Rebuild vs. Remanned

Joopin

Joopin

Super Moderator
I was talking to my mechanic today and I brought up the common problem of the oil coming out of the air intake. Everything I have read on this board points to cleaning out the PCV valve, which I did, and was not effective. My mechanic told me that the reason that happens is because the engine has bad rings. The pressure escapes back up through the valve cover and into the intake. He basically the only way to fix it is to replace the rings and pistons... so basically rebuild the engine. Now for the quesitons.

He told me he could rebuild my 4.0 for 2k OR put in a "remanned" 4.0 for $2400. I guess the remanned comes all together and they just through it in... and the rebuild is just that. So after much consideration I am dumping the idea of a V8 swap for now and sticking with the 4.0. So which should I choose: the rebuilt which I could throw in a beefier cam and stuff like that, or a remanned, which I don't even know the advantages of besides making my wallet lighter. Any ideas?

Oh and one more question, does anyone know where to get a breather oil cap for a 4.0 valve cover? He said this would help my oil spewing problem for now.

Joop
 

rebuild it.... and use the 4.2 crank and rods... you'll have a 4.5... those parts have to come out anyway.... not a bad idea to upgrade the cam.... BUT... you can find someone to rebuild it cheaper than that... if you were closer to me, i'd do it for 200
 
Well here in Jersey the average rate is 60 bucks an hour, and this guy does great work. He has rebuilt a v8 for me before. So where could I get a 4.2 crank and rods? Should I just buy them new? Is this the stroker thing you were talking about? I am definately putting in a beefier cam... any suggestions where to get that?

I still am skeptical about doing a rebuild... I was thinking after the initial post, if the rings were bad, wouldn't I be burning oil too? Currently, there is no smoke coming out of the tail pipe. I'm gonna buy a new PCV tomorrow and see if that works... if it don't... :shock:
 
you might be burning oil... but bad rings can sometimes mean a one way deal... not often though... you might be getting blowby, which will pressurize the crank case, forcing oil into your intake... you can get it bored .030 over for a 4.6 and that will clean up the cylinder walls... you can get the crank and rods from an old motor, or you can buy new, either way
 

spend some extra money for a stroker? Consider me broke!
 
I would find out what you are getting from both. You may get everything replaced with a reman and only rings from the mechanic or vise versa. Find out what is replaced in both. If it is the same go with the mechanic then find have the Mechanic through in some performance parts.
 

did you clean or replace the pcv valve. if the valve is stuck open you'll have these problems. shake it. does it rattle? no, then replace it. it shouldn't be more than 5 or 6 bucks.

you shouldn't have to replace the pistons. only the rings and hone the cylinders. unless the cylinders ar out of round or they walls are worn to severly, but at that point you'd have run into other problems already. and at that point you would have to have the block bored.

just something to think about before you go drop all that money into the engine.

that seems like a lot to pay for that work, but i've never paid to have work done, so i really have no idea if that's a good price. some of that stuff is retarded. i know i had to pay over $100 just to have them look at my transmition when i had my cutlas.
 
$400 difference I would be thinking warranty. Alot of Remanufactured engines have a decent warranty. That would be nice insurance that all was done right, but you wouldn't be able to add all the performance stuff to it. Coming from a guy with a 4banger, I say go for the remanned one, but if you're power hungry then rebuild.
 

Well both engines come with a 3 year warrantee so thats not an issue. Snitty and I were talking about this before and the pcv valve is non existant on the 4.0 so it looks like thats not an option.

Im pretty sure I will go for the rebuilt now, this way I get to make it into a stroker. I will have to pay extra for the other parts (4.2 crank, connecting rods) plus I found out last night that since I am replacing the crank I will have to get the whole engine rebalanced, which is another 250 bucks. So in the end the remanned and the rebuilt/stroker will cost about the same.

One thing my mechanic was concerned about were the pistons... He is wondering if there are special ones since the throw on the crank and connecting rods will be longer. He was telling me the pistons might be waaay too close up top. He has built stroker engines but never on a 4.0 and he is wanting me to supply him all the info on that conversion. I will have to find something on the net for now... any links you guys have would really help.
 
Heres some other links for you.

http://www.jeep4.0performance.4mg.com/stroker.html

http://www.jakesracingengines.com/jeep page 2.htm

I am in the middle of doing this myself. some people will go with used parts I decided to go with new parts. I am doing a few other things to it at the same time so it does not make since to go with used. Make sure you understand what you are getting into. There are other things that you will need to replace. You will also need new injectors. These will run you another 210. Do your research before you decide.
 

