Rebuilding a 4bd1t. What do u think of the condition of these pistons and liners? (1 Viewer)

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Hi guys. I got my 4bd1t all torn down and after i got the head off, i noticed the condition of the pistons seemed better than i was expecting.

This engine has 190k and after easily wiping the very fine soot off with a rag (just a dry rag) from the pistons, this is what they look like:

Just wondering it they look normal for 190k or not. I really dont have any experience taking engines apart.


Also wondering if the rust on the camshaft will be a problem?

And, what else should i do to this engine besides a re seal kit, crank & piston bearings, and new piston rings (assuming i keep the old pistons and sleeves).

Still see a cross hatch pattern on the liners but i have no idea what condition warrents complete replacement. Obviously they are expensive from isuzu.

Thanks guys. Lots of learning here.

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Wow. It looks like someone took a crap in that engine. Wash and clean it out and pull some bearings to check on them. If they look ok I'd venture the journals are clean....ish. These engines have chromed liners. You can't hone and put new rings in there. If the cylinders aren't scored and the rings are within spec I'd say run it as is, but that's just me.
 
do I have to hone in order to put new rings in? I thought I read on 4btswaps of someone just replacing the rings on their isuzu and not the liners or pistons.
Ya, as u can see there is some rust on the rocker arms, but I do have a spare engine with a good one. Water got in the valve cover while it was sitting at the junk yard for 2-3 years and made its way into the pan. When I drained the oil, about a couple water bottles worth of water came out and then the oil, which a good amount of the oil was a thick sludge /snot consistency.
I'll pull the crank and see what that looks like.
 
The water and dirty sludge is not ideal, but the rust on cam needs to be dealt with. Worst though is the oil pump drive gear on the cam looks really worn, and that's bad.

AS mentioned above, clean the internals, pull the caps and see what you find. I would pull the cam and really check it close. If the gear is not too bad, I suggest sending the cam, lifters and rocker assy. to Delta Cam for reconditioning - They come back like new! The last 4BD2 they did for me cost about $150,00 with shipping. If the cam is bad, look for a used one.

I've seen people do a lite hone on chrome bores just to remove glaze and let new rings seat.

Buy factory gasket set, they are far better and you don't want issues.
 
Doug I was under the impression that honing these chromed liners is not as effective as regular ones as they are so hard. Have rings seated well doing that on other engines? Ive got a motor with low compression and was going to hone and re-ring and was stopped in my tracks when I read about the chromed liners.
 
You are correct that honing has little affect on the chrome bores. What the honing does is do an extreme cleaning of the bore to remove any glaze. You may leave a few fine lines on the plating, but that is not necessary, or really desired.

My buddy is a engine machinist and deals with Porches and other cars with plated cylinders. He uses a ball hone for a quick clean - a few passes up and down. For any stubborn areas they use fine sand paper to clean the plating. then run the hone.

The plating is very smooth when new, and the rings are designed to seat against that surface. So as long as the bore is cleaned with the hone, you should be good.
 
Liner and ring part numbers I've posted here on 4btswaps: The Part Number Thread - Page 2

The liners are graded, four grades each seperated by 0.02mm diameter. Big difference in NVH between getting it right and wrong.

Isuzu 4BD1T genuine pistons were not available whenever I checked. You can buy matched cyilnder/piston/ring kits or just the liner and rings alone.

Those look good enough to run. My warning is do not ever try aftermarket liners or rings. They're all garbage. Stick with genuine and make sure the grade is correct. It's expensive but worth it.
 
Ya the camshaft acually isn't that bad after rubbing off some loose rust. I'm not that worried about it acually now. Thanks Doug720 for the cam link, I may consider that. I know that the cam bearings need replaced as they didn't look too good, but the crackshaft looks great. Main bearing looked completely fine too. I got this thing all tore down to bare block and took it to the car wash yesterday and got soaked spraying off as much of that block as possible.

I didn't remove the liners when I did this though. I just air sprayed the crap out of it when I got it back to the garage and heated it up a little bit with a weed burner. After some die grinding of the block in a few more places this block will be ready for a acetone wipe and some grey urethane paint.

Wondering if others have painted their heads as well when they painted the block. Seems like a hassle cleaning and prepping for paint all the little nooks and crannies on that 4bd head.


Also bought main and rod bearings on ebay a few months ago and didn't realize that that was a graded part. So now I need to figure out what is the right ones I should have gotten.
Is there a way to measure them?
 
The mains and rod bearings should be standard as the the crankshaft has a Ti-Ni coating. If that finish is damaged, you likely need a new crank, as the Ti-Ni finish can not be ground.

