Engine Rebuild Questions

[Trapn6.0]

I'm pretty shure my rings are shot. Burning a lot of oil all the time. Like a permanent smoke screen. I'm not sure if its going to be better to rebuild or just buy a reman and keep it as a spare. Or any ideas are welcome.

[Trapn6.0]

Forgot to add its a 90 with a 4.0. Ax15.

[Geonovast]

Really depends on your budget, how long the truck can be down, and how comfortable you are rebuilding your own motor.

[HOrnbrod]

Throw a known good low mileage engine in then rebuild your old one as time and finances permit. Like a budget stroker. :thumbsup:

[comanchedude]

Well do you really want to rebuild yourself? Do you have the place time and the tools. It can be fun to learn. You won't save much if any any money if you do it correctly as the machine shop work is costly..well in my area it is. And if you make a mistake well it's on you..if you just want to get your truck back running near new then as suggested you can get a used engine..low miles may be hard to find. Or just order a new reman and you get warranty with that also. But generally if you buy a brand name like Marshall or Atk it would be very rare to have problems as the large reman companies are state of the art in engine remains. It's all about what you want to do if you have a passion to build it yourself then do it.. If not get used or reman . My 2cent

[jimoshel]

You won't know what you will need until you tear the engine down. Inspect the cylinder walls for scoring. Mike them for out of round and taper. Remove all valves. Inspect the valve face for pits, uneven seating. Chuck them up in a drill press and eyeball for warpage. Valve seats for pits and burning. Mike the crank journals for wear and out of round. I have gotten by on some engines just with a valve job and rings and rod bearings. I've also had some that required total rebuild, Bore cylinders, new pistons, new cam. Crank turned or replaced. You just won't know until you inspect it. If your not planning on doing a lot of engine work then farm it out. Otherwise do like I did. Get every thing you need and do it yourself. I have the equipment to do everything except turn a crank. I think it all paid for itself with maybe the fifth engine I did. When buying parts, get quality, not cheapos. There should be a mechanic or knowledgeable person near you with whom you can discuss the various aspects of things like 3 angle valve job. chrome vs cast rings, etc. Although they're not as good as FSM the Chilton, Haynes manuals do give you some guidance and the specs for the various measurements.Good luck.

[Trapn6.0]

Thank you for all the info. I know how o do a rebuild I built diesel race engines for 7 years. But I think I might just go for a nice reman with warranty just for the pure fact of gettin it back on the road. Should I got with a reman for my year or is there a better year to go for that is still bolt in?

[jimoshel]

Sorry. From your question I mistook you for a novice. For a straight bolt in any 4.0 from '87 thru '90 will work.

[Trapn6.0]

Are the earlier models any better?

[Trapn6.0]

Sorry. From your question I mistook you for a novice. For a straight bolt in any 4.0 from '87 thru '90 will work.

No problem I have a bad habit of just typing not thinking. I know a lot of the diesel world by this is my first comanche I've owned. And the first gas owned in over 10 years lol.

[1987Comanche]

Look for my thread on the ATK reman 4.0 engine I put in my '90. The first engine from them was a horror story...it started spitting up cam bearings shortly after I put it in.

[Akula69]

We are finishing up the rebuild on a 99 HO and only farmed out the pressing of the wrist pins and cam bearings. all told it's now at about 1100.00, so a quality reman is not out of the range at 1400.00-1700.00. The main reason we didn't go that route is were concerned about the quality of parts they might use.

 

Besides, my son needed to work through his first re-build..but it sounds like your past that point.

[Trapn6.0]

Yea I'm past the exciting stage but I still enjoy knowing that I put it together with the parts I know are in it.

[92tanMJ]

You won't know what you will need until you tear the engine down. Inspect the cylinder walls for scoring. Mike them for out of round and taper. Remove all valves. Inspect the valve face for pits, uneven seating. Chuck them up in a drill press and eyeball for warpage. Valve seats for pits and burning. Mike the crank journals for wear and out of round. I have gotten by on some engines just with a valve job and rings and rod bearings. I've also had some that required total rebuild, Bore cylinders, new pistons, new cam. Crank turned or replaced. You just won't know until you inspect it. If your not planning on doing a lot of engine work then farm it out. Otherwise do like I did. Get every thing you need and do it yourself. I have the equipment to do everything except turn a crank. I think it all paid for itself with maybe the fifth engine I did. When buying parts, get quality, not cheapos. There should be a mechanic or knowledgeable person near you with whom you can discuss the various aspects of things like 3 angle valve job. chrome vs cast rings, etc. Although they're not as good as FSM the Chilton, Haynes manuals do give you some guidance and the specs for the various measurements.Good luck.

 

Hey I just bought an 92 4.0 MJ over spring break before I left for college. The PO said it needed a head gasket and when I checked the oil I found some white milkiness at the end of the dip stick. But when I test drove it, for quite a while actually it didnt over heat or blow smoke out the tail pipe or anything. The oil pressure unit I think is broken because it reads more than 80 psi. like its flat on the opposite side it started on. There is also coolant all over the engine bay like one the belts is throwing coolant all over.

 

suggestion? Just to pull it apart and see whats up and go from there?

 

Do I have to always get the block resurfaced? Can I get away with not doing it when its just a bad gasket?

 

*and I do want to do the work myself, so I won't be taking it to a shop to get done and I will not buy one of those rebuilt motors..

[jimoshel]

Very first thing to do is check compression.Even reading between cylinders is more important than high-low readings. A far out reading is a clue as to what and where to look for, Remove the head. On the '92 sometimes one of the back bolts won't come out. Not enough clearance between it a nd firewall. Pull it up as high as it will go and hold it with a clothes pin. Clean the top of the block and mating surface of the head. Important that it be clean. Inspect for cracks and indications of coolant leaking into a cylinder. Use a straight edge to measure if block or head is warped. Any gap between straight edge and block, head surface should be less than .003 inch.

[92tanMJ]

Very first thing to do is check compression.Even reading between cylinders is more important than high-low readings. A far out reading is a clue as to what and where to look for, Remove the head. On the '92 sometimes one of the back bolts won't come out. Not enough clearance between it a nd firewall. Pull it up as high as it will go and hold it with a clothes pin. Clean the top of the block and mating surface of the head. Important that it be clean. Inspect for cracks and indications of coolant leaking into a cylinder. Use a straight edge to measure if block or head is warped. Any gap between straight edge and block, head surface should be less than .003 inch.

 

Do they sell dies to use to check for cracks or is it just something you do by eye and a microsope or something? And I'll have to check it all out when I get back. Man its killing me not being home and not being able to work on it! :fs1:   I bought it Friday and left for school that sunday! :cry:

[jimoshel]

I've heard of dyes but never used any so can't vouch or recommend them. First eyeball it. One of the reasons for a baby butt clean surface. Then magna-flux.