Exhaust valve contact all four pistons! PICS ADDED

[Mark(The Miser)UK]

If it were me, i'd probably replace those rode bearings and forget about the valve marks.... seen a lot worse :-)

Sadly, i think i've only ever seen one IDI diesel without some valve marks in the pistons!

As has been covered, the big thing if the head has been skimmed is to make sure the valve seat is cut and that the valve is cut back also (i think it was 'b' in those scans). The valve length should be cut back the same amount as the valve seat, otherwise the valve lift will be more than it should be, at all cam positions, hence the marks in the pistons.

Same amount off the valve stems assuming shim gaps correct in the first place and not near bottoming out

[Mark(The Miser)UK]

Sick and tired of trying to silence the apparent piston to valve tick from the last 3 years or so. Reset the cam to standard, and measured cam advance, using the 'recommended by  Fatmobile' technique of locking  cam and reading off flywheel error...

 I have been running my cam advanced by3 1/2 teeth on the flywheel, or 2.73deg x 3 1/2 or advanced by 9.5 degrees of crank 4 3/4 degrees on cam!

Ticking still there but  engine now running smoother  which is partly down to injectors settling in after a rebuild.  Ticking still there with engine switched off and going down an incline in gear. Any ideas what it could be?

[rabbitman]

Sick and tired of trying to silence the apparent piston to valve tick from the last 3 years or so. Reset the cam to standard, and measured cam advance, using the 'recommended by  Fatmobile' technique of locking  cam and reading off flywheel error...

 I have been running my cam advanced by3 1/2 teeth on the flywheel, or 2.73deg x 3 1/2 or advanced by 9.5 degrees of crank 4 3/4 degrees on cam!

Ticking still there but  engine now running smoother  which is partly down to injectors settling in after a rebuild.  Ticking still there with engine switched off and going down an incline in gear. Any ideas what it could be?

Man that's messed up!! What was the cause of this?

[Mark(The Miser)UK]

Sick and tired of trying to silence the apparent piston to valve tick from the last 3 years or so. Reset the cam to standard, and measured cam advance, using the 'recommended by  Fatmobile' technique of locking  cam and reading off flywheel error...

 I have been running my cam advanced by3 1/2 teeth on the flywheel, or 2.73deg x 3 1/2 or advanced by 9.5 degrees of crank 4 3/4 degrees on cam!

Ticking still there but  engine now running smoother  which is partly down to injectors settling in after a rebuild.  Ticking still there with engine switched off and going down an incline in gear. Any ideas what it could be?

Man that's messed up!! What was the cause of this?

I'd just like to add, that it was me who created that humungus timing anomaly. I had done it in about 3 stages in an attempt to alleviate my perceived piston to valve kissing.
My results were somewhat inconclusive, which is disappointing .

Now I've just this week gone back to cam locked at TDC, ticking still there but engine running slightly smoother.

It's not excessive shim gaps, as they are mostly tighter than spec, or in lower region of the range. Oil supply squelches out onto cam with mere hand cranking.

On doing a  rering last year,  I could not find any play  in small ends or big ends.[I'd actually bought new bearings for the purpose.]
I didn't check crank bearings other than side to side float, which was minimal.

I'll just live with it until a problem develops.

[Mark(The Miser)UK]

Are you sure your Bentley says that? Read again, and I think that you will find that the 'd' =0.5mm is for a different diagram.

I just checked again and I'm 100% sure that what it means.

I'll take a picture of the diagram and wording and post it in the next day or two.

Candyman, Candyman where are you?
Oops I mean Rabbitman

[rabbitman]

Oops, it's kinda rare for me, the bentley, my camera, the camera cord and a computer to all be in the same place at once.

From the '85-'92 Bentley Manual.

[wil892]

Thats just what I'm looking for, thanks rabbitman. I will measure the current distance, which I am almost certain is less than 0.5mm and will post the findings here. If it is less than 0.5mm surely the shop who built the head has something to answer for. I will tackle that when I have some hard evidence though!
Thanks

[RabbitJockey]

in that case, you should get a new head or head rebuild out of them, new pistons, new rod bearings, rodbearings, head gasket, head bolts.  but if the valves are already level with the deck, the head has probably been skimmed too far and they owe you a new one.

[Mark(The Miser)UK]

Oops, it's kinda rare for me, the bentley, my camera, the camera cord and a computer to all be in the same place at once.

From the '85-'92 Bentley Manual.

Excellent, that kind of makes sense.
Did Bentley drop the next picture of the 'd' on the valve thickness?
Does your copy cover the last of the mechanical heads too, which is what my manuals are covering?Bentley  have earned themselves a Ranger badge

[wil892]

Hi

Got an update on this. I checked my Bentley and sure enough it specs the minimum recession of the valve face from cylinder head face as 0.5mm.

So I cleaned up the head and measured the distances of all the valves with the dial gauge.
Inlet valves are recessed between 0.5mm and 0.6mm
Exhaust valves are recessed between 0.15mm and 0.21mm!!!

The head was a new cast and was sold to me as brand new with new valve train parts, so surely this head has been sold with a fairly major flaw. Would these measurements indicate that valve contact could have occured due to mis preparation of the cylinder head?

On another note, one of my prechambers has a crack after 18,000 miles, and the prechambers have created a pretty big ridge in the combustion chamber as if they are pushing their way out.

[rabbitman]

I'd bring it back to the guy and tell him you want a new head. To be a sold an out of spec NEW head is pretty low.

I doubt you can get anything done about the prechambers though, they'd say you timed it wrong or something but I'd sure try.

[RabbitJockey]

sounds like a crap head all around.  definitely the heads fault

[wil892]

One more update, and a question!

After seeing the state of the non genuine head I decided to buy a genuine one. Today it turned up, no cracks between valves but same cracks in pre chambers that prompted me to buy a new head a couple of years ago. I've taken some close up shots, do these look in pretty poor shape or is that what happens to these heads? It seems both GTD heads I have had now had these cracks in.
Cylinder 1:

Cylinder 2:

Cylinder 3:

Cylinder 4:


I don't seem to have much luck with these 1.6td heads, but luckily this one was too cheap to miss.
Will

[rabbitman]

I don't think I'd run it like that, too big of risk.