2H Rebuild Question - Rebuilt kit issue - Do rebuild kit liners come machined in the kit already? (1 Viewer)

[doug720]

My buddy owns a race engine machine shop and does many engines with liners. I asked him about this issue.

In his opinion:

If liners need to be machined, they must be done after installation in the block to keep them round. They also line bore them to be square to the crank.

Most steel liners are machined in place, chrome or plated liners are typically matched sets - fitted pistons and rings - just install them.

That is how my Isuzu parts come - chrome liners, fitted pistons and rings

 

[vincent85]

Update on the engine rebuild:

Me and my friend who is a diesel mechanic thought long and hard about pulling the liners and having the new un-machined dry liners that came with the rebuild kit installed and machined in the block. However, after heavy deliberation we decided to keep the liners we have in the block. The reason is they are within tolerance specifications after checking the piston ring gap according to the engine manual and they are in excellent shape with no pitting at all. There was a little vertical scoring, but that came out with us honing the liners. The cost benefit analysis came down to spending allot of unnecessary time/money to send a block off to have new liners put in, when the liners I have in it are perfectly serviceable.

We honed the piston liners in the block and are preparing for the install of the rebuilt pistons. We also took a straight edge tool and some feeler gauges to measure the head of the engine to ensure it was completely level and within required tolerance levels according to the engine manual. This is important to ensure a good seal for compression when you bolt the head back to the block. According to the specifications in the engine manual it is a little out of tolerance levels for the measurements that I got. I am sending the head off Monday to a machine shop. They will machine the head to the correct tolerance levels, install the new intake/exhaust valves, and pre-combustion chambers.

 

[vincent85]

My buddy owns a race engine machine shop and does many engines with liners. I asked him about this issue.

In his opinion:

If liners need to be machined, they must be done after installation in the block to keep them round. They also line bore them to be square to the crank.

Most steel liners are machined in place, chrome or plated liners are typically matched sets - fitted pistons and rings - just install them.

That is how my Isuzu parts come - chrome liners, fitted pistons and rings

Doug, thank you for taking the time to ask you friend for that information. I appreciate it!

 

[RufusTheDufus]

Piston ring gap is not what you should have checked to determine if your cylinders are good. You need to put a dial bore gauge in each cylinder at multiple locations and measure to see if the bores are barrell shaped. this should have been done after honing too

 

[vincent85]

Piston ring gap is not what you should have checked to determine if your cylinders are good. You need to put a dial bore gauge in each cylinder at multiple locations and measure to see if the bores are barrell shaped. this should have been done after honing too

We did do that, sorry I failed to mention that. We did allot of things while working on the engine, I just did not listen every little detail (I guess it is safe to say that is not a small detail). My buddy has a Snap On bore gauge we used, that checked the diameter of the cylinder liners. Man you should see the cross hatch after we honed the liners. It looks great!

 

[RufusTheDufus]

I'm not surprised your bores are within spec. I pulled some horrible pistons out of an H in the past. While the pistons were junk the bores were still within spec.

 

[vincent85]

I'm not surprised your bores are within spec. I pulled some horrible pistons out of an H in the past. While the pistons were junk the bores were still within spec.

Wow! You were no kidding. I was surprised as well, it is just a testament to how robust these vehicles are. Two of my pistons had broken rings on them. When you take apart the engine it will really tell its own tale. I was amazed at all the little details people are lazy on when assembling. Over time these small issues combine to make larger issues. I was not surprised after taking this engine apart it had heating issues. I mean it was ridiculous, one of the fuel injector nozzles that seats in the engine head was missing its o-ring seal! LOL.

 

[roscoFJ73]

Do the old liners still have visible cross hatching pattern on the bore?

 

[vincent85]

Do the old liners still have visible cross hatching pattern on the bore?

Yes they do, we honed the old liners.

 

[ozcrusier]

I would prefer the stock liners if they were in tolerance the as liners have had 35 years to heat treat themselves and stay straight being a proven product. I'm interested to know if these Alfin slugs are forged and a lower compression ratio from a stock 2H piston.

 

[vincent85]

I would prefer the stock liners if they were in tolerance the as liners have had 35 years to heat treat themselves and stay straight being a proven product. I'm interested to know if these Alfin slugs are forged and a lower compression ratio from a stock 2H piston.

That is a excellent point and I agree! I dropped off the head yesterday to get it machined back to tolerance levels according to the engine manual. When that comes back I will begin putting everything back together, mounting the turbo/intercooler, and tweaking everything. Here is a picture of tonight's work. We finished putting on the new main crank bearings and dropped in the rebuilt pistons.

 

[Jan-78FJ40]

What are you doing about the main bearings-just leave them. Did you spec them?
cheers,
Jan

 

[vincent85]

What are you doing about the main bearings-just leave them. Did you spec them?
cheers,
Jan

Sorry guys, my previous message has been edited. I had a typo. I did not put in cam bearings last night, I mean to say I put in the new main crank bearings .