91 Jeep cherokee problem Help! - JeepForum.com

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post #1 of 24 Old 12-31-2013, 06:40 AM Thread Starter
91Cherokee7
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91 Jeep cherokee problem Help!

OK the engine in my 91 Cherokee ticks/knocks after i drive it for about 30min(engine at normal temp), i turn it off let it sit for about 10 minutes then thats when it does it when i start it back up. I have to let it sit for about 1hour for it not to do the knocking non stop but it does it for 2 seconds after its been sitting for awhile and at that point the engine is cool. O and the engine does not lose any HP the check engine has never come on. So any ideas what it could be? Lifters, rockers,pushrod. Any Help will be apperated.

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post #2 of 24 Old 12-31-2013, 12:02 PM
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Hi and welcome.
Sorry this had to be your first post.
Can you tell where the knock is coming from? Top or bottom of engine. You can use a piece of hose to help narrow it down.
How's the oil pressure? Does the knock increase tempo with rpms?

http://www.jeepforum.com/forum/f177/92-xj-sadness-2075657/index2.html
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post #3 of 24 Old 12-31-2013, 05:20 PM Thread Starter
91Cherokee7
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I say top part but i could be wrong its hard telling without taking off the valve cover, the noise is loud and slightly gets louder when i increase rpms and the oil pressure is around 35-40 sometimes 45. Its normal for it.O i forgot to say that now since its winter and cold 25 degrees it does not do it as much but then again the engine does not get as warm in the cold.
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post #4 of 24 Old 01-01-2014, 05:31 PM
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If the engines not warming then I would think u have the wrong or no thermostat.

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post #5 of 24 Old 01-02-2014, 05:41 AM Thread Starter
91Cherokee7
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I replaced the thermostat about 2 years ago. I may just take the valve cover this friday and check the lifters. I just hope its nothing mayor because i want to keep the 4.0 engine as original as possible. I want to see how long it last's. I keep everything about my Jeep update on here and i might make a video when i take off the valve cover.
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post #6 of 24 Old 01-02-2014, 11:17 AM
uberxj92
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Use cardboard to make splash guards. Or you'll have a mess.

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post #7 of 24 Old 01-08-2014, 06:49 AM Thread Starter
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Its been really cold and snowing so i have not been able to take the valve cover off yet. I hope to do it soon.
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post #8 of 24 Old 01-09-2014, 04:39 PM
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What brand oil filter are you using?

If you own a Renix Jeep, you'll want to check this out.

An index to over 30 write-ups can be found in the link below

www.cruiser54.com

My Jeep Technical Photos

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post #9 of 24 Old 01-10-2014, 07:45 PM
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Quote:
Originally Posted by 91Cherokee7 View Post
OK the engine in my 91 Cherokee ticks/knocks after i drive it for about 30min(engine at normal temp), i turn it off let it sit for about 10 minutes then thats when it does it when i start it back up. I have to let it sit for about 1hour for it not to do the knocking non stop but it does it for 2 seconds after its been sitting for awhile and at that point the engine is cool. O and the engine does not lose any HP the check engine has never come on. So any ideas what it could be? Lifters, rockers,pushrod. Any Help will be apperated.
What is your oil pressure when the engine is cold and at hot idle? Metallic noises usually means too much space between parts. or no oil pressure for a number off reasons. One being blockage but then the noise would be there when cold also. The other....too much space.

Do you know what was good about the good old days? I wasn't good, And I wasn't old!

Senators and Congressman should wear uniforms like NASCAR drivers so we could identify their corporate sponsors....
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post #10 of 24 Old 01-11-2014, 03:30 PM Thread Starter
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I have been using STP oil filters but i may switch to NAPA GOLD.............. Engine oil pressure when cold is 32 (ish) When hot 40 to 45.
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post #11 of 24 Old 01-11-2014, 04:41 PM
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Quote:
Originally Posted by 91Cherokee7 View Post
I have been using STP oil filters but i may switch to NAPA GOLD.............. Engine oil pressure when cold is 32 (ish) When hot 40 to 45.
STP filters are absolute ****.

If you own a Renix Jeep, you'll want to check this out.

