Engine Rebuild 101?

[dieselcruiserhead]

My new to me 4BT (same as a 6BT) has coolant leaking out of the head gasket so I am thinking while I have it torn down for the head job, maybe I'll just go ahead and rebuild it while I'm at it... I am a pretty competent mechanic and a few head jobs and I have replaced a piston bearing on my 4BT before but never actually rebuilt an engine before...



I know the B's are sleeved, the complete kit is "complete" with all gaskets and such -- could anyone say whether a standard rebuild kit from Cummins comes with new pistons and sleeves?



I don't have a rebuild manual for it or anything. . I am aware of the machining it will need (deck and head, cyl wall honing... that's it?). Don't have any special tools, for example will I need a sleeve puller?



Anyone have any general advice for me on this? Something I should do myself or fork down the $$ to have someone else do it... ? Can't really afford the quotes I have been getting to have the rebuild done, but I think for $500 or less I could probably get the machining done and the kit is about $725 or so + tax. . I could afford this. .

 

[Greenleaf]

The Cummins 5. 9 is parent bore. I would believe the 4 cyl little brother is the same.



Forgot to say you need to order a service manual. Period.

 

[dieselcruiserhead]

While I am at it are there any performance modifications you guys have found while in the rebuild/machining stage? I am planning on keeping the VE pump. .

I was thinking of possibly doing the porting technique as as described here on piers:

http://www.piersdiesel.com/TechPortHead.htm





Bottom line though is this will not be a high power engine, I plan to get up to maybe 160 hp at most, using a single HY35 turbo (9cm2 housing wastegated, bigger impeller with 4" air intake) and probably Bosch 190 injectors. Original power rating for these is 105hp/~260 torque non aftercooled and 120hp/305ft lbs factory air/air or air/water aftercooled... I have the non aftercooled model but will be adding an air/air aftercooler at some point and it will be dyno tuned, so getting up to 160 hp should not be too tough...



Any thoughts?

 

[RTillery]

For a good valve and surface job on the head, you might try Cleggs at:

801-225-7554 in Orem. They have a modern shop with very good equipment and it is family owned and operated. Give them a call and tell them Roger Tillery sent you. They may be very competitive on the parts too. Good luck.

 

[dieselcruiserhead]

LOL I use Cleggs already, they are great... Thanks and appreciated. . !

 

[1stgen4evr]

"I know the B's are sleeved, "



If you have a sleeved engine, it has already been rebuilt. The B is NOT a factory sleeved engine. The single most desirable improvment you can make on the four cylinder engine is to have it balanced. Also think you will find very little wear on the engine unless it has LOTS of miles or maybe run with poor maintainence.



"piston bearing"?



Not being critical. Everyone starts somewhere but I think you need to get the manual and do a good bit of reading.



James

 

[Moab4x4]

Get the Book !

Dittos to get the manual, it is invaluable with regards to pictures, diagrams, and torque specs. It also tells you what to heat up /cool down for press fit pieces (IE cam gear) and more.

The manual indicates that you can bore it and get oversize pistons if it needs it (my old motor will). If you need to bore it enough to have to put in a sleeve it is REALLY worn out.



I looked at the porting and decided that it was not for the amateur that didn't have a spare head around.



I would dynamically balance the crank assy though. Your machinist will do that for you and tell you everything to bring in.



I don't know how much lighter the 4 is than the 6 but for example, the manual says to use a hoist to carefully lift out the crank, it is HEAVY. I wouldn't do it any other way. I would be afraid of binding it while trying to pick it up.



Get an impact socket to fit the rod bolts. 12mm ?? I broke my craftsman socket on mine. (yes I was turning it the right way )



I used lots of egg cartons and labeled where the bolts came from from each assembly. It is turning out to be useful now.



Can't think of anything else useful, just keep it clean and read about it first.

Ken

 

[JLEONARD]

The manual indicates that you can bore it and get oversize pistons if it needs it (my old motor will). If you need to bore it enough to have to put in a sleeve it is REALLY worn out

There are two methods recommended by Cummins... one is to bore oversized and use an appropriate size piston.

