Hey folks -

So I decided last week that I was just never going to get to my '61 Mk2, I've had it for about a year and a half and all I'd really done is put air in the tire. I decided to sell it and go look for a Mk2 that was a good driver, something much closer to done that maybe needs a few things yet, but not everything. As I started working with it though, getting it ready for listing, and fixing things I'd ignored, I was reminded just how good it really was, all considered, and I started to second guess myself on selling it. There are of course a number of things needing attention, but the one I have the hardest time with, is determining whether the engine needs serious attention or not - It has a noticeable knock when cold, and as you know, a shop rebuild can be expensive. I think what I have going on is piston slap, and if so, that's generally not catastrophic, but I don't have a great deal of background with the XK engine. I've listed the car as having likely piston slap, so I'm not trying to hide it, but I would like to have clearer idea of what this means for the XK 3.8.

Below are two videos that show the difference between a warm and cold start, and how temp impacts the knocking sound. Also keep in mind that nothing else has been done to this engine - so there are all sorts of rattles and a minor miss going on that could probably be fixed with a tune up, but the important thing we're dealing withe there is the knock - which you'll hear (comes from #4 cylinder). I'd be interested in your thoughts and feedback as to whether piston slap is the correct probable cause and then thoughts on how best to deal with it, assuming any remedy is warranted if piston slap is the cause. For the sake of helping with opinions, Compression was 160 - 165 psi across all six, oil pressure around 25 at idle, 40+ at higher RPM. Engine temps are normal, no abnormal exhaust gases although it does smell a little oil / rich at higher RPM and develops a stumble over 3000 RPM - though again, old points, wires, valves probably need adjustment, etc)

The best comparison may be found starting the cold start video at time index 1.54 and the warm start video at time index 1:00

Cold start 72 degrees ambient, first start of the day (the squeak is the hood rocking) Warm Start. Suspected piston slap in cylinder 4 virtually undetectable when engine is warm. You need to have your ear (or phone) right next to the exhaust manifold to make it out.
Thanks,

Allan.

 

These were considered a long lived engine in their day but then mileages over 100k miles were considered large, whereas nowadays cars go to 200k miles and beyond. There's no doubt if somebody wants to buy it, they'll comment on the piston slap. Whether it would affect the price a lot on a sale, I don't know, you'll only find out when you try to sell it. Most people buying a car like yours, (average, not rebuilt), will have budgeted for repairs and probably an engine overhaul if they've got any sense, that is. You don't say what miles are on the car, but it is probably in need of an overhaul incl a rebore.

FWIW, the 1980 Series 3 XJ 6 I owned for 14 years had some piston slap which, like your car, disappeared when the engine warmed up. Interestingly, both my engine, and the 3.8 XK you've got, both have cylinder liners, the 2.4 and 3.4 engines never had them.

 

I've included the presumed piston slap in the listing, that way potential buyers are aware before they even come out to look. I wondered if perhaps the cylinder liners could just be replaced, rather than rebuilding the whole thing - seems like a healthy engine otherwise, to me anyway.

 

It's very hard to tell from the video what the noises are, it would be interesting to hear it rev.

My first thought would be the check all the tappets are set reasonably within tollerance and go from there.

If it is piston slap then a rebore and pistons will be the only way to cure it although in the old days they used to just bore out one cylinder and fit an oversize pistion. Thats what had been done to mine when I stripped it.

 

In the old days, I don't think people drove their cars the way the do now.
Wouldn't putting in an over sized piston throw things out of balance ?
I guess one could remove one of the other pistons and make the oversized one the same weight by grinding a bit of material of the bottom of the skirt. Hmmm.

On the second video the knocking noise is barely discernable and if I hadn't heard it when the engine was cold, I don't think I would have noticed it.

And yes, revving it a bit when cold would be helpful.

I do agree with you Homer, a lot of noise is coming from the tappets (lifters).

 

I guess the size difference is so small at 10 thou over (which is what was in my car) that you wouldn't notice in a road engine and the car probably wasn't worth much at the time so if it had been a bit rough people would have accepted it.

 

Ask and ye shall receive.... Video posted below. Its a tad windy, sorry about that, but the noise is pretty clear at idle and by the higher RPM, you can't hear it at all, then you can hear it come back in once the RPMs drop. This was another cold start, seems to be starting right up on the first attempt after I wired up the choke / starting carb.

Oh, and yes, the tappets are loud - I imagine its been quite some time since they were adjusted. The oil in the engine looks pretty clean, but I've no idea how old it is or what type.

