Fixed cold start tick, came back after OC

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JeepWJ19

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Hey all,

So my 4.0 is very picky. I have been on a very long quest to try to find the right oil combo to make her quiet. And then I did. When I had a mix of 5qt PYB10w30 and 1qt of 5w30 it ticked on cold start in weather that was below 50*F. I was consuming a tiny amount of oil and I topped it up with PHM5w30. Then the ticking stopped altogether. Since then my latest OC has been 5qt PHM10w30 and 1qt PHM5w30. Now it cold start ticks every time the weather is above 60*F.

So talking to another jeep guru who loves oil said that PHM 10w30 is super thick compared to PYB10w30. So we got in a long discussion and it seems like my 4.0 doesn't like those 10w oils. Usually it has great oil pressure (55-60 psi on startup) and 40-50psi at operating temperature. So I found it weird that the combo of 10w30PYB, 5w30PYB and a tiny amount of 5w30PHM was able to quiet that cold start tick (no matter what temperature was outside).

I was thinking, it seems like my 4.0 wants a better flowing oil, not so much "thickness"? Thus I was thinking of switching from running 10w30 to just running PHM5w30 year round. Now the only other thing is, I heard and I forget where, is that the 5w30Pennzoils like YB and HM have been shown to shear at 3,000 miles? Is that still true? Would replacing a qt of 10w40 be able to protect it?

Thanks all!
 
I got this jeep 4 years ago with 80 thousand miles. Since then I have racked up to 133k miles and have used the MOPAR OEM MO-090 filter and the FRAM TG16 - whichever one I felt like buying that day. I give it 4000k mile OCIs because there's a lot of times that I make quite a bit of short trips and I do the occasional off roading during the winter.

Runs like a charm and the ticking goes away pretty soon, maybe within a 30 seconds of driving?
 
Last edited:
I don't have the early model castings (99-early 2002s). I have the better designed head etc in my 2002 since it was at the end of the 2002 production. If it was a cracked piston skirt the ticking wouldn't stop after the first 30 seconds of cold start. Nor would it have lasted this long, especially since I like to give it some gas (relative for a 4.slow).

I think if it was a cracked skirt my jeep would have blown up by now LOL!
 
My Jeep did that on its previous oil change and took a little under 2k for it to quiet up.

I didnt have that issue with my current blend.
 
From what I read, even though the PHM is thicker, the 5w30 still flows better than 10w30PYB so that's why I was thinking that if I switch to 5w30, it SHOULD solve it again. The only problem is that shearing issue - if it's true
 
Originally Posted By: JeepWJ19
I don't have the early model castings (99-early 2002s). I have the better designed head etc in my 2002 since it was at the end of the 2002 production. If it was a cracked piston skirt the ticking wouldn't stop after the first 30 seconds of cold start. Nor would it have lasted this long, especially since I like to give it some gas (relative for a 4.slow).

I think if it was a cracked skirt my jeep would have blown up by now LOL!


I am not exactly sure when the production started or ended (except it was there in 2001), but I believe the issue was the piston rings were closer together than they had been in previous 4.0 engines and after 100K miles of cylinder wear, the piston would begin to wobble and eventually crack one of the piston skirts.
 
Originally Posted By: dlundblad
Here is KCJeep's UOA with 5w30 oil.
https://bobistheoilguy.com/forums/ubbthreads.php?ubb=showflat&Number=2948797

Yes it was a slight brew, but Blackstone mentioned it was in the 5w30 range. Regardless, its enough to keep me away.




Thank you, I could never find his thread. He's the one I've been talking to constantly. He brewed a 5w20 with it - well I can understand why it would shear. But PHM is thick and discussing with him - adding a qt of 10w40 should help out that shearing some.
 
Originally Posted By: JeepWJ19
Originally Posted By: dlundblad
Here is KCJeep's UOA with 5w30 oil.
https://bobistheoilguy.com/forums/ubbthreads.php?ubb=showflat&Number=2948797

Yes it was a slight brew, but Blackstone mentioned it was in the 5w30 range. Regardless, its enough to keep me away.




Thank you, I could never find his thread. He's the one I've been talking to constantly. He brewed a 5w20 with it - well I can understand why it would shear. But PHM is thick and discussing with him - adding a qt of 10w40 should help out that shearing some.


Perhaps. It'd definitely be interesting to see this backed by a UOA.
 
Originally Posted By: dlundblad
Originally Posted By: JeepWJ19
Originally Posted By: dlundblad
Here is KCJeep's UOA with 5w30 oil.
https://bobistheoilguy.com/forums/ubbthreads.php?ubb=showflat&Number=2948797

Yes it was a slight brew, but Blackstone mentioned it was in the 5w30 range. Regardless, its enough to keep me away.




Thank you, I could never find his thread. He's the one I've been talking to constantly. He brewed a 5w20 with it - well I can understand why it would shear. But PHM is thick and discussing with him - adding a qt of 10w40 should help out that shearing some.


Perhaps. It'd definitely be interesting to see this backed by a UOA.


I might have to be the guinnea pig for that. It seems that Pennzoil is the only oil my 4.0 likes. BTW how did your recent brew of the (I THINK 10w40 with 5w20 with fram????) go?
 
Originally Posted By: Donald
Originally Posted By: JeepWJ19
I don't have the early model castings (99-early 2002s). I have the better designed head etc in my 2002 since it was at the end of the 2002 production. If it was a cracked piston skirt the ticking wouldn't stop after the first 30 seconds of cold start. Nor would it have lasted this long, especially since I like to give it some gas (relative for a 4.slow).

I think if it was a cracked skirt my jeep would have blown up by now LOL!


I am not exactly sure when the production started or ended (except it was there in 2001), but I believe the issue was the piston rings were closer together than they had been in previous 4.0 engines and after 100K miles of cylinder wear, the piston would begin to wobble and eventually crack one of the piston skirts.


You're probably right, but again, I really really really don't think my jeep would have lasted this long if it truly did crack or break a piston skirt.
 
If it was a crack, it wouldnt go away once hot. I have been preaching this for the passed 3 years and 40k+ miles.
 
On startup my oil pressure is right at 55-60psi judging it off my guage on the dash which I assume is great/good. Dont really know how fast, id say normal.

I just find it weird that it was completely non existent when I had that weird mixture of PYB10w30, PYB 5w30 and PHM 5w30. It is probably lifter bleed down but it seems like that is because the 10w by itself doesnt flow good enough.

What happens when I use just 10w is it'll start for the first 5 seconds fine then the engine shakes a little and the exhausts burbles. Which I assumed being the too thick of oil causing bleed down.
 
Still have a 1993 4.0 Grand Cherokee with about 250K miles. Never been touched but it has a nice cam rattle on startup. Found it likes 10W30 dino in summer.

Havent run it in the winter for about 7 years but when I did it got 5w 30 dino. Tried syn and syn blend a couple times, which helped a little but very little.

Did try a 15 w 40 one summer. Was a bit quieter when real warm but on cool mornings like around 30 or so it was a little stiff acting.
 
If its related to deposits on lifters then follow Molakule's advise. I had a dirty lifter issue that was cured by using Pennzoil Ultra but it took about 600 miles to free it up. The Mola's solution of using a high detergent additive is quicker and cheaper.
 
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