First off, as the title implies, this post is in regards to valve springs for my 1999 XJR. I am well aware of the dangers of a timing chain failure and the catastrophic engine damage that can occur due to the fact that this engine is an interference engine (which for those of you not familiar with the term, means that when the valves open they actually stick far enough into the cylinder to interfere with the piston, expect for the fact that the timing of the camshaft prevents this).

What I have not seen anyone discuss is the damage that may result due to a broken valve spring. Since it is the valve springs job to return the valve to its closed position, if the timing chain is working but the valve spring breaks, the valve could be left in its open position.

So my first question is:

1 - What kind of damage could result in this engine due to a broken valve spring?

While pondering this, and the fact that I may need to update the tensioners on my recently acquired XJR, I thought it may not be a bad idea to check the condition of my valve springs and potentially replace them.

This led me to the EPC.

I downloaded the "V3 10.2009" edition of the Electronic Parts Catalog (EPC). My car is a 1999 XJR, last 6 of the VIN are 862xxx

In the EPC, I selected the following:

XJ Series (From vin 812317 to F59525) (Canada/Mexico/USA) > Engine > Camshafts & Valve Gear > Camshaft & Valves

This brought me to image TB6140B, which shows the valve spring as item #7.

There are two options for valve springs, depending on the last 6 of the VIN. The options are:

For VIN up to 853935 - Part #NCC2535AA

From VIN 853936 - Part #NCE2535CA

This leads me to my second question:

2 - What changed engine-wise between these vin #'s and what's the difference between these two valve springs?

Because my VIN is 862xxx, it appears that I would need NCE2535CA.

Now this is where my problem arises... when I do a Google search for "NCE2535CA", I only get about a dozen results that all appear to be in Russian!

I have a little bit more luck when I search for "NCC2535AA", as this turned up a page on jagbits.com and also an Ebay listing.

So finally, I present to you my third question:

3 - Where can X308 valve springs be purchased?

Thanks so much for all the information provided on these forums. I have been soaking it up like a sponge!

-Caleb

 

Hmmm... I forgot to color my third question, and I don't see a way to edit the post. Oops!

 

I just realized that 853935 is the last VIN # of the 1998 model year, and 853936 is the first VIN # of the 1999 model year.

Anyone have any idea why they would have switched valve springs between 1998 and 1999?

Also, perhaps the reason I can't find NCE2535CA is because it has been superceded by a different part #?

Thanks!

-Caleb

 

The AJ27 heads are different as well as the tappets. I am sure the springs are also different. Here is a Tech Tip from August 2003 describing the superseded heads and tappets.

"Models – XJ/XK AJ26
Information: Please be aware that when ordering replacement heads for a AJ26 engine that the heads have been superseded to AJ27 heads and the tappets will have to be replaced with a AJ27 tappets. This will be necessary to gain proper valve clearance."

bob gauff

 

Bob's onto it, if you've an AJ26 engine you'll need the earlier springs, if your engine is a 27, then the part# AJ81381 will fit - they're used right up to the 4.2 engine.

They're a dollar a piece from the Dealer

 

Thanks for the responses so far.

I'd like to clear something up...

It's sounding like 1998 had the AJ26 engine and 1999 model year got the AJ27 engine?

I was under the impression that both 1998 and 1999 model year got the AJ26 engine and the AJ27 wasn't introduced until 2000 model year?