Topic: 98TJ engine question

[rroadkilll]

It seems that My TJ is running low on oil and I think it is sucking it up throught the air intake...

I have a 4.0 intake tube and a 4.0 TB installed and it has been for a while...

Recently I replaced the IAC and TPS since I sucked water in and screwed it up...

After replacing the items I took a 200 mile trip and got 15+ mpg!!!   About 150 miles into trip I saw the oil pressure fluctuating and I pulled off the highway to stop at a gas station to get some oil. The check guages light came on and the oil pressure was at ZERO!   I added a quart, should have added 3, and took off for home.

Just droped it off to get some work done on it, at a friends, and while driving there I saw the oil pressure gauge fluctuation again...  Pulled in the driveway and the check guages light came on again...  The distance between the 1 quart is about 75 miles...

Any ideas???

Also, what year engines is a direct bolt in with NO issues???

[sharpxmen]

It seems that My TJ is running low on oil and I think it is sucking it up throught the air intake...

I have a 4.0 intake tube and a 4.0 TB installed and it has been for a while...

Recently I replaced the IAC and TPS since I sucked water in and screwed it up...

After replacing the items I took a 200 mile trip and got 15+ mpg!!!   About 150 miles into trip I saw the oil pressure fluctuating and I pulled off the highway to stop at a gas station to get some oil. The check guages light came on and the oil pressure was at ZERO!   I added a quart, should have added 3, and took off for home.

Just droped it off to get some work done on it, at a friends, and while driving there I saw the oil pressure gauge fluctuation again...  Pulled in the driveway and the check guages light came on again...  The distance between the 1 quart is about 75 miles...

Any ideas???

Also, what year engines is a direct bolt in with NO issues???

that is a lot of oil to just be sucked out thru the filter

i think a '91+ would be issue free replacement but you might need the temp sensor from your current cyl head and maybe the oil pressure sensor (not sure if they're the same). Keep your current distributor (don't think they're different but just in case) and intake manifold with all sensors to make sure.

belt routing is different also

[rroadkilll]

Thanks...   

How about a non OBDII engine???

[Jeffy]

Actually if anything it should be sucking it up through the CCV and into the intake manifold below the TB.  You should see residue of you take the TB off and look at the bottom of the intake.

Did you check your oil at the dip stick to see where the oil was at?

[sharpxmen]

Thanks...   

How about a non OBDII engine???

91-95 is a non OBD2

you just use the engine but you keep everything from yours (including all accessories) and that will make it ODB2 again (that is by using your Electronic Fuel Injection)

[penske2704]

 dude i just finish a 95 yj engine swap to my beloved tj 98 last night

  yes a 91-95 engine is direct bolt on but you have to swap smal things   

-- all sensor including crank sensor on the bellhousing ( not the same plugs )
-- distributor shaft  ( not the same plug again )
-- fuel rail and injectors  ( yj injector are a lower fuel rate ) 
-- oil pan and oil pick up tube  ( yj oil pan sump is larger and does not permit the exhaust down pipe to clear )
-- put a new clutch since your there
-- you will see a small sensor next to the valve cover rear  r/s when looking at your engine from the front
    i dont know what it is for but you will let it unplug since wee dont have the conector for it
-- i had to put the tj engine mounting brakets that are bolting to te engine block ( yj one are not wide enuf )

     thats is about it ****   good luck

[rroadkilll]

dude i just finish a 95 yj engine swap to my beloved tj 98 last night

  yes a 91-95 engine is direct bolt on but you have to swap smal things   

-- all sensor including crank sensor on the bellhousing ( not the same plugs )
-- distributor shaft  ( not the same plug again )
-- fuel rail and injectors  ( yj injector are a lower fuel rate ) 
-- oil pan and oil pick up tube  ( yj oil pan sump is larger and does not permit the exhaust down pipe to clear )
-- put a new clutch since your there
-- you will see a small sensor next to the valve cover rear  r/s when looking at your engine from the front
    i dont know what it is for but you will let it unplug since wee dont have the conector for it
-- i had to put the tj engine mounting brakets that are bolting to te engine block ( yj one are not wide enuf )

     thats is about it ****   good luck

Thanks for the heads up...

I have a few guys in my club going through the engine on Sunday to see what's up with it!!!

I'll keep everybody posted!

[Jeffy]

-- you will see a small sensor next to the valve cover rear  r/s when looking at your engine from the front
    i dont know what it is for but you will let it unplug since wee dont have the conector for it

That is for the temp gauge on the YJ.  The temp sensor in the thermostat housing is for the PCM while the gauge is on the back of the head.

[rroadkilll]

Few club members looked at my Jeep and this is what was posted...

Compression is as follows from front to back. 150, 110, 130, 135

[sharpxmen]

Few club members looked at my Jeep and this is what was posted...

engine warm or cold, if it's warm i would pass, if cold squirt some oil in #2 cyl (the one with 110), if it goes to 140 or so then you have some piston ring problems there, otherwise it's a valve.

i assume this is the new engine you were mentioning, or is it yours?

[rroadkilll]

Well...   I have finally had time to work on it after the 700+ mile move!!!

Still have the oil problem...  about a quart a week (250 or so miles a week)

Took the other motor apart and found a "ring" on the top of the cylinders! 

Looking for information about getting it bored out and then installing everything in it, or maybe getting the 98 motor bored out and fix that one...

was also looking into swapping a 5.0 into it but I think I'll keep the 2.5 for a little longer depending on cost!

Can anyone give me detailed information on rebuilding a motor, maybe a PDF file or something?

here is what I have to work with...





And all the stuff I need to toss!!!

[sharpxmen]

download the 94 FSM from the FAQ section, has most of the things you need in there (specs, pics, detailed info on clearances and so on) - it's the same motor with very minor differences.

[elpablodiablo23]

I just rebuilt an engine for my first time and I only used the $20 book from autozone.  If you do that though, the only thing I didn't like about it was that the torque specs for some of the miscellaneous stuff was in different sections (not in the 2.5L section).  For instance some information about the crank was under a completely different section because its the same specs as the other 4 engines that the book will detail.  Other than that, the machine shop you take it to can give you a pretty good lowdown on what you'll need/special things to do on your own

[rroadkilll]

I think, for the sake of time, I'm going to have a machine shop build the short block for me...

We got talking the other day and told him I may run ford injectors and he said if I'm looking to get better performance that I need to do some other things like compression...

What do you guys recommend for upgrading the 2.5 internals???

[sharpxmen]

if you want to keep running 87 octane pump gas you won't be able to increase the compression that much. If you can find a Mopar performance gasket and use +.030 larger pistons you'll end up somewhere around 9.4 to 9.5:1 compression (vs. stock 9.1 or 9.2 depending on year). Roller rockers (even with stock ratio of 1.6) will give you some performance increase. A cam will also give you some more ponies. Mopar valve springs might be required depending on the cam you decide to use. Ford injectors you'll have to size properly based on your mods. I don't see the point in going with forged pistons as they'll run you about $500 and if you start there might as well look at an engine swap. KB Silvolite and Speed Pro hypereutectic pistons are good enough for the 4 banger (you'll not going to spin it more than 5500 rpm anyway, or at least i wouldn't. For crank you don't have any options (at least reasonable) so you're stuck with the stock one, you can balance it and will make a bit of a difference. Port your cylinder head and intake manifold and you'll gain a bit more. add a high flow exhaust and the engine will breath better and free up some more power. Stay under the red line on your tach to keep it healthy (the limiter will kick in anyway but i heard conflicting reports here about where and if it cuts out).