Hi All,

I have a coupe which engine lost quite a bit of oil, but never overheated, and currently has ZERO rod knock but it is clearly more worn than before.

Is it possible (a good idea?) to replace JUST the bearings and leave the rest of the long block alone? I am thinking to tear it down to the long block and replace the timing gear, crank bearings, connecting rod bearings and piston rings. I am trying to find the best cost/reliability option and If I can avoid pulling the heads and the associated costs, it seems like it might be less expensive than the other options.The said motor has 138K miles on it for point of reference.

If I pulled the heads I would have the valves redone costing me around an extra $300-$400 plus the gasket and seals ($400?) I am trying to stay under $1500, because if I reach that point, I'll just start looking at craigslist/wreckers for a low mile engine/car.

 

I don't think it's a good idea to do the bottom and not the top. Not at 135k.
How long was it oil starved? I know you were in traffic and got stuck...not blaming you.
Have you done a compression check?
Have you done an oil change and sent an oil sample for analysis?
If you have compression, I'd put it back together and run it until it gives in...and save up for an LS conversion or try to find a good used motor, but there is sooo much you can't tell about a used one regardless of miles on it.

 

Ya, maybe you are right- I just didn't want to add the costs involved but it may be the wiser thing to do. No compression check yet- I may, but I can tell it has less power- it was a good, tight motor. 2 miles from engine light to stopped. Oil change is probably a good idea- I'll do tomorrow. It is together and running fine (albeit too loose for my taste) Used motor with good compression or a full rebuild is in the cars I am afraid.

 

Probably best. There are oil journals to keep the top in one piece same as the bottom. If you bring the tolerances on the bottom up with a intolerant top end, you might have a serious top problems soon. Half a rebuild may be throwing good money after bad. I'm not certain, but I don't think you can even do the bottom with rings without the heads coming off....the motor has to come out either way, not doing the whole thing on 135k motor doesn't make sense to me.
Compression test should be next. If there is any of the original oil anywhere a sample of that may be good to save as well. They don't need much to analyze it at a lab...

 

Mr. Snyder,

Never give up on a 4.2! Definitely, change the Oil & Filter...If it runs OK and not showing signs such as smoking or knocking, you may have escaped for a while but something happened or it would not have lost its oil to start with....See if you can track that down first.....or Heck just drive it until it craters!! At 135,000 miles what do you have to lose?

Billy Clyde

 

Billy! That's what I think I am going to do- It's running fine, but with a little light noise.

 

Billy Clyde he was on the freeway and lost an oil cooler hose. It split and had a sudden oil loss. 2 miles after the light came on he shut her down.
I'm with Billy C too. Run it after changing out the hose (or all 4 of them) and fresh oil.
I would still do a compression test. That's easy and will tell you a lot right there. No knocks? Run it.
There was still some oil in that motor after 2 miles is my guess. I bet it's a nasty mess in there right now though. Clean her up and patch her back.

 

Quick question- of the variants- Stype, XJ8, XK8 and Range Rover, which long blocks are compatible (that is if I remove everything but the cam covers to the timing cover and swap over)? I know they squeezed .2 litres out of the Rover motor so that's a bit appealing. (by the way, oil change on this motor and will drive it until it starts making angry noises) For the next 6 months or however long it lasts I am going to keep an eye out and grab a low mile motor.

 

I would also try and get one of those magnetic oil drain plugs so at each change, you would be able to check if there are any metal shavings. Might also be useful to try and open the oil filter to check for the same at each change. Also, clean the oil pan before your next change so you can run a magnet through the old oil, same idea. Just a thought.

 

So i changed the oil and put a stethoscope to the top and bottom end and the looseness seems to be in the top end- does that seem right?

 

There again, Mr. Snyder,

I would say you are lucky to have just been able to change the Oil and have it run! You are lucky to have been able to drive it 135,000 miles before you had any major trouble and really lucky that it started up and is drivable after only an Oil change! Having to only change the Oil is more than most folks could ever dream of! You, Mr. Snyder, are a lucky you know what and should run down and buy a Lottery ticket right now!

Billy Clyde in Houston

 

But I didn't win last night! I guess I'll have to go buy more...