Started the car recently and heard a lot of clattering and clanking. Stopped it immediately and did a number of checks to determine the source . Using a stethoscope ,the sound seemed to be coming from the back end of the left cam shaft. Removed the oil filter and checked for metal but none found.
After starting and stopping the engine a few more times the sound became less and then quit completely and the engine now sounds normal and the oil pressure is good …40lbs at idle. It therefore seems to me that the problem was a stuck valve which may have been caused by a lean fuel condition on the rear carb. Obviously I’m concerned the problem may re-occur and could potentially damage the engine. Other than fixing the carb issue what other action should now be taken before I drive the car again ?
I doubt it was a stuck valve if the engine is now running OK as these are an interference engine, I know because I recently purchased a 3.4 ‘S’ that had skipped the timing chain. 6 bent inlet valves = zero compression.
It sounds to me like a typical xk engine startup after a long hiatus. It takes awhile for oil pressure to build sufficiently to get the cam journals to float on their bearings.
Thanks for your reply. I’ve had the car for 15 years and during that time it has run extremely well. The car was started and driven in late May without any sign of a problem. It’s typically driven about 3k miles per season and the oil is changed each year. Only use 94 octane fuel .
Thanks for your reply. If it was not a stuck valve and the engine is now running as normal what do you think caused the problem? Had it checked by a local professional engine builder who has rebuilt built 3 or 4 E-type engines and he too thought it was likely a stuck valve.
Perhaps a tappet guide came loose, raised up, and then got hammered back into place by the camshaft? Do you have tappet guide hold-downs installed?
-David
For my own piece of mind I would do a compression check bafore I drove anyhwere, quick and easy job…
LLoyd
A step backward, after making a wrong turn, is a step in the right direction.
Kurt Vonnegut
Thanks for your comments. Really don’t know enough about engines to answer your question. Will be consulting an expert this week to discuss the problem and repairs required.
I would be concerned if you use the expert who diagnosed a stuck valve as I doubt that he knows much about the Jag engine if he dosen’t know that they are an interference engine. Just my 2c.
There was a noise on a prolonged cold startup that’s now gone and everything appears back to normal. Valve train noise from lack of lubrication - chain slap and tappet chatter - resolved when oil pressure came up? There would be some extraordinary bearing wear vs a well lubed startup but you’re unlikely to cause any further damage. The XK’s a tough engine. It’s probably ok. I’d drive the car. (An entirely inexpert opinion happily conceded to somebody who knows better.)
Edit: I think David’s advice above is good. It has been known to happen, is easy enough to check out and a cheap fix.
Hi Nick,
Sounds to me the problem could very well be related to a loose tappet guide. Noise is described in the article below as a “clatter” which is what I heard.
I think I should have this possibility checked out before I drive it any further.
http://www.georgiajag.com/Documents/HeadArticleJCNA07/XKHead.htm
Thanks,
Don
Did a little reading on tappet guides . Sounds like a loose guide ( common XK problem) is likely the cause of my problem . Especially since the noise is described as a " clatter" which is exactly as I would describe it.
Do you know if tappet guide hold downs were typically used on engines used in '68 E-types?Any idea what it would take in hours for a professional mechanic to determine if a loose tappet guide is the problem?
Thanks!
Don
They were never installed by the factory, AFAIK.
Don,
I’m pretty sure the factory didn’t fit hold-downs in the E-Type era. Maybe on the later XJ engines, where he problem seemed more prevalent. I’m sure that someone with more engine knowledge, such as @Dick_Maury could give precise details, and maybe comment on the likelyhood of this being your problem. I would think that removing the cam cover and inspecting the tappet guides and cam lobes would be all that is required to say if this has happened with your engine. As I understand it, this normally happens when the engine gets very hot, so it doesn’t quite match your description of it happening when you started the engine cold.
-David
David,
If a tappet guide is found to be damaged or loose the fix does not look easy. Removing the head does not appear to be a simple task nor does removal and replacement of a tappet guide. In fact where do you find tappet guides, at the usual part sources?
Seems to me that if something like this happens once it is quite likely to happen again .
BTW - do you have any idea how long it takes to get the head off …,worst case?
Thanks for all your help, much appreciated!
Don,
Most of your questions are beyond my level of experience. Hopefully someone who has worked on multiple XK engines and done these tasks more than once can comment. FWIW my opinion would be that if it were my car I’d remove the cam cover, and take a look. If there is evidence of one (or more) of the guides having risen and taken a bash from the corresponding cam lobe, I’d consider (if the damage is superficial) “tapping” the guide back home and fitting a hold-down kit. These can be fitted with the head in place, are available from the usuals, and several folks on the forum have done so and can probably advise on the details. The first step is to determine if this is what happened, as it is probably only one of several possible explanations…
-David
it would be possible for you to take the cam covers off, and carefully examine the relevant parts
(not valves)
if no damage is apparent, you then have the option of replacing the cam gaskets ~$50, continue driving
or send it to the mechanic on a flatbed
or add stakedown yourself, if needed (and confident to do it it)
cylinder head removal can be stubborn on a 4.2…you do not wish to think of worst case at this time
Stake downs have never been fitted from the factory.
The stake down kits can be fitted without taking the had off, just cover all the oil drains and use grease on the drill and tap to contin the swarf.