Hello,

I have been messing with the engine lately, finally decided to finish replacing the rest of the fuel hoses and get it started after a long period of sitting. Flushed out all the fuel lines and the car started after a few tries.

Loud tapping noise from exhaust side, sure enough it is the tappet guide on the number 4 cylinder getting hit by the cam lobe. The damage is not severe in my opinion, the tappet guide is dented up, but not all the way around, and does not seem to be missing any chunks.

I think I should be able to reseat it, but I would like to hear other opinions or instructions on how I should do this. I am thinking of using a bearing driver and hammering the guide back down after removing the cam and tappet. I tried using a punch to tap it back down, but stopped pretty quickly when it didn't seem to help.

Of course I need the stakedown kit, any recommendations on that are also welcome. I haven't driven this car more than a few feet, so I don't know the full history, but it appears that the head was previously worked on, and the engine appears pretty clean. So I'd rather not mess with removing the head.

Question on slackening the cam chain-- is it okay to use the needle nose pliers technique on the tensioner instead of the special tool?

 

Yep, take the camshaft off, remove the bucket, dont drop the shim, find/make/whatever a suitable punch type arrangement to sit on the guide sweetly, BASH it down. It will take some driving, and of course CAUTION will be a priority, you DO NOT want to break it. Our S2 waaaaaay back had 3 moving around and clobbering the crap out of the camshaft, and 2 went down sweet as, but one was a pain. I used a "heat and strip" hot air gun, and heated the local area as best I could, I did not want to use oxy, as damage would be definate, and then drove the thing home.

I used a stake down kit from the local Jaguar indy supplier, and fitted it very easily, never heard from it again.

 

what makes them lift up in 1st place???

 

Aluminium heats up and expnds more than the steel guide, friction is lost, banging follows.

NOW, when you go to bash it back down, and the damn thing will NOT move, you ask WHY. As I said some go back home sweet as, others require a different language totally.

One theory is that the actual cam bucket (follower) jams in the outer guide, and the valve spring actually forces the guide out of the head, I doubt it, the springs are strong, but not that strong, try it, you can compress them by hand, with some serious GRUNT.

My belief is that the engine has got HOT, and the cylinder head has lost its grip on the guides. It is a "bad" design as is, and stake downs should have installed from day 1. Some have drilled and grub screwed from the side, NO GOOD, coz by the time you get enough "grab" to hold the guide in place you can distort the guide, and then the bucket jams more, the valve does not close, and the piston does obscene things to said valve.

 

i wonder why not let them run in aluminum, like V12.

maybe noise when hot?? better than liftin a follower guide, cant lift if it aint there!

 

I removed the cats to lower the exhaust temps. Hopefully that will prevent the tappets from moving. Didn't foreign versions of the Jag not have this problem because they dont run cats?

PS--dont tell the DMV I removed my cats...thank you.

 

yeah, DMV?.... Just wanted to report someone.

I have read a few different explanations. I guess the engine was initially designed before it was accepted practice to let the tappets run in aluminum. An article by Roger Bywater who worked at Jaguar stated that the interference fit was made less tight by adjusting the sizes of either the bore or the tappet guide diameter, and that also contributed to problems. The issue of heat from running the US emissions equipment seems to be one of the major issues. Many people in other countries never had the problem.

Thanks to everyone for the help. My plan is to measure tappet clearance before removing the cam. Then if any clearances are too tight, I can check the shims sizes after removing the cam, and order some shims if needed. Then I will knock the tappet guide down with a socket and hammer or maybe use my big brass hammer somehow. Finally I will install the stakedown kit. I have not done a lot of thread tapping, but I will go slow and careful.

I've read a little about tapping aluminum, they say that using alcohol is good to lubricate the tap. I plan to do more research before I jump in.

 

Found this nifty DIY cam tensioner tool that I may use instead of the needle nose pliers technique:
http://www.jcna.com/library/tech/tech0030.html

JCNA has a great page of tech stuff:
http://www.jcna.com/library/tech/index.php

 

Okay, I started by getting a feeler gauge set with angled blades (Autozone $5) for checking tappet clearance. Rigged up a starter button to bump the engine over and check the clearances between the cam and tappets. 3 of them were outside spec, but only one was showing not enough clearance at .008. The spec is .012-.014, and some of them had .015 and .016. So I wrote all those measurements down, then removed the cam using needle nose pliers to release the cam chain tensioner.

Removed the cam and found the cam bearings look like they need replacement. I removed the tappets one by one and checked each adjusting shim. Wrote down the letter of each shim to calculate the thicknesses of the ones I need to order.

Some of the tappets were tricky to pull out, like the one the had the damaged guide. I wiggled that one out finally. The other tricky one did not appear to be damaged, but it still was getting stuck. I cleaned it and attached some gray foam double sided tape from 3M (sold as emblem and trim adhesive tape). With the tape on the tappet surface, I found a electric motor capacitor with a flat bottom and stuck it to the tappet, and this allowed me a handle to pull the tappet out easier.

I placed the head of my 4 lb copper hammer on the guide that was sticking up, then pounded the hammer with another hammer to drive the guide back down. It went right down easy. I found a large socket, and used it to give the other guides a few assurance taps to make sure they were fully seated.

