Trooper Engine Rebuild Questions

I have read many topics about drilling the extra holes in the pistons to solve the oil consumption problems. I will be having my machinist drill the holes when he's doing other work. I could do the drilling (and even have a drill press) but I would rather have him do the drilling since he does it every day and if the pistons are damaged, it's on him.

From my reading so far... I take it that there is no official Isuzu service bulletin describing the process? All I have found is a post with a photo from JLEMOND that shows a piston with magic marker lines on it showing the location to drill the additional 4 holes in each piston.

Is there any other post/info I should know about? I want to provide something to my machinist to tell him where to drill the holes (he seems to view the Internet as a vast conspiracy theory... and he may be right!).

Thanks!

I found this old thread where Jerry explains in exact detail where to drill the extra holes. Down to the measurement of the new hole from the old one (18mm).


To be perfectly clear and for the record for anyone who doesn't fully know the issue, the OE pistons through around 2001 or so only had (2) oil drain holes drilled per side, thru the oil control ring land (the bottom piston ring land). This leads to poor oil control and carbon buildup on the rings, which exacerbates oil burning.

The way you can tell if your 3.5 has the old-style pistons, is by which type of PCV valve you have. If the valve just "plugs in", your engine has the old-style pistons. If the PCV valve screws in, then supposedly the upgraded pistons with 4-holes-per-side are installed.

If you have old-style pistons, be sure to keep up on your EGR maintenance, as anything that causes higher combustion temps will make the carbonification even worse.

Some improvement has been made by using engine cleaner additives, such as Gumout Regane fuel cleaner. Worst-case carboned-up solution is to spray a bunch of Mercury Power Tune (outboard motor carbon cleaner) in the intake until you have a mosquito fogger out your exhaust, then pull the spark plugs and spray the remaining contents divided-up into all cylinders, let sit overnight. Bump over starter to expel excess in the morning, reassemble and Drive it Like You Stole It! That should hopefully break loose the carbon. Use a quality-rated diesel oil (more cleaning additives) such as Rotella.

I found some pretty good pictures of aftermarket pistons which have the upgraded holes in the oil control lands - 4 per side. These pics are attached. Very clear views of where the holes are located, and the view from the inside of the piston should make your mechanic feel better about where to drill.

Hope that helps!.............ed

Transmission crossmember broken bolt problem.

The transmission crossmember area gets a lot of winter road salt/mud and the crossmember bolts were a bit hard to remove.

One of the bolts broke off with about 1/8-3/16" sticking out (the zone around this bolt is very rusty corroded). It has been soaked with penetrant for several weeks. I tried vise-grips, etc. to turn it to no avail and have drilled out the bolt all the way through to a 1/4" hole. I put a screw extractor in to a good depth and tapped it in and a wrench with cheater pipe does nothing except threaten to break the extractor. The rusted threads seem to be fused.

I can certainly keep drilling the hole bigger and try the extractor deeper into the bolt... but I'm getting closer to the threads. I don't want to break the extractor.

If I was going to try to heat with a propane torch... should I be heating the bolt, or the hole or both?

Thanks!