Hey everyone........ I just picked up a 94 4.0 4x4 to drive through the winter ! Just like another member here. it has a idle that is less than satisfying. I have not done a compression check yet, but after changing the plugs, I too see that my #5 has an issue !
I am also loosing coolant, without any leaks, which leads me to believe that I have a bad intake gasket. I was talking to a friend of mine , and he mentioned that he had put two sets of heads on a 4.0 at one time, due to them cracking ! Anyone heard that this is a problem with a OHV motor? Gaskets are pretty cheap, and well ........ so am I , I guess. So changing the gaskets, would not really be a big deal, although I may have the option of a motor that has close to 100,000 less miles on it, that I know is good, so I don't really want to go through the labor, nor spending the money for the gaskets, if it has a cracked head, and may not accomplish what I am working for ! Looking through the forum, it appears that no one else has had this problem. Any chance my friend is giving me bad info?

 

THe heads are known for cracking and losing coolant with out leaks. It usually cracks around the exhaust valve and drips in the chamber.

Check https://www.alabamacylinderhead.com/ For new castings, my 95 expo is leaking making it unreliable for long road trips. I think both heads are cracked, maybe i should put new plugs in it.

 

Your friend is right, I had the same issue with my Ranger. The heads like to crack between the intake and exhaust valves. I did the work myself and it was about $450 for brand new heads plus having the valves and valve springs switched over to the new heads.

 

, huh, that is good information ! I jumped in and changed the intake gaskets yesterday, and the lower intake bolts on the drivers side were all finger tight ! Runs like a champ now, I will have to keep an eye on the coolant to see if it still may have cracked heads ! I'll keep my fingers crossed . Too bad I can't find a set of aluminum heads to put on it !

 

I checked out those heads..... that's pretty cheap! great info, thanks !

 

How about that it ran great for about 65 miles, then started making noise ! Pulled the dipstick and the crankcase appears to be full of water. I guess I am looking for another 4.0 ! anyone ???????

 

Did you change the oil after doing gaskets? When you open the top end like that trash and water will find its way in.

I will bet changing the oil will solve the noise issue, the question is will the water comeback? If the lower didn't seal well it will leak water into the valley or out side the engine. Which is what mine was doing.

I have my 4.0 open to the world right now, valve covers were finger tight. My truck has had these gaskets done once under warranty, the dealer put rtv everywhere. They even sealed the washers, I just might do that trick when i button it up. Also broke my heater bypass valve.

 

I had some bottles of oil that have been sitting in my garage forever, that I figured I wasn't out anything to dump in, and at least try that ! I did not pull the filter, , just dropped the oil, and dumped in the new stuff, but it made no difference. Seems to run good, and the noise has changed some, but I haven't checked it to see, if it is full of water again !

 

I have heard alot about this head issue with the OHVs. They say there known to go at 100k. My OHV is about to roll 200k here soon and I'm assuming maybe my heads have been done already...maybe ha. You got me worried though. My coolant seems to disappear and I have to continually check on it, but I've never had a issue with my motor running under par. I just got my valve covers and oil filter housing gaskets replaced and of course right after I get that done I find out about the intake gasket is another one that I probably should have gotten replaced...Anyways I Hope you get it running solid again soon!

 

Yup, mine has 224,000, and I am still not convinced that mine have ever cracked ! check your intake bolts first, I bet that they are only finger tight, just like mine were !