Cam noise compression issue

[I am Groot]

Engine rebuilt 1000 miles ago.every cylinder shows 160 psi except number 6 that shows 100 psi but then 120psi if we drop a bit of oil in. Number 6 cam noise very heavy.
Is it possible valve is sticking?
should i live with cam noise?

[flying farmer]

I would remove the cam cover and check the valve clearances on no 6. If you have a wide clearance and low compression on that cylinder it would suggest a bent valve that isn't closing properly.

The noise could be from the wide valve clearance or the valve touching the piston on every stroke if it is bent.
Removing the spark plug and blowing down a length of heater hose or similar held tightly over the spark plug hole will tell you where the air is escaping.
An overly tight valve clearance would give the same compression issue but not the noise.

[I am Groot]

Neil, stupid question because i just cant remember. Can I adjust the clearance once the covers off or does that require shims and a major strip down. Also the compression was zero and i couldnt believe at one point so i ran the engine again and more regularly get 100 psi area. Presume the valve is sticking perhaps because its slightly bent but wondering how this could have happened because its a new problem not aparent when first rebuilt.

is it ok to drive or coukd i cause piston damage , could it be a broken valve spring?

thanks for the help! Payback for the oil pump!
rgds
nigel

[dasadrew]

Adjusting the valve clearance is indeed done using shims, but doesn't require a complete strip down. You have to remove the cam after fixing the sprocket to the support bracket in the front cover area to avoid the chain tensioners misbehaving. Don't forget to measure all of the clearances before you take out the cam as getting the right shims will otherwise be a lottery game!

Drew

[I am Groot]

Thanks Drew its coming back to me now along with the location of my Easter eggs that i hid myself!

[I am Groot]

Just to remind me check clearances by bringing each piston in turn to TDC feelers under inlet and exhaust. What's the clearance measure on both and whats the furthest out that works quietly or reasonably?
thanks
nigel

[I am Groot]

Sorry forgot to ask, so our feeling is this valve most probably but is it possible its the head gasket at number 6 area. Not losing water, oil is clear, not overheating but i have had condensation from exhaust even last Thursday when it was warm out. Apart from that nothing pointing to head gasket as yet. Just my paranoia !

[flying farmer]

Just get the cam lobe pointing away from the cam follower on each valve in turn so you are measuring on the base circle, crank position isn't important.
Inlet clearances should be 8-10 thou, exhausts 16-18 thou. Clearances don't want to be less than the minimum, I don't think you will notice any problems with a couple of thou bigger than the max, but I have no idea at what gap they get noisy.
Has the engine been stood for some months without being run? A common problem is leaky inlet manifold gaskets letting water sit around the valve. This then corrodes and sticks in the guide. This had happened to one engine I bought to rebuild, it had a bent valve. I have often found cam buckets to be corroded into their bores on engines stood for a very long time.
Some years ago on my P reg Stag , I took it for its MOT this being the first time it had run in 6 months. The valve gear got very clattery on one bank by the time I had done the 7 mile round trip. Investigation revealed the problem to be loose cam sprocket retaining bolts.
Bearing in mind these have locking plates, the only way they could have come loose is if the bolts had stretched
.
I wondered if it was a stuck bucket problem on that bank which over stressed the bolts. I changed the bolts and fitted new lock tabs and the problem never re-occurred , though I have never left any of my engines for more than a couple of months without starting since then!

[flying farmer]

Sorry forgot to ask, so our feeling is this valve most probably but is it possible its the head gasket at number 6 area. Not losing water, oil is clear, not overheating but i have had condensation from exhaust even last Thursday when it was warm out. Apart from that nothing pointing to head gasket as yet. Just my paranoia !

Condensation not unusual even in warm weather, but slight leak from inlet manifold gasket can draw water into any of the 4 rear cylinders. First time it happened to me I kept seeing puffs of steam from the left hand exhaust when I closed the throttle at high revs. In my ignorance I thought it was the head gasket, so changed the left hand head gasket.
Water loss wasn't noticeable, but in a few months the inlet manifold gasket blew again. This time it dumped coolant all over the driveway, fortunately just after I had returned from a long journey!

[richardthestag]

I would worry about zero compression and now 100 along with noise.

tolerances between valve and piston are very tight in the stag engine. valve stuck open only 1mm will clash

I had these on my engine when rebuilt. ok I redlined it

[I am Groot]

Thanks Richard its good to be really worried rather than just wondering if i should be a bit concerned!
nigel

[I am Groot]

Condensation not unusual even in warm weather, but slight leak from inlet manifold gasket can draw water into any of the 4 rear cylinders. First time it happened to me I kept seeing puffs of steam from the left hand exhaust when I closed the throttle at high revs. In my ignorance I thought it was the head gasket, so changed the left hand head gasket.
Water loss wasn't noticeable, but in a few months the inlet manifold gasket blew again. This time it dumped coolant all over the driveway, fortunately just after I had returned from a long journey!

Yes I forgot about that, last year after rebuild manifold leaked but thus year no leek in the v but i think i to rear left ie, pot6. If I remember correct the gasket type without slot wouldnt help this and i would think Telford engines struggled to prevent the leek they used 2 gaskets apparently. The car was idle from November until mid March as it was at the body shop. The condensation is always from left exhaust! I think we know whats happened here.

Neil Thanks huge help!

[richardthestag]

Did you get to check cam-bucket clearance yet?

kind of want to hope that it is perfect but then low compression is probably going to mean head off.

out of interest if you do a wet test on any other cylinders do they go up by 20psi also?

wet test normally seals rings but not valve seats

[Mark Serj]

Don't forget to slacken off the cam caps slightly before re-torquing and then measuring the clearances before you remove the cams. This will give better consistency of measurements

[I am Groot]

Thanks guys, no time yet but get to it soon and let you know