Jeep Wrangler Forum

Jeep Wrangler Forum (http://www.wranglerforum.com/)
-   TJ Tech Forum (http://www.wranglerforum.com/f210/)
-   -   oil pump bad? (http://www.wranglerforum.com/f210/oil-pump-bad-240315.html)

Wheats 05-05-2013 01:40 AM

oil pump bad?
 
I have an 02 4.0L with the typical fluctuation of oil pressure.
I have already changed the oil pressure sender(mopar oem) the readings are fine when driving and also when I stop at lights. The only time when the check gauges light comes on is when I turn off ignition, go into a store return and start it up. Once I rev it up to get the light off it's all good until I turn it off again.

Is it possibly the oil pump. I'm running 10/30 gastrol oil and Mopar filter.

Thanks
Ken

Wheats 05-05-2013 07:57 PM

Bump, any thoughts

jkp 05-05-2013 08:25 PM

Not if the oil pressure is fine the rest of the time.

Sounds like the oil filter may be leaking down, resulting in a slow build up of oil pressure on start up.

How many miles on it?

jherrington 05-06-2013 12:13 PM

if it worked on the way to the store, i would think the pump would work once you started it back up again.

did you notice any difference what-so-ever after replacing the sending unit?

Wheats 05-06-2013 02:09 PM

Quote:

Originally Posted by jkp (Post 3723066)
Not if the oil pressure is fine the rest of the time.

Sounds like the oil filter may be leaking down, resulting in a slow build up of oil pressure on start up.

How many miles on it?

96 K

Quote:

Originally Posted by jherrington (Post 3725066)
if it worked on the way to the store, i would think the pump would work once you started it back up again.

did you notice any difference what-so-ever after replacing the sending unit?

No change as it did the same thing before I changed the sender.
It only happens on restart when it's at operating temp. Once I rev it and get the gauge to go off it will be good even stopping at long traffic lights.

Thanks

jkp 05-06-2013 03:33 PM

I'd try a new filter first, cheap and easy.

Wheats 05-07-2013 12:59 AM

Quote:

Originally Posted by jkp (Post 3725761)
I'd try a new filter first, cheap and easy.

Did that twice,different oil and filter no change

Thanks

jherrington 05-07-2013 02:43 AM

Quote:

Originally Posted by Wheats (Post 3727975)

Did that twice,different oil and filter no change

Thanks

Filter with back flow preventer?

Wheats 05-07-2013 02:27 PM

Quote:

Originally Posted by jherrington (Post 3728096)
Filter with back flow preventer?

Good thought. I don't have any esperience with those, any brand i should try.

Thanks

jherrington 05-07-2013 02:52 PM

Quote:

Originally Posted by Wheats (Post 3729834)

Good thought. I don't have any esperience with those, any brand i should try.

Thanks

I wouldn't be the guy to ask. I use a Bosch extra capacity filter and I think it's got one. Napa gold might.

jkp 05-07-2013 03:21 PM

The Mopar filter has the anti drainback valve. You should be able to see the rubber through the small holes in the top of the filter.

The computer looks for oil pressure to be within a certain range within a certain time.

Yours is slow coming up for some reason.

You may have to get a mechanical test gauge to see what is going on.

scot68 05-07-2013 03:33 PM

Pick up an inexpensive mechanical oil pressure gauge, remove your new pressure switch and plumb it into that port. Drive around for awhile and repeat the conditions where you experienced the low reading on your dash gauge.This way you'll know if you actually do have a problem. Autozone has cheap gauges for around $20 bucks.

Wheats 05-08-2013 12:10 AM

Quote:

Originally Posted by scot68 (Post 3730092)
Pick up an inexpensive mechanical oil pressure gauge, remove your new pressure switch and plumb it into that port. Drive around for awhile and repeat the conditions where you experienced the low reading on your dash gauge.This way you'll know if you actually do have a problem. Autozone has cheap gauges for around $20 bucks.

Good idea, I think that's my next step

Thanks

Wheats 05-16-2013 01:20 AM

Quote:

Originally Posted by scot68 (Post 3730092)
Pick up an inexpensive mechanical oil pressure gauge, remove your new pressure switch and plumb it into that port. Drive around for awhile and repeat the conditions where you experienced the low reading on your dash gauge.This way you'll know if you actually do have a problem. Autozone has cheap gauges for around $20 bucks.

