Yes, cylidnder, sorry brain is on vacation. Should be around 120-150 dry test, with no more then 30 psi variance between cylinders

 

Ok so I have not done the compression test yet. The reason being I think it's my cat!

I overheat at freeway speeds ONLY. If I floor it I have what seams to be no power. I just chocked that up to 33s and stock gears. I can wheel all day in 4 low and never overheat.

What do you guys think?

 

In 4LO, the motor is not having to work hard at all....4HI, stock gears, big tires.....lots more load on the motor. Any/all cooling system components MUST be in top notch condition when the motor is under extra load.

 

Ok true. But offroad 4hi I don't overheat. Lots of low end power but hi end/freeway no power and overheat.

 

You could power-brake it with the rad full, and the cap off and watch for bubbles. Even a little 2000* head gasket leak into the water jacket will heat it up quick.

Numbers aside, it's the relative difference in compression readings that will show a problem. A new starter with killer battery and cables is gonna test higher. If you do go there, google "wet compression...) You take a set of numbers first, then add a couple tablespoons of oil and take a second set. A low that comes up indicates a problem with rings. A low that doesn't come up would be something above the rings. (gasket/valve).

A shroud is very important for air-flow. Trailering a load up my hill at 15-20 mph without one would be a joke. I'd never make it.

In your shoes I'd make sure the condenser/radiator isn't full of bugs or something.

 

My ebrake is basically non existent. But I have burped the system multiple times no bubbles. Plus it's an open system so no real need to burp, right?

I'm still going to do the compression test just thought I would ask about the cat issue. As far as I know it's the factory exhaust with 200,00+ miles on it.

I leak no fluids and burn no oil so I think my rings and head are ok......did I just jinx myself?

 

Can u explain precisely how u went about your "closed" to "open" cooling system conversion?

 

Got a rad for 92 and up got a universal overflow bottle from auto parts store. And installed them.

The efan was already hooked up to a switch for water crossings and has no affect on overheating bc it was overheating before the switch was installed.

 

The point is just a little 2000* plus combustion gas getting past the Head gasket will heat the coolant fast. (nothing to do with burping). The test is a two person job. One holds the brake petal firm, and applies medium throttle, while the other (who is not in front of the Jeep), watches for the afore mentioned combustion gas bubbling out. Just an easy two minute test. It won't tell you the HG is good, but it can be pretty clear if it's bad. Once I had a geyser shoot up and hammer the hood!

Once with crap power from a clogged cat I just loosened the header pipe bolts. Night and day, power was back, cat was clogged. You can google a "vacuum test for a clogged cat"

Having the numbers from a compression test is neat anytime. Save them, down the road they may well help with some other issue as well.

 

TEST it.


CRUISER’S VACUUM TEST FOR EXHAUST RESTRICTION

Your vacuum gauge should come with an instruction booklet outlining the procedure. Hook the vacuum gauge up to a source on the intake manifold. Start the engine and note the vacuum reading. Usually 17 to 21 inches of vacuum. Throttle the engine up to 2,000 to 2,500 RPM for 20 seconds or so and the vacuum reading should stabilize to the same reading you got at idle. Let the throttle snap shut. The vacuum reading should shoot up about 5 inches of vacuum higher for a second and then come quickly down to the original reading. If the vacuum reading stays high and comes down slowly with jerky needle movements, you have an exhaust restriction.

 

The new bottle both fills/empties from the bottom and no pressure can form inside the bottle? New 15 lb "open system" rad cap? Coolant level in the bottle rises (hot motor) and falls (cold motor)?

 

All true but I think the rad cap is 18#. Not sure.

 

16#

 

Do the tests.....comp, hg.

 

#1 115 #2 122 #3 132 #4 130 #5 125 #6 120

I'm still at a loss. Does this mean my head\valves are bad? No oil in coolant no coolant in oil.