4.0L I6 Jeep

[440Magnum]

Originally Posted By: MrRPM
Originally Posted By: wsar10


running the <> out of it @5k RPM's is not a good way to get to 300k mi.


haha, well this is true. Its a jeep thing though =P
everyone says its a strong engine, well Im gonna test it. haha

but those are my extremes, i may only do that twice a year.


It is a strong engine, but it DOES NOT like sustained high RPM. And there's pretty much no point, its torque is all done by ~4000 RPM anyway and beyond that you're just flogging for no gain. As came up in another thread, the 4.0 is a gasoline engine that performs much more like a diesel. Its all about torque.

 

[jdoria]

I just picked up a 1998 Cherokee with the 4.0l as a project. I just completed a ton of work to it. After reading some Jeep forums, I ended up filling it with Rotella T3 15W40. It's been in there for about 120-150 miles and I KNOW its the wrong oil for this engine. Ticks at start-up then fades. Water temps and oil pressure are fine (I installed a new oil pump, water pump, gaskets, and did a radiator flush with Casade...)

I found this forum and ended up buying 3 gallons of Rotella T5 and 3 gallons 10W30 and Penzoil 10W30 dino. I also picked up 5 of the largers Wix 51515 oil filters. Even though I just did all of the engine gaskets, Im going to stick to an HD dino or blend with this car.

This weekend I plan to change the oil to Rotella T5 10W30 and let you know how it feels/sounds.

 

[jdoria]

One warning...
If you go with a larger oil filter and change the filter from the top of the engine, be careful not to hit the oil pressure sending unit with the filter wrench. The sending unit sits just below the distributor and sticks out over the oil filter. It is made of plastic and mated to a metal threaded nipple. I hit it while removing an oil filter and split it in half.

Fortunately it only cost ~$25 and was simple to replace.

 

[MetalSlug]

btw if your jeep 4.0L made a sound like tractor, its completely normal.

 

[jdoria]

I've never heard a tractor. Are you referring to piston slap or the inherent ticking these engines display in their higher mileage?

I have 3 of these now, all either being restored or complete. Great projects.

 

[MetalSlug]

Originally Posted By: jdoria
I've never heard a tractor. Are you referring to piston slap or the inherent ticking these engines display in their higher mileage?

I have 3 of these now, all either being restored or complete. Great projects.


tick, if you heard the slap noise, its very bad new.

 

[84zmyfavorite]

Ive got 6 Cherokees, 4 of have the 4.0, and none of them sound like a tractor. Well my 84 with the GM sourced 2.8 Liter V6 might sound like a lawn tractor. Actually I call it the Briggs&Stratton cause it does sound dorky and make about as much power as a Lawn Tractor. Yes, 4.0s can be a bit noisy, which means parts are getting worn. My beloved 01 SilverStone Metallic 4.0 Liter Cherokee has 64,??? miles on it now, and runs as smooooth as it sounds. A "Still" non-moving Heinekin on the valve cover while at idle is my gauge. Now 87s got faded paint an 291,??? on her all original everything and is fairly smooth as well. My 96 has its AX15 5 speed is pieces in my living room, so its 248,??? mile 4.0 isnt running now, but is a smooth and powerful 4.0 as well. My 99s 4.0 is in pieces as well, Sealed Power pistons and Hastings cast rings are to be ordered tomorrow. I will break this motor in with a mix of Havoline SL rated 10w-30 (2003 circa) and Havoline 10w-40 from 2009. My 01 has Quaker State 10w-40 in it now. My 87 has 14,000 mile Accel 10w-40(SF rating), my current daily driver, my Brown 84 with the GM V6 has 22,??? mile Accel ND30 in it. For you Jeep, I would use Rotella 10w-30 T5.

 

[84zmyfavorite]

Piston slap is very common in High mileage 4.0s. That and a wrist pin egging out #2 piston is the reason my 99s 4.0 in getting a rebuild. 24 hours of Porting to the cylinder head and 20 thousandths milled off, hopefully will help move this 2 wheel drive XJ even a bit Quicker!

 

[84zmyfavorite]

Yes, some 4.0s DONT like 15w-40 HDEOs, and some LOVE it. Ive seen this also.

 

[84zmyfavorite]

I mean, Heard it also.

 

[MrRPM]

What would be the advantage of using a larger oil filter?
hold more oil? [censored] thing already holds 6 Qts.

also, about the M1 0w-40...my local walmart sells it but only in 1qt containers. what do you guys think about running 4 qts TDT and 2 qts 0w-40 in the winter, good idea or waste of time?.

I hear alot about rear main seal leaks...where exactly is the rear main seal? Im pretty positive my jeep does not leak any oil right now but id like to keep an eye on it.

 

[jdoria]

I think the advantage is just having more filtration area, and some more oil volume. I got just under 6.5qts in.

Rear main seal is simple on this car. Its a two piece gasket, that cost ~$8 directly from Jeep. It sits between the engine and the transmission, if you see oil there, its likely you need to replace the gasket. The transmission doesnt need to be dropped to replace. I have done the rear main seal on all of mine.

While you are under there, for another $40 you can replace the tansmission fluid, filter, and gasket. Maybe you want to do the O2 sensors too?

Thats the beauty of these old Jeeps, everything is inexpensive, durable, and simple. I spent about $4k in total on my 1998 and the thing is NEW. I did do a lot of the work myself for the experience, that saved me a bit on labor. You can google everything and find 43,503 responses and make your own call on how to do something. the aftermarket support is over the top.

 

[Donald]

What year is the Jeep? On some years you need to watch out for piston skirt failures.

 

[MetalSlug]

Originally Posted By: Donald
What year is the Jeep? On some years you need to watch out for piston skirt failures.


happent alot in 99 and early 2000 I think. but I know peoples at other forum happent in his 2004.

 

[Kuato]

Question for all those recommending the Rotella T6 5w40 for the 4.0...do you know if it is a thinner 40w when up to temp?

I've always considered using it but am a bit put off by the 40w going into something spec'd for 30w

 

[Lead Shoes]

The 4.0 loves 40wt oil, it will do excellent on T6 5w40 especially in a warm area.

 

[wsar10]

Originally Posted By: Kuato
Question for all those recommending the Rotella T6 5w40 for the 4.0...do you know if it is a thinner 40w when up to temp?

I've always considered using it but am a bit put off by the 40w going into something spec'd for 30w

If your concerned with it than run T5 in 10-30, its a heavy 30wt

 

[jdoria]

What about Amsoil Heavy Duty Diesel Oil in a 10W-30? It was recommeneded to me and Im going to try some after the Rotella is out of the engine.

 

[MrRPM]

thanks for the info on the main seal, also i have already done the tranny filter service. when I bought the jeep i did everything, i love to do maintenance and it makes me feel better knowing im doing everything I can to make my jeep last.

should O2 sensors be replaced even if there are no problems? I figured once the jeep throws on the engine light is when its time to replace them (if the CEL is for the o2 sensors)

my jeep is a 2001, can you give more information about these piston skirt failures? is it due to lack of lubrication or [censored] pistons?

 

[440Magnum]

Originally Posted By: 84zmyfavorite
Ive got 6 Cherokees, 4 of have the 4.0, and none of them sound like a tractor.


I think they sound like tractors (specifically like an Oliver 1600). But then I mean that as a compliment- an Oliver 1600 was smooth as silk, purred quietly at idle, and had torque to reverse the earth's rotation.