Well I installed a mechanical oil pressure gauge and on a cold start up pressure is @ 50 then drops to 40 then when driving it's about 20 then after driving for awhile at idle it drops to about 3-5psi.
I don't hear any knocking or anything unusual motor sounds really tight.
What's the next thing to check

Thanks

Angus Brown 05-16-2013 08:34 AM

Umm, 3-5psi isn't high enough in my opinion. Anyone know if the 4.0 I6's oil pump has a high pressure relief spring in it like other makes of engine? Sounds like that spring is going out. That or there is a leak in the block somewhere, but that's exceedingly rare because it would mean a crack in an oil passage, and it should be far more noticeable even when the engine/oil is cold.

I'd replace that oil pump.

flflash 05-16-2013 08:44 AM

Put some Good Mobile 1 10w30 Synthetic oil in it and see what happens. You've either got oil breaking down due to heat or the cam bearings are excessively worn.

jherrington 05-16-2013 03:06 PM

An oil change won't help him.


Don't you mean crank bearings?

Wheats 05-17-2013 12:39 AM

Quote:

Originally Posted by flflash (Post 3761209)
Put some Good Mobile 1 10w30 Synthetic oil in it and see what happens. You've either got oil breaking down due to heat or the cam bearings are excessively worn.

I've done 3-oil changes with different filters and presently has Mopar filter and castrol 10/30


Quote:

Originally Posted by jherrington (Post 3762542)
An oil change won't help him.

Yea I'm done changing the oil.
Bearings? I only have 95k on it and motor sounds great even with low to 0 pressure.
Whats next?












Don't you mean crank bearings?


scot68 05-17-2013 01:22 AM

Quote:

Originally Posted by jherrington (Post 3762542)
An oil change won't help him.
Don't you mean crank bearings?

^^^ This... My guess is also worn bearings. IMO your options are rebuild your motor, replace the motor or you might buy some time by replacing your oil pump with a high volume pump. If it were me I would try replacing the pump first since the motor isn't knocking. Pump, pan gasket, rear main seal, anaerobic sealer, RTV and High Tack. The RMS is not manditory but if the pan is off why not. Altogether should cost you about $150.00. Replacing the pump is not as complicated as it may sound, if you have basic mechanical ability you can do it yourself no problem. Can't paste links on my phone but check out DailyDrivenTJ.com - Welcome for a decent write up on the RMS, this will show everything except removing the pump which is simply 2 additional bolts and a little clearancing of the oil pan for the high volume pump.

All Terrain JK 05-17-2013 06:10 AM

Quote:

Originally Posted by Wheats (Post 3760580)

Well I installed a mechanical oil pressure gauge and on a cold start up pressure is @ 50 then drops to 40 then when driving it's about 20 then after driving for awhile at idle it drops to about 3-5psi.
I don't hear any knocking or anything unusual motor sounds really tight.
What's the next thing to check

Thanks

Had this same issue with my son's '00 4.0. Ran great, no knocks or rattles, just low op when warm. I figured it probably had worn crankshaft main bearings.
Quote:

Originally Posted by scot68 (Post 3764403)

^^^ This... My guess is also worn bearings. IMO your options are rebuild your motor, replace the motor or you might buy some time by replacing your oil pump with a high volume pump. If it were me I would try replacing the pump first since the motor isn't knocking. Pump, pan gasket, rear main seal, anaerobic sealer, RTV and High Tack. The RMS is not manditory but if the pan is off why not. Altogether should cost you about $150.00. Replacing the pump is not as complicated as it may sound, if you have basic mechanical ability you can do it yourself no problem. Can't paste links on my phone but check out DailyDrivenTJ.com - Welcome for a decent write up on the RMS, this will show everything except removing the pump which is simply 2 additional bolts and a little clearancing of the oil pan for the high volume pump.

