Hello Mr. I wish you were in my part of town. I was driving for about 1/2 hour stopped at a light, and car(2001 Grand cherokee straight six 125 miles) just did a big exhale and coolant splattered every where, and the resevior filled to the top. Towed it home, drove to garage and radiator cracked bust at the seem, on the passenger side. cant test anything from what the mechanic tells me. That I need to replace radiator and thermostat. ( I will attempt my self). Say it was a head gasket do you think I can do it alone?
and if not. You said 1000 dollar job on modern cars for a head gasket. what exactly should I expect to pay for a 2001 grand cherokee, they are asking me for a bit over a thousand, and its no way a modern car. please reply. thank you!!
{black}:excitement: help!
You probably have the infamous Jeep 4.0 "0331" defective cylinder head casting of that time period. The problem is likely not the head gasket but a cracked cylinder head. The crack can be seen through the oil filler hole and you can see the coolant flowing through it with the engine running. (See video link below.)
How is your oil pressure? Chances are it has been leaking for a long time and only now has become severe. When coolant mixes in with the oil it damages engine bearings and the result is low oil pressure initially and eventual catastrophic engine failure. Oil pressure will tell you the story, factory spec is at least 13 psi at hot idle, at 37-75 psi at 1600 rpm and above. (That's ideal factory spec, though a general rule of thumb for those old pushrod engines when they are a bit worn is 10 psi per 1000 rpm.) Oil pressure should be checked with a mechanical guage. Dash gauges, if so equipped, are notoriously unreliable. If you already have low oil pressure it's too late to do anything but replace the engine if you want to keep the vehicle.
So, if you have a cracked cylinder head but the bottom end of the engine is still OK you have some options. One would be to obtain a used or reconditioned "TUPY" head from a late 2002+ Jeep 4.0 where the bad design was fixed. (You'll see "TUPY" cast between the #3 and #4 exhaust rocker arms, where the crack would be on a defective head.) Another would be to purchase a new redesigned aftermarket head like a Clearwater, which costs about $600. The problem of course is that for someone who does their own work installing a $600 cylinder head with a new head gasket, while a big job, is doable. If you have to pay a mechanic that changes things and if there are any problems of course the mechanic will point fingers at the replacement head.
Another thing to factor in is that assuming it's an automatic transmission, unlike the "regular" Cherokee, which uses an Aisin/Toyota transmission that is near bulletproof, the Grand Cherokee uses a Chrysler transmission that is much weaker. So you could fix the engine only to have the transmission crater on you. (It is 20 years old!)
https://www.youtube.com/watch?v=H5Ji5guoDXg
