just picked up a 94 Explorer with a 4.0 with 225,000mi on it.I got it for FREE.(i was gonna use it for a parts rig)The guy said he thinks the head gasket went.The oil isnt over full or foammy.It has a slight miss but not bad.Doesnt smoke,tick,rap or rattle.I held the throtle to the floor just to see what would happen,nothing,it went to 5500rpm's and stayed there.I did that three times.I think its a decent engine.Were these heads known for cracking like the 2.9's??Think i should fix it??Should at least find out what the miss is.

 

If the oil does not look like choclet milk, then I would go for it. It could still be a crack head/blown head gasket that is licking into the cylinder and the water is being pushed out the tail pipe.JMO

 

More likely to be an intake gasket problem then a headgasket problem on that year 4.0L.

The heads are not prone to cracking on the 4.0L, but of course if people run them hot, then anything can happen.

I would have grabbed it, too.

 

I also have a 4.0 explorer ('92) that I got for free with an apparent head gasket problem. On mine, the cooling system is filling up with oil at a horrific rate (about 1 quart every 1/2 hour of operation or more, if I had to guess). It steams out the exhuast and bubbles in the radiator. The back two cylinders on the driver's side are not contributing much to the engine's power (did okie cyl balance test by putting small pieces of copper wire sticking out from under the spark plug wires at the spark distributor thingie and shorted each out successively while running, noting RPM drop; because AFAIK one is not supposed to just pull a wire on electronic ignitions due to potential damage -- not to mention 60kv!).

Does this definetly sound like a head gasket on that side, or is it still possible it is just the intake manafold gasket?

Also, I checked with one of the auto parts suppliers here and they had two headsets for this engine. One with the head bolts, and another without. Does that mean that I should replace these headbolts? If that is the case, I was almost thinking of going studs, which apparently give you a lot more clamping power for the same torque (as per Smoky Yunic). Any suggestions in this arena? It looks like one possible reason why they used the TORX style head bolts (at least the ones I can see) might be due to clearance problems near the exhaust manafolds. Think I will have problems using machine washers and nuts on the studs in those areas?

Also, I tried to drive it home (with lots of water, oil, and various kinds of radiator sealer after an all night flushing session with water and dishwashing detergent) and on the way it overheated a bit (I shut it down as soon as it started pinging) but now it appears there is a radiator leak on the passenger side (oil showing up there coming out from underneath a cover). It appears the radiator end caps are plastic. Could mild overheating have cracked that darn thing? If so, is there any way to repair it, or is it a throw away?

While I'm in there (with the heads and EFI all apart) are there any easy performance mods I can make?

Thanks in advance,

-Kevin

 

come to find out the impeller come lose from the shaft on the water pump.I took the thermostat out and it still got hot,so i took a heater hose off,started the engine and NOTHING CAME OUT,even if i reved it up

 

Another question I have is, I know that lower intake is notorious for pumping oil into the cooling system without coolant going the other way. I have the thing off now, and I can't see how that happens, unless the whole valley is filled with pressurized oil. I see the coolant passages in the corners (and the gasket is bad) but I don't see any oil passages next to them. The whole bottom of the intake appears to be an oil spash area but there are no oil jets. Anyone care to explain to me how the oil gets pumped into the coolant?

Thanks,

-Kevin