I know you're getting all kinds of advice, some conflicting. That doesn't make it easier.

There are no rocker arms in these engines, so scratch that one. The cam lobes turn and press on the buckets to open the valves, that's it. To me, the sound seems to be coming from the rotation of the camshaft...either some kind of interference with the shaft itself or its interaction with the buckets and valves.

If it were a timing issue, the engine would be running roughly. It seems to be running smoothly, other than the tap or knocking sound. That being said, when you DO take off the valve cover, check that the flats of the exhaust and intake camshafts are perfectly aligned. Regarding the valve cover gasket, you do not need to install a new gasket if the current one is fairly new...otherwise, I would definitely replace it to avoid the headache of a leak later.

Question: why all the error messages (seen in the second video)? Do you have electrical connections undone, pieces missing, etc?

I wish I could tell you whether it was safe to drive to Tony's shop or not...he can surely be of help with this diagnosis, that's for sure.


.

 

The cam cover gaskets are brand new, they've just gone on because i fitted a complete new set of timing chains, tensioners and guides (upper and lower tensioners, primary and secondary chains).

It's good news that the gaskets can be re-used if i'm careful with them, i thought the gaskets would be one hit wonders.
The car is running smoothly, no missing or rough running, power delivery seems normal.
In fact everything seems normal except the noise, which suggests no problems with spark plugs or timing.

The error messages are traction control and ABS (i think the ABS module needs the soldering fix and one of the harnesses is faulty as well).

Check rear lights is probably because i removed the high level rear light, due to 3 of the LED bulbs not working.
I may also have a reversing light not working, but these things are comparatively minor and can be fixed relatively easy.

Restricted performance has been showing since i bought the car, but doesn't seem to slow the car down any.
I was hoping that after cleaning the MAFS sensor with electrical contact spray, and also giving the throttle body a good clean inside and out, the restricted performance message would disappear, but it hasn't.

I uploaded another video, mainly as a test because the engineer has just left after setting me up with fibre optic broadband.

The video is not brilliant, and i was interrupted while shooting it, but it does give a better indication of the noise when the car is revved.

The noise seems to be associated with one cylinder, but i still don't know which one, or the cause.
Hopefully the video will be viewable by clicking a previous video link.

I figured if i can get it to Tony (XKRacer) he'll be able to find the problem.

He's probably also got a stethoscope.

 

XKRacer (Tony) will sort it for you for sure , he's got a wealth of experience with XK's and comes from an engineering background , I'd take his advice on whether or not to drive to him or trailer the car ,

NikasilNik

 

Listening to that second video does make me wonder....... Sounds different from the first... Take the left hand cam cover off again and check the buckets, sounds like one is sticking... See if you can push down on each one and that it comes straight back up again, you wil have to rotate the engine.... Check your valve gaps inlet is .20mm exhaust is .25

 

What's the official name for the buckets?

The terminoligy is a language in itself.

I've got no useful pictures of the valves in any that i took, as the valves are covered by the camshafts.

From what i can tell the lobe pushes down on the top of the valve and as the lobe passes the valve, the valve springs back up.

What do i do if it doesn't spring back up lol.?

And is the gap i'm supposed to be measuring between the bottom of the lobe and the top of the valve?

Does the lobe not actually touch the valve?

 

You have the valve which has the spring on it, on top of that is what most call the bucket, technical term is the valve cap but that gives the inference it is small, it's 35mm in diameter. Set in to the bucket/cap is a shim which runs on the lobe of the cam... It is the bucket that moves up and down with the valve

 

You can see the buckets/caps below the cams in this picture.

 

The valve clearance is measured when the cam lobe is 180* or straight up from the cap.

 

Now i know what i'm playing with. The bucket is the round shield on top of the valve, and RJ237 has pre-empted my next question about how to measure the clearance.

I may have to leave it till tomorrow.

I've just got home from a 14 hour shift and am waiting for a text telling me i'm back at work in 8 or 9 hours.
As soon as i get to it i'll keep you posted.

Thank you yet again guys.

 

Another question:

Would a sticking bucket be visible to the naked eye, as the camshaft was turned either by a socket on the crank bolt, or by turning the motor on the starter with the fuel pump fuse out?

If it is, it's not looking like that's the problem.

I can't see any signs of wear or damage to the cam lobes either, and the inlet and exhaust flats line up.

I'm just having a cuppa before i pop round to my local Halfords for some metric feeler gauges.

Will try to shoot some video to show whats happening later.

 

Measured my valve clearances just now (was too knackered yesterday).

Perhaps someone can tell me if these measurements mean anything related to the noise.

Starting from the cam lobes at the rear of the engine on the left bank, 8 lobes per cam, with 7&8 being the forward most.