^^ This is exactly what I did. Purchased a Melling high volume oil pump and installed it. Pretty straight forward job. The hardest part for me was getting the exhaust loose at the manifold. I had to cut the bolts. I also had to install an aftermarket oil pan because the plug in the old one stripped out the threads. I did not have to modify the that oil pan at all but I don't know about the OEM pan. I couldn't imagine it would be more than modifying the internal baffle. It has been a year since the install and still running great. It starts up at 60psi, idles at 20-25psi warm, and highway cruises at 50-55.

Wheats 05-17-2013 11:17 PM

Quote:

Originally Posted by All Terrain TJ (Post 3764673)
Had this same issue with my son's '00 4.0. Ran great, no knocks or rattles, just low op when warm. I figured it probably had worn crankshaft main bearings.

^^ This is exactly what I did. Purchased a Melling high volume oil pump and installed it. Pretty straight forward job. The hardest part for me was getting the exhaust loose at the manifold. I had to cut the bolts. I also had to install an aftermarket oil pan because the plug in the old one stripped out the threads. I did not have to modify the that oil pan at all but I don't know about the OEM pan. I couldn't imagine it would be more than modifying the internal baffle. It has been a year since the install and still running great. It starts up at 60psi, idles at 20-25psi warm, and highway cruises at 50-55.

Thanks. As soon as I get time that's next on my listhttp://www.wranglerforum.com/images/icons/icon14.gif

jherrington 05-19-2013 07:34 PM

Quote:

Originally Posted by All Terrain TJ (Post 3764673)

Had this same issue with my son's '00 4.0. Ran great, no knocks or rattles, just low op when warm. I figured it probably had worn crankshaft main bearings.

^^ This is exactly what I did. Purchased a Melling high volume oil pump and installed it. Pretty straight forward job. The hardest part for me was getting the exhaust loose at the manifold. I had to cut the bolts. I also had to install an aftermarket oil pan because the plug in the old one stripped out the threads. I did not have to modify the that oil pan at all but I don't know about the OEM pan. I couldn't imagine it would be more than modifying the internal baffle. It has been a year since the install and still running great. It starts up at 60psi, idles at 20-25psi warm, and highway cruises at 50-55.

Did you adjust the pressure relief valve any?

All Terrain JK 05-19-2013 08:54 PM

Quote:

Originally Posted by jherrington (Post 3772276)

Did you adjust the pressure relief valve any?

I did not.

Wheats 06-23-2013 10:24 PM

Quote:

Originally Posted by All Terrain TJ (Post 3764673)
Had this same issue with my son's '00 4.0. Ran great, no knocks or rattles, just low op when warm. I figured it probably had worn crankshaft main bearings.

^^ This is exactly what I did. Purchased a Melling high volume oil pump and installed it. Pretty straight forward job. The hardest part for me was getting the exhaust loose at the manifold. I had to cut the bolts. I also had to install an aftermarket oil pan because the plug in the old one stripped out the threads. I did not have to modify the that oil pan at all but I don't know about the OEM pan. I couldn't imagine it would be more than modifying the internal baffle. It has been a year since the install and still running great. It starts up at 60psi, idles at 20-25psi warm, and highway cruises at 50-55.

Well I installed a high volume oil pump although it's better it still drops to zero and check gauge light comes on after driving for awhile(no ticks or knocks). At this point I'm just going to drive it and deal with it down the road.

Thanks for all replies

jherrington 06-23-2013 11:42 PM

Quote:

Originally Posted by Wheats (Post 3892593)

Well I installed a high volume oil pump although it's better it still drops to zero and check gauge light comes on after driving for awhile(no ticks or knocks). At this point I'm just going to drive it and deal with it down the road.

Thanks for all replies

Sorry to hear about that.. If you plan on rebuilding, I would do it as soon as you get the funds/time. Letting your engine wear too much in the state that its end could make it too worn to rebuild

Wheats 06-25-2013 05:33 PM

Quote:

Originally Posted by jherrington (Post 3892875)
Sorry to hear about that.. If you plan on rebuilding, I would do it as soon as you get the funds/time. Letting your engine wear too much in the state that its end could make it too worn to rebuild

Any idea on cost and whats involved if I do it now vs if I wait.

My daughters are home from college and of course are driving the jeep so it will have to wait until end of July

Thanks


All times are GMT -5. The time now is 07:05 AM.