Builds Family haulin'

[Cruiserdrew]

as usual.. great ilustrative thread .. thanks Mike ..

Yep-Mind blowing, and now a cool diesel rebuild.

Smog laws here in Cali blow, but I can see a 4bt in my FJ40's future.

 

[Dirtgypsy]

Looking good Mike! hHit me up when you are ready for me to head out. I would really like to be in the way when you start the actual rebuild and install portion!

Clint

 

[boots4]

With standard sizes (bearings, pistons) being used and the cylinder walls being in decent shape I'm optimistic that I won't have to bore but thanks for the tip. I do however question if this had been rebuilt like I thought it was when I started the project. Kind of a moot point now since it's getting some love anyways.

Thanks guys.

Clint I'll let you know.

 

[Kief]

I wouldn't be surprised if the rebuilt or reman'd 4BT's are not of the highest quality as the PO's may often go with the lowest price unit. I also think the 4BT is worked pretty hard in the big step vans and of course last much longer than a gasser but the head is often the weak link. Make sure your machinist checks for cracks.
Are you going to redo the rings and see if that will reduce your blowby or do you think that is just the boost?

 

[boots4]

I wouldn't be surprised if the rebuilt or reman'd 4BT's are not of the highest quality as the PO's may often go with the lowest price unit. I also think the 4BT is worked pretty hard in the big step vans and of course last much longer than a gasser but the head is often the weak link. Make sure your machinist checks for cracks.
Are you going to redo the rings and see if that will reduce your blowby or do you think that is just the boost?

The head being the weak link was his opinion too as he's work on cummins heads before. We'll get together on Monday to see what he found. The common crack is between the injector hole and the valves and there is an acceptable level of crack where the head can be reused but if it extends into the valve seat then further repairs or a head replacement is required, at least per the service manual (it's a very good manual).

As for rings, they'll absolutely get replaced, in fact since I've got it out I'll be pretty close to doing a rebuilt. Things I want to replace period are all bearings (mains, connecting rods both ends), rings, do a honing, rear main seal, probably the pistons, and then the head job. Probably won't play with the cam or tappets and the push rods all look to be in good shape but again I'm going to see what the rebuilder thinks to get another opinion. I haven't decided about the injectors yet since they are easily accessible whether the engine is in or out. I may want to wait on those until I get to the bigger turbo. Getting them tested is probably a good idea. Kind of waiting to see what kind of prices I'll get on the rebuild kit/parts and other work.

 

[boots4]

update

My optimism has been replaced with reality.

The engine rebuilder said the head looks like it's got a lot of miles but that it's usable with some fixes. The intake guides were good but the exhaust were loose. He also came over in the evening and honed the cylinders with a really nice honer and we found that the cylinders have some spots that didn't clean up. He was willing to hone it some more but recommended a bore job and he wanted to mic the crank to make sure it was in good shape which all required a complete tear down. Upon inspecting the crank there was a definite thrust problem. I was debating whether to just hone it up, do the ring job and replace the bearing and get back into it in a couple of years but after talking it over with the we decided to go ahead to just get it done now. So I started to tear the block apart even more. This time I got ziplocks bag and boxes to better organize the rest of the parts. My goal was to get it bare the next day and take it into him before I had to start work today. That way he'd have it the rest of the week while I was at work.

To pull everything off would require understanding the timing alignment. I refreshed with the manual before I carried on. There are marks on the crank, cam, and injection pump gears for alignment and these match up when cylinder 1 is in TDC. So I found TDC with my alignment pin. I also took these pics so I could look at them when I'm ready for reassembly.

This is the crank and cam.

This is the cam and injection pump.

Pic of the three gears. The oil pump and the steering pump have already been removed.

The cam comes out by removing the two bolts in the 1 and 6 o'clock positions in the pic above and slides out. I then cheated and removed the gear housing leaving the injection pump bolted on to keep my timing position on the injection pump.

With that out of the way and the rear main seal housing unbolted I was ready to removed the mains and pull out the crank. The mains have a stamped number on them which makes them easy to get back in the correct spot. 1 starts at the front of the engine.

And goes goes up to 5 at the back of the engine.

Here's the massive crank, the rear seal housing, and the zip lock is full the the tappets that ride the cam. With the engine upside down they stayed in place while I pulled the cam out and I had plenty of access to pull them out with the crank missing. I wiped them down and numbered them so I'd get them back in the same spot.

