Experience with new motors?

2000
ATK 4.0
159k...(bout 10 whole miles on motor)

Stock motor had piston slap that was beginning to sound like a rattle can in a paint shaker and being a sucker for my jeep... in goes a new(Reman). Ill also note that she got two new upstream O2's, brown dog rubber motor mounts, and a set of banks headers.... and yes i have no money now

Anyways, shes in and purring however im wondering if anyone with experience with new motors can lay some concerns of mine to rest, or bring them to light.

So first up, oil(10w-30) pressures kinda got this "all over the map" deal going on. When i fire her up it will hang at 50 and raise to 60 under load. after awhile she "normals" out and stays at 40 raising ten under accel load and dropping 10(from 40) at idle. but after a good drive itll drop down to 20 at idle and go back and forth between 40.

New brown dog rubber motor mounts went in with the motor. got quite a bit of vibration at idle. does it in park and neutral but not nearly as bad as when i put it in drive. once gas is applied it gets worse for a split second and then all but disappears. i'm assuming the mounts need time to set in? i figure ill let her wiggle for awhile, see what happens and then try loosing the thru bolts a tad if it doesnt get better.

she wants to get hot in urban stop and go driving. did fine(tick below 210) leaving work, freeway for 20min, then she juuust started to climb up by the time i reached home. nothing extreme, a tick mark past 210's the highest its reached so far, i was driving all around town, but her normal was a tick below before. t-stat on her is only a few months old so i opted not for a new new one. i should note that while driving around town i was rocking a leaking rad cap which was replaced prior to the drive home. im guessing this heat and the oil pressure issues are related

I knew there was gonna be "new stuff" going on and im aware that shes still getting her grooves in, im simply curious if stuff like this can be expected during the "break-in" process. My mechanic(old school guy, hot-rodder, even let me help with the swap) didnt seem all that worried about any of this and told me to "keep yer eye on her", watch fluids, listen and go from there.

Thank you for reading all that haha. Any insight is greatly appreciated as always

The oil pressure drop would bug me, but the higher temperatures I would expect. Piston rings are breaking in with rough cylinder walls. That's an abrasion/polishing process. Once the rings and walls are well acquainted they will get along better and there will be less heat. As a matter of personal preference I like frequent oil changes during this process.

I would inquire of the rebuilder regarding the oil pressure. That sounds like the tolerances on the bearings are too loose. It tells me they should have ground the crank and gone with a plus size bearing, but opted instead to regard it as at the extreme end of acceptable tolerances. I don't know what kind of warranty comes with that motor, but I would be making sure all the i's are dotted and t's are crossed so I could make a claim if need be.

MrAnderson said:

itll drop down to 20 at idle and go back and forth between 40.

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It does all that at idle?

It should hold steady oil pressure at idle... not jump all around.

What filter are you running?

My engine has about 2000 miles on it, its stays at 40psi at 198º (my gauge shows this as a tick under 210). Dont trust the gauges... get a scan gauge II to see your temp readings.. you may be freaking out for nothing.

But I could not find where the scan gauge II reads oil pressure... for that you may need a mechanical gauge. I would be concerned if the pressure is fluctuating while sitting at idle though. That is weird.

Talyn said:

It does all that at idle?

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Tony_SS said:

It should hold steady oil pressure at idle... not jump all around.
I would be concerned if the pressure is fluctuating while sitting at idle though. That is weird.

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i do apologize, it doesnt jump around at idle, it follows the same routes as before and i just shortened it. after a decent drive itll hang at 20 when idling, rasie to almost forty under load. it does not change unless change is applied... i may not know much about this stuff but if my oil pressure gauge is flying all about and im not doing anything yea... weird's a word i might use, daaaaaa f#%k? with red flags shooting off in the background is more likely though

also, ill give atk a call either way

The oil pressure sounds completely normal to me.

Here is mine running 10w30:

Cold start: Hangs around 50, then goes to 60 when under load or revving engine

Once warmed up: Hot idle is around 20 psi, goes up to around 40ish when under load or driving. Highway doing 60 mph when hot is 45-50 psi.

Two other XJs I maintain are the same as mine. Yours sounds normal to me.

The running warm issue could be a few things:

-Was the radiator flushed when the swap was done? Sounds like it might be clogged or worn out.

-How old are your fan clutch and water pump?

"ron" from atk is gonna give me a call back

jeepkid03 said:

The running warm issue could be a few things:

-Was the radiator flushed when the swap was done? Sounds like it might be clogged or worn out.

-How old are your fan clutch and water pump?

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as for the flush not sure really what that entails. we did drain all the fluid out during the install and he saved it to put back in(which i thought was odd) because its only a few months old because a few months ago i replaced a weeping water pump with a new unit. fan clutch could be stock for all i know but is quite clean, thought about going to a zj one so ive looked and played with it

he (mechanic) mentioned there might be bubbles in the system, i figure i can keep my eye out for a slanted place to park and burp any bubbles out. he also mention domething about putting a hole somewhere near my t stat to allow any bubbles to come out. had all kinds of shit on my mind on the time and cant recall the details

There could be air in the system. The newer model cooling systems are self-burping, and after a couple temperature cycles they are burped. You just have to add coolant to the overflow tank if you notice it is lower after driving.

