Compression #'s (help)

Just did a compression test to check the head gasket/head. Here are the numbers.....
1: 134
2: 139
3: 140
4: 145
5: 138
6: 135
Its a 91 xj (what else?) with 183,000 miles that is running HOT. Iam going thru the motions of tracking down the problem. here is what I have done...
changed t-stat, radiator cap, temp sending unit(back of head), coolant temp sensor(t-stat houseing), flushed the radiator/block, basicly everything except the water pump/radiator.

What does every body think?

Thanks.

Compression numbers are all right - how hot are you running?

Remember that the 4.0 has a design operating temperature of about 210-215*F - and can only be lowered with effort.

With your mileage, you may want to think "radiator" - I've heard it from several ChryCo/Jeep techs that the older XJ's (up to, say, 94-95) tend to lose radiators after about 150Kmiles. I replace with Modine - and so (usually) do they.

Get the high-efficiency version. Being in Texas, you probably need it.

5-90

I second what 5-90 said with the addition of,

check your radiator for restrictions, there is a high possibility of collecting trash between the radiator and condenser, also there is a rubber shroud between them on some year models, this can become misshapen and restrict airflow. make sure your fan shroud is in place and check your fan clutch before you end up buying a new radiator.
large grains of sand can also become lodged in the vanes as well.

5-90 said:

Compression numbers are all right - how hot are you running?

Click to expand...

Thats what I was thinking on the numbers.
Right below the RED on the temp gauge.
Think Iam gonna get a new gauge and try that befor the waterpump & radiator thing.

Thanks

You didn't mention the fan clutch- if everything is decent, but the fan clutch is not doing its job, then you will run hot- even with an otherwise good cooling system.

Another thing you didn't mention is when is it hot? All the time or at idle or highway speeds...

K

4xBob said:

You didn't mention the fan clutch- if everything is decent, but the fan clutch is not doing its job, then you will run hot- even with an otherwise good cooling system.

Click to expand...

A bad fan clutch will allow it to heat up when stopped in traffic but the temp will drop to normal as soon as the vehicle starts moving. If it STAYS up near the red, I would look for a new radiator. Ten years and between 100,000 to 150,000 is the most that we should expect out of the OEM radiators.