I've just rebuilt 2 of 750S motors. Both motors leak coolant from the outside head studs, specifically, from the threads in the nut or between the nut/washer/head alloy. And that is when there is no pressure. 1 motor just sat overnight and has not even been started...bugger!
I used a gasket from a Laverda parts supplier, but I do not think they are OEM. I did not use an adhesive/sealant. All tensioning ect was done in sequence and in stages up to 45Nm. New O rings and gaskets (hand made) were fitted to the base of the barrels.
I've stripped one motor and measured up the head gaskets, comparing them with an old one I have. The steel compression rings on both are compressed to within about 0.01mm of each other, indicating that there is little change in the fitting. The tops of the liners are about 2 thou (.05mm) above the barrel surface.
The big difference is that the areas not compressed on the OEM gasket is still about 0.05 mm thicker than what the steel ring has compressed to, whereas on the aftermarket (?) unit it is about 0.05mm THINNER, and as a result, the blue sealing "stuff" has not compressed.
I've never had to put a sealant on a head gasket before( that I can remember).
I have a tin of ACDelco/3m EC-776 sealing compound (bought for sealing head studs in a Chev) and I'm thinking about painting both sides of the new head gaskets with it.
Or should I be looking at something else? Opinions appreciated.
Regards, Greg
I used a gasket from a Laverda parts supplier, but I do not think they are OEM. I did not use an adhesive/sealant. All tensioning ect was done in sequence and in stages up to 45Nm. New O rings and gaskets (hand made) were fitted to the base of the barrels.
I've stripped one motor and measured up the head gaskets, comparing them with an old one I have. The steel compression rings on both are compressed to within about 0.01mm of each other, indicating that there is little change in the fitting. The tops of the liners are about 2 thou (.05mm) above the barrel surface.
The big difference is that the areas not compressed on the OEM gasket is still about 0.05 mm thicker than what the steel ring has compressed to, whereas on the aftermarket (?) unit it is about 0.05mm THINNER, and as a result, the blue sealing "stuff" has not compressed.
I've never had to put a sealant on a head gasket before( that I can remember).
I have a tin of ACDelco/3m EC-776 sealing compound (bought for sealing head studs in a Chev) and I'm thinking about painting both sides of the new head gaskets with it.
Or should I be looking at something else? Opinions appreciated.
Regards, Greg