Tappet Chest Gaskets

[ianh1968]

I have recently been involved with a "freshen up" of a Morris Minor 1098cc
engine from 1964...

This engine has been "maintained" by various people over its 50 year history
and some of the work has not been too good... Various parts are either
missing or different to what I would expect to see.

The tappet chest gaskets that came off this engine were cork, albeit
plastered on with a copious helping of clear silicone sealant. The retaining
bolts just had steel washers on, and again, silicone.

The owner has supplied some replacement "neoprene" seals which have
been fitted, but these have not worked out very satisfactorily. This type appear
to be too "slippery" and even with only very light tightening of the retaining bolts,
they are not staying in position. The rearmost gasket is now also leaking.

I have not had an open tappet chest engine apart for over 20 years, but a quick
bit of research has revealed that there are different shaped covers around and
some of these require a cork gasket, and some a rubber gasket.

Attached is a photo...

MM1098.Small.jpg

Any advice on what this engine should have, and also any suggestions on how to
get this all together without it leaking would be very welcome.

... and Spider, if you are reading this, I did "stone" the block!

Ian

[Spider]

Bhahaha, Stone the crowes,,,,,,,,,,

I'm pretty sure those side plates should have a cork gasket. In regards to the clear silicon, I realy seriously doubt that it is a grade that is compatable with oil. I would adhere the gaskets in place on to the side covers, using a grade of silicon sealant that is compatable with oil, the one I use most of the time is Loctite RTV Blue, a small bead on one side of the gasket, then with the gasket on a flat surface, place the side cover in to the gasket and let the silcon cure. Then fit to the engine with nothing else, just cork to cast iron. I have heard of some guys using contact cement, but it's not compatable with oil or heat. If the cover is fitted before the silicon cures, the silicon tends to act like a lubricant and some upon tightening, the gasket just tends to slide away from where it's under pressure and will leak for sure. Cork gaskets also need to get wet with oil to seal.

The centre bolts of course should have the cup washer on them and the rubber seals which appear as short rubber tubes. I have used fuel hose here in desperation, but cutting the ends perfectly square can be a bit trying.

The bolt should only be tightened to 2 ft/lbs.

[rich@minispares.com]

don't forget that the bolt used with the later rubber seals was longer than the one used with the thinner cork seals, so if your using the short bolts that where original to a 'cork' engine, you may be struggling as from memory you can only get a few theads in to the block, so it tends to make the seals more difficult to locate

[ivor badger 2]

You are using early cork back plates with later rubber seals and neither work with the wrong pairing. Fit the correct seals and stop joining the engine bodgers.
Coating the early cork seals with gasket sealant, even from new was quite normal. Can you still get red Hermatite?

[Dr S]

How do you tell the difference? Mine had neoprene on and that's what I've refitted ( fairly easily held with a dab of grease ) but they do look identical to those shown.

Beginners guide to identifying would be much appreciated

[dklawson]

I have done what Spider does with the use of RTV. My technique may be a bit different though and may be worth considering if you have time to wait.

Clean and degrease the tappet covers and apply a thin bead of RTV to the area where the gaskets sit.
Apply a thin film of grease to the flat surface around the opening in the block.
Press the gaskets to the block so the grease holds them in place and the gaskets are flat against the block.
Fit the tappet covers "finger tight" only.
Allow the RTV several hours (or over night) to cure. Tighten the covers properly the next day.

I use a nearly identical method on valve covers. The engine has wonderfully flat surfaces and the grease will hold the gaskets nice and flat to them. The RTV bonds those seals to the covers and fills the gaps and distortions. Waiting for the RTV to cure before tightening prevents the gaskets from sliding out of position under pressure. If you take these steps you will be able to remove the covers multiple times (if you ever needed to). This method also works wonders on distorted valve covers.

[ivor badger 2]

The early cork seal backplates have a flat gasket face or a rolled out edge backplate (later) as in the photo. The later rubber sealplate has a similar outer edge to that in the photo, but rolled inwards giving a groove that holds the rubber seal in place. The groove holds the seal and prevents it from being forced out of the plate when tightened.

AGAIN, you cannot successfully mix the two systems.

[ianh1968]

Thank for all the replies - A correct set of parts is now being ordered
and will be fitted as soon as they arrive.

Cork + seals + metal cup washers...

I'll let the goo set for even longer than I did last time, and we should
be OK.

Ian

[1071 S]

Maybe I have a different contact adhesive???

Following the advice of a (successful) local racer I use contact adhesive on one side of the gaskets and blue hylomar on the other... Now if I could just stop the front main seal from leaking....

Cheers, Ian