Rebuild questions / piston ring install?

[dieselcruiserhead]

Thought I would post here as 4BT's are basically Gen1 motors. . If not mods you can move over to the conversion section. . Also curious about your guys experiences as a lot of the gen 1s are starting to get to rebuild age I imagine...







Anyway,



I have a 4BT with about 180K that I am going to throw into this land cruiser I am building. The engine is out now, mostly clean now also, and in need of complete regasketing including the head gasket (which leaks oil & coolant out the side) but the motor itself runs great and is actually super powerful. It might have slightly low compression but if it does, it is minimal would be my guess. I put over 1000 miles on the bread truck before the rebuild, as I said ran great. Havn't done a compression test yet but plan to, but need to replace the head gasket regardless...



Cummins complete gasket kit is about $600. . Rebuild kit about $700 or $800 if I remember correctly, using OEM. There are some cheap aftermarket rebuild kits that are name brand as low as $500 shipped. I would probably not consider one of these for the piston parts etc, most likely, except unless I choose to not rebuild and only use the kit for the gaskets, as its cheaper than OEM and gaskets are not as important. I would probably need to buy a second Cummins headgaket regardless as Cummins recommends you use a thicker headgasket to replace any metal removed in the head milling process. And they only sell the thicker gaskets separately and they are $50 each so not that bad.



Question is, I haver never rebuilt an engine before. I have good technical knowledge and ability and now think I would probably be fine. . But seating the pistons right, the measurements etc that are needed to do this (correct??) - or do you simply bolt all the new stuff together on the crank, use thread locker and torque wrench and you are good to go with a diesel? Any feeler gauges/precision measurements that I will have to do that requires "special knowledge?"



I was reading this thread about good techniques to get the pistons to seat right. This is on V8 gassers but I feel that its probably the same basic thing for diesels... ? Here is the link:

http://www.circletrack.com/howto/4639_maximum_power_piston_rings/

( <-- Good reading I feel like regardless )



I have no problem doing everything mentioned in the article except it is a little confusing for me using the feeler gauges, etc. And the piston leveling tool, bot can probably figure it out? But I do have the big thick 600+ pages Cummins manual that I think goes though all this?



RE machining, here is the ala carte menu for machining from my favorite machining shop that is very competent and well known & respected...

$65 head milling

$220 head milling and valve grind (probably required is my guess)

$60 cylinder honing

$90 block deck mill

$125 cyl boring including honing

$125 crank grind...



Here's a cost breakdown of what it will cost according to requirements:

- Head milling alone, best case scenario, $65.

- Head + valves, head gasket job only, $220



Machining if rebuild the motor:

- If everything OK valve wise (probably doubtful) + cyl wise, head + deck mill, cyl honing: $215

- Valve job needed, head + deck mill, honing. $370

- There is some scarring in the cyls, $450

- Scarring in cyls, need a crank grind too. . $575



All this, plus parts (+ tax)...



So far, this whole truck has been an expensive build, pretty much everything on the truck is new or rebuilt, truck is/will be entirely restored, but problem is I am running out of money and am fairly poor right now, literally every spare cent right now is going to it, I have probably about 70-80% of the stuff bought already now and almost all big ticket items paid for already. If I tore this stuff apart, at this point hate to say, but it would probably take a few months to get the $$ to put everything back together...



Also, I am a little "scared" I supposed because I havn't ever rebuilt a motor before. Also I am wondering if I should do all this too because the engine runs well so far...



I guess I should wait an see what the compression test says? Anyone have any advice on rebuilding techniques or is it relatively easy you think? I have done all sorts of crazy machanic jobs, probably over 6 headgasket jobs, timing belt/gear jobs, including on several fancy fuel injected cars and other diesels. Never rebuilt a transmission myself but am a pretty capable, smart, and patient/cautious mechanic. . I can also probably dig up a friend or two who has decent engine rebuilding experience to maybe help me out probably, I would have to bribe them with something, but probably worth it. .



I talked to a local diesel engine rebuilder/specialist, and he said "180K on a B series - nothing at all, I wouldn't rebuild it, replace the head gasket, do the cheap gasket kit, and call it quits. " Then I'd be in it probably less than $700 which I could do a lot easier than $1500 or so I think at this point. .



