Running hot and low oil pressure

[ScottB]

I have a 2005 TJ, 4.0 automatic with 143,000 miles. The TJ was bone stock when I got it a year ago; not so much now. I have put about 6,000 miles on it.

Today while out wheeling with some friends, I took the wrong path and went a really deep mud hole. Completely covered the winch and front bumper. I had to be winched out. Everything was fine.

In Alabama it is hot, so I was wheeling with the AC on, but the going was slow. After the mud incident, the AC worked fine for about 20 minutes, then all of a sudden hot air out of the vents and the check gauges light and the buzz and temp gauge was in the red but not all the way on 260. I immediately shut down and the radiator was hot! The overflow was boiling, but no anti freeze was leaking from anywhere.

We began pouring water ON the radiator and it would boil instantly. After about 20 minutes, everything cooled back down to 210 degrees. I got to moving and everything was fine. Motor ran fine and engine stayed cool.

It was time to head home; no AC. About 20 miles down the highway, hot again. I shut down and repeated the above. This time, I ran the heater on high at 60 MPH and everything was fine.

While driving, I turned the heater off and in less than 2 minutes hot again.

Repeated the same cooling process.

When I was about 1 mile from home, I turned the heater off and hot again in no time. This time the oil pressure plummeted and there was a whining noise, much like a power steering pump; even when sitting still.

My thoughts, there is mud in the radiator fins and not allowing it to cool or a water pump is going out. I don't understand the AC thing at all and I'm guessing OPDA with the noise and the low oil pressure.

I do have a Mopar oil pressure sensor.

The motor runs fine, when cool, and responds normally.

I am not leaking any fluids.

Thoughts ..............................

 

[Stockli]

Did you make sure your belt isn’t slipping?

Your fan is turning? Yeah rinse out the radiator.

What exactly was covered in mud?

 

[ohiopatriot]

Definitely rinse out the radiator and condensor fins thoroughly.

The cooling system and AC condensor need air flow across those fins to cool them. The AC condensor sits in front of the radiator.

Change the oil since the engine was running hot.

Make sure belt is OK. Then drive it and see if symptoms persist. You'll probably be OK, the 4.0 is a tough old cast iron engine.

 

[ScottB]

Did you make sure your belt isn’t slipping?

Your fan is turning? Yeah rinse out the radiator.

What exactly was covered in mud?

The belt was squealing for a couple minutes, but then stopped. The drive home was 70 miles. The fan is turning; well at least it is at an idle.

 

[Jerry Bransford]

Take your time cleaning up your radiator's cooling fins with a garden hose. It's highly likely a significant percentage of them are completely covered with mud so they can't provide any cooling.

 

[ScottB]

Take your time cleaning up your radiator's cooling fins with a garden hose. It's highly likely a significant percentage of them are completely covered with mud so they can't provide any cooling.

The AC condenser is in front of the radiator. I assume I will need to remove the AC condenser to get to the radiator cooling fins?

 

[Stockli]

spray the condenser and radiator down with simple green and fluid the fins with a hose until it runs clear. Shouldn’t need to do much more than that

 

[ohiopatriot]

If you don't flush them both thoroughly the air can't flow through to the radiator. It stands to reason if the radiator fins are significantly covered the condenser fins are highly likely to be also. No need to remove but take your time and flush well.

 

[Xposure]

Do you have a automatic? The previous owner of my Jeep sank it in like that and got water in the vent of the trans which ruined the transmission. You might want to change your trans fluid unless you can easily tell it didn’t get wet. Also, if automatic it appears the trans fluid runs through the radiator for cooling so if your coolant is running hot your trans fluid may be getting cooked too so even if it’s fine I may would still change the fluid.

 

[ScottB]

Well.............I flushed and I flushed and I flushed. I then went for a 20 mile drive. Everything was fine. Temp did not raise and Jeep ran fine; until I pulled into my neighborhood. Immediately hot again. I still have this whining and scrubbing type sound while running and at idle. The sound increases when the RPM's increase. I am now thinking water pump. Never heard one make noise before, but I guess they can.