Great thread and link!!

I am sure Skyjeeper was trying to point out that 4.0s commonly pumps oil into the air filter system. Usually its only the pvc system has gotten clogged with sludge. I figure you have already checked all the hoses and passage ways.

On that note, the 4.5 idea sounds awesome!!! I love my 258, wouldn't trade it for the 4.0 liter. I have injection so I have more power and no carb issues. But the extra lungs of a 4.0 liter would be nice as long as drivability stay good and the torque curve stayed low. I'd be interested in knowing if the the power curves stayed smooth. Alot of time when you stroke or even just cam something you get flat spots, and other annoyances. But man if those aren't an issue then full steam ahead baby!!!
 
Hey ecor, are you using one of these stroker kits? They are a little pricey... another thing is I'm having someone else do this for me, so he will be ordering most of this stuff for the rebuild anyway, so I'm trying to stay clear of those kits.... unless you know of one for 500 bucks, then I'm interested.

Another thing, you said I need bigger injectors... is that a nessesity? or is it just another upgrade. Thanks for the links by the way!
 
You can get away with just the crank and connecting rods but the idea is to make more power. To do this you need more fuel and more air. The air is the easy thing. Chang the intake and the exhaust and your done, they will work with the cam to make everything breath well. As for the fuel you would change the injectors to a higher rate like the 24lb frd injectors. Both are bosch injectors so you will not have a problem with wiring. I'm going with new parts as a matter of preferance. check ebay and junk yards for motors, I do have a set of crank and connecting rods on ebay now, they were the ones that I was going to use until I decided to go with new parts. I will have about a $1000 into parts when I am done with my motor but I have a few parts in mine that you won't need. they changed the block again in 99 and I have to convert my cam back to the old style to make it work. I also need a girdle spacer which you will not. In all if I had to pay labor I would be about at the $3000 mark for this. so the price that he has given you is not bad. He has to turn the crank anyways when he rebuilds your motor. The labor should not be any different to change to these parts. Let me know if you run into any other questions
 

Well I just spoke to Accurate power... they sell a stroker kit for 1700, this guy was telling me that I would NOT have to rebalance the engine because its not that drastic of a change I guess. So there is the cash for the new injectors... So you are buying these parts seperately, not in a kit? If that can be done with the same results, it seems it would be cheaper than going for the kit. As for the new parts, I know how you feel, if I can afford it I usually buy new parts, which I will do for this project.

So I am telling my mechanic the only changes are:
4.2 crank
4.2 connecting rods
new cam (was going to get anyway)
New injectors 22 min. psi
bored .030 (he was going to do anyway)
Misc. rebuild stuff

is that it?
 
installed a new yoke, do i do anything special?

He should have a new timing set in his rebuild also. It just might cost a little more for a cloyes set...
 
about the pistons quenching too high.... it is not to worry about... they actually end up a small amount lower at TDC than it did stock. the crank's throw is about a 1/2 longer (1/4 each way)... and the rods are about 1/4 inch shorter... so when the crank is at TDC, the shorter rod makes up for the extra quarter inch... and when it draws back, and the piston is at the bottom... the piston draws down an additional half inch... quarter from the crank, quarter from the distance in the rod... this gives you almost a half inch of total stroke... and that is where the cubes come in...

it is still a good idea to balance the assembly.. because you will be adding a new crank to your old balancer and flywheel... this is a whole new assembly for each part, and they were never balanced for each other... but.. i'm sure you CAN get away with not doing it... besides... this is a torque monster for low rpm... not a rev screamer
 

Here's a link I like. This guy's Jeep is well.....not really my style, but homeboy knows how to build a straight six. The stroker section goes over some of the options, and gives his results with the mods he chose and the results of going other routes. Read the ported head section also, even though the intake side of HO 4.0s and 2.5l cylinder heads do a good job, the exhaust can use some work even on a factory engine.

http://www.jeep4.0performance.4mg.com/index.html

Power isn't free, I don't care how good you are. It costs money to go fast, depending on how fast your wallet can take you there ARE other options besides a stroker, and often a properly built factory stroke engine will meet the needs of most people. The problem with a "budget" stroker is that the rest of the engine is usually neglected. I've seen too many smallblocks send big-block boys home crying to believe that cubic inches are a suitable replacement for a properly setup combo.
 
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