Hi all, Im tearing the head off my 89 XJ40 to inspect/replace the head gasket. Im at the point in disassembly where I have to undo the timing chains.

Unfortunately I dont have access to any Jaguar service information, just the online repair resource service we have at my work, which can be hit and miss at best for information.

Upon disassembly, it states to remove the valve from the upper chain tensioner, and insert a 3mm allen wrench, and turn it clockwise to relieve tension on the timing chain. That sounds simple enough, but for re assembly it tells me to install a special tool, over the tensioner, and tighten the center bolt of this tool, and then removing it and using the 3mm allen wrench to now turn counter clockwise.

I cant seem to find any information on this tool, or if its available to purchase. Ive looked at a couple threads online about changing the head gasket on the 3.6, and I havent seen any mention of this tool. Is it absolutely necessary, and if so, could it be made?

Cheers, David

 

Hi David,

Welcome to the Jaguar Forums! It's great to have you with us.

I did the head gasket on our '89 once and have done it on our '93 twice (about 90,000 miles apart), and I have never needed any of the special Jaguar tools. At the time, the primary service reference I had was the Haynes XJ40 Manual, which you can download here:

https://www.mediafire.com/?hx8bttsy4kxxr#3267xri9vx4v6

Regarding the chain tensioner, I don't recall having to replace the tensioner with anything while I did the head gasket work. There is a trick to reinstalling the tensioner, which is explained in Haynes.

There are a couple of tricks for dealing with the timing chains that will eliminate the need for another special Jaguar tool. Off the top of my head the procedure was something like this:

1. Rotate the engine until cylinder 1 is at TDC on the correct stroke per Haynes, and the notches in both camshafts are oriented perpendicular to the top of the head, so that if you actually had the special tool its prong would fit into both cam notches.

2. Remove the guard plate at the top of the timing chain/sprockets.

3. Flush the tops of the timing chains and sprockets with brake cleaner or similar solvent to wash away all traces of oil and allow them to dry.

4. Use a paint pen or an auto paint touch up brush to paint alignment marks across one or two teeth of each cam sprocket and the chain link that is in contact with those teeth. Allow the paint to dry completely before proceeding.

5. Stuff rags or towels down into the timing cover to prevent dropping anything down into the cover, like sprocket screws or retaining tabs.

6. Remove the cam sprockets and allow the chain to simply rest on the rags or towels you stuffed into the timing cover.

Reassembly is just a matter of ensuring that your paint marks align as you tighten up the cam sprockets.


Another couple of tips I can think of:

If you find that the aluminum on the head has eroded between a coolant jacket and combustion chamber or oil port, you can repair the eroded area with JB-Weld epoxy. Use the regular or high-temp versions, which take longer to cure but will hold up better than the quick-cure versions. Use a razor blade or similar to carefully scrape the repair flush with the surface of the head.

Also, I would recommend using the Permatex Copper Spray-A-Gasket on both sides of the new head gasket to help seal small scratches and imperfections in the mating surfaces of the block and head.

Cheers,

Don

 

Thanks for the tips Don! I will definetly be using the paint pen trick

Do you recall having to re torque the head bolts after a few hundred miles?

Cheers, David

 

You don't rerorque torque to yeild bolts

 

Absolutely not! Follow the instructions in Haynes and you'll be fine. Here are some additional tips:

1. I recommend that you use new head bolts. Jaguar originally specified that the bolts must be replaced, but subsequently reconsidered and allowed for reuse up to two times if the bolts are not corroded or otherwise damaged and have not already been marked with two punch marks:

http://www.jagrepair.com/images/TSB/...ad%20Bolts.pdf

However, other authorities disagree, including head gasket manufacturer Fel-Pro:

Proper installation and use of T-T-Y Bolts - Fel-Pro Only


2. Take the time to cut the heads off of two of the old bolts and slot their unthreaded ends for a screwdriver so you can use them as guide rods for reinstalling the head, as explained in Haynes.

3. Follow the tightening pattern in Haynes to tighten the cylinder bolts to about 20 ft. lbs. or so, then follow the same pattern to tighten them to 44 ft. lbs. Then, in the same pattern, carefully turn the bolts an additional 90 degrees (1/4 turn).

During the additional quarter turn, the bolts actually stretch. This is called the Torque-To-Yield method. So the bolts should not, under any circumstances, need to be retightened. At least until you have to replace the head gasket again in another 100,000 miles.

