4.0 Head gasket install

[OWEN]

My friend from college has a 98 or 99 cherokee and it sounds like it needs a headgasket (overheating and dissapearing coolant, none of it on the ground). I was just wondering if any of you have any eperience doing them...Is it a really big hassle or pretty simple? I will probably also replace the water pump if I do the job. How long does it take and what should I look out for?

[Hydra]

I did mine, and I am really not that experienced with internal engne work, took me maybe 5 hours due to a bad seal on the intake/exhaust gasket but I think 4 hours is probably a good estimate. Make sure you buy all the gaskets before you start, head, intake/exhaust, valve cover. Label all the vacuum lines if you pull off the intake manifold, and most importantly remember to use the right torque sequence on the intake manifold, the first time a disregarded this, something got caught up without me knowng, spent 2 hours trying to figure out where I was suckng so much air in from. Other than that it's pretty ok, after you do it you'll be glad jeep used an i6 instead a v6

[customcreationsllc]

Does the exhaust smell like antifreeze?
A pin hole in the radiator or hose will do the same thing. They will only leak under pressure and it will come out as a mist never leave a drop.
Use a coolant pump to pressurize the system look for leaks.

You can also pull the spark plugs and look for coolant leaking into the cylinder it might take a little while.

You can also do the reverse pressurize the cylinder with a leak down tester I saw this on trucks yesterday take a spark plug smash out the center of the spark plug and weld on a hose fitting the you can pressurize the cylinder see if it is leaking into the coolant system via a pressure gage on the coolant system increasing. You can figure out what cylinder it is.

Like with any head gasket, make sure you see a visual blown area of the head gasket. If not then there it is most likely a cracked head.

That is why it is good to diagnose which cylinder is bad.


The new jeeps not sure what year are known for the head cracking. A friend of mine works for Jeep said if you ever get a jeep with a coolant leak you cannot find pressurize the coolant system and look in the valve cover for little bubbles of coolant = cracked head.


Don't want to scare you but it is good to know what is the problem before you just start changing parts.

As as actually doing the head. It is a push rod motor with hydraulic lifters so it is like the easiest kind you can do no need to set the valve timing or valve clearance.

Good luck

[OWEN]

Does the exhaust smell like antifreeze?
A pin hole in the radiator or hose will do the same thing. They will only leak under pressure and it will come out as a mist never leave a drop.
Use a coolant pump to pressurize the system look for leaks.

You can also pull the spark plugs and look for coolant leaking into the cylinder it might take a little while.

You can also do the reverse pressurize the cylinder with a leak down tester I saw this on trucks yesterday take a spark plug smash out the center of the spark plug and weld on a hose fitting the you can pressurize the cylinder see if it is leaking into the coolant system via a pressure gage on the coolant system increasing. You can figure out what cylinder it is.

Like with any head gasket, make sure you see a visual blown area of the head gasket. If not then there it is most likely a cracked head.

That is why it is good to diagnose which cylinder is bad.


The new jeeps not sure what year are known for the head cracking. A friend of mine works for Jeep said if you ever get a jeep with a coolant leak you cannot find pressurize the coolant system and look in the valve cover for little bubbles of coolant = cracked head.


Don't want to scare you but it is good to know what is the problem before you just start changing parts.

As as actually doing the head. It is a push rod motor with hydraulic lifters so it is like the easiest kind you can do no need to set the valve timing or valve clearance.

Good luck

Thanks for the help, I am a professional tech so by all means I pride myself in not being a "parts replacer." The jeep has a new rad and hoses (not done by me) originally installed to correct this problem, but it didn't fix it, according to my friend. That is a good test for a cracked head... I wouldn't have thought of that. Furthermore every engine I have ever done a headgasket on, (aside from small engines) I have sent to the machine shop to be checked out and planed, so the mating surface is flat.

Shes bringing it to my shop tomorrow. I will pressure test it and probably pull the plugs to diagnose it. I just needed an idea of what to tell her for how long it will take, and how long it will take up room in my shop