Hello, I’m currently rebuilding the engine in my 08 tC. I have it all disassembled and just measured the roundness of the cylinders. All of them but #4 show very slightly being out if round. However, according to the 2AZFE manual, the average of the 4 measure points still come out to less than the maximum cylinder diameter.

My questions is: is it okay to rebuild with new standard pistons and rings without machining the out of round? The maximum it was out was .002” on two cylinders.

The engine had 255,000 miles on it and besides the oil consumption issue, has never had a rod knock or anything, nor was ever run dry. Cylinder walls looks great, just need a hone.

 

A Toyota certified tech on Youtube says major Toyota engine components can not be machined and have to be replaced. I don't have the specific link but I believe he was talking about shaving heads and or honing cylinders. Apparently there's not enough meat to machine away.

The tech's name on youtube is TheCarCareNut. Sorry I don't have the link but it concerned oil-ring damage that resulted in replacing the short block because it couldn't be machined.

 

Fender, thanks for the reply! I saw one of his videos talking about that when I first considered taking the engine out to fix it and remember him saying something about that. I can still see the crosshatching in all of the cylinders but it has a little shine to it with some glaze. After some research I read on another forum that, because of a special lining, if the cross hatching is still present it's good enough to reuse. So I think I'm good just getting it cleaned and not honed.

As far as the bore diameter, the rebuild manual states that the Maximum Diameter is 3.4894in after averaging the 4 measuring points in the cylinder. Even though very slightly out of round, the average is still below that maximum. In my head, though slightly out of round, it's still round enough to get an even seal from the new rings. What's your opinion on going ahead and reusing the block since it's below that maximum and the cross hatching is still present?

 

Good question. Full disclosure, I'm not experienced enough to opine. I still follow what you're saying, though. The wear is only slight. I wonder if CarCareNut would be so kind as to address your situation himself? I'm sure he's busy but I bet he prioritizes questions according to relevance. Sorry I can't help. Good luck with the rebuild..

 

Can't re-bore aluminium composite liners. If measurements are within spec, re-use them as is.

Best to get ungapped rings and gap them yourself to minimum clearance. I usually run them in couple hundred miles, then disassemble to inspect. Then install another set with tighter clearances. Repeat until I start seeing fretting marks at ring-ends. Then I go back and re-install previous set of rings. This gives maximum sealing and power. Especially important if you've got worn cylinders. Using stock replacement rings will just get you "pre-worn" rings and less power than possible.