Adivce on swappin out motors

[bitzer]

My Cummins 4bta is about to quit on me. It sleeve-less so it is not rebuild-able that way. I could get a block for it and swap parts, but by that time I might as well find a decent used one. I'm going to be looking at engines in the next few days. Some I can hear run and some not. I've never swapped one out before, but I'm sure I can handle it. I've also got a diesel mechanic that I can call on if need be. Anyway I'm thinking stuff like motor mounts, bell housing, out put shaft, etc, could be different. I won't know until I start looking around, but I plan to take a bunch of measurements and notes and pictures before I go shopping. That and some calls into the local Cummins dealer to see if serial numbers may be more compatible to others. The motor I'm really looking at is coming out of an over the road truck. They want $2500 for them. It sounds like a small delivery truck or something. The seller has 75 of these he wants to get rid of and he said another guy just bought one for a skidder. I will see if I can get that guy's number and see what he ran into. I know this is pretty wide open, but thoughts? My Cummins is a 1989 4BTA. Its in a 1990 Franklin 132XL.

 

[mdavlee]

Those can be bored a little over. Same size piston as the 5.9. Is it inline injection pump?

 

[bitzer]

Its got the rotary pump. Yeah I talked to some guys about boring. Its going to cost the same if not more and will be more time down. Thanks for the thought though!

 

[Trx250r180]

how bad are the cylinders ? one in my cat 6 cyl looked pretty bad ,i got it serviceable with some stone hones ,is still running strong today

 

[treeslayer2003]

no sleeves? why do they sell kits then?
I bet the bell housing will have to be changed Bob, trucks use the bigger housing but you might put your back end on it.

 

[treeslayer2003]

huh, I see kits with and without liners.........I did not know this. so some have liners and some don't?

 

[treeslayer2003]

how do you know it will need boring? maybe it not that bad. I have done Detroits that broke the rings but the liners were fine. I just honed um and they been runnin for years now.

 

[bitzer]

Honestly I haven't torn it apart yet. There is a lot of pressure building up in the crankcase. I'm losing 2-3 quarts per hour of oil out of the breather. Its pretty much blowing oil out everywhere at this point. The Cummins 4bts did not come with liners. I ran the breather line to a reservoir to catch the oil. Every hour I shut the machine off and let the oil drain back into the case. I ran it like that for the last month. The next job is far from home and I'm not going to push it any more. Maybe its not as bad as I think. I don't know.

 

[bitzer]

The thing is it sounds just fine when its running. I haven't babied it at all in the last month and it still seems to make good power. It does need ether to get going at the start of the day now.

 

[Rookie1]

Its turbocharged right? It will still make good power with that kind of blowby. Id keep on with your idea to replace. If you had more time rebuild could be an option. No liners means its like a gas engine,small block chevy for example, and the block would have to be bored out and oversize piston and rings be installed.

 

[northmanlogging]

Blow by is generally a ring issue, but I'm not a true mechanic so grain of salt and all that...

motor swaps can be fun, never done one on a skidder/forwarder, although Iwould assume that pulling the radiator, stripping the exhaust, fan, alternator, then unbolting the torque converter (or not) then the bell housing, and last the mounts it should pop right out, just remember to NOT cut any wires or houses, its easier to adapt later, and most will plug right back in and be ready to run.

 

[treeslayer2003]

jmo, but I think you got more a broken ring issue than any thing else. won't know till the heads off.
IDK the little cummins very well so I ain't much help to ya.

 

[Knobby57]

I was under the impression that a off road and a over the road 4bt is a different animal . Off road is built to run at a fixed rpm. The block may be the same and it may not , there are several versions of the 4bt some have the bell housing bolts clocked to twist the motor to fit the application . May also have different crank , pistons . Cam, injection pump.and who knows what . Make darn sure you can use what you buy . Just because it looks the same does not make it the same .I would rip it apart and find the failed part before anything. Most machine shops can sleeve a block . It's not a hard thing to do. Also odds are any used engine you find from over the road truck will most likely have a pile of miles on it already .


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[treeslayer2003]

hey Bob just a thought....are you losing any coolant?

 

[Knobby57]

Have you done a leak down test on the cylender yet , this would give a good idea what's going on


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[dhskier2]

Check out the folks at www.4btswaps.com
I haven't cruised their forum in awhile, but I remember them being a bunch if good people.
I can't remember if they have an equipment thread, or all just vehicle stuff. But if it's 4bt, they'll know how to answer your questions

 

[Marshy]

Might be luck and find just a broken ring. Of course at that point you will already have the block off so I would think having a shop check the cylinder bores would be the deciding point for either repair or replace. Might just re-ring it and hone the cylinders and be good for many more hrs... GL

 

[Trx250r180]

As much oil as you are using you may have lost a turbo.oil cools the turbo and of it lost sealing could be feeding it through the exbaust

 

[mdavlee]

Ring would be my guess for the blowby that bad.

 

[HuskStihl]

I'd just mod the muffler, delete the base gasket and retune. The franklin can't be much different than u'r 390's