Hi All,
When my Engine (3.8) gets warm I sometimes get a horrible noise coming from the R/H Cam (inlet side) The Engine has been totally rebuilt and the cams have been shimmed properly.It has good oil pressure.
The Engine Builders have come across this before with an E Type which the Customer in desperation, sourced another head which they line bored the camshaft journals, and correctly shimmed the cam. The thought is that the cams are flexing is this possible?
Any suggestions?
Cheers Ray

 

Some XK engines, mainly the 4.2 engine in the XJ6 can be affected by the cam buckets lifting. The cam buckets are a pressed fit into the head and then the lifters sit in the buckets. When the engine gets hot the metals expand allowing the bucket to lift hitting the cam lobe as it rotates. Look for evidence of wear around the inlet valve buckets in your case but it is normally the exhaust side that goes first as this gets a lot hotter than the inlet side.
The solution is fairly simple and that is to fit a "Stakedown" kit. It comprises of some shaped bars that fit between the buckets pinning them in place. The plates are held in place with screws which (and this is the tricky part) are either self tapping "Tex screws" or you have to drill and tap the head to take the fixing screws.
I fitted a kit to my engine several years ago as I had a noise after my rebuild and the kit sorted this out. I went for the full kit on both inlet and exhaust and did the drill and tap route. I found it very easy to fit, you do not have to remove the cams and as long as you use common sense when drilling and tapping the alloy swarf is easily collected and removed with a small vacuum nozzle. I used Loctite on the screws when I fitted them.

Below is a link to the kit, a photo of what you get and one of the kit installed on the exhaust side.

https://www.scparts.co.uk/sc_en/tapp...kit-22484.html


The kit includes the plates, Allen key screws with the correct drill bit and tap to fit.

The "Stakedown" kit fitted to the exhaust side of my engine.

 

The stakedown kit only needs to be fitted to the exhaust side. If the inlet is making noise, I'd want to double check all the clearances, just to make sure everything is still in spec.

 

I suggest your first action is to remove the inlet valve cover and inspect. Check all cam clearances.

 

And check oil flow to that cam. If the Y pipe has been sent to the platers it could be partially blocked. Also check the pipe for a dent,

Also read this.

https://www.jaguarforums.com/forum/m...cation-209831/

Wrong


Right

 

Yes, I had forgot about oil flow. Those passages in the cam feed pipe are fairly small, and moreso if the pipe has "heart disease" and has deposits inside that restrict the flow. It's easy to clean the outside and difficult to clean the inside if there has been oil coking.

 

I found the best way to clean the inside of the pipe, but you have to remove it first, is to push a rod of a suitable width and flexibility down the pipe whilst flushing it with a degreasing agent. Welding wire is good for the job.

 

Yes ~ and Jaguar drilled the cams to increase oil flow on start up & reduce cam rattle ~ but if the oil can't get there in the first place things can be noisy.

 

There should be a dense 'oil fog' when you take the oil filler cap of a running XK engine. If not, there's definitely something wrong with the oil supply.

 

I have seen both inlet and exhaust buckets come loose. It seems to be more prevalent in the 4.2 engines however I have experienced it in 3.4/3.8 engines.
i would suggest lifting the inlet cam cover and looking for a loose bucket.
There are a number of ways to hold buckets down including "staking" by drilling and tapping a grub screw onto the side of the bucket from the valley side of the head.
Another way is to drill and tap a hole beside the bucket and use a machine screw with a cheese head to lock it down.
But I think the "stake down" kit is the best cure.