I noted a post where a member bought gaskets and tensioners for an AJ27 engine only to discover his was an AJ26. Just how can you tell if you have the newer AJ27 or the earlier AJ26? To most of us they look just alike. I have searched for "images" of each only to get the same exact photo displayed for both! I'm about to launch into the timing chain preventive replacement ordeal and need to know. Also, I note that Lincoln LS 3.9 engine pieces are half the price of JAG, so if you are on a limited budget why not use them?

 

From what I understand there are a few indications;

1. The VIN of your vehicle will state if it's AJ26 or AJ27 from 2000MY onwards

XK8/R, 11th digit in your VIN; C=AJ26, E=AJ26S, N=AJ27, P=AJ27S
XJ8/R, 11th digit in your VIN; A/B=AJ26, D=AJ26S, K/L=AJ27, M=AJ27S

2. The throttle body of an AJ26 has a large vacuum canister for the cruise control, the AJ27 does not

3. The coils on the AJ26 are 2-wire, the AJ27 has 4-wire coils.

BUT

The supercharged cars had a grey zone where the electronics were AJ27S but the engine itself was AJ26S...but since you have an XK8, that shouldn't affect you.

 

My VIN is "A06528" so it must be an AJ26...but it has no canister that I can see. In photos I can see a canister that is about tomato can size and has what appears to be a vacuum hose coming out of the top. Mine does not have that. I just put the coil covers back on an hour ago, but did not count the wires. No big deal to pull off again. If it has 4 then I'll assume it is an AJ26 & 1/2.

 

The 11th digit of your VIN is the one before the "A"

 

I went back out and pulled the coil cover off once more....and they have
4 wires.


I then went back out and checked the VIN again...NA06528.


This car was traded back to Hennessy in Atlanta with less than 9,000 miles on it, so I was beginning to think they had replaced the engine. Maybe not.
So, am I safe with regards to the tensioners, or should I pull the valve covers off and take a peek? Whatja think?

 

Definately an AJ27 then...

Unless you have documentation proving that the tensioners have been replaced to the 4.2L version (p/n: C2A1511 + C2A1512) then I would change them out, even if the engine only has 9000mi on it.

 

Thanks, CAMBO. That information is exactly what I needed to hear. I will pull one side of the engine covers off and see just what is in there. If it is plastic, I'll have the entire timing chain system redone, 1st and 2nd, chains, guides and water pump. I understand that some 2000 models have steel tensioners, but I think mine is fairly early in the production year and, at best, has the 2nd gen plastic installed. 49,000 just rolled over.

 

My 11th character is K but the coils only have 2 pins, do you know where the engine stamping is. Also whilst I'm talking about contradictions its a year 2000 and the identification plate states it an x300 but I would of thought it should state x308 shouldn't it?

 

To confuse matters even more i have an aj27 with the 11th digit being H 😂 and 4 wire coil packs. Built in 04 1999🤷