How-to drill oil drain holes in 3.5L pistons

[89Vette]

And, here is the reason for the iffy longevity that some posters have reported. There's been arguments/debates over what the issue really is. But, I posted on this after talking to Jerry in 2010.

Those tiny holes you see are where the oil has to drain back into the pan. If they get clogged, oil pools in the cylinders and starts creating the havoc -- that eventually leads to engine failure.

It's why I would be cautious about doing anything like: using engine cleaners, running heavier than recommended oil, skipping an oil change, or adding things like teflon treatments to your crankcase.

I believe these holes are either fewer or smaller than idle (compared to other engines). It doesn't mean the engine can't work or last a long time -- just that dilegence to recommended maintenance is the key to success.

I would think doing anything like this would benefit by balancing/rebalancing the rotating assembly -- though doing it equally to all cylinders SHOULD minimize the impact.

The fact that this mod is even mentioned is the biggest tell-tale to me -- but it's nice to see this posted as a way to improve any rebuild effort.

Thanks for posting!

[VX KAT]

And, here is the reason for the iffy longevity that some posters have reported. There's been arguments/debates over what the issue really is. But, I posted on this after talking to Jerry in 2010.

Those tiny holes you see are where the oil has to drain back into the pan. If they get clogged, oil pools in the cylinders and starts creating the havoc -- that eventually leads to engine failure.

It's why I would be cautious about doing anything like: using engine cleaners, running heavier than recommended oil, skipping an oil change, or adding things like teflon treatments to your crankcase.

I believe these holes are either fewer or smaller than idle (compared to other engines). It doesn't mean the engine can't work or last a long time -- just that dilegence to recommended maintenance is the key to success.

I would think doing anything like this would benefit by balancing/rebalancing the rotating assembly -- though doing it equally to all cylinders SHOULD minimize the impact.

The fact that this mod is even mentioned is the biggest tell-tale to me -- but it's nice to see this posted as a way to improve any rebuild effort.

Thanks for posting!

can you edjamacate me...I'm not understanding the correlation between using engine cleaners or teflon treatments and the potential for clogged holes on the piston??

and what rotating assembly? how would more holes affect balancing the "rotating assembly"?

sorry Mark...didn't mean to TJ your thread....

[MSHardeman]

And, here is the reason for the iffy longevity that some posters have reported. There's been arguments/debates over what the issue really is. But, I posted on this after talking to Jerry in 2010.

Sorry y'all. I totally spaced out and didn't explain WHY you would want to drill holes in your pistons.

As 89Vette said, one of the theories as to why some of our engines burn oil is that Isuzu used some bad/iffy rings and not enough oil drain holes in the pistons when they originally built these motors. The oil drain holes in the pistons are there, as Vette said, to drain oil back into the crank case. As the rings, and oil scrapper travel down the cylinder wall they are supposed to squeegie the oil off of the cylinder wall, and either push it back down into the crank case out of the bottom of the cylinder, or force it into the drain holes. The original drain holes are thought, by some, to be too few and too small thus not draining enough oil, or getting clogged and not draining any oil at all.

The pistons in the new Isuzu motors have more, larger, drain holes and this may be why most of the new motors don't burn any oil. Jerry's instructions above provide a way to make the existing drain holes larger, and add additional drain holes to hopefully stop the oil burning issue in the older engines. Jerry has done this fix to numerous engines and he said that it works very well. He didn't mention that it might throw the balance of the engine off, but since you would be removing such a small amount of material and can't see how it would effect it that much, if at all.

Obviously (well, maybe not to some), the engine has to be completely taken apart to accomplish this fix, so it is really for those who are looking into re-building their engines, or who have the time to take their engine apart to do the fix and then put it back together.

If you get a re-built/remanufactured engine, it is not guaranteed that the shop used the new Isuzu pistons so you could be getting an engine that will have the same oil burning issues as before. Jerry said that he has ordered a few remanufactured engines to see if they were using the new pistons, or at least drilling them out, and most, if not all of them, had not.