On the cam, check the center gear teeth carefully. They looked bad in the picture you posted. This gear drives the oil pump, so it needs to be good.
 
Do you guys have any links of folks that have honed and re ringed and put new rings in? I'm going to have to look into this more. Pretty interesting.
Thx

I've never come across that. Most people run what they've got until the blowby becomes a problem (which is usually damage rather than just wear).

A note of warning. Only use genuine rings. Many aftermarket rings are chrome with too much tension and you get adhesive wear between the rings and the liners. I went from new (but not genuine) pistons, rings and liners to having the engine run on it's own oil in 27,000km.

Then I replaced those liners and pistons with aftermarket (loose and sloppy fit, don't do that, makes the engine very noisy), aftermarket pistons and genuine rings. The difference in friction even during assembly was astounding. It ran so clean on first start that I could see up the exhaust pipe to the first bend.

I don't know exactly what material the genuine rings are. But they appear to be a type of cast iron with chrome plating on top and bottom surfaces. They slide better and seal better than any others.
 
The mains and rod bearings should be standard as the the crankshaft has a Ti-Ni coating. If that finish is damaged, you likely need a new crank, as the Ti-Ni finish can not be ground.

My engine with previous owner had valve stem seals go through the oil pump and into the oil galleries. The crank polished back to mirror by hand.
These are amazingly hard and almost never get damaged. Normal wear doesn't touch them.

Yes I've got all the 4BD1T horror stories!
 
Dougal, so ur saying that using aftermarket pistons and liners with oem rings would be a good choice? I really would only want to use oem for everything and just bite the bullet $$. I don't think I'm gonna touch the pistons and liners. They seem fine so well run them until I need to shell out the 1000 for oem pistons and liners.

And yesterday I brought home a new 1993 4d34-1at3 with bell and manual tranny. I litterally stiped the truck clean of all the wiring harnesses, computers etc. Thinking about swapping this in my landcruiser now instead of the 4bd1t. This 4d34 has 160K miles on it, 30K less than the 4bd1t.

I'm wondering if there is a MPG advantage to going with the 4d34 because of the computer controlled IP?

4bd1t vs. 4d34???
 
Dougal, so ur saying that using aftermarket pistons and liners with oem rings would be a good choice?

No. It'll make it noisey, rattly and with higher blow-by. I'm never doing that again. I'd run those stock pistons, liners and rings.

BTW those letters stamped into the block deck (C,C,B,C) by each hole are the liner grades. Record those so you can reorder that grade without stripping the engine again.

I'm wondering if there is a MPG advantage to going with the 4d34 because of the computer controlled IP?

4bd1t vs. 4d34???

No mpg advantage. Just harder tuning.
 
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Dougal, i believe i read in the manual the letters really mean nothing. They just coinside with the liner grade which is a number 1-4.
If u could further explain this it would be great because the manual stated:
“The liner grade is printed in permenant ink on the block and the piston grade is stamped into the block just for reference”
If you cant buy pistons on their own without purchasing the liners whats the point of the letter piston grade? And why would they not stamp the liner grade into the block because the permanent ink does not last.

The letter grade of the piston makes no sense if u cant purchase pistons separately.
If i wanted to order new liners and/or pistons then i would need a bore gauge to measure either the inside of the liners or the inside of the block (w liners removed) in three different places up and and down the cylinder and then per a table in the manual i would equate that to my 1-4 liner grade.

Ive been meaning to purchase a bore gauge just for this purpose as i didnt think piston letter grade made any difference when it comes to liner grade
 
Dougal, i believe i read in the manual the letters really mean nothing. They just coinside with the liner grade which is a number 1-4.
If u could further explain this it would be great because the manual stated:
“The liner grade is printed in permenant ink on the block and the piston grade is stamped into the block just for reference”
If you cant buy pistons on their own without purchasing the liners whats the point of the letter piston grade? And why would they not stamp the liner grade into the block because the permanent ink does not last.

The letter grade of the piston makes no sense if u cant purchase pistons separately.
If i wanted to order new liners and/or pistons then i would need a bore gauge to measure either the inside of the liners or the inside of the block (w liners removed) in three different places up and and down the cylinder and then per a table in the manual i would equate that to my 1-4 liner grade.

Ive been meaning to purchase a bore gauge just for this purpose as i didnt think piston letter grade made any difference when it comes to liner grade

Pistons for other engines are available in A and C grade. My local Isuzu truck dealer didn't have genuine 4BD1T pistons last I asked, but it may be a different story worldwide.
Perhaps those letters are simply factory records for the stage between liner install and piston install?

0.02mm between liner grades. A set of T gauges and micrometer will do it. I may be doing exactly that this winter.
 

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