Hello everyone, I have a question that I hope someone can help me with. I'm working on a 2000 Vandenplas XJ8 with the 4.0 V8 with a no start/dead misfire condition. I found 3 dead cylinders in the engine with zero compression. So I've decided to find an engine replacement. However, the engine I found is believed to be from a 99 XJ8 and when inspecting the engine I found some small differences from the 00 model. Like there is some type of vacuum pump on the throttle body of the 99 and also I'm guessing there are sensors on the front of the cylinder heads for VVT (variable valve timing)?
My question is this engine from the 99 Jag swapable or am I going to end up with a bunch of check engine light codes? Would I have to swap over the cylinder heads since my 00 Jag does not have the VVT? If that's the case I may have to return the engine since the heads on my car may have burnt valves.
Thanks for any info anyone has.

 

You need to search the archives for the info on AJ-26 to AJ-27 engine conversion. You are "going the wrong direction" and will have to use the old heads, oil pump, throttle body, transmission ring gear and probably some other stuff I have not remembered. And the real issue is that you probably have a bad head now, since a timing chain tensioner is probably the root cause.

So, get the AJ27 engine, or just replace the head, assuming the piston isn't knackered too bad.

 

Thank you, that's exactly what I needed. Hmm, how do you distinguish between an aj26 and aj27 engine?

 

By the differences you noted! Most notably where the VVT connector exits the head. I thought the AJ 26 engine for the normally aspirated car was only used for MY 98 models. They then changed to the AJ 27 through 2003. The SC version used the AJ26 through MY99, so I am not sure about your MY 99 engine.

The AJ 26 engine has two position VVT operation while the AJ 27 has a continuously variable VVT, which apparently required an upgraded oil pump. The AJ27 has an improved fuel injector system, electronically controlled throttle plate position, different coils and ignition amps, linear lambda sensor, and a different count of teeth (holes) in the transmission ring gear. The AJ 26 engne used a vacuum cruise control so it has the canister you noted on th ethrottle body. The AJ27 has cam position sensors on each bank.

PM me and I will send you the MY 1999 update document.

 

Oh ok got you. I'm not very familiar with these engines at all, I'm a Honda dealer mechanic by day! lol. Well the salvage yard said it's from a 99 XJ8 but it wouldn't surprise me if they're wrong. So the engine will be returned to them and I'll be back on the hunt for a motor.
Even "if" I wanted to swap everything from the AJ27 motor to the AJ26, there would be no point. After my compression test I also performed a cylinder leak down test on the suspect cylinders just to find over 90% leakage and air escaping thru the throttle body. Wouldn't be surprised if it did destroy the cam tensioners and throw the timing all to hell.
Thanks again for all the info. Wish I asked before picking up this used motor. Lesson learned.

 

Welcome !
We love to have real mechanics report in around here. Hondas, Jauguars- theyre just cars!

 

Actually in your situationi'd prefer to find heads and swap everything (oil pan, front cover and cam covers, intake and TB, flexplate) from AJ27 to AJ26. New gaskets and seals, valve job, new chains and tensioners - that'll be a whole new engine

 

Contact DSnyder. He just did a similar conversion on his XK8. MoscowLeaper is a very knowledgeable source as well. Between the two, you should have no problems getting it done.

 

Hi Tech,

I indeed did just do this- there are a few parts to swap over (including both heads) but you will have a fresh engine when you are done, and the amount of additional work to swap the parts is nominal in the big picture.

 

I have not tried to swap an AJ27 into an early AJ26 but I did diagnose and repair the problem created by someone who did this and did NOT replace ALL the different components (and did not tell me this is what was done).

It turned out that the one thing that was NOT changed was the torque converter drive plate. They have different sensor segments!!!!

There is a specific list of components that need to be used with one engine or the other.

The basic 4.0 engine blocks are the same but there are different sumps/heads etc. that are different.

It is easier to replace the engine with a 'like' component.

I just removed the left head on a 2001 XJ8 for a dropped valve a few weeks ago and reinstalled it. If the low cylinders are all on one bank it might be easier to just do the one head if the chain failed.

Sometime the valves DO NOT bend even though the exhaust cam stops turning if it stops in a 'GOOD' place.

bob gauff

 

You guys saying to just swap the heads are missing the point. He almost certainly has crashed valves, so his head is the problem. And how in the heck can you say going from a MY2000 engine to a MY 98 engine will give a "fresh engine". Geez.