My thrust bearing (spot #4) was missing one of it's shoulders. This unfortunately is common in the cummins engines that have the three piece unit. The good thing about cummins is that they redesign their parts and now the replacement is a one piece unit so that's what will get put back in there when I get to assembly. I had the three piece that is now only two. The shoulder falls out and sits in the pan which allows for lots of thrust.

There was also some wear on the block because of this. The rebuilder was concerned about this so I'll see what he has to say now that the crank is out and he can get a better look at it.

Here's a pic of another part of the block that is not worn for comparison purposes.

With this movement on the crank the bearings have their edges worn due to the way the crank journal is shaped (hope that's the right terminology).

That bronze-ish colored sludge on the bottom of my pan is what I believe was the shoulder that fell out. How it turned into sludge... I have no idea.

I've run out of time so there's more to come probably tomorrow.

 

[Tapage]

Nice work Mike .. in this pic .. the letters mean something .. ? ( timing settings ? )

 

[boots4]

Yes the letters are different timing settings for different engine configurations I believe. If I had my manual in front of me I might be able to look it up and see what the differences are but you are right.

 

[boots4]

Update cont.

The block is stripped. Pulled the oil cooler and the push rod access panel. Cleaned off the head gasket remenants from the block.

Here is after the initial honing to see if the cylinders would clean up. You can see the wear mark at the top of the piston's travel that stayed.

Cylinder 1 has some other imperfections that look like it could have been rust at one point.

Cylinder 2

Cylinder 3 had some vertical marks.

Took the block and crank into the rebuilder in style! It's nice when the younger generation can help out the older . My generous neighbor helped me load up the the block and drove me to the rebuilder. His 100 drives a little smoother than my 60... ok, maybe a LOT!

I still had a an hour of daylight when I got home so I decided to yank the steering box and tear it down. That's as far as I got before I went inside for the night.

That's all for now.

 

[Cruiserdrew]

It will be interesting to see what the rebuilder says about the wear.

Goo photos.

 

[brokenparts]

Hope it works out man.... I got a extra TBI motor laying around if it doesnt.

 

[Falco80]

Great job Mike, i'm enjoying seeing the inner workings of this Cummins engine. You've got it apart now, so you may as well do the job properly instead of doin it further down the track. Looking forward to more pics as always!

 

[boots4]

Just got off the phone with the rebuilder and after mic'ing it he said it actually looks pretty good. The numbers show according to the manual that I can go with the standard sizes for bearings and pistons. He doesn't believe it needs a bore job and that honing it will infact take care of the imperfections on the walls. The crank mic'ed better than what the manual suggested as well. So that was some good news. Now I can call up a outfit in Oregon and get a kit ordered now that I know what sizes I'll need. I might even get the kit before I have to go back to work next week. Optimism returns.

 

[baxter650]

Any thoughts on a hotter cam grind?
PDR Diesel Performance: 4BT Cummins

 

[baxter650]

I met one of their guys who has a very hot twin turbo 4BT in an old Bronco, crazy power.

 

[boots4]

Certainly looks appealing but it's not in the cards for now. Thanks for the link.

 

[Cruiserdrew]

So where in the end was the coolant leaking from, that lead to all of this?

Glad your block was good, even with that thrust wear.

 

[boots4]

So where in the end was the coolant leaking from, that lead to all of this?

This was the gross leaker at the front of the block on the passenger side. The head gasket wasn't sealing anymore.

The coolant passage @ 5 o'clock on the left cylinder was the other leak showing up at the rear of the block. You can see how there is no smooth surface on the ring around these ports which meant no more seal.

Reasons I can think of are that the head may have a slight warp from the overheat two years ago on a pull up a steep grade when the upper radiator hose separated and I had to drive another 200ft to get off the road, but it's crazy that it is showing up now. That side of the head is the exhaust side and by looking at my head you see the discoloration from hot exhaust. I stick to the 1200F rule and don't go much higher for any amount of time. Then of course the gasket could just be old and was ready for a change. So perhaps a combo of stuff but the good thing is it got me inside the engine and the engine needed other work.

 

[GLTHFJ60]

I'm excited to see how well the block cleans up after coming back from the rebuilder!

I love how Cummins continues to improve the parts for older motors.

 

[brokenparts]

so? What's the story Mike?