Then I am also weary as engine runs great now, what if I did all this and the pistons didn't seat right or something like that. . Of course I will take every step to break in engine correctly, but sure would be a bummer if I went to all this time + expense for nothing, when engine ran great before... But that said, I like the idea of a fresh rebuild to match the rest of the car...



Thoughts / comments?

 

[dpuckett]

Besides the head gasket leaking, what makes you think it needs rebuilding? I'd say make sure the head and block are flat, get a head gasket of your choics and bolt it back together. Leaks are no big deal on a diesel, and are NOT necessarily indicative of a deeper problem. Gaskets for diesels are made of the same stuff as gaskets for gassers, but diesel gaskets have to deal with MUCH harsher oils (namely acids in the oil) and environments thereof than gassers.



I agree with the diesel mechanic you spoke to- put a head gasket on it and be done with it. I'd bet you find cross hatch marks in the cylinders. Both of mine did in the mid 200s and neither were stock; hadnt been for a long time.



This last time, I bought a head gasket, intake gaskets, t-stat seal, and manifold gaskets. Everything else got resued, including the turbo to manifold gasket. I have parts galore from the head gasket kit I bought 3 years ago. I kept more stuff for "just in case" or "later" than I used.



Dont worry, esp if it was kept stock. Drop some PODs or 190s in it and rock on.



Daniel

 

[dieselcruiserhead]

it doesn't need it, but as I said pretty much everything in the truck is new or rebuilt, trans, everything. . Sounds kind of dumb but it is a complete total frame off restoration, theory is it will be like a "new" truck when done. . I have never had a new vehicle before so I am telling myself this will be, LOL. And it will be a daily driver...



I am also telling myself I am going to all this trouble now so I don't have to do it later, including an engine rebuild when it does get tired. I am thinking, everything else on this truck is new, why would I put an engine in with 186K miles and no known history other than the 1000 miles I've driven it in the bread truck before I pulled the motor. Theory is I'd like to get another at least 100-200K before having to rebuild anything, hopefully... Everything on the truck is being done with meticulous analness I suppose. So that is the desire to rebuild...



Basically it comes down to if I should rebuild it or not while I have it out. I want to learn how to rebuild an engine at some point regardless. I am not worried about the leaks about being anything serious, I am planning on regasketing entirely. If I use OEM gaskets, it is only $100-200 for the complete kit with rebuild parts. And possibly as little as only $65 more in machining for a cyl hone...



Also the thrust washer bearing issue which I think is the same for all gen 1s too (?), and leaking oil pan gasket, I will have to replace at least one bearing regardless...



Could someone maybe post up on the actual process of new pistons & rings. I can get the rings on there easily enough but is it complicated to actually put the new pistons in and are there percision measurements &/or anything special I would need to know other than whats out there on the 'net?

 

[BPaulsen]

If you were an experienced engine builder, having a show truck and too much money on hand, why not spending a couple thousand to rebuilt the engine as well. But you are not. And I predict that you would run into problems you can't solve yourself and have to hire expensive help or simpy mess up along the way. Therefore . . . it it ain't broke don't fix it. Fix the oil leaks, and while the head is off visually inspect pistons and cylinders for excessive wear. Most likely there's nothing to worry about. A BT4 ain't no VW TDI which basically would be dead at 180K.

 

[cerberusiam]

Also, I am a little "scared" I supposed because I havn't ever rebuilt a motor before. Also I am wondering if I should do all this too because the engine runs well so far...

Truthfully, this is probably not the engine to learn on. If you do mess up, it could cost you big time.



I have built 50 to 60 perofrmance and stock engines over the years and could do one half asleep, but, I would have to do some research and talking to a diesel specialist to make sure I did not miss something.



If you really are serious then start looking for rebuild manuals from Cummins, and, find a diesel guy that would be willing to share his experiemce. Might cost you something to pry the info loose but it would be worth it.



Otherwise, do the gaskets (good ones from Cummins) and check your crank end play. If the end play is in spec don't sweat the thrust bearing. Good luck on whatever you decide.

