zondervan

Ok so i have a 1988 cherokee 4.0 pushing coolant out faster than i can put it in. I am 100% positive it needs head gaskets and 98% sure it will need a head..i have not visually inspected the head yet... what are the chances it will need an engine? How can i tell that?

1976gmc20

Perhaps by visually inspecting the head

zondervan

I know inspect head...but what could damage block....anything?

1976gmc20

Coolant in the oil, I am told.


But I had an old Chevy six that was spraying water all the way around the head gasket. I replaced the gasket (under 4 hrs) and drove it for several more years before stupidly deciding to sell it.

zondervan

Coolant and oil are not contaminated. Only blowing coolant out...so....SHOULD only be head...right

zondervan

Coolant and oil not contaminated so it SHOULD only be head. Its only blowing coolant out

1976gmc20

Hopefully one of the real jeep experts here will advise.


But it might be helpful if you could say where is the coolant coming out ???

cruiser54

Could be as simple as a blown head gasket.

As asked, where is the coolant coming from.

zondervan

Exhaust blowing coolant out of radiator / resivour tank. i pulled the valve cover tonight and through the oil build up between cylinder #3 & #4 i did find a crack that matches all.the pictures in the forums. Tomorow night im going to pull the head and basicaly the entire reason i started this post is....what should i look for on the block for damage if any from this cracked head. Ive done quite a few head gaskets on other vehicles just not a 4.0. Im not familiar with the issues that these engines have and i dont want to mis something vital.
Just to refresh....1988 4.0 2686 head casting....are there any typical block issues from a damaged head and head gasket?? oil is fine. coolant is blowing out through resivour from exhaust. Found crack between #3 &#4 cylinder.

XJ-kee

Coolant causes bad things to happen with...metal in your engine. To find the best idea of what's wrong,draining and dropping the oil pan can be informative. Thick sludge might be hiding or the bearings might be bad.

You can get an ok idea by what your oil and head look like too. Is the oil at all milky When you drain it? Any white residue under the valve cover? any green spots or thick, sludge like oil on the rockers or pushrods? Coolant on top of the pistons? run your finger nail down the cylinder wall, does it feel like it has pitting or ridges Or is it smooth?

Coolant mixes with the oil and can cause it to get super thick so it doesn't flow as easily. Also, when it mixes with oil for a long time it can also become a little abrasive and cause the ridges or pitting in metals. I'm sure there are more, but this is what I can think of at the moment.

If you've been dumping a LOT of coolant in it for quite some time...that might be a Pretty bad thing.

zondervan

Dang it all!!! READ DANG YOU ALL!!
OIL OK
COOLANT ONLY COMING OUT OF RESIVOUR BECAUSE OF EXHAUST
NO COOLANT IN OIL
NO OIL IN COOLANT
CRACKED HEAD AT #3 & #4 CYLINDER

COULD THE CRACKED HEAD HAVE IN ANY WAY CAUSE DAMAGE TO BLOCK???

cruiser54

Not likely. They're quite sturdy.

Was it run this way for a long time?

zondervan

No ....did not run for long like this....sat outside all winter...father went to start it
...a while later noticed coolant pouring out .... smart enough guy he shut it right off.

andrewmp6

Do a simple compression test that will tell you if you have a head problem or not.Being it sat all winter a freeze plug could have let go which will leak coolant.

XJ-kee

no need to be feisty, you're talking to a lot of people who have replaced their head because of this crack. We're a wealth of knowledge and just trying to understand what exactly is going on. Did you only visually look at the oil, or did you test it? Just because it doesn't look all that bad doesn't mean that it's not actually contaminated. It's true that they can crack on the exhaust side.

However, the reason we're all asking about the coolant and oil mixture is because you specifically said cracked head between 3rd and 4th cylinders. If it was only cracked on the exhaust side there would be much less chance of block damage. If it was cracked before you parked it all winter, it would be a slow leak into your oil that can damage over time.

What I meant by my post was visually inspecting the oil under the valve cover. If you confirmed there is a crack in the head, coolant will start clinging to the rockers and valve springs after it turns into a minor sludge. If it's come to the sludge point and the rockers are covered and everything looks generally gross under the valve cover, there's a good chance that same mixture was down on the main bearings which can be bad.

If the rockers/other components under the valve cover have good oil all over them and no coolant spots, then you can replace the head and be much better off. As cruiser54 said, these 4.0 engines are very robust. If you read my post, pull the head, inspect the cylinders, run your fingernail on the cylinder walls, see if they look ok. Other than that you can't really do that much unless you drop the oil pan, and at that point you'd be better off to just replace the bearings anyways. Maybe I'm Overkill, I dunno.