1586 DT436B Main Bearings

[d9gdon]

Are these the right bearings for this block?

The service manual clearly shows offset drilled holes for the piston cooling jets, where the new ones are lined up.

...and these bearings are more narrow than the block. This is what the engine had in them when I took it apart, but remember that this has turned out to be a 466 block.

The one image obviously shows a pic above...the other two are from the side, right and left.

These bearings are the narrow ones, I think 1.22" wide.

Now that I think about it, the service manual shows the offset drilled bearings, but these are what is offered now as replacement bearings.

This post was edited by d9gdon on 04/07/2023 at 06:37 pm.

 

[caterpillar guy]

I think the inserts are to narrow for the rods and thus don't fit the holes right. It would seem to me that the holes should fit over the holes in the rod better than that. The oil flow seems restricted to much with those. I would contact the people you got the bearings from and send pictures like you have here for them to see what is going on.

 

[Dieseltech]

The bearing book I have shows the bearing width is correct. In a perfect world the holes would align, but they don't always. Long as the passage way TO the piston jets is
LARGER than the jet, oil will flow fine as the jet restricts flow anyway. You could use a debur tool on the bearing back side and open up a small groove .050 deep and
1/8-1/4 inch long if you are nervous about it. I've done that before.

 

[fastfarmall]

Dieseltech, i am impressed with your knowledge, and reference material,you got a wealth of experience i would say!

 

[d9gdon]

(quoted from post at 11:10:35 04/08/23) The bearing book I have shows the bearing width is correct. In a perfect world the holes would align, but they don't always. Long as the passage way TO the piston jets is
LARGER than the jet, oil will flow fine as the jet restricts flow anyway. You could use a debur tool on the bearing back side and open up a small groove .050 deep and
1/8-1/4 inch long if you are nervous about it. I've done that before.

Yeah, they have a big chamfer on the back side of the bearings.

They will have more than enough hole showing to supply the piston cooling jets after I look at it again this morning.

I saw another rebuild on Red Power site, and their block was the same.

After a lot more research this morning, these seem to be correct so I went ahead and set my crank in there and all 7 main bearings measured 4 thousandths clearance with Plastigauge which I'm happy with. This is a used STD/STD crank if you can believe it. The machinist was blown away with how good it was.

When I get back to it hopefully later this evening, I will measure the thrust clearance and see what I get there.

I have to pull the crank again to lube the bearings up with Lubriplate and retorque.

Thanks for the comments. I don't wanna spend all this money and make a mistake going back together.

Not 100% happy with the machinist on this, either we had a miscommunication or something but I spent 3 hours replacing a bent piston cooling jet and cleaning 3 others.

One was stopped up completely, one was 75% stopped up and one was 50% stopped up. I knew about the bent one before the machine shop got it. I had told them to vat the block and install new cam bearings...I guess I just assumed they would clean the oil passages as usual...nope. I had to knock out the steel expansion plugs and make sure the passages were clean.

I was standing there when I took it in to the machine shop and he got a phone call that his long time crankshaft technician had suddenly passed away from a heart attack the previous night, which shook him up badly and I felt bad for them.

I don't guess I can blame him too much...

This post was edited by d9gdon on 04/08/2023 at 12:17 pm.