Freshly rebuilt L28/N42 puffing smoke

[Boog]

They didn't give me any paperwork. I guess that's what I get for going with the cheap guys. They said my block just needed a hone, as it was in good shape. I'm still planning on using the compression tester this weekend, any other information I should gather to come to a conclusion?

[seattlejester]

Dry, then wet compression will help determine which half of the block is the problem portion if we are still thinking it is oil related.

 

Throw up some pictures to how you have things routed?

 

Can you show us the spark plugs?

 

Are you still running megasquirt? Can you throw up a log? Might show something else.

[Boog]

I'll take pictures and pull a plug tomorrow, I might have time to go out and collect a log. Compression test on Friday. Thanks for the help so far Brian.

[seattlejester]

No worries, John

 

A picture of all the spark plugs in a row will be illuminating. A singular plug won't help too much. Plus you will have to pull them all anyway for a compression test, might as well pull them all at once.

[NewZed]

Tried to find specific info on what ITM sends with their pistons but there's none readily available.  I got the impression that they might use Nippon rings.  Found an interesting article about piston rings that's pretty informative, in general.

 

http://www.npramerica.com/attachement/Introduction1.pdf

 

This guy says ITM pistons come with chrome top rings but I couldn't find it on the ITM site.  Chrome rings take longer to seat, I believe, it's a harder material.

 

http://datsunzgarage.com/rebuild/

 

Another cool reference - http://korihandbook.federalmogul.com/en/section_3.htm

[Boog]

Compression numbers (1-6): 130, 160, 150, 140, 160, 140. Cold engine, 55 degrees out. I had just enough oil in the bottom of a quart to do a wet test on the #1 cylinder, which brought it up to 160. Couldn't get the pictures on here, but I got them in an album at this link: http://imgur.com/a/fxeX5 Sorry that the plug numbers are out of order in the album. 

Edited April 9, 2017 by Boog

[seattlejester]

Hmm last time I did a wet it brought the numbers up quite a bit more then that. If the block was bore honed, the rings all gapped and all that, then those values shouldn't be that variable which does point towards the head being problematic. Once again that is with the assumption the rings were gapped and the block honed.

 

Cylinder one which looks the most oily also didn't go up that much with a wet compression test at least the last time I did one it was almost 200.

 

The only questionable thing in this is when you said there was no oil when you connected the valve cover hose back to the intake. I suppose it is possible the vacuum could hold the oil from leaking down or something, but it is still a bit of a red herring. Is the intake clear of oil? Can you take off the intake boot and shine a light down in there? Once we establish the cylinders are not getting oil from the intake tract, then it more or less comes to the chamber.

 

The chamber could get oil from 3 maybe 4 spots. The pistons not scraping off sufficient oil (bottom), an oil passage leaking into the combustion chamber from a blown head gasket (side), or directly from the top via a valve seal (top). The compression test should have ideally ruled out the bottom or the top, but those numbers lack consistency which makes it hard to judge.