Hello,

So the story goes that I let family borrow our 1995 jeep 4.0 while I worked on their ranger. They found the biggest longest hill they could find and overheated the **** out of it. Let it cool down, and then did it again. Long story short, I did a compression test after towing it home and here's the damage.

Cold compression test
Cylinder 1 - 100 psi
Cylinder 2 - 20 psi
Cylinder 3 - 80 psi
Cylinder 4 - 80 psi
Cylinder 5 - 135 psi
Cylinder 6 - 135 psi

I haven't run it all that much after they reported it overheating. The head was recently rebuilt after it boiled over on me a year back but it never really ran perfectly.

I wanted to ask for advice if doing another head gasket is all I should do. Should I get the head machined again or should I yank the engine and rebuild the whole thing. Or just stick a new engine in it?

I appreciate your help!

I bought a 98 that had wack compression readings:
1:110
2:0
3:0
4:0
5:110
6:110

You really need to take the head off to see what is going on. In my case, there were holes in 2 of the pistons form the thermostat rusting shut. Ended up putting a used engine (replaced a few thigns along the way). This is my saga: https://www.cherokeeforum.com/f2/0-c...233952/index2/

At the very least crank the engine with the valve cover off to check valve function, and then have the head checked for flatness. I suspect you're going to find more than just another blown head gasket. Stop doing automotive work for people that abuse your vehicles.

Yes, last time I'm doing work for that side of the family.

I'm going to obtain a leak down tester and make sure it's not a bad piston, then I'll pull the head and hand it to a machine shop and see what they say.

If it's a bad piston I think it would be more cost effective to just slap a used engine back in.

Stop guessing and pull the head, nothing will tell you more than a visual inspection of the piston and cyl walls

So I did a leak test at 90psi on cylinder one and two after warming up the engine. I wanted to make sure I had one cylinder I knew was okay-ish to compare to the bad one.

Cylinder 1 - 22% leakage, small amount of air coming from the intake.
Cylinder 2 - 83% leakage, large amounts of air coming from the intake and a small amount coming from the oil cap.

I triple checked cylinder 2 because I read online it's easy to get a false reading by not having the cylinder at TDC and it'll just spit air through the intake. I think that number is correct. I verified TDC with a endoscope.

Seems like I just need the valves done? What's your guy's thoughts.

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Pull the head off. Damage can then be seen, wise decision to follow. That is the way.

Does it still run well ?

If its damaged, it will idle poorly

If it idles poorly, has the evidence you have, maybe check the oil filler cp for salad cream

All evidence points to engine damage

If the driver did exactly as you said, they would be up for the damage bill if it was me

I'm going to guess that the missing part of this cylinder pronounces this engine as decreased.

That white damage on the cylinder wall would have to be bored out and sleeved, right? If I wanted to rebuilt at least. It's rough to the touch.

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Thank you for all your help.

Yep that will do it. No need to sleeve it but definitely needs to be bored about .010” or more. A good machine shop can verify. Complete rebuild coming your way.

Are you fixing (rebuilding) yourself or paying someone to rebuild...other than the machine work that most people can't do. ...meaning can you remove and disassemble yourself? Otherwise its cost prohibitive and most reman engines are shaky quality at best

I can do the work of tearing the engine down myself probably and having the machine work done by someone else.

I found someone on Craigslist willing to sell a parts car with a rebuilt engine that has 26k miles on it for $1500. Is that reasonable? They had an electrical fire and the harness needs replaced, but I figured if I just needed the block it could be a decent deal.

$1500 sounded like it would cost more than rebuilding the engine myself honestly. Even with having a shop do the machine work. I found a few used engines already pulled for $800 but their milage isn't listed.

It seems like rebuilding it myself may be the best option?

Also there's a number 50 marked on the top of the piston. Does that mean these pistons are 0.05in over already?

www.car-part.com almost every salvage yard in the country uses this and if mileage is not listed, their number is and you can call.

Thanks for the link.

I found one with a video of it running before. Seems to run alright but the milage is unknown. Compression is between 150 - 165. Seems like good numbers. Worth a gamble? Would run me $800 about.
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​I found out what cost prohibitive meant with engine rebuilds. $1000 - $1400 depending on the condition for the machine work. And that's not including parts. Ouch.
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