Does the temp creep up at idle? That would point to a bad fan clutch. Fan clutches wear out every 5-7 years, so if its original it is definitely due for replacement. I would avoid the ZJ fan clutch. They are very loud and annoying and hurt gas mileage.

so i just talked to Mr Ron whom was quite pleasant, he says my questions are valid and understands my worry but to him it sounds like everything's going normally. as long as the pressure stays within specs 13-75 its nothing to worry about. although he says i should have replaced the pickup tube :/ i cleaned it myself. he basically told me thw same thing my guy did. check fluids often, listen and let her break in.

the next projects on the list are cooling related... 2 or 3 row rad and triple e-fan kit so the clutches days are numbered as it is

You dont need to go crazy on aftermarket cooling... a factory radiator and fan clutch will do. Anything else and you cover up the rear problem. Verify the temps, do not trust your gauges. High temps will lower the oil pressure. You want to be around 200 or less for normal driving.

To get rid of a bubble do research. Point the front end up a little. Start it w/o the cap on. Turn your heat on high and let it warm up to temp. That should clear out any air. Keep an eye of coolant level too.

the rad and kits been on the list awhile now. i get vap lock from under hood temps, has gotten alot better since wraping the rail and installing the LeBarons but the fan kits the kill shot oh and the rad in its not even a year old... got that baby from learning to be gentle when replacing an upper rad hose

i mentioned that i would keep my eye out for a slanted place to park cause i have looked into the bubbles thing

id like to say thanks for all the input up to this point real quick

MrAnderson said:

i do apologize, it doesnt jump around at idle, it follows the same routes as before and i just shortened it. after a decent drive itll hang at 20 when idling, rasie to almost forty under load. it does not change unless change is applied... i may not know much about this stuff but if my oil pressure gauge is flying all about and im not doing anything yea... weird's a word i might use, daaaaaa f#%k? with red flags shooting off in the background is more likely though

also, ill give atk a call either way

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Sounds fine to me.

is the oil pressure sending unit new? Have you considered hooking up a mechanical gauge? what about using a IR gun to check temps all around the engine?
just some ideas.

at first glance it seems OK. If you burp out the air, make sure the Fan clutch is good, make sure the eFan is coming on, and just change oil and use good oil during the break in, it should be fine.

I was a freak on changing oil during breakin. Did my initial 2000 rpm for 20mins. Changed oil. 500 miles later oil changed. 500 miles later changes again. I'm at 1000 miles... getting crazy, but I think I'll go another 1000 and change it. I also use a magnetic drain plug and have picked up some minor dust each time.

You never said what oil filter??

blondejoncherokee said:

is the oil pressure sending unit new? Have you considered hooking up a mechanical gauge? what about using a IR gun to check temps all around the engine?
just some ideas.

at first glance it seems OK. If you burp out the air, make sure the Fan clutch is good, make sure the eFan is coming on, and just change oil and use good oil during the break in, it should be fine.

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the sender units not new but was functioning fine prior to swap, can gain access to mech gauges and a gun. will look into it.

gave the fan a spin and theres the normal resistance, seems up to par. efan almost got my finger so thats working fine i bought 6 quarts of mobile 1 full syn 10-40 anda wix for when she rolls over 500, but i know asking if thats a good oil opens up a can of worms haha. i will note that the only 10 40 they had in mobile 1 full syn says high mileage on it which iirc means it has detergents in it which makes me wanna go another route?

I have run 10w30 valvoline conventional on mine since day 1. I used some lucas ZDDP during break in for the first 1000 miles.

I have read to avoid any synthetic oil until the rings are seated which usually doesn't happen until 2500 miles.

I plan on running conventional until at least 3 or 4k miles and then going to a synthetic after that.. maybe Rotella T6 or Mobil 1 synthetic.. not sure yet.

Electric fans are pricey and you have to play around with the temp sensors a bit to figure out when you want the fans to turn on. They may help power and gas mileage a tiny bit, but they are more money then they are worth in my opinion.

I have a 2000 (complete with pre-cats and previous heat soak issues) and mine runs 195-206* all day long even in summer heat, verified by my Scan Gauge II.

My cooling system is newer stock parts besides a CSF 3 row radiator, Hesco high flow thermostat housing, and Stant Superstat 195* thermostat. I have had this setup for 2 years now and the highest I have seen the temp reach was 211*. This was on a long hill climb on a summer day pulling a trailer. Two seconds later the temp dropped back down to 200*. I don't even have hood vents on my Jeep. :rof:

Tony_SS said:

I have read to avoid any synthetic oil until the rings are seated which usually doesn't happen until 2500 miles.
.

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whats all this ?

manual and site says to run all syn after 500

jeepkid03 said:

My cooling system is newer stock parts besides a CSF 3 row radiator,

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its on the list