Also, the motor is hard to turn over, kinda of like a lower battery, but runs fine after starting. I checked and it is not a battery issue.

Is it possible that the water pump is bad and it is putting a strain on the engine during starting??

Still no AC, so I thought the noise was from the AC compressor????

Still randomly at idle, oil pressure drops to low.

 

[Stockli]

Check to make sure your ac pump is not seized or starting to fail, make crud in the clutch. Make sure your belt is not slipping and that your fan clutch is not messed up. I’d pull the belt and start by spinning the ac and see what it feels like. And then clean everything and reinstall and tension the belt.

 

[Boinked]

Also, the motor is hard to turn over, kinda of like a lower battery, but runs fine after starting.

i would pull your belt and look for a pulley that is very hard to turn. might have a barring about ready to seize. when mine started to crank like that my ac clutch pulley froze. but yours could be any pulley.

Still randomly at idle, oil pressure drops to low.

mine shows the same thing. i have even tested it with a manual gauge and it shows good oil pressure. any time i get a little moisture under the hood it stops working for a while then returns to normal (ish). I have looked for a permanent fix but all i could find was to add the manual gauge.

 

[ScottB]

Well, not to be deterred, I rinsed the radiator again and more mud, lots more. So, another drive and no more running hot, so maybe that was the problem.

I removed the belt and the pulleys turn easy. I noticed that the AC compressor has a scrubbing feeling and is not silent.

I'll replace the AC compressor and see if the sounds goes away.

 

[ScottB]

Update.......
The scrubbing/grinding sound stopped. The AC compressor completely locked up and started to destroy the serpentine belt.

Also, the fan was not turning very well. It could be completely stopped with the engine running. The fan clutch is worn and needs to be replaced. Probably a big part of the reason the Jeep was running hot.

 

[Boinked]

Update.......
The scrubbing/grinding sound stopped. The AC compressor completely locked up and started to destroy the serpentine belt.

Also, the fan was not turning very well. It could be completely stopped with the engine running. The fan clutch is worn and needs to be replaced. Probably a big part of the reason the Jeep was running hot.

Well it sounds like the a/c clutch baring. You might get lucky and be able to put a new clutch on it. No need to break open the a/c system. So you can save money not buying a compressor. That is if your a/c worked before.

 

[Stockli]

Update.......
The scrubbing/grinding sound stopped. The AC compressor completely locked up and started to destroy the serpentine belt.

Also, the fan was not turning very well. It could be completely stopped with the engine running. The fan clutch is worn and needs to be replaced. Probably a big part of the reason the Jeep was running hot.

Yep the mud ate your bearing and probably caused your seal to rupture loosing coolant. I’d also swap out the fan clutch but I would bet that ac compressor was causing your belt to slip on the fan pulley not turning it fast enough

 

[ScottB]

Yep the mud ate your bearing and probably caused your seal to rupture loosing coolant. I’d also swap out the fan clutch but I would bet that ac compressor was causing your belt to slip on the fan pulley not turning it fast enough

The fan clutch does have a a slight wobble so it is also being replaced.

This is another reason why I hate mud.

 

[Xposure]

If you turn the a/c off the pully clutch should disengage and free spin, not turning the compressor.

This is another reason why I hate mud.

I agree....When we got the Jeep my son asked if we were going to take it “mudd’n” (that’s how you say it in Alabama haha) and I said...nope, it’s for trails and we will try to avoid the mud as much as possible. The previous owner ruined the auto trans by going in a mud hole that was deeper than he thought and got water and dirt in the vent hole of the transmission. He tried to rebuild it himself with a buddy twice, then had a shop do it for $2k.

 

[Matt77]

Glad you figured it out. Last time I had those symptoms it was the thermostat getting stuck but then you dunking it in the mud musta been something different. Lol

 

[Jerry Bransford]

Mud is a great destroyer of 4x4 vehicles