 

Why are you calling this "Piston Slap"? Piston slap is when the piston is moving in the bore, ie back and forth. If this was "Piston Slap" the compression on that cylinder would be none existent not up at 160 to 165 psi.

The noise you have here I am sure is valve shims although it might also be a lifting cam bucket sleeve.

Have you checked the valve clearances? They should be 4 thou on the inlet and 6 thou on the exhaust. If these are larger this would account for the knocking noise on cold start up and then when the engine gets warm and the metal expands the noise will drop or go away completely.

If the noise is constant hot or cold it might be a lifting cam bucket sleeve. The cam pushes down on to the top of the cam bucket which sits in a steel sleeve and under this are the shims which control the valve clearances. In older engines the sleeve that holds the cam bucket in place can lift slightly and then the cam hits the lip of the sleeve as it rotates. Sounds awful at slow speeds and continues at higher speeds but is not so noticeable due to the speed of the rotating cam lope which causes the knocking to go into a continuous noise.. Check there are no marks on the buckets and cam lobes by removing the cam covers where you think the noise is coming from. To accurately locate where the noise is coming from get a long screw driver or metal bar and put on end to your ear and the other end on different parts of the engine. It acts as a stethoscope and allows you to pinpoint where the noise is before you pull the engine to bits.
The bucket sleeve can be knocked back down but if worn could rise up again so there is a thing called a "Stakedown Kit" that can be fitted to hold the bucket sleeves down in to place. Normally it is an exhaust bucket that moves because of the heat rather than the inlet side.

 

Piston slap is just one of the most likely causes, the other being a wrist pin. But testing thus far seems to point toward piston slap. As I understand it, its the pin-end of the piston that slaps, so the skirt, not the dome end, and since compression tests are done on a hot engine where piston slap would be less pronounced and the piston fitting best, I don't think a good compression test necessarily rules out piston slap - though I could always do a cold test and see if there s a material difference. In addition, the noise goes from unavoidable, to barely detectable, once the engine has warmed up - which to a great degree eliminates a bad bearing, and is a classic sign of piston slap - but, may also apply to a wrist pin.

I have taken a mechanics stethoscope to the car, yes. You cannot really hear the knock in the cam cover, or even top of the head. The noise is most readily detected from the exhaust manifold, and second to that, the block behind the manifold. I admit the tappets are clicking like crazy and do need attention, but this noise is not coming from the cam cover. I also isolated the cylinder to #4 by shorting the spark plug - when I do that, the noise is virtually gone - like when the engine is warm.

 

Personally if it were mine and I weren't taking the engine out I would check and reshim the tappets and live with it until it gets worse, depending on how much you use the car it might be years.

The problem is that if I were buying it like this I would look at the cost of an engine rebuild and factor that into what I wanted to pay for it. Out of interest what have you advertised it for and what is the rest of the car like?

 

There are around 100 photographs here: https://drive.google.com/drive/u/0/f...7dMt5RnHtI7LC3

I bought it for $6k, so that's what I'm asking, unless I keep it, of course....

The car needs some attention to basically everything, but as project cars go, this one starts, stops, all major systems function and the main wire harness, generator / PS pump unit and brake servo have been replaced with new. So now, as when I bought it, I feel it has a lot going for it and so as I started working with it, I began to second guess my idea to sell. BUT....to get it into what I call "presentable" shape (so not a show-winner, but a respectable driver) it will take some investment, and as as you point out, if an engine rebuild is needed, that really starts to change the calculus. As a project that doesn't need an engine rebuild, it may make sense to keep it and have fun with the restoration, but if this noise does mean a rebuild, I'd be better of selling it and taking my project budget and just buying a car that's much closer to done.

I also just performed a cold-engine compression test to see if that was in any way useful - doesn't seem so - 168, 165, 165, 165, 168, 170 PSI, 6 through 1. (4 is the one with the "noise")

 

I don't know what the market is like by you for this but here in the UK it would be just under £5000 which wouldn't be too bad depending on how much welding it needs.

I guess you need to see what the interest in it is like and then work out how much a better one will cost versus restoring this one (and how much you can do yourself), the thing to consider is that you can build this car to exactly what you want, the colour etc. and make any changes you like rather than buying something else done to someone elses taste. The other consideration (that may be more of an issue in the UK that you have) is whether a better one is actually better or is just like this with some filler shoved in the holes and a nice paint job.