An index to over 30 write-ups can be found in the link below

www.cruiser54.com

My Jeep Technical Photos

http://www.cherokeeforum.com/g/album/1725214
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post #12 of 24 Old 01-11-2014, 05:06 PM
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Quote:
Originally Posted by 91Cherokee7 View Post
I have been using STP oil filters but i may switch to NAPA GOLD.............. Engine oil pressure when cold is 32 (ish) When hot 40 to 45.
Usually....cold oil pressure is higher than hot oil pressure. That is odd.

What weight oil do you use? I use 10W-30 Mobile 1 Full Synthetic oil. I change it every 6,000 miles. I also use a Napa filter. The one for the 4.0 is a Napa 21085.... BUT..... I use a Napa 21515 which is actually a Ford 5.0 filter which has ~35% more filter volume. Has the same threads and diameter but is ~1 1/2" longer.

Oil pressure is not as important as oil flow. Oil pressure is a measurement of resistance not flow.

All oils thin to 10 weight when the engine is at operating temperature with some exceptions.

How does the oil flow when it is cold is most important. Even at air temperatures of 75F, cold regular oil is as thick as molasses.

Years ago a trick was done to clean up an engine oil system and remove small engine 'noises' like sticky lifters. This can be dangerous if not done properly.

One would add a quart of kerosene to the base pan oil. Then the engine would get fired up and left running AT IDLE for four or five minutes. LISTEN very carefully. Any increase in engine noises means shut it off. The biggest clogger in an engines is detergent mixed with oil/crud particulates. This basically is an engine 'physic'. Shut of engine wait for an hour and drain well and let it drain until nothing is coming out. Fill it with clean oil and a filter and see what that does for noises.

Spec this out;

http://www.youtube.com/watch?feature...&v=PDERMk_cYlo

Do you know what was good about the good old days? I wasn't good, And I wasn't old!

Senators and Congressman should wear uniforms like NASCAR drivers so we could identify their corporate sponsors....
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post #13 of 24 Old 01-11-2014, 06:05 PM Thread Starter
91Cherokee7
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Quote:
Originally Posted by cruiser54 View Post
STP filters are absolute ****.
I know. After I changed the STP filter on my moms car I will never again use them.
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post #14 of 24 Old 01-11-2014, 06:20 PM Thread Starter
91Cherokee7
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Quote:
Originally Posted by laybackman View Post
Usually....cold oil pressure is higher than hot oil pressure. That is odd.

What weight oil do you use? I use 10W-30 Mobile 1 Full Synthetic oil. I change it every 6,000 miles. I also use a Napa filter. The one for the 4.0 is a Napa 21085.... BUT..... I use a Napa 21515 which is actually a Ford 5.0 filter which has ~35% more filter volume. Has the same threads and diameter but is ~1 1/2" longer.

Oil pressure is not as important as oil flow. Oil pressure is a measurement of resistance not flow.

All oils thin to 10 weight when the engine is at operating temperature with some exceptions.

How does the oil flow when it is cold is most important. Even at air temperatures of 75F, cold regular oil is as thick as molasses.

Years ago a trick was done to clean up an engine oil system and remove small engine 'noises' like sticky lifters. This can be dangerous if not done properly.

One would add a quart of kerosene to the base pan oil. Then the engine would get fired up and left running AT IDLE for four or five minutes. LISTEN very carefully. Any increase in engine noises means shut it off. The biggest clogger in an engines is detergent mixed with oil/crud particulates. This basically is an engine 'physic'. Shut of engine wait for an hour and drain well and let it drain until nothing is coming out. Fill it with clean oil and a filter and see what that does for noises.

Spec this out;

http://www.youtube.com/watch?feature...&v=PDERMk_cYlo


10w-30 Valvoline.. I may post a video up tomorrow 1-12-14 showing the oil pressure and maybe when I first start it up it might do the knocking should for a sec. I may also look into the kerosene trick (MAYBE). And that video showing the conventional oil when its -35 out is making me switch to Synthetic Oil.
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post #15 of 24 Old 01-11-2014, 06:23 PM
cruiser54
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So, does it tick on startup and then reduce and/or go away?

If so, shut it off immediately. wait a few seconds and restart it. Tick gone?

If you own a Renix Jeep, you'll want to check this out.

An index to over 30 write-ups can be found in the link below

www.cruiser54.com

My Jeep Technical Photos

http://www.cherokeeforum.com/g/album/1725214
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