I purchased a set of needle files (Harbor Freight) to file away the damaged inner edge where the cam struck the tappet guide, hopefully this will allow the tappet to once again rotate smoothly in its bore.

My valve clearance measurements (cyl 1 closest to firewall):
So I need to order:I hope replacing the cam bearings doesn't throw off the valve clearances I measured.

Looks like the parts will cost $50-60.

 

Dont forget the "D" rubbers, 2 required.

Also 2 gaskets for the breather cover at the front.

The new cam bearings should give a different reading, not by much, and probably not enough to upset your careful lists.

 

keep us posted, sounds interesting.

question , being not familier with the in-line 6, so it does have replacable lower cam insert bearings, and if top bearing is worn would that change clearence??

most of my Jag engine experiance is V12

Ron

 

Thanks, I have added those items to my list, probably going to order everything Monday. Seems like prices vary a lot for the stakedown kit, anywhere from $30 to $55. So my initial cost estimate is probably going to double. Shims are anywhere from 2.25 to 7.50 each.

The bearings also vary a lot in price, anywhere from 55 to 80 bucks.

ronbros, yes there is an upper and lower cam bearing insert, so the cam is fully surrounded by replaceable shells. If the bearings are worn enough, it would affect clearance, they appear to be worn on both the upper and lower shells. I am not sure, but I think wear on the upper bearing is less critical since it would only increase clearance which is a safer situation than having decreased clearance.

Going to call and check with Welsh, Coventry West, SNG Barratt, and Fastlane, trying to get all the best prices I can since it seems a lot of money can be saved by shopping around. Let me know if anyone has other good sources.

 

Finally received my parts. Ordered from Peachparts "Fastlane" store and Coventry West. Spent about $120 (plus shipping from CW). Peachparts does free shipping over $100, so I ordered some unrelated stuff to round it up. Tappet hold down kit was much cheaper from CW, cam bearings were cheapest at PP.

Here are a few scans of what I received.


CW sent the wrong washers, I received these drain plug washers instead of cam cover washers, but they are correcting that. I will be charged for the proper ones, then I get the refund when I send these back with prepaid UPS label.


These lockplates retain the cam gear bolts to prevent the bolts from loosening. The old ones were really torn up, I think someone worked on this engine before and reused them.


This is the box for the cam bearings. The brand name shown on the site was "Vandervell" and it says "VAN" on the sticker here, I don't know if that is any different than Glyco. These will be fine I'm sure. Part of the Federal Mogul family. Engineered in Germany, made in Australia, with an address on the bottom of Kontich, Belgium.






The shims:

These look unfinished on the outer edges, compared to the Jag originals which have the circumference machined. Also, there are no markings indicating any part number or thickness. Luckily I only ordered three and was able to use my cheapy calipers to figure out which were which.

Not shown: cam cover gasket

So now I have to psyche myself up for drilling into the cylinder head. I am debating whether or not to use the self tapping screws provided, or to get some nicer bolts/capscrews that are stronger, and use a tap to make the threads. Opinions? I have not tapped threads before, but I am willing to learn.

 

Try to smack the chilled cast iron tappet guide evenly (top and bottom) with a soft brass/copper drift/punch with the cam in place. It might work better if the engine is hot. I have NEVER had to remove a cam to hammer the guides back into place and install the holdown kit. I have installed DOZENS of holdown kits back in the 80s and 90s and I even left the severely damaged (chipped by the cam lobe) ones in place (NOT CRACKED) if the customer wanted to take a chance and did not want to replace them. If the guide had a vertical split or completely shattered then the head had to come off for repair.

bob gauff

 

Thanks for the info! Already removed the cam and knocked it down. I tried tapping on it before, but it didn't seem to be moving. Since I didn't have any brass drifts, I didn't want to damage it and mushroom the top edge of the tappet guide. My plan is to reuse the tappet guide, and just do a little filing of the top inner edge to make sure there is no ridge.

Good to know that it is possible to do without removing the cam. I should have invested in some brass drifts a long time ago.

Motorcarman, did your kits come with the self-tappers? Did you use those with success?

 

I have not installed a kit in about 10 years. I have bought kits that came with sheet metal looking screws but I drill and tap 1/4 20 holes and 'locktite' the bolts to the head. Hex socket (allen) bolts are what I like to use.

bob gauff

 

Thanks again Bob, that was what I was thinking about-- going with the allen style bolts. I appreciate the details you provided.

 

sounds like a good idea, hold down kit.

any pix of it installed, ??

 

come to think of it.
why didnt Jag put them on as standard OEM!!

this is a true statement, English engineers think they are so superior, they dont need any improvments.

best thing to ever happen to Jag was Ford,(good with the bad), and finally best of all is TATA of India.
now the best of all Jags ever.

and YES!! i still like my 78 XJX roadster V12, with all its quirks.

 

Well I put the cam back in with the new cam bearings, and now all the tappet clearances are too tight, except for cylinder 6, which is now too loose! So looks like I will be needing a few more adjusting shims.


I read some forums and several people recommended using a machine shop's services to resize the shims instead of buying new ones, as it is much cheaper. Any advice on that?