Following the general thoughts and my gutt feeling I pulled the head.
The valve stem on no 1 was fairly mushroomed. Rockers were ok, well as far
as they are ok after some 50k miles. I decided to take the head off after
all to be double sure and replace the offending valves. Though they are not
exactly cheap for valves they aren't that expensive either. Result is that
neither of the valve guides is extremely tight (cast guides, non phosphor
bronze) but not sloppy either. No burning on the valve seats. As for the no
1 rocker, which is the worst, I decided to replace it in case its got a hair
crack or summing. As thought, none of the valves is currently stuck. I'm not
using any guide seals as the engine is not using excessive oil. Oil feed,
well, its getting fed as it was intended by the factory...As for any obvious
reasions for what happened, no clue. If it goes back together ok, it should
be a repair in the region of £ 80
which is not too bad. Parts to be replaced: 3 valves, one rocker,
rockershaft, one stud, head gasket, exhaust manifold gasket and water pump
to head gasket.
Thanks for the advice.
Cheers. Gernot
> ----------
> From: Dave Terrick[SMTP:dterrick@pangea.ca]
> Sent: Tuesday, May 18, 1999 4:51 PM
> To: Gernot Vonhoegen
> Subject: Re: TR6 valve stuck?
>
> Oooooohhh, Bad Gernot, Bad!!
>
> Seriously, been there. I rebuilt my race motr using silicon bronze
> guides
> and fresh valves. The motor got hot (cooling problem, air lock) and the
> valves, then pistons stuck. It starts like a loud clicking/tapping sound
> and lasts only a while before..... If you have a fresh head I would do as
> you suggest and just make sure they are now free. The mushroomed valve
> stems are going to be a problem if they are spread much more than "a bit"
> as
> you must set the valves on them and they must be square to the rocker.
> How
> are the rockers? Could you square the valves using a small grinder while
> still on the car?
>
> Otherwise, I's get a pair of valves and a gasket set and pull the sucker
> off. If it was a tight guide, you'll be all right. If it degenerated
> into
> a burned valve then you have a problem. Try a leakdown test on that
> cylinder with both valves closed and at TDC for that cylinder to see if
> there is "much" leakage. Exhause V from tailpipe, intake from carbs,
> scored piston or ring problem from rocker cover as excessive blowby. All
> the above are with reference to the other 5 pots.
>
> Good Luck
>
> Dave T
> Winnipeg
>
|