knocking

[jeepthing]

i overheated my 90 xj with 197k a few days ago. now the motor knocks, and leaks a little bit of oil, and it never leaked any before. anyone know how i could cure this or how long the motor will last?

 

[Eagle]

How badly did it overheat, for how long, and how did you cool it down?

 

[Bored400]

Same thing happened to me. The difference in my case is that my XJ already had a bad head gasket ( a little coolant in the oil ) and leaked oil quite a bit. I was at idle, the temp spiked...I had a carfull of kids, so I risked it and drove home. I started powering out in drive, stuck it in 3rd and limped in with coolant blowing everywhere, engine cutting out and knock in the top side. I'm guessing that a couple of things went wrong:
1. Fan clutch crapped out?
2. Water pump died?
3. As a result, it overheated and killed my already beaten head gasket.

Ok, so my question is: In my repair, how far do I go?
The water pump may or may not be shot, the fan clutch is gonna go regardless. The t stat has to be replaced, and I know I'm gonna have to replace that head gasket. Do I go ahead and try to re man the head or just go get one? I've heard horror stories about valve seats shifting after a re man...I guess I'm just looking for the complete fix....for under $1000.00
Any thoughts?

 

[Shorty]

by all means thermostat and H2O pump! check head for warpage using straight edge and feeler gauge. check bottom end bearing clearances and put her back together with new hoses. They're tough little engines and will prolly run again for a long time more!

 

[Ecomike]

I'd go pull a low mileage engine out of the junk yard and replace it, probably a lot cheaper short and long run, or find one on the local Craigs list or for sale forum here...etc. That engine may cost more than it is worth to rebuild. And save all the good parts off of the old one for spares, or use them as needed, like the A/C compressor.

 

[Bored400]

I'd go pull a low mileage engine out of the junk yard and replace it, probably a lot cheaper short and long run, or find one on the local Craigs list or for sale forum here...etc. That engine may cost more than it is worth to rebuild. And save all the good parts off of the old one for spares, or use them as needed, like the A/C compressor.

If I can get another 50k out of a little rebuild, that's all I want. I can buy an Auto Zone head for around 200, water pump, gaskets, hoses, t-stat,etc. for another maybe 300. Are you thinking the bottom end is shot too? I'm of the opinion that the devil you know is better than the one you dont, and I'm not so sure a guy can get a decent low mileage motor for under a grand around here!...This is my 3rd engine build project ( built a 400b Chrysler and a 360 Chrysler ) and I spent a helluva lot of money on both of them...I dunno. I'm going to dig into this thing and see what I see. I would think that I could rebuild the top end and get a few more years out of it though. Is my thinking flawed?

 

[Bored400]

ok, maybe I'm impatient...but I've got my DD in pieces and I need opinions! Should I pull the whole mess out and go with a long block or fix what's broken and run it? Honestly, I'm wiping the grease off of my hands to write this as we speak!

 

[Shorty]

can't tell you what's better 'til I know what you've found. Zone/Advance reman head is good start (could probably do as well at a local machine shop), but can't say about bottom end- oil thins with heat- don't know how hot it got or how much damage was done.

dig in and report back!
--Shorty

 

[Ecomike]

ok, maybe I'm impatient...but I've got my DD in pieces and I need opinions! Should I pull the whole mess out and go with a long block or fix what's broken and run it? Honestly, I'm wiping the grease off of my hands to write this as we speak!

What concerns me is that you ran it with water & antifreeze in the oil for some time (how long?) before it over heated, and then kept on running it till it boiled over. I am amazed it did not sieze up. Water and antifreeze thin the hell out of the oil leaving little lubrication, which makes more heat, which thins the oil, which makes more wear which makes more heat.....I think you get the idea. You may have put another 300.000 miles of engine wear on that thing since the water and antifreeze first got loose in the engine.

I bought a 4.0 off the for sale forum here for $100 about 4 weeks ago, a good known working 87 engine with only 167,000 miles on it, paid 300 for freight from Wisconsin to Houston. Have you checked Ebay, www.craigs.org or the for sale forum here, or the local chapter for sale forum in your area, and be sure and check this site:
http://www.car-part.com/

 

[Bored400]

Motor is on the stand, head is cracked. Ok, new head. Block seems solid though. I think I got lucky. Looks like I'm going to have to bore the block, but I'm thinking I'll only have to go like 10 over and slide new pistons in...the cylinder walls arent gouged, but the piston skirts on 3 & 4 are shot...coincidentally, that's exactly where the crack in the head happened! I've already got it apart, so I'm going to rebuild it. The crank is going to need a little help, but it's salvageable too. I'll see if I cant post a few pics in a different thread. Thanks for the links Ecomike, and thanks for the thoughts Shorty! I'll follow up!