Cheers,

Don

 

Well thanks for the advice all, but Im looking at something more major than a headgasket.

As I was pulling it apart there was alot of evidence that someone, who maybe didnt know all what they were doing, was into this engine. As I pulled the head off, I found coolant jackets full of corrosion and pieces of silicon gasket material, several chunks of head gasket missing around coolant jackets, but what I couldnt ignore was the pinkey-fingered sized hole in the #2 piston. Im searching for another engine/parts car. This engine has nearly 300,000 kms on it, warranting a full rebuild should I open it up. I think finding another engine or parts car for a few hundred dollars is more in my budget

Does anyone know if a 3.6 ECM would run the slightly newer 4.0 AJ6?

 

[QUOTE=davidsxj40;1533439]Well thanks for the advice all, but Im looking at something more major than a headgasket.[QUOTE]

Well that's a bummer, David! The good news is that finding another engine shouldn't be terribly difficult or expensive.


I think it is possible if your 4.0L engine came from a '90-'92 car. Those used the same single-pintle fuel injectors as the 3.6L engines. The '93-'94 cars used dual-orifice injectors with a fuel flow rate that was 30 cc/min less than the single-pintle ones but were more efficient because they aimed the atomized fuel more directly onto the backs of the intake valves. The fuel mappping was revised accordingly.

I assume the engine would bolt right onto your transmission. The 4.0L cars had the ZF 4HP24 electronically controlled transmissions, but I think the 3.6L cars had the 4HP22 hydro-mechanically controlled gearboxes. That might work fine, or it might not. The 4.0L engines produce more torque, which could potentially affect gear shift quality.

I can't remember if the MAFs are the same, or other critical sensors. There may also be differences in the emissions system. And in the electrical harness.

There might be some minor challenges with things like the heater control valve or lack thereof - though probably not insurmountable.

I'd have to think about any other possibly challenges. Hopefully others will respond with ideas and maybe even personal experience.

Cheers,

Don

 

Whereabouts in BC are you David?

Larry

 

Larry, Im in Abbotsford, the car is in Langley. However if there was a good running Jag engine involved I may make a couple hour drive for it...

 

I wonder if the 92 and up 4.0 would work if I use my original intake, injectors and associated sensors?

 

Well you'd better check that out, but if it's ok to use one, I have a 94 4 litre motor with only 69,000 miles on it!

Car is in Brentwood Bay, about 10km from the ferry.

If you want to go for it, you'll need to bring a cherry picker and a truck/tools - we can just unbolt it and load it up - all the ancillaries are already off.

cheers

Larry

 

Larry, if you were on the mainland Id jump all over that. Unfortunately fares for the ferry are a little outrageous, and out of the budget.
Ive recently realized Ive got too much money wrapped up in too many projects. This Jag was free and so far only cost me a transfer of ownership fee and a day permit, so it might go on the backburner for a month while I unload some other projects...

Thank you for the offer though, and if in a month or 2 you still have it and its in the picture I may take you up on it

 

Understandable Dave, no prob, I hardly ever go over to the mainland anymore, outrageous fares for sure, would probably cost more to come over and get it than it would to buy it!!

Good luck with your projects!

cheers

Larry

 

Hi David,

I completely understand the need to put this on the back burner, but for future reference, another difference I thought of is that the TPS was changed at some point, I think when the 4.0L engines were introduced along with the electronically-controlled transmission. An extra trace was added to the TPS to provide throttle position info to the TCM.

But if your intake will bolt directly on the 4.0L head you could just use your throttle body and TPS. You might check the part numbers for the intake manifolds and gaskets to see if they are the same for both the 3.6L and 4.0L engines. You can look up part numbers for 3.6L and 4.0L years at jaguarclassicparts.com.

As far as I know, the only significant mechanical change was to revise the crankshaft and connecting rods to lengthen the stroke, but there may be some other differences (longer cylinder liners? revised cams?).

Please keep us informed when you can resume work on the Jag.

Cheers,

Don

 

Well Don, Im trying to price out parts for the rebuild, and maybe buy all the required parts over a few weeks then do a rebuild.

The main hurdle Im having to overcome, is I cant seem to find a supplier for, even just one piston. Then Id also need rings and bearing shells, which when I can find them they have been pricey. And then on top of that Ill need gaskets and headbolts and all that fun little stuff too.

If Im understanding correctly, since my pistons are domed, I have the "high compression" pistons?