Ok, so I pulled the plugs and watched as the motor on my newly acquired XK8 turned and sure enough I can see the seats from the plug hole. The car was overheated and driven while hot.

SO- now the question is whether I want to use the existing motor and replace the heads (I would only have to buy one side, as I have an AJ26 on a stand)
OR purchase a good used engine.

Could there be problems with the bottom end from the overheating, and how can I check before going through the trouble of replacing the heads only to find the bottom end is shot?

Thanks in advance for your input!!

D

 

The first main bearing and oil pump would be my first concern.

Are you planning on fitting the head(s) in situe? have you measured the valve gap on both heads?

Was it waterpump failure?

 

I think she ran it low on coolant and the hoses burst (front and rear)
I plan on attacking it in situ IF I can be (relatively) sure that the bottom end was not destroyed.
I can see the seats move around on the valve heads when the motor is cranked.


Trying to keep costs down, but I don't want to go through this twice..

 

Hi Dave,
I'm thinking happy thoughts for you, as it's an XK why not look at a newer engine swap as it's probably going to be kept in the family

 

Roger- $$ is the dominant factor, I can spare time and effort

 

looks like you and I are going to be rebuilding jag engines.. I'm waiting for parts.

 

How much was the machinist work.

 

D, how would you be able to tell the condition of the bottom end without looking at the crank? If time and effort is not an issue, I would pull the motor. Don't think you want to go throught it x2.

 

Tire- Thanks for (wise) logic. However, I was looking more for that guy from high school yelling "just do it man, it'll be fine!" "What could possibly go wrong?"

LOL. I am waffling back and forth- I know the RIGHT thing to do, but part of me just wants to hear it run. I may also just put in a used motor and call it a day.

One other (minor) issue- I already have an engine on my stand, and would have to dismantle and remove it to work on this one. I guess I figure that if I put it back together and have bottom end problems, I will just pull the engine and work on the bottom end, leaving the top in place?

 

As a serial destroyer of straight six XK 4.2 engines in my youth when ££'s was the big factor, I always gambled on the 'quick fix' instead of going for the 'safe' full engine replacement. The engines have got more complex since those days but the risk is similar.

Almost forty years and many Jaguars later, I read your post and it got me thinking what I'd do in your situation with a V8.

Gut instinct is still to go for the quick fix of replacing the heads and take the gamble.

BUT ......... and it's a big BUT. Only you know how badly overheated it was.

Hot enough to drop valve seats brings with it the risk of cracks in cylinder block surface, oil ways / waterways - either already happened or sufficiently stressed to lead to future failure.

Bearings have to be a major concern and the only way to tell is a strip down.

Curiosity would force me to at least remove the heads and see the extent of the damage. Check for distortion on the block face and apply crack detection spray. If these pass OK, the odds are looking better for taking the gamble.

Graham

 

Hi Dave, so far everything is flat and clean, only expense was to clean the heads and front cover $110 at the local engine machine shop.

 

An 01 is a Nikasil treated bore, which does not react well to serious overheating. I would consider thi sengine a paperweight and find a replacement engien that works with the ECU and tranny in the car. Getting bottom end parts is hard for one thing, the other is that the nikasil would need to be redone to be sure it was not scrubbed away or damaged. To redo the nikasil, the cylinger would have to be bored and retreated, with oversized pistons installed. These pistons run $270 each. You can also have the block sleeved but this works with mixed results. Then you get to the heads...you will need new or good used ones as the old ones would have damaged seat receivers. They would have to be welded up and remachined at a big price. they would likely have other damage as well. If it were mine, i would find th ebest used engine I could afford and go with that. I might call Coventry West and see if they have a rebuilt one just for grins.

 

D, if when in high school I knew 10% of what I know now I'd be owning a hangar full of Alfas, jags, jensens... Well you get the idea:-). I was thinking of you personally, how it would suck if turned out that the engine would also need a bottom end after all your hard work.

You do know what you are doing and I'd like to wish you the best! Keep us posted.

 

Oldmots- Thanks for the gentle reminder... Nikasil...

$$ prize goes to a used motor. Even if I took the engine in my garage (AJ26) and swapped parts over I would be looking at a higher cost of parts than a used motor.

*sigh* Looks like I will be doing an R&R.

 

DSnyder, I recently wrecked my XJ8, with an XLNT motor with metal tensioners. Have sold the trans, but motor and the rest of the car is in very good condition. Contact me off-list if interested. mlords@sbcglobal.net

 

I am looking at a short block with 70K miles on it. I can use a head from my spare motor and buy a passenger head- including gaskets it should come in around my budget, plus time to build the long block....

 

01's are NOT Nikasil engines!!

If the valve seats are doen, I hope you at least scope the heads and pistons. Overheating usually kills the bottomend first on high mileage cars, something to think about.

 

Manufacture date 1/01 so.... it could go either way, no?

For what I am paying for the short block with 70K miles on it I should be good to go, and I won't have to risk the bottom end being toasted. I worked a low mileage tranny in with the deal, so the car should be on the road by this weekend provided I can find an inexpensive used passenger head locally.

 

D, the last of nik engines were produced in August 2000. I don't believe your engine is a nik. The block numbers info is in the forum. Will dig it up when I'll be back tonight.

 

Thanks!
I purchased a tranny and for a *small* amount extra got a 1998 short block with 70K miles.

I was planning to swap the block and see if a machine shop can revive the passenger head (or both) possibly taking an existing (good) drivers side head from a 1998 to save on costs. I am guessing a 70K nikasil block beats out a 2001 overheated steel block, but I would love to hear input.

Engine and trans come out this weekend and I start the week long process of cleaning and reassembly. I hope to reinstall the motor and trans next weekend and get her on the road.

On a SIDE note, has anyone restored the leather seats with leatherique dye and crack filler? The seats are in 70% condition with only one small tear, I am hoping to restore them.