Hi there,

I'm adressing some oil leaks I'm having on my 82 XJS V12 H.E.
I have done some reading and the oil leaks on the top of the engine are mostly coming from the half moon seal, cam cover gaskets, oil pressure sender, banjo bolts for the oil feed pipes., sweating tappet blocks

In the mean while I have sourced a couple of aluminium half moon seals and a couple of improved banjo bolts with thicker washers for the oil feed pipes
And looking at the engine I noticed that the tappet blocks are sweating as well.

So i have got a couple of questions;
1; Can I do al these repairs with the engine still in the car? (which is preferable because I don't have the tools to take the engine out)
2; I have read a lot of horrible stories about the paper cam cover gaskets, so the gortex ones are preferable or will locktite 518 do the job as well?
3; Can I just simply remove the camshaft and tappet block without disturbing timing; valves, valve springs and tappets falling apart?
4; the oil pressure sender is dirty/oily on top, and I think it doesn't work that well any more, with cold start I have an excellent oil pressure at the gauge of 50+, but when the engine heats up it is almost dropping to zero, while driving at 2000 rev/min I got a reading at the gauge of aprox. 20 (NB there is enough oil in the engine

Hope you guys or girls can help me out,

Thanks

Michel

 

What's a Tappet Block?

You can just remove the cam cover and replace the gaskets etc.
You'll always get more oil pressure with cold, thik oil than when the engine is hot - have you changed the oil revently and what weight of oil are you using?

 

Michel,

1) Yes, but the banjo bolts are a PITA seriously, as access is non existent.
2) Gortex is the go, or Hi Temp RTV only as I do, but that is NOT for the feint hearted,
3) NO. You will need to release the mega $$$$ boomerang shaped chain tentioner to get the camshafts off.NO valves etc will fly out.
4) Normal. The Smiths sender is flaky right out of the box, and the earth circuit of the instrument cluster leaves a lot to the imagination.

In all my years:

The banjo bolts etc are the least leakers, they get blamed for oil from the cam cover and the "D" seals.
The oil switches are common, both of them.
The cam cover gaskets as common.
The tappet blocks sweat, YES, and there is NO gasket there, it is a chemical seal, and unless it is dripping on the exhaust manifolds, AFTER the rest is down, forget it, until the engine needs to come apart, usually at about 700k mies.
The o/ring seal on the distributor leaks oil, sometimes.
The thin paper gasket of the plate in the bottom of the "V" also leaks, sometimes.

I would NOT touch the banjo bolts unless you are 100++% sure they are leaking, I have never had them leak, UNLESS previously played with by some fool.

Same for the tappet blocks, I reckon most of the sweating is coming from above.

Check the crankcase breather system, as it is prone to not working correctly, and then the engine cannot breath as designed, and the crankcase gets pressurised and oil finds it way to the outside.

 

Hi Bladerunner,

The tappet block is the part that holds the camshaft and is known for leaking oil because there is no sealing between the tappet block and head (metal to metal)

Below a short a video of what the tappetblock of our beloved V12´s looks like


I´m using 20W50, and I know, the oil pressure drops a bit when the engine gets warm, but that is not the main issue, I just want to stop the oilleaks on the top engine.

Cheers

 

Hi Grant,

Thanks, this was the info I was looking for

I will take your advise and leave the tappet blocks for what they are for now, I know they sweat, but need to find out how bad it really is.
was thinking why not seal them as well while I'm in there.

I will definitely check the crankcase breather system

Any solutions or suggestions for the Oil switches? are their upgrades which will do a better job?

thanks

 

Further to Grant's point about the tappet block/head seal. This is a metal to metal seal, probably because it is 100% vital to the valve/camshaft clearance setting. The line of the join is canted outwards, as it follows the angle of the V. The oil in the area is NOT under pressure, it is finding its way back to the sump under gravity and a bit pools along the seam. Mine leaked, not catastrophically, but enough to make the outside dirty and occasionally smoke off the exhausts on starting.
As I had my engine out I decided to do the cam cover gasket and half-moon seals and generally clean up the V. Taking advice from a friend I did the following to the tappet block seals: Cleaned the external join very thoroughly and roughed up the metal with wire wool; then applied (see photo, and it could be done far more neatly as the Management has often pointed out) a bead of high temperature silicone round the join. It has been dry as a bone since.

As Grant mentioned, doing the cam cover gaskets is fine engine in car, but you have to remove the intakes first. They come out as a single unit with the injection rail, once the inlet manifold bolts (all 24) are undone and the injector loom and fuel lines are unplugged. Nice ally half moon seals are available, and also the timing chain access hole plug - see Warrjon's recent post. These are really worthwhile upgrades, as is renewing both oil pressure senders while access is easier. I did my cam feed banjos, but engine-in-car they are impossible, and as Grant said they do not leak if undisturbed from the factory. I used the Gortex gaskets, and (as per the Great Palm) used slightly longer cam cover bolts with Allen key heads and a decent washer under the bolt head.

Ever since doing this in 2011 I have had no leaks from this area at all. Also, do NOT worry about low oil pressure at tickover when the engine is hot, this is 100% normal.

 

David Manners and the other Jaguar specialists have the required senders. Some are tapered threads, if so, tightening just enough is all that is required. If parallel threads, a drop of weak grade loctite to ensure the threads seal is a good plan.
Also, remember to buy new inlet manifold gaskets for when you replace the intakes.

 

hi Greg,

Thanks for your reply, what bolts did you use for your cam covers, I think I have read somewhere that in a certain time frame it went from UNC to Metric, is this the case ?
or can I just go to the local hardware store here in the Netherlands and buy a couple of M5 or M6 (don't know the exact measurement) bolts

You mentioned taking of the intakes, this was part of the plan and I want to replace the spark plugs and leads and distributer cap as well, because of the access
What do you think, should I replace the coils as well?, and if so do a 2 coil conversion to 1 coil? as mentioned in the great Kirby's book?

Anything else what makes sense to do when the intakes are of?

 

Just remove a cam cover bolt and test it, it might be metric or UNC or UNF! BUT be careful as UNC can easily be mistaken for metric.
As to the coils, I am a fan of the two-coil system, so if you have it, leave well alone, say I. Equally lots of others, Grant included, like the single coil replacement, so it is up to you - single coil is simpler and does away with some loom, and of course would be a new one.

Give the dizzy a good lube and ensure it is not jammed and springs back - as per the Great Palm.

 

Whilst the centre coil is off, look at the mounting bracket, where it attaches to the pedestal plate.

Currently, those 2 bolts need to be REMOVED, to remove the coil.

I slotted those bracket holes, as in opened the horizontal slots with a vertical cut, so those 2 bolts only need to be LOOSENED and the coil lifted out.

Simple, and the chances of dropping said bolts into the depths of the "never to found again" are eliminated.

My 85 is Metric camcover bolts, as is the 76 PreHE. The other HE is UNC, British logic strikes again.