 

Oh c'mon.
What's the problem to swap the valve guides and valves? Or get the used heads?
IF the MY98 have no wear of liners - the engine will be better than any MY2000.
With fresh heads, new gaskets&seals, tensioners, chains on so on. Much better than drop-in of the MY2000 engine in unknown state.

 

Moscow:
Please advise why the MY 98 is better than "any 2000"? There must be something you know I do not. The MY 98 has the unknown history. The MY 2000 suffered what I will bet is a chain failure. There was no reported problem before, so why not do the work on it's head on one side? Then do the chains. I do not think they are trying to do a project, but rather a quick drop in to get the car running.

The price of the work you guys desribed is considerably more time and money than dropping a junk yard motor.
Remember guys, this is a NA engine so it is not just heads and chains, it is oil pump, sump, front cover and all.

 

MY98 is better 'cos it's nikasil. If it doesn't have a wear now - it will run forever.
Mine had a chain failure too. With a bent valve. And with a damaged piston (small, almost invisible crack). Swap the head? ok, here you go, to find a burnt hole in a piston in a next 1000 miles.
Junk yard motor? Yeah, sure. Don't forget to remove the cam covers and front cover to replace chains and tensioners (or are you preferring to do that with an enigne in a car?), crank seals and, after that, you have no idea what's inside.
If one person, with minimal skills and available JTIS, have two engines - it'll take no more than a day and a gasket kit to make an AJ27 from AJ26. That's way better then dropping in a possible boat anchor from a junk yard.

 

MY98 is better 'cos it's nikasil. If it doesn't have a wear now - it will run forever.
Mine had a chain failure too. With a bent valve. And with a damaged piston (small, almost invisible crack). Swap the head? ok, here you go, to find a burnt hole in a piston in a next 1000 miles.
Junk yard motor? Yeah, sure. Don't forget to remove the cam covers and front cover to replace chains and tensioners (or are you preferring to do that with an enigne in a car?), crank seals and, after that, you have no idea what's inside.
If one person, with minimal skills and available JTIS, have two engines - it'll take no more than a day and a gasket kit to make an AJ27 from AJ26. That's way better then dropping in a boat anchor from a junk yard.

 

+1 to Moscow- I would rather go through an engine and KNOW what I am dealing with. A day of work is well worth it for the peace of mind.

As a matter of course, you would tear down the 2000 motor to see if there is further damage or is salvageable. I also think Nikasil is better long term after reading all the info. (although I am admittedly not an expert on engine liners.)

 

Sure, it's better to know what's inside in your engine. And it's better to waste a day for the engine works, rather than waste 2 days for the unplanned swap of the next engine from a junk-yard.
Nikasil is better, indeed. Even with a russian gas i have no problems with it. And there's NO WEAR at all.

 

Well, I happen to agree with you about the Nikasil- all else being equal- IF you know the engine's condition or have tested the blowby BUT for the archives, that opinion is definitely in the minority. That said, I have a Nikasil XJR with 175,000 miles that uses a little oil and a 2002 XJ8 non Nikasil with about the same miles that uses no oil between 10,000 mile changes. So I am adamant that a statement that any 2000 engine beats a 1998 is just a superficial answer.

And again, that is not the question the OP posted.

 

Well looks like things went from bad to worse. I found out this morning from the owner of the Jag that the salvage yard won't take the used motor back. They're saying it was an "as is" sale and that the motor should work. So for now he's just going to hang on to the car and try to take the salvage yard to court to get his money back. He just can't afford to put anymore into the car.
I really hate that for the owner but I think he got in over his head when he purchased the car in the condition it's in now. He says he purchased it for very cheap and thought it would be a quick fix. Initially we were able to start the car with long periods of cranking and stomping the throttle pedal but it sounded horrible and I could tell it had dead misfires in it from the flashing check engine light. But I guess any V8 running on 5 cylinders is going to sound horrible.
If anyone is curious it was actually the two rear cylinders on the left bank and the front cylinder on the right bank that were completely dead. If it were my vehicle I would just pull the motor out and pull the heads, send them off to be re-machined, change all the tensioners and gaskets and put it all back together. That's assuming no piston to valve contact.