Split seals, broken springs and too much tension!!

[Marcusj1000]

Hi all.

And so the saga continues........

I currently have the top of the engine disassembled in order to allow me to change the valve stem seals, valve springs and set everything up properly. In disassembly I have found some valve springs broken, I'm not sure how this could happen but I'm replacing all of them as a precaution. I am attempting to do this work without removal of the heads and by feeding new nylon rope into the cylinder and compressing it against the valves by manually turning the engine over. This appears to work and will hopefully save me time.

My question is as follows.... Does anyone know of a method that will allow me to slacken the cam chain tensioner and set up the cam timing properly but without purchasing the specialist jaguar tools. I am also looking for a valve spring compressor tool, I have purchased one but I'd doesn't really fit with the engine. Does anyone know of somewhere that has them for hire? Or, dare I say it, does anyone have these tools that they would be happy for me to borrow?
I can't imagine that I will ever need them again and so I am loathed to purchase them.

Any other "bodge it" methods that anyone has come up around this area with would be gratefully received.

Thanks in advance.

Marcus.

07813640351

[MarekH]

Dear Marcus,

To sort out your cams, prior to any teardown, rotate the engine clockwise a few times and settle exactly at 1A TDC as per the timing mark (or as per any other documented procedure - but don't rotate the engine backwards or else chain tension will be lost). Take a sharp chisel and punch two marks against both of the #1 cam bearing caps where the cam timing tool would normally slot in. When you reassemble the engine, you should be able to align these in the same way, if not more accurately, as by using the cam tool.

Before you disassemble anything, take a scribe and label all of the bearing caps with "A" or "B", their sequence number and an arrow to make sure you reassemble them the same way as they currently point.

Reassembly torque is "8", from memory, not the documented "9".

kind regards
Marek

[42south]

Hello. I have done my valve stem seals this way. I just fed in enough rope to stop the valve falling in, it doesn't need to be jammed packed tight. I did not turn the engine at all, it is not necessary, just feed in more or less rope depending on where the piston is.
We used a small magnet on a wire to lift the collets out whilst we held the spring compressed, couldn't get the proper tool, used a 4.2 engine tool with minor mods.
Mark the position of the cam sprockets before removing them.
I would recommend that you download Kirby's XJS book from the jag lovers website, He has lots of good info on this task. Pay particular attention to his method of releasing the timing chain tensioner, it can be easily broken, ask me how I know!
For stem seals I put them on both inlet and exhaust, my car is running great, oil consumption is down. We used the ones Kirby mentions in his book, stay away from the jag original seals, they won't last.

[Marcusj1000]

Hi all,

Thanks for the responses. Apologies for not getting back to you quicker.

I have had a bit of a breakthrough with the rope trick. Once I got the correct valve spring compressor (sealey cantilever sort, hooks onto a tappet block stud @?25) and a decent nylon rope the job took about 2.5 hours to replace 48 springs and 24 stem seals. I was worried the rope trick would be a bit of a bodge and I'd loose a valve but it was so easy to do with the heads intact.

On further inspection of my broken valve springs (only the small ones broke) I can see witness marks and have come to the conclusion that the previous engine assembler didn't compress them along the centre line of the spring and as a result they were distorted and slightly arched. I assume that the inner and outer springs were wearing against each other and a few finally gave up. I don't know but I do know that in now have shiny new springs and 24 stem seals (both inlet and exhaust) so everything should be shipshape. Now to reassemble, set valve gaps and drive off into the... Er... Snow!

With reference to the valve gaps, you'll see from my previous post that the gaps were too shy, even with the smallest shim. I have decided to make a spacing gasket out of 0.2mm shim steel to lift the tappet block and buy myself some extra clearance. I have measured all the component thicknesses and created an excel spreadsheet to calculate the best shim/tappet combination to get the best clearances. I will let you know if it works!

Marcus.

[PeterCrespin]

The gasket-less tappet block seal is somewhat leak-prone so take care now that you have doubled the interfaces.

The inner springs are supposed to rub the inner bore of the outer springs marginally. The interference helps damp out surges and harmonics AFAIK, although that was a worse problem on side valves and valve gear with longer springs. I can't remember the last time I replaced springs on a car or bike where there wasn't some polishing evidence of contact. I suspect your springs broke due to poor metallurgy or abuse.

Pete

[42south]

Hi
Check out loctite 518 gasket product. I used it on the tappet block and the cam cover with no gasket. It seems to have done a great job.