Overheating and Overhead display problems.

[Peteyg]

Hummmm? Never heard of that. I wonder what could cause that. :dunno:

I'm pretty sure my radiator was clogged and the water pump was pulling monster suction. The problem went away after I replaced the radiator.

Another thing to note:

Way back when, on my TJ when the radiator died I replaced it was an all metal 3 row one, and my engine ran HOTTER. This time around I bought an OEM spec radiator and I'm running dead-on normal now.

 

[heyhar]

I think many of the 'seasoned' veterans on here would agree with me when I say you should use ONLY a genuine JEEP T-stat, from the dealer. We've got four XJs, and although none have been chronic over-heaters, from our experience, the JEEP T-stat works the best. The little check-ball constantly helps to burp the system, in which the radiator cap is not the highest point in the system.

I just went through the same deal with my '04 Outback. Just had the head gaskets and the timing belt done, with a new T-stat installed. It kept wanting to over-heat, so I got hold of a dealer T-stat for it. Now, it behaves. Even though the store-bought T-stat had a bleeder, similar to the genuine piece, it just wasn't allowing the system to purge air. The 'real' one has a beefier spring, and is an all-around nicer item. If you're running out of ideas, give this a try. It doesn't cost much, and is easy to do.

If that doesn't do the trick, post back and I'll tell you about the clogged cooling passages I found when I had the head off my '92 to replace the lifters...

 

[weebur]

I will try to do the compression test this weekend. When doing the test do you take out all the plugs and do the test or just one at a time?

The way I've always done compression tests is to disconnect and ground the coil wire if so equipped or disconnect the coil pack connections, and then unplug the electrical connections to the injectors--(don't skip these steps), with carb cleaner and compressed air blow out the area around the plugs to remove any dirt or other crap that might be blown into your face/eyes and/or sucked into the cylinders. Wear safety glasses.

Remove all the plugs (lets the engine get to several hundred RPMs), brick or a stick between the seat and the gas pedal to hold the throttle body valve all the way open. The battery should be fully charged (~12.6V with the engine off) or hook up a good battery charger.

Then run the test (crank the engine for a few seconds with a remote starter or helper) as is (dry), note the figure then squirt some engine oil in the plug hole (wet) and note the reading. If there's a big difference between dry and wet readings it could mean bad (worn or broken) compression rings. Bad readings between two adjacent cylinders could mean a bad head gasket.

If your numbers are OK you could do a “Leak Down” test with the cylinders wet; bad numbers here might indicate bad valves. Let’s hope for the best.

There are different guidelines from different manufacturers but as a "rule of thumb" the readings should be about 10-15% between cylinders. I'm not sure what Jeep says, but I'm sure someone will chime in. Get back to us with your numbers.

 

[seasoned_geek]

My 1990 Wagoneer LTD (XJ with woodgrain) had the same problem for a while. I replaced the electric fan, put in 3 different thermostats, even replaced the temp sensor which is in the side of the radiator.

The 1990 (and probably other years) has a split cooling system. A small mechanical fan which runs all of the time and an electric fan which runs when the temp sensor tells it to OR WHEN THE AC IS TURNED ON. I would go for weeks without overheating, then suddenly she would puke steam while idling. I tested and swapped and did everything I could with the relay, but, after replacing every component identified by the Haynes manual for that circuit, I would still get hot if I didn't turn the AC on. (BTW, the replacement electric fan I found for $39 was the best investment I ever made. My volt meter used to dive when the old fan kicked on, but the new one doesn't even cause that gauge to wiggle.)

If you have the split electric fan and have this problem here is what you need to fix it:

http://www.ebay.com/itm/190556682461?ssPageName=STRK:MEWNX:IT&_trksid=p3984.m1439.l2649

When people are pushing and pulling on things they can end up getting the red battery power lead pulled too far down in the relay socket. You can test all day with jumper wires, but, if you look close you will see the pin-1 lead is about 1/4 " or more lower than the other pins. It doesn't even touch your relay.

 

[O-Gauge Steamer]

The way I've always done compression tests is to disconnect and ground the coil wire if so equipped or disconnect the coil pack connections, and then unplug the electrical connections to the injectors--(don't skip these steps), with carb cleaner and compressed air blow out the area around the plugs to remove any dirt or other crap that might be blown into your face/eyes and/or sucked into the cylinders. Wear safety glasses.

Remove all the plugs (lets the engine get to several hundred RPMs), brick or a stick between the seat and the gas pedal to hold the throttle body valve all the way open. The battery should be fully charged (~12.6V with the engine off) or hook up a good battery charger.

Then run the test (crank the engine for a few seconds with a remote starter or helper) as is (dry), note the figure then squirt some engine oil in the plug hole (wet) and note the reading. If there's a big difference between dry and wet readings it could mean bad (worn or broken) compression rings. Bad readings between two adjacent cylinders could mean a bad head gasket.

If your numbers are OK you could do a “Leak Down” test with the cylinders wet; bad numbers here might indicate bad valves. Let’s hope for the best.

