head coming off again

[Andre Steyn]

Hi cedric, I noticed that ring too I wonder if with the fact that the motor was rebuilt and then left to stand for a year might not also be to blame. I coated everything very very well with oil during assembly and I think possibly with the long wait all of it drained off and caused the sleeves to dry up. And with the statup well maybe broke a ring, but saying how is it possible I stil got the power and economy I did despite that ring? The pistons are coming out today so I'll try post some pics again.

[Andre Steyn]

Oh yes forgot to add, the bits that look like metal shavings are left over somethings from combustion not sure what though and why! In my mind I'm doubting fuel cos on the dyno I had it set so that there is zero visible smole even under hard acceleration.

[ricster]

I've just been looking at the pics again.... the pic may be playing tricks with my eyes, but are those bores perfectly round..... it looks slightly oval if i look at the gaps between the sleeves and piston all the way around.

On pic "Andre.jpg" there looks like 2 different shades ( silver to the left and dark grey to the right. Its a clear vertical line, like the end of a ring ..... will be interesting to see once the pistons are out

[Michael]

Andre, those Autopower pistons are fine. I have rebuild a couple of Navara 2.5dci engines with those pistons and never had any issues with them and the Navara boost quite a bit more that the Patrol engine. I have also bought a set of these for my engine.

[Tinus lotz]

I've just been looking at the pics again.... the pic may be playing tricks with my eyes, but are those bores perfectly round..... it looks slightly oval if i look at the gaps between the sleeves and piston all the way around. he right. Its a clear vertical line, like the end of a ring ..... will be interesting to see once the pistons are out

I agree with cedric .....something looks wrong here iam no expert but it looks as if the sleves are oval ......

[Peter Connan]

First off I want to make it perfectly clear that I am not an expert, and even less so on Diesel engines, but:

1) I do not think it is a broken ring/broken rings. My reasoning is that there is a mis-alignment between the score marks where it passes the dark area, and I believe that that would not be the case if it were a broken ring.
2) For the same reasons as above, I don't think it is a problem with the gudgeon pins,or a bur or something else on the piston.

I think you need to measure the bores and pistons. The bores need to be measured in multiple places. Of particular interest would be to check for ovality, taper and whether that dark area is of a different size to the rest of the bore.

[Peter Connan]

Tinus and I have just had an idea, although it's a long shot, but just maybe if the crank thrust washers are not correct, and the end play between the conrods and the pistons not enough to make up for it, the pistons may be pushed against the bores?

[Andre Steyn]

Bore and piston pics

[Andre Steyn]

As you can see , no damage to the pistons. Any ideas? Frans recon carbon and piston to sleeve clearance.

[Andre Steyn]

Thanx michael that puts my mind at ease quite a bit. I've heard alot of good things from driftcar racers about autopower pistons. Cedric, the ring we thought was broke is completely intact, all the rings are! They aren't even seized, not even a scratch!!!!