If blocking off the vent at the back of the rocker cover only *reduces* the
leak from round the tappet cover, and it definitely from past the seal, then
there really must be a major misalignment somewhere between the cover and
the crankcase. I'm wondering if you have the correct cover now, i.e. has it
been changed for the wrong one in the past? Short of just sitting and
looking at the two pieces and how the edges align, and checking dimensions
and with a straight-edge, it's a bit difficult at a distance. On another
thread someone mentioned using silicone sealant and only lightly tightening,
then leaving overnight before fully tightening. I mentioned elsewhere that
I have removed my covers once in the past, and refitted them using the same
cork gaskets and Hermetite Red, and they didn't leak before or after.
Given that the leak is from the seal I don't think sealing off the tappet
cover vent will help with that. In answer to the specific question about
the oil drain holes in the head these *are* the path for crankcase venting
in normal circumstances as air comes into the rocker cover, down into the
crankcase, and out through the tappet cover. Having both the in and the out
on the rocker cover will ventilate that and stop a build-up of scum, but is
quite likely to allow condensation and hence corrosion to develop further
down where it cannot be seen, so IMHO it would not be a good idea to seal
off the tappet cover port.
Paul.
----- Original Message -----
From: "Christian, Wellner L. CIV COMNAVAIRSYSCOMPATUXENTRIVERMD AIR 4.1.1.4"
<wellner.christian@navy.mil>
To: "Paul Hunt (T)" <paul.hunt1@blueyonder.co.uk>; "MG Digest (E-mail)"
<mgs@autox.team.net>
Sent: Wednesday, March 10, 2004 11:11 AM
Subject: RE: Desperate - Oil Leak From Front Tappet Cover
Paul,
Thanks for the help. As near as I cal tell, the cover is not cracked. I
cleaned it thoroughly inside and out. No clogs. Although I did not examine
it closely for cracks. Seems like a pretty solid piece.
Agree with you on the valve cover vent. However, if I open up the vent
tube, the leak comes back big time even if the tappet cover is left hooked
to the carbs. Its basically the same leak as venting the tappet cover to
atmosphere.
When I first looked at the leak with the manifolds off, the cover was fairly
dry as was the block areas to the sides and top of the cover. The block
directly under the cover (for the full length of the gasket) looked like
someone had poured oil on it immediately before I looked at it (very shiny).
As I see it, I cannot remove my crankcase vacuum set up until I have
installed a fix that will stop the tappet cover leak. Normally I do not
disconnect PCV systems, but my only option as I see it is to install an
earlier tappet cover that was made before Leyland got so cheap that they
couldn't afford gasket channels. Any suggestions on which one to use ????
I was thinking about MGA or 18G versions but I haven't seen either so I
don't know if they have the gasket channels or if the MGA version will fit.
Also, what about sealing off the tappet cover vents entirely and venting
only through the valve cover??? Any ideas on this ?? Don't know if the oil
drain holes in the head are big enough to allow venting.
Is this front tappet cover seal normally a problem (once its been removed)
????
Thanks Again, Skip
'74 MGB
-----Original Message-----
From: Paul Hunt (T) [mailto:paul.hunt1@blueyonder.co.uk]
Sent: Wednesday, March 10, 2004 4:59
To: Christian, Wellner L. CIV COMNAVAIRSYSCOMPATUXENTRIVERMD AIR
4.1.1.4; MG Digest (E-mail)
Subject: Re: Desperate - Oil Leak From Front Tappet Cover
It definitely is not normal although it can be difficult to get a good seal.
Is it definitely coming from round the seal? Or is the cover cracked, the
crack being closed with the cover off but opening when tightened. Is the
breather pipe cracked? Is the pipe clear or has the gauze flame trap.oil
separator behind it got bunged up with solidified gunge?
I've found in the past that silicone sealant causes gaskets to get squeezed
out of position so I don't like it. Some also 'skin' very quickly in air,
in the time it takes to get a bead all the way round. I use Hermetite Red.
I realise you did it to try and cure a leak but unless you allow air in to
the rocker cover, either via the charcoal canister or a vented oil filler
cap if no canister, as well as sucking on it from the carbs, you will not
get adequate ventilation and in most cases condensation will build up
causing internal corrosion and that creamy scum on the oil filler cap. If
the canister has been removed you should block off the rocker cover port and
replace the non-vented oil filler cap with a vented one as this filters the
air as well as restricting it.
PaulH.
----- Original Message -----
From: "Christian, Wellner L. CIV COMNAVAIRSYSCOMPATUXENTRIVERMD AIR 4.1.1.4"
<wellner.christian@navy.mil>
To: "MG Digest (E-mail)" <mgs@autox.team.net>
Sent: Tuesday, March 09, 2004 7:09 PM
Subject: Desperate - Oil Leak From Front Tappet Cover
> I have a 1974 MGB. Car has had a bad oil leak from the front tappet cover
> since I bought it. I sealed the valve cover vent and left the tappet
cover
> vent hooked to the carbs to pull a vacuum in the crankcase. This slowed
the
> leak by about 80 percent.
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