What are the signs of a bad head gasket/cracked block?

[54cj3b]

I also have a 88 and in cold weather the trans slips till it warms up I added a transmission conditioner into trans and it no longer slips mine also has 300+
motor seems to build condinsaition regularly and is slowly loosing power other wise it runs like a top but with high milage its time to do a rebuild or just replace eng but Im going to wait till it dies these 4.0s can go forever even with bad compression and leaks

 

[superj]

on the zj, the bands in the trannies get loose and you have to tighten them with a torque wrench. a good sign for htem being loose is when you shift in forward or reverse, it takes a few seconds for the gear to engage after you move the shifter. supposedly you just drop the pan and get your torque wrench on the adjuster and tighten to 25in/lbs. (if i remember right) the trannies are the same for the 4.0 zj and hte 4.0 xj, right?

 

[JeepGirl247]

I also have a 88 and in cold weather the trans slips till it warms up I added a transmission conditioner into trans and it no longer slips mine also has 300+
motor seems to build condinsaition regularly and is slowly loosing power other wise it runs like a top but with high milage its time to do a rebuild or just replace eng but Im going to wait till it dies these 4.0s can go forever even with bad compression and leaks

That's somewhat reassuring - regarding the cold weather issues. I plan on keeping my eye on everything. What kind of "transmission conditioner" did you add? And, is 300k on BOTH the original engine and original transmission?

 

[JeepGirl247]

Okay..just a quick question..

What is the difference between something like this simply being condensation or something major?

 

[MudderChuck]

Okay..just a quick question..

What is the difference between something like this simply being condensation or something major?

Doubtful you'd get enough airflow (hence condensation) through the crankcase to to be noticeable. But possible I guess if you have significant blow by.
Condensation out the exhaust pipe can be fairly robust at startup, before it changes to steam and mixes in with the exhaust. There can be about a cup of water in a cubic yard of air, depending on the humidity. I once took about a quart of ice out of my gas tank.

Borrow a radiator pressure tester from NAPA or somebody. You may have to fabricate an adapter, though they may have an adapter that fits.
When I've had head gasket leaks, I always noticed myself loosing coolant slowly. Might take a couple of weeks to be noticeable.
Oil gets hot, normally most of the moisture evaporates. If it is coolant in your crankcase, it can't be good. The water likely evaporates out, what's left is likely some sort of sugar (poisonous pancake syrup).

 

[54cj3b]

orig eng and trans

cant remember the name of it but it was thick and was in a tall white bottle with red cap/filler got it at wally world

 

[JeepGirl247]

orig eng and trans

cant remember the name of it but it was thick and was in a tall white bottle with red cap/filler got it at wally world

300K on BOTH original eng and trans - way to go! Yes, the 4.0's are strong engines.

 

[JeepGirl247]

MudderChuck-
Yeah, there is blow-by issues with the engine - it gets a ton of oil into the air filter to the point that it's 100% saturated and I replace it often. The exhaust pipe smoke is usually more noticable while it is idling even after it's been driven about 10 miles or so - like while setting in traffic if the wind is blowing it towards the front of the Jeep where visible.

 

[superj]

white smoke, very light grey or blueish, or black?

white is water in your combustion chamber (like a headgasket leak)

grey to blue is oil

black is to much fuel (like a diesel truck exhaust)


the grey/blue is sometimes hard to differentiate from the white as it can be very light light grey. take a pic of your exhaust plume in good light and post it

 

[MudderChuck]

MudderChuck-
Yeah, there is blow-by issues with the engine - it gets a ton of oil into the air filter to the point that it's 100% saturated and I replace it often. The exhaust pipe smoke is usually more noticable while it is idling even after it's been driven about 10 miles or so - like while setting in traffic if the wind is blowing it towards the front of the Jeep where visible.

You have to make sure the small plastic tube from the rear top of your valve cover is open and not plugged. And the opening the tube goes into on top of the valve cover is open all the way through the gasket. And the nipple the plastic tube is plugged into at the intake manifold is open all the way through. I disconnect everything and blow through it all periodically. If that little tube gets plugged up, the filter tends to get a lot more oil soaked, than when it's open. That plastic tube is often brittle from age and easy to break. I've also seen that tube rubbed all the way through on the bottom and leaking (vacuum) air.
I've found if you are pushing any serious amounts of oil through the exhaust, there is often a coating of oil at the end of the exhaust pipe. Check and see if the soot is oily or not.

 

[JeepGirl247]

The oil isn't coming out of the exhaust...the smoke is whitish...I meant there was blow-by inside the engine area...

...The only pic I have of the exhaust right now is one at nighttime with the camera flash..I took it 'cos the smoke was really white and the camera makes it have a bluish tint to it...

 

[54cj3b]

if it was cold or damp out white smoke is normal hot exhauast hitting cold air causes smoke to be white

 

[jeepn360]

I had smoke coming out of the oil filler tube on my CJ,to find out it was the cam,the exhaust lobe was badly worn.

 

[JeepGirl247]

Thanks for the responses.

I had a compression test done and it showed low pressure in all 6 of the cylinders, but the mechanic who ran it said that the head gasket was not cracked and that the engine block was fine.

Does that sound reasonable or was it just a brush off because he thinks the engine is old and shouldn't be fixed or something?

 

[SteelHeadz]

Low compression and smoke out the tail pipe indicates worn piston rings and possibly the valve seats as well. I would say that the mechanic is looking for a quick job as opposed to doing a rebuild which would take him more time and effort. Instead, the easy way out is to just R&R the engine. In some ways i would agree to a fresh engine IF it's infact a NEW engine, otherwise, rebuilding the one you have i think is worth rebuilding.

 

[JeepGirl247]

Thanks...I trust my engine a lot more than some other engine out of a junked XJ 'cos at least I know it's history and that it has not been abused....

 

[JeepGirl247]

Meaning, I would rather use the engine in my Jeep to rebuild than some strange one...