beo

Hey everybody, i'm new here, i've had jeeps for years and used you all as a resource for tracking problems and making repairs. Now i've reached a stumper and I need help and opinions.
I recently bought a 2001 grand cherokee, 4" lift, all that jazz. It had the infamous relay problem and it overheat something terrible. I replaced the relay and the fan comes on, but the second time i drove it after the repair it came up with a misfire in cylinder 3 and 4 and now i've got no compression in cylinder 3. what did i burn? what should i look for? is it worth an engine swap in this day and age since it's old and got a whole bunch of miles?

Bustedback

What engine do you have?

beo

it's the 4.0

dave1123

Sounds to me like a blown head gasket. Usually when it gets hot, cylinders 3&4 get the most problems as the head tries to warp upward breaking the seal. The 2001 still has the infamous 0331 head on it as well, which is prone to cracking, so get it checked when you pull it off. JMHO.

beo

Thanks guys, i'll check it out. is there a way to quickly find out if it's the head gasket without a teardown? also how do i check for cracks in that head? I prefer to do most work myself if at all possible.

dave1123

Take the radiator cap off a totally cold engine, start it, and watch for bubbles in the radiator. This will show compression getting into the water jacket.

What worries me is usually there will be a loss of compression on #4 as well if the gasket is blown out between them. This may not be the case and you just have blown the gasket between the cylinder and the water jacket.

The head crack usually appears inside the valve cover between the 2 valves directly under the filler cap. You may see the crack with a strong light or maybe just a green or brown stain line where coolant has leaked into the oil. My head didn't crack there, but into the exhaust passage, resulting in lots of steam and coolant dripping out of the tailpipe. If you see a "TUPY" molded into the head in that area, the head has already been replaced with the later one.

There IS a way that you can find out EXACTLY what is wrong with that cylinder. You take out that spark plug and turn the engine so that that cylinder is on TDC compression (both valves closed). Then put a fitting in the spark plug hole and snap on an air hose. It's got to be right on TDC or the engine will flip over. Once it's charged with air pressure, listen in the throttle body, the exhaust pipe, the oil filler cap, and watch the radiator. Bubbles in the radiator show a bad gasket. Hearing air leaking in the throttle body shows a leaking intake valve. Tailpipe? Exhaust valve. Oil filler? leaking rings. It's not unusual for an older engine to leak a little air from all these places EXCEPT the radiator.

That's about all I can tell you. Good luck checking it out.

beo

so i did some tests and finally bit the bullet and pulled the cylinder head, the gasket was blown between 3 and 4. It is the 0331 head, but i didn't see any cracks in the usual places. I'm going to have somebody check it for cracks and warp and if everything is okay i'll get a gasket set and go for it.

Bustedback

Bite another bullet and replace the head.

beo

Any tips to find a cheap replacement. This might be on the trading block soon anyway.

Bustedback

There is a place called Clear Water Cylinder Heads, or something like that. A new head is about $400 complete. But don't quote me on that.
O'Reilly's has reman heads for 450 dollars, plus $178 for the core.

dave1123

Okay, voice of experience here! The Clearwater head is $455 complete with valves and shipping BOTH ways. You have 30 days to return the head or get charged another $100. They send you a prepaid return shipping label. I called them because it was getting close to the 30 limit and was told they don't even send you and e-mail until after the 30 days.

The head weighs 85 lbs which is 7 lbs more than the stock head. It's guaranteed for 5 years not to crack unless overheated enough to melt the sensor tab they put on it.

One thing I WILL warn you about. The head is drilled for both the front and rear temp sensors with a plug in the rear one. Mine was painted over but not tightened and didn't leak until 3 days later. I freaked out when coolant started bubbling out around the top of the intake manifold! Just check it before you finish the install.

That 0331 head is a ticking time bomb. If it's not cracked now, it will probably crack later. The only other option is to find a used 0331 head from a 2002 or later with the "TUPY" molded into it.

Just Google "Clearwater Cylinder Head" and Odessa Cylinder Heads will pop up. Their phone number is 727-556-2909. Their website listings are confusing, so it's best you call them for ordering. I had mine in 3 days because they have a warehouse here in NY.

On the return, they tell you to put it in a plastic bag before shipping. I washed mine with kerosene and a garden hose, used the original bag and shipping box/packing.