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Unread 08-28-2012, 06:16 AM   #1
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1994 ZJ 
Join Date: Jul 2012
Location: Rabat, Morocco, N/A
Posts: 10
Engine rebuild or faith???

My ZJ 4.0 with 160.000 on the clock was drinking coolant like there was no tomorrow. So took off the valve cover and found the most delicious chocolate milkshake:

Decided to take the head off and have it inspected, while checking the rest of the components. When I had the head off I inspected the cylinders and found these marks on the cylinder walls:

So.... Does anyone have any good advice on what to do with those marks, are they common or only because the engine has been overheated?

I am having the cylinder head checked by the machine shop, and maybe changing valves, seals and springs. But If I put on the head with the cylinders looking like this, how many miles can I expect to get out of the engine? I want it running at least 10.000 miles more before I either sell it or part it out.

I might be able to find an old 4.0 engine, rebuild it and put it in, but I need this one running while I do the rebuild.

And - Does anyone know any good rebuild kits - I live abroad and need to have everything shipped - so I'm looking at having everything sent at once, so I don't have to pay too much in shipping.

Any help is appreciated, thanks

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Unread 08-28-2012, 08:01 AM   #2
ratmonkey's Avatar
1997 ZJ 
Join Date: Dec 2006
Location: , Pennsylvania
Posts: 19,794
Good candidate for at LEAST a .015" over bore....that's some nasty looking marks.
The rings are probably marginal right now, a fresh rebuilt head will blow the bottom end out in a hurry. just got done replacing a motor in a Wrangler that went through the exact same situation. Reman head with no bottom end work, ended up with no compression in two of four cylinders after a week then damaged the fresh head by driving on it longer.

Do NOT only do half the work now, you'll be doing all of it in very short time if you do.

Looks like the gasket blew between almost every cylinder. You ran this for a while while it was using coolant, didn't you?
'97 zj 5.2, some stuff, some other suff, and some things that even work sometimes.

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Unread 08-28-2012, 08:24 AM   #3
Registered User
1994 ZJ 
Join Date: Jul 2012
Location: Rabat, Morocco, N/A
Posts: 10
- I have to admit I did drive it, knowing something was terribly wrong... I don't know how long the PO drove it like this... Got it for next to nothing, knowing that there was some serious work to be done.

But it actually sounded ok when it ran, it was a little noisy, but no more than you would normally expect.

Guess I'll have to do the whole rebuild - Do you have any advice on where to get the kit?

Does anyone know this:

http://www.perfectengine.com/Jeep_4_...th-mkj242c.htm ???

I've heard a really bad story about Titan Engines, but this kit sounds proper:


I have been looking around, but mostly found larger stroker kits at around 1200 $ - I don't need all that extra power, so I will do minimal work on the block and parts and only have the machine shop remove whats necessary to get it back in good shape.
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cylinder honing , zj

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