There are different guidelines from different manufacturers but as a "rule of thumb" the readings should be about 10-15% between cylinders. I'm not sure what Jeep says, but I'm sure someone will chime in. Get back to us with your numbers.

^^This is good advice.

ALL of the plugs need to be out to run the test as the engine needs to be able to crank at full speed. You can disconnect the coil by unplugging it from the harness.

If you do not have a compression tester, get one that screws into the spark plug hole and has an o-ring on the connector to seal it.

Run all of the cylinders dry. Then squirt some oil into the cylinder to be checked wet, personally, I like to use a 5w engine oil. Crank the engine through at least two compression cycles to distribute the oil in the cylinder and then check it with the compression tester.

Here is the official Jeep approved method for a test:
<<FSM QUOTE ON>>

1. Clean the spark plug recess with compresses air.
2. Remove the spark plugs.
3. Secure the throttle in the wide open position.
4. Disable the Fuel System.
5. Disconnect the ignition coil.
6. Insert the compression pressure gauge and rotate the engine with the engine starter for three revolutions.
7.Record the compression pressure on the 3rd revolution. Continue the test for the remaining cylinders.

The specs for a good engine are:
Pressure range...827 to 1,034 kPa (120 to 150 psi)

CYLINDER COMBUSTION PRESSURE LEAKAGE TEST
The combustion pressure leakage test provides an accurate means for determining engine condition.

Combustion pressure leakage testing will detect:
* Exhaust and intake valve leaks (improper seating).
* Leaks between adjacent cylindres or into water jacket.
* Any causes for combustion/compression pressure loss.

1. Check the coolant level and fill as required. DO NO install the radiator cap.
2. Start and operate the engine until it attains normal operating temeratures, then turn the engine off.
3. Remove the spark plugs.
4. Remove the oil filler cap.
5. Remove the air cleaner.
6. Here the FSM says to calibrate the tester we can't do that... But it does say to run between 70 psi minimum to 200 psi maximum input pressure. So, shop air works.
7. Perform the test proceedure on each cylinder per the manufacturers instructions.

While testing, listen for pressurized air escaping through the throttle body, tailpipe and oil filler cap opening. Check for bubbles in the radiator coolant. All gauge pressures should be equal with no more than 25% leakage.
FOR EXAMPLE: At 552 kPa (80 psi) input pressure, a minimum of 414 kPa (60 psi) should be maintained in the cylinder.

CYLINDER COMBUSTION PRESSURE LEAKAGE DIAGNOSIS CHART

Condition.
Possible Cause. Correction

Air escapes throughThrottle Body.
Intake Valve. Inspect valve and valve seat. Reface or Replace.

Air escapes through Tailpipe.
Exhaust Valve. See above.

Air escapes through Radiator.
Head Gasket leaking or cracked head/block. Remove cylinder head and inspect. Replace defective part

More than 50% leakage from adjacent cylinders.
Head Gasket leaking or crack in head between adjacent cylinder. See above

More than 25% leakage and air escapes through filler cap opening only. Stuck or Broken rings: cracked pistons; worn rings and/or cylinder wall. Inspect for broken rings or piston.Measure ring gap and cylinder diameter, taper and out- of-round. Replace defective part.

<<FSM QUOTE OFF>>
So, what you will need to make is a tester or, go have it done. The tester has a gauge, a connector to screw into the cylinder head, a valve to shut off the incoming air pressure and a schrader valve so the pressure can be dumped at the end of each test. Not difficult to make.

Here:
http://www.google.com/products/cata...T76CBY2DsAK9xsGRCQ&ved=0CHoQ8wIwAA#scoring=tp

is a quick web search. You can get one for under $75, or... Look at the picture and build one.

Hope this helps.

 

[scubamark13]

Well I did the compression test here are the results:
#1 149
#2 149
#3 147
#4 149
#5 147
#6 145
The plugs were light gray with a copper tint to them. To me it looks like it may be running a little lean but I am no expert.
I didn't remove all the plugs at once I did them one at a time, but I am pretty happy with the numbers.
The only thing left is the temp gauge and I am going to install an aftermarket one this weekend. Do any of you have pics or know where I can install a gauge?

Thanks,

Mark

 

[Pelican]

Did you ever check temps with an IR thermometer as suggested in several posts?

I went through a very similar situation with my 93 where the dash gauge would indicate temperatures climbing above 210 while driving at highway speeds (although not dangerously high in my case). Checks with an IR thermometer consistently indicated that temperatures were "normal". I finally replaced the after-market gauge sender in the back of the head with an OEM unit which took care of the incorrect readings.

Perhaps you have already checked with an IR but if not, I would certainly do that before going to the trouble of messing with a separate gauge.

 

[scubamark13]

No I haven't checked it by IR yet I have asked everyone I know if they have one but nobody does. I am thinking I will head over to harbor freight and see if I can get a cheap one. This is something I should have done in the beginning.