I have a 1980 model Daimler XJ6. Upon investigating 'tappet noises' and wanting to redo the clearences etc. I noticed the upper timing chain has numerous broken and missing outer rollers. No doubt contributing to the rattle.

Having had lot's or experience with motorcycles and in the past have replaced damaged timing chains by simply using a chain breaker and lots of care to thread a new chain in and then fix a new permanent link in, not a circlip type link.

Has any one here ever attempted this with a Jaguar? Can this chain be replaced without removing the head? It doesn't seem possible without breaking the chain.
I am not in a financial position to do a complete overhaul at this time, but I cannot simply do the valve clearances and put it back together like this. I would be too scared to drive it anywhere. Engine seems in fairly good condition and the lower chain looks OK. No doubt previous owner has over tightened this upper chain to try to reduce noise.

If this is not advisable, can the front timing cover be removed and all chains done without removing the head as outlined in the factory manual?

Thank you all for such a great site, has helped me a lot since owning this car.

regards,

Ron.

 

Ron, In a word, YES. Top chain only is doable that way with time, CARE, and steady hands.

I did one of ours a looooong time ago. I split the old chain, and attached the new chain and carefully wound the engine by hand until the new appeared and then attached the joiner, and clip (the correct way around), then adjusted as needed.

You will need 2 VERY GOOD helpers, that understand that if the chain slips/jumps, valves are going to get bent, and that is where I had the right people on the day. Do not forget, these engines CANNOT be wound backward, the lower hydraulic tensioner hates that.

I cannot find my notes from back then, but 3DR102 comes to mind as the length of that top chain.

I have seen that failure before, and I believe it is due to an over tight top chain tention on that micro wheel.

FORGOT THE MOST IMPORTANT THING.

One of those helpers just dropped in (the daughter) and we were discussing that little task, and having a laugh, and she reminded me that the break in the chain was made on the RH side, so the old chain fed out of the RH side as the new went in and over the inlet cam, on to the idler, up and over the exhaust, down thru the lower drive, and back up to the inlet cam sprocket where the joiner was fitted, and clipped. Keeping the new chain ON the inlet sprocket as the engine was turned was the hardest/scariest part, and very time the lobes "dropped over" the heart missed a beat.

 

Thanks Grant,

I do understand that 3 people are needed, one to turn the crank, slowly.
one to hold the chain firmly on both sprockets and one to feed it, along with backup wire etc. So now I will give it a try, yes the chain was tight as a rod, no play at all.

Just one more question, you say you used a circlip, how does that go? I was thinking of a new link and using a pin flaring attachment that comes with the breaking tool, is possible to over do it though and end up with a tight link, if a circlip is fine then I will use one. A bit concerned about if there's enough clearence etc.

many thanks again, nice to know some one has done it successfully before.

regards,

Ron.

 

OK, the clip I used was the one that came with the joiner link with the new chain.

It is always installed with the "heel" of the clip facing the direction of engine rotation. I am told the other way (open end) facing the rotation runs the risk of that clip being pushed off, and that would be sad on any day, and I think once you see the clip as supplied it will be very clear.

I have also done the same with my AJ16 engine top chain, and that was significantly easier.