You also need to consider whether you will be able to finish the project as you don't want to take it to bits and then run out of time/enthusiasm/money and end up with an unfinished project that you have spent even more on and is worth less than it is now.

Why not have a look at the tappets, see if that makes a difference and then decide whether its worth keeping?

 

All good thoughts. I definitely like the idea of making it my own, and knowing what was done and how, but that also takes time and effort ;-). I've done the interior on my '65, and I've already got another wood set I could use, so I'm not worried about that. Same goes for the mechanical things - I'm fairly competent there, but the body and paint is something I'd need to farm out - and that seems to be much more expensive than I recall (getting quotes of $20,000.....absolute nuts for a driver if you ask me......) so if I also need to factor in a $15K engine rebuild - it would be easier, though not as much fun, to just go buy one. There are many available in the $25 - $35K range that would work quite well.

I'm sort of at a point of inflection - to move forward in discovery, I need to start spending money in the thousands - tires, wheels, fix the rear suspension so that its road safe, then take it down for a proper paint estimate, but if I do that, then I'm really getting into it to where I might as well just go the whole way. Basically I've done all I can without burying myself in it, and the engine condition is the key tipping point. I guess when it comes down to it, I'll just need to make a call on it - either assume the engine will be fine and move ahead, or sell it and move on. No amount of internet searching or feedback is really going to give me an answer.

 

Looks like someone's Grandmother had a say in the upholstery !

 

Um...yea...pretty sure polka-dot velour was not a Jaguar option in 1961. I'll admit that part of my reason for wanting to restore is so that it doesn't go to its end, with THAT interior.

 

Here, check these RR Silver Shadow interiors, I saw a black car once with a red velour interior, looked like a pimp-mo-bile, and totally original.
Astonishingly, if memory serves, the velour interiors were more expensive then leather and wore very well.

(scroll to the bottom of the link)

https://www.rrsilvershadow.com/EKleur/Kleur9.htm

 

Having looked at the photos, it looks a good basis for a full rebuild, i.e strip down to a bare shell and go from there ! My Mark 2 took me 7 years from a bare shell, but I was married at the time, so had to give way a lot to SWMBO ! Anyway, we're still married 39 years later. Car was sold a year after completion, and I bought an XJ6 that I owned for 14 years - another story !!

 

Hello all -

I hate it when I am searching for some information or help, and you find a post that seems to be your exact issue, but nobody bothered to come back and close the loop!...SO....I am doing there here for future readers.

The issue (primary) with this engine is what my mechanic (classic Jaguar experienced) thought might be either a stuck wrist pin, or piston slap, but likely a pin. I decided to have the motor torn down and rebuilt, because even though piston slap is often not terminal and many, many engines have long lives even with some slap (new engines seem to come with it from the factory) not knowing the true cause would be annoying, and, since I'd decided to KEEP the car and remove from the market, I figured I better just bite the bullet and get her done properly. SO! removed and disassembled....Verdict?......

Piston skirt drag on cylinder 4 and also some on cylinder 1. But as you will see below, there were other...erm issues....Most notably the fact that the support for the exhaust cam had been completely broken off. Whoever last changed the timing chain (it has been changed, that much is clear to see) must have used a sledgehammer. Unsurprisingly, the chain was also a few teeth off - which added to the noise from the unadjusted tappets and may have magnified the slap / drag on the piston skirt since things were somewhat out of time. Fortunately, the engine was very clean inside, and aside from the noted chain sprocket support, no other damage. The engine will be getting a hot bath next, new parts have been ordered and the crank is going in for its facial and manicure.




Hmm.....spot the one difference.....

So...there it is....that noise from post #1, is an engine with a drag on the piston skirt, that needs tappets adjusted, that is also at least two teeth out of proper time ...oh...and has a missing sprocket support.

 

That looks like someone has given that a bit of hiding on the exhaust cam, although i'm sure you will change this part during your rebuild it doesn't actually do anything when the engine is running, it seems to just be there to hold the sprocket when you remove the cams to set the tappet shims.

Do you have any close up photos of the damage to the cylinder walls, I would be interested to see how bad they are for the noise it made.

Well done on the decision to rebuild the car, I don't think you will regret it as you can build it to exactly how you want it and will be safe in the knowledge that its all been done correctly and if there are some parts you don't rebuild at least you know what they are.

 

That loop is only used when lifting the head, as it allows the two cam sprockets to sit there and maintainn the ignition timing. Hope fully you'll be able to find another casting from somewhere. How somebody broke that off is a story in itself; Charlie Allthumbs maybe ?