I have a 98 xj8 that has had the replacement motor will steel liners. The motor spun a rod bearing and im rebuilding it. Im running into some problems bc I got another used bottom end and it has the nikasil liners. MY question is are the rings and pistons different between the nikasil and steel liners? I would think the pistons are the same bc the bores are the but the rings are different but would like someone to confirm. Also when I go to order parts Jaguar doesnt have a listing for steel liners in 98 so which year motor would you order the rings? Any thoughts would be great thanks

 

The rings for a nikasil lined engine are different and when I have removed the pistons from one I noticed that the rings had very little tension. I figured that if they had high tension on the cylinder wall it would scrape/wear the coating faster and lower friction is one of the advantages of nikasil.

Each ring/liner combo needs different materials. You can't put chrome rings in a chrome bore and iron rings don't last long in iron bores etc. I have a damaged nikasil engine (AJ27) that I took to a machine shop and had steel liners installed. The rings I got from BPI were very stiff and were made for steel liners. A good machine shop can match the pistons to the bores for a good fit.

The problem you are going to run into is the rod and main bearing selection. The bearings are fitted to each engine by block crank bearing diameter and crank journal diameter for EACH journal. There is a code on the side of the block for the original journal measurements so machining the crank will throw those specs 'out the window' and you will have to get out your calipers and micrometers to calculate your own bearing selection.

Maybe some aftermarket company has a generic .010/.010 bearing set for Jaguar 4.0 V8 and a machine shop can do the grinding????

bob gauff

 

Bob do you know where excatly the code on the side of the block is for the orginal journals measurements? And is this code for the rods and mains or just the mains Thanks in advance Jeremy

 

Sorry smitty I did not see your question and I forget to go back to some posts. I will have to go to my 'Service Training Course No. 180 V8 Engine Repair' for info on reading the code on the block. There are codes for block, crank and rods for each journal. If the original parts are in the engine, then the sizes apply. If any one thing changes, then you have to recalculate that component.

It's been a while since I read the training course book but without it you might have trouble deciphering the codes and ordering the correct size bearings.

If you can find a copy of 'Service Training Course No. 180 V8 Engine Repair' then you will have all the info needed to repair/rebuild the AJ26/AJ27/AJ28 engines.

bob gauff

 

Bob thanks for reply. You said that there are codes for the block, crank, and rods for each journal and If any one thing changes, then you have to recalculate that component. Correct me if im wrong but i thought all the block and cranks were the same and they took up the tolerances with the different colored bearings. Reason im asking is bc I bought other jaguar motor with a good crank but the block has nikasil liners, so I was going to swap the crank overto my block with the steel liners, get the codes off the block I swap the crank from and put those colored bearings in my steel lined blocked. Do you see any problem with this? Also I google the
service training course manual no 180 and came up with nothing anway you could send me the write up on finding the codes on block thanks in advance Jeremy

 

There are main bearing bore diameters for the block (5 letters with a selection from A to Z) and main bearing journal diameters for the crank (5 letters with a selection from A to W). Then you have rod journal diameters for the crank (4 letters A,B or C). I think the con rod big ends are all the same because there is no code for them. The row of 8 numbers is the piston/bore grade 1, 2 or 3 and are individually matched.

A machine shop can measure the crank bore and the crank journals for a final oil clearance of .001"-.002" (.025mm-.050mm)

The main bearing selection chart is an X/Y type chart with main bearing bore along the X and the main bearing journal along the Y. The intersecting values are the color coded size bearings (blue/green or green/green etc.)

It is difficult to cover everything here in a forum just typing. (that is why Jaguar has training classes)

You will have to decipher both block codes to get the correct bearings for a crank swap.

hope this helps.

bob gauff

 

Bob thanks for the reply. Im a pretty decent mechanic but this might be a little over my head. Im trying to put this motor back together as easy as possible. If I use the crank and rods from the motor with nikasil liners and put that setup in my steel lined motor the only codes I would need would be the ones off the block with nikasil liners correct? I thought all blocks and cranks were mass produced and they took up the tolerances with the color coded bearings is this correct? thanks in advance Jeremy

 

You will need the crank BORE code for the steel liner engine and the crank JOURNAL code for the nikasil engine. Then make the determination of the bearing thickness to get the .001-.002 oil clearance.
If you have ever rebuilt a VW aircooled engine, you will understand the OD and ID diameter align-bore issues associated with the crankshaft (ie. you can bore the block and leave the crank diameter, you can turn the crank and leave the block ID, or you can make the block bore larger and the crank journal smaller. They all need different bearings to keep the dimensions for the crank/block clearances.

If you use the same rods in the same place on the crank then you need to use the nikasil engine rod journal code.

bob gauff

 

Are you sure the steps 0.001 was in inches? According to the documentation I have this is in mm.

 

I am not talking about the steps of the bearing selection, I am talking about the OIL clearance between the bearing and the crank journal.
QUOTE
"A machine shop can measure the crank bore and the crank journals for a final oil clearance of .001"-.002" (.025mm-.050mm)" UNQUOTE

Some of the bearing selections are in .001mm steps (crank mains) and some are ranges (con rod) and piston/cylinder bore grades are in ranges.

Hope this clears up some mysteries.

bob gauff

 

Misread your post, so its clear.