy vir jouself baie moeilikheid. ......ek dink jy moet bietjie op die aussie forum vra en hoor wat daai manne se ....miskien het hulle al so iets gesien? ??

[Andre Steyn]

Baie baie waar, en op die stadium sit betroubaarheid in die boom!!! Ek het nogal nie aan die aus forum gedink nie, sal dit bietjie probeer en kyk wat sê die manne daar.

[ricster]

Andre, I took mine first to Bosch in Alrode, where they set up the pump and injectors ( I didn't have a dial gauge so set it up by luck !!!). I then took it to CRD in Alberton, cost me a fortune !! but seemed to be ok but still had high EGT's. Since then Mynhard at SAC in Centurion has been taking care of my fueling