The other is to bore for a sleeve and use standard sized pistons.



I know a boater who rebuilt his 2 Cummins 6BTs by using the sleeve method... he had one or two scored cylinders in each engine and only sleeved those cylinders. Then used the stock pistons.

 

[dieselcruiserhead]

Yes you guys are correct, sorry for some reason I though these were sleeved but they are not. This is the original engine on the original rebuild from Cummins, and it is running great, just the head gasket is leaking. . I discovered the coolant earlier but after I removed the turbo yesterday, I noticed it is leaking oil pretty badly also.



It has had about 16 years of pretty hard life (about 180K miles) from Frito Lay as a delivery truck. I was so this was why I was thinking a rebuild. Also the engine is out and I have it torn down for at least all new gaskets so this is why I was thinking I would rebuild it. .



But truth be told it is running very well and seems pretty tight. . No weird smoking at all and it starts on a dime. The 4BTs have no cold start system and even when cold it fires right up on a half turn. . So I am not thinking maybe I will just do the headgasket and save the rebuild for some other time.



I did acquire the 588 page complete manual for it, thank you guys for the recommendation, it is awesome and I am pretty pysched about it...



I also have a friend who was a Nascar engine builder (says he has about 1500 engines under him) and he has a complete machine shop at his disposal. . After a few questions about the rebuilding process he said he would help me rebuild it and even do the machining for free... But then again, it is running great so I am not thinking why rebuild it. . if is doesn't need it. . ? The big advantage for me is the engine is out and somewhat torn down, so it would be future labor I suppose... But again it will be tought to fit the cost of it in right now...



Next step I suppose is I am going to try to dig up a compression tester, if the rings are in good shape then I guess I'll leave it be. . ? Or would you guys pass up the opportunity, even if you could barely afford it?

 

[JLEONARD]

Cruiserhead,

I'd probably to the dumb thing and rebuild it.

However if it were a financial burden I would let it be if it checks out. Look at the cylinder walls when you pull the head. If they are scored then you know what you have to do. I'll wager the lower end is fine.



Jay

 

[Moab4x4]

Ditto to what Jay said. Look at the cylinder walls and let them tell you what to do. If there is any measurable ridge in the metal (not just in the carbon ) then I would rebuild it.

If the walls are smooth all the way up and look good. HG it and get it on the road.

 

[dpuckett]

OK, assuming they have the same lower end components as their big brothers, the 4cylinder making 105hp would equate to roughly 157. 5hp from a 6cylinder. Not quite what our trucks are rated at stock. Now, my 91 was bumped to the 225-250 range by a previous owner, who ran it hard pulling tractors all over the country on a 35ft flatbed. I changed the head gasket at 255K and still had cross hatch marks in my cylinders. At 180k, your Frito Lay engine should be fine. I could be wrong, but I'd save the money for go fast goodies. These engines dont make enough power or get used in a heavy engouhg duty cycle to get worn out in 200-300K unless they arent maintained. Now, the 350 Chevy box truck at work with 120k is nearly worn out... .....



Daniel

 

[dieselcruiserhead]

The 105 hp model (1990 and everything) is equivalent to a 6 cyl 6BT from a '89 or '90 era. They were non intercooled so it is about the same as an early gen 1 which is 160 hp and 400 ft/lbs I believe. the 4BTA which is the factory air/air or air/water aftercooled is 120 hp/ 305 ft/lbs, which I believe is the same as a slightly later with the air/air intercooler that came in the Dodges from what, '92 on?



Anyway, thanks for the advice. . I wish I wasn't so poor right now. . I have my vacation time right now and am spending a lot of money restoring the truck, so I wish I had the extra $$ lying around to rebuild but don't. Even for hte parts alone it might be a stretch. . So, I think I'll take your guys advice. . I have a feeling it is just fine in there. . Thanks, Andre