4.0 sounds like a diesel
#1
Newbie
Thread Starter
Join Date: May 2013
Location: portland OR
Posts: 23
Likes: 0
Received 0 Likes
on
0 Posts
Year: 1990
Model: Cherokee
Engine: 4.0
4.0 sounds like a diesel
Hey guys I just did another oil change o switched to valvoline high miles synthetic blend with a wix filter my engine now sounds like a diesel someone told me I might need new main bearings. Is tgat tge case? If so can it be done without pulling engine? Any advice would be great. 1990 cherokee 4.0 renix with 240k also she's seems to be getting gutless on freeway what could be causing loss of power??
Ty in advance
Ty in advance
#5
Junior Member
Join Date: Mar 2014
Location: Mid-Mich.
Posts: 75
Likes: 0
Received 0 Likes
on
0 Posts
Year: 1995
Model: Cherokee
My XJ has sounded like a diesel for 19 years! If it got louder after an oil change, see Salads's answer, or better yet, look at your oil pressure gauge. It should have about 20-30psi at idle, and 40-50 at driving rpm's. Maybe you're just paying more attention to noise because you just changed oil? If you're running a good oil pressure, you should be fine. One thing I've learned about 4.0's is that at higher mileages, [above 150,000] they like thicker oil. Salad had a great oil thread a while ago about using 15x-40 Rotella and it helped me quiet my XJ down a little. But they still make noise.....
#6
Newbie
Thread Starter
Join Date: May 2013
Location: portland OR
Posts: 23
Likes: 0
Received 0 Likes
on
0 Posts
Year: 1990
Model: Cherokee
Engine: 4.0
I was wondering about that. It did get louder after switching to the synthetic blend. I'm using the 10-30 blend for high mileage engines. I've heard once you go synthetic your stuck with it. Is tgat the same for the blend? Or should I go thicker oil next time?
#7
Junior Member
Join Date: Mar 2014
Location: Mid-Mich.
Posts: 75
Likes: 0
Received 0 Likes
on
0 Posts
Year: 1995
Model: Cherokee
No, that's not true. You can switch back and forth between synthetic and convential with no problem. As a matter of fact, most oil companies also sell 'blends' of synthetic and convential at a slighty reduced price than full synthetic. Look at 'Salads' thread on this forum about engine oil for 4.0's. He's not paying me to say this, but it's one of the most comprehensive review of engine oils I've ever seen. I used his advice on Rotella, and I was happy w/results. Old 4.0's like thicker oil.
Trending Topics
#8
Herp Derp Jerp
Join Date: Nov 2011
Location: Parham, ON
Posts: 18,251
Likes: 0
Received 13 Likes
on
12 Posts
Year: 1999
Model: Cherokee
Engine: 4.0L OBD-II
lol you have to go and set your title to whatever you want it to be :P
What oil was in it before? Some engines do better or worse on some kinds. If I observed a change like that I'd just go back to whatever you were running before assuming it wasn't molasses.
For fun, have you eliminated the flexplate bolts as a source of noise?
What oil was in it before? Some engines do better or worse on some kinds. If I observed a change like that I'd just go back to whatever you were running before assuming it wasn't molasses.
For fun, have you eliminated the flexplate bolts as a source of noise?
#9
Seasoned Member
Join Date: Sep 2009
Location: Coventry, CT
Posts: 273
Likes: 0
Received 1 Like
on
1 Post
Year: 2000
Model: Cherokee
Engine: 4.0 high output, Alabama Cylinder head, 60mm bored TB
Try going back to whatever oil you ran before and see if that helps. I've noticed my 4.0 is a bit more noisy than normal when running a synthetic oil compared to a conventional. It doesn't hurt anything, but theres definitely a difference.
#10
::CF Moderator::
Join Date: Aug 2011
Location: Prescott, Az
Posts: 43,971
Received 1,559 Likes
on
1,263 Posts
Year: 1990
Model: Cherokee (XJ)
Engine: 4.0
lol you have to go and set your title to whatever you want it to be :P
What oil was in it before? Some engines do better or worse on some kinds. If I observed a change like that I'd just go back to whatever you were running before assuming it wasn't molasses.
For fun, have you eliminated the flexplate bolts as a source of noise?
What oil was in it before? Some engines do better or worse on some kinds. If I observed a change like that I'd just go back to whatever you were running before assuming it wasn't molasses.
For fun, have you eliminated the flexplate bolts as a source of noise?
https://www.cherokeeforum.com/f51/ho...ocking-125547/
Straightshooterjeeps cracked flexplate diagnosis
I removed 3 of the 4 bolts.
Then loosened the last bolt about half way.... I left this one in to maintain connection between the tq and the plate. Just so I wouln't have to fiddle with putting bolts back in too much.
Now the flexplate is pretty much seperate from the torque converter.
Got my flashlight pointed up in there
Grabbed a big flathead screwdriver and started prying on the flexplate
Don't see anything yet
Turn the flexplate a half rotation
Pry again
and there it is! A big fat crack up near the center of the plate.
When the flexplate is loose from the torque converter you can get it to "flex" real good and you just might be able to spot your crack.
Just to be sure you do have one before dissasembly.
It was very obvious at this point, but before pulling those bolts I looked and looked and could never see a crack.
Hope this helps save someone a little time.