Inlet:- - - - - - - - - - - - - Exhaust:
1 = 0.1 mm- - - - - - - - -- 1 = 0.25
2 = 0.1 mm- - - - - - - - - -2 = 0.25
3 = 0.15 mm- - - - - - - - -3 = 0.25
4 = 0.18 mm - - - - - - - - - 4 = 0.25
5 = 0.20 mm- - - - - - - - - -5 = 0.25
6 = 0.18 mm - - - - - - - - - 6 = 0.25
7 = 0.18 mm- - - - - - - - - - 7 = 0.25
8 = 0.20 mm- - - - - - - - - - 8 = 0.25

Clearances were measured with the lobes pointing 180 up from the valve surface, using feeler gauges that had sizes of 0.10, 0.13, 0.15, 0.18, 0.20, 0.23, 0.25 and 0.28.
Where a thicker feeler gauge wouldn't go in the gap, the next size down was used.
So for instance on inlet 1&2, i couldn't get a 0.13 in there, so the next size down was 0.1mm.

When the lobes for exhaust 1&2 pointed up, the lobes for inlet 5&6 pointed up, the lobes for exhaust 5&6 pointed up at the same time as the lobes for inlet 7&8, and the lobes for exhaust 7&8 pointed up at the same time as the lobes for inlet 3&4.
But when the lobes for exhaust 3&4 pointed up, the lobes for inlet 1&2 pointed down, and vice versa.

Is this normal?

Could it be that the gap for the 1&2 inlet buckets is so small, that the back side of the lobe is hitting the buckets as well?

 

No, you've still got clearance.
Tight clearances are wrong but shouldn't make a noise unless the tightness was due to something sinister like a loose valve seat or you've got valve damage as a result.
Someone more knowledgeable in the 'valve department' than me is needed here.

 

My amatuerish logic tells me that if i can get a feeler gauge between all the cam lobes and buckets, i've not got a sticking bucket.

Do you think thats right?

 

Hi Roadhogg,
can or could you rotate the inlet buckets for the cylinder in question ?. Can it be pushed open at all ?
you need to make sure a valve is not jammed open, Try useing a wooden dowl to push the cam buckets open.

the next step is probally a compression test. you could check the plug to see if it is a different shade compared to the others.

what I dont understand is you did not have this issue before you started all the work you have done. from the videos It really sounded like a missfire and probally one from a valve jammed open or similar. I have just repaired an engine with a faulty valve, and the missfire was similar.

Of course this could be well of the mark. I would not start the car until you know whats what. As steve in france suggested, you need a response from a valve expert.

you may not have a big problem yet, but I would not assume it ok to run the engine. by the way it sounds like you have done a great job on the timing.

stephen

 

Hi,
Its sounds a possibility, given the timing is correct, ive copied an image from bluexk8ragtop thread. this had two valves with similar problems.

We all would like to see roadhogg get this sorted, it must be driving him crazy. 10 out of 10 for sticking with it.

 

 

steveasy:
I had trouble getting my fingers on the buckets to rotate them, because the cams were in the way.
Also they are smooth surfaced, and although i tried with some of them, i couldn't really tell if they were moving, or if my fingers were just sliding across the surface.
I guess i could mark them with a felt pen, and try to move them with something soft and grippy to see if they turn.

I'll try again tomorrow, weather permitting.

Regarding the misfire, as i said earlier in the thread, it doesn't seem to be misfiring, it's running on all 8 pots and the inlet/exhaust timing is ok.

It's just that noise.

I will check the plugs tomorrow as well though, to see if there's any discolouring of a plug.

 

Seems to be a post missing here, saying something about OP having a hydraulic failure.
I'm sure i saw it a minute ago.

Btw who's OP?

 

OP = original poster - and I'd posted on the wrong thread (too many open windows) so I scrubbed it.
Your posts #35 + 36 show exactly what I was worrying about - a displaced valve seat but in the wrong direction - that would INCREASE the clearance.

 

Hi Roadhogg,
from the video of the car ruuning, I though the engine sounded irregular, that is why I think it could be valve related and why I think a missfire exists.

it is a little strange that on the cyl where the noise MIGHT be coming from, it has reduced clearences. why ?.

is it possible to have a valve that will not close properly, and leave a gap between the valve and the bucket.. ?. this could create the noise you hear.

This is why you need specific advice now from a person who has worked on the valves from this engine. If it was my car, id do exactly what you are doing and ask the questions on the forum.

Incidently when you did the timing, was it out at all, when you originally checked the timing before starting work on it ?.

Please bear in mind it might not be valve related at all, but what else could it be, I cant think of anything from that area of the engine.

Steveeasy