 

[JLEONARD]

There is some scarring in the cyls, $450

If you have scarring you should take care of that via a rebuild... at least repair the damaged cylinders... ie at least hone and re-ring... might need more depending on the depth of the scarring. It is an acceptable method to repair a Cummins by only repairing the one or two cyls that are damaged... even if they need to be bored . 10 over and new pistons.

Scarring in cyls, need a crank grind too

Seperate issues. Don't make that assumption. Likely the crankshaft is fine and based on my experience I would prefer to leave the crank alone.



Hope this helps.

Jay

 

[bgilbert]

I have built 50 to 60 perofrmance and stock engines over the years and could do one half asleep, but, I would have to do some research and talking to a diesel specialist to make sure I did not miss something.

This is a good point. I would give Haisley Machine or the Lafayette, IN shop of Scheid Diesel a call and ask about your concerns on the pistons and rings. They have plenty of B series engine building experience.



You sound very capable of doing the build if you choose to. The Cummins manual's are very good.



I too would like to learn how to build one of these B series engines. But I don't have the money or the special tools needed to check clearances and measurements etc. It would be very satisfying to know when the engine starts and drives down the road, that you built it.

 

[dieselcruiserhead]

Thank you for all of your responses guys. . I am still about 50/50 in fact leaning more towards the rebuild actually. . I posted this over on the new 4BTswaps.com site too, and most are saying leave the rings as is. But at the same time I am thinking maybe a rebuild. .

I too would like to learn how to build one of these B series engines. But I don't have the money or the special tools needed to check clearances and measurements etc. It would be very satisfying to know when the engine starts and drives down the road, that you built it.

Yes I agree, that has been the philosophy of the whole truck, I have basically done everything other than rebuild the trans, which I had a professional shop do...



I need to order up that compression tester and take it from there. . But there are a lot of cummins diesel guys around here, it is almost Cummins diesel mecca down in Salt Lake City. . See if I can find someone who really knows there stuff that I could pick their brains. .



Thanks guys...

 

[dpuckett]

Stock engine, fleet maintained, I'd leave it alone. It should be good for another 4-500K, at the very least.



DP

 

[JLEONARD]

I'd leave it alone. It should be good for another 4-500K

I believe he said there is scarring on the cyl walls. If that's the case it needs work.

 

[dpuckett]

I took it to mean IF there is scarring- as far as I could tell, the engine is still running right now. Am I mis reading something?"



DP

 

[HFletcher]

I've posted this twice and nobody ever responded, but I pulled a piston from a first gen with about 170,000 miles. (I was gonna rebore and sleeve the engine) The engine borer was much sharper than myself and pointed out that the ring grooves in the piston were badly out of spec. He urged that I do nothing unless I repistoned the motor. I'll say the same thing as last time - food for thought! I would at least check that, regaardless of crosshatching etc.

 

[dpuckett]

Good point. I thought of that when I had my head off, and I couldnt get the pistons to move in any direction, so I just put the head back on, (forgetting to line up an exhaust manifold gasket, and getting a real funny noise), and drove it.



DP

 

[JLEONARD]

https://www.turbodieselregister.com/forums/showthread.php?t=154180



go here and there is a similar discussion about scuffing.

 

[dieselcruiserhead]

No cyl wall scoring that I am aware of. As I mentioned earlier, seems to run great and plenty of pep. . But I haven't taken apart yet. . I am still about 50/50 but thanks for the responses guys. . I'll subscribe to this thread so if there are more comments it will email me. Thanks guys. . Andre

 

[dieselcruiserhead]

back to top for this. .



I have the motor down to a long block now before I do the compression test and start pulling the head off. Talked to a number of Cummins mechanics, given that hte motor runs well right now I really don't think its going to need any percision maching. i think a head mill, deck mill, possibly a valve grind, and a hone and that's it. So standard rebuild kit I think should work well. These guys are saying with a standard rebuild it is super easy, no percision measurements required and that I should figure everything else out pretty easily myself...



Also I'll be leaning over the shoulder of a V8 build here some time this week also. . I'm thinking it might not be too hard. .

 

[dieselcruiserhead]

Finally got around to doing a compression test. . Pretty much 350 across the board, at 186K. . Makes me happy. . Plan is now, take head in to see how it is (should be fine), replace all new bearings, button er up, and take if from there. . Thanks guys... A