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MG MGB GT V8 Factory Originals Technical - valley pan gasket

well, I got the engine to run with the Rover FI setup, no fuel leaks. Pressure testing the cooling system did not give as good results.

I removed the old 4bbl setup which was assembled without any type of sealent, & never leaked. I have swapped manifolds in the past without leaks, but this time, there is a major leak with the FI manifold at the rear of the engine. Since I am going to have to remove the manifold, I am considering use of a Rover composite valley pan gasket in place of the metal one.

Has anyone out there used the composite gasket & have any advice or comments? I have to assume the leak is at the rear of one or both cylinder heads, as there is nowhere else in the rear of the engine for water leaks. There is no heater in/outlet in the rear of the FI manifolds as there is for a carb manifold. Any theories as to where else the leak might occur are also welcome.

As a point of interest, the engine is a Buick 215 with a Rover serpentine front cover from a 4.2, 1990 Rover FI system, Volvo 240 turbo fuel pump & filter, gas tank modified by Glenn Towery with an internal swirl pot. No O2 sensors as of yet, but they will come soon.

In doing the wiring, I found that the fuel pump was energized for only a few seconds when the ignition was turned on, but energized while in the start mode. By turning the ignition on & off several times, I was able to pressurize the fuel rail & the engine started on the first try.
Jim Stuart

Jim - I got the same result when I started up a 3.9 with an old tin gasket a few years back - the composite cured it. The emphasis then was on total cleanliness, getting the new torque absolutely right and using the appropriate antifreeze/inhibitor.

If you have any deformity of the mating surfaces - use the sealant designed for use with that compo gasket.



I've just had a new composite gasket fitted by our local Rover specialist.

He used silicone gasket sealant in the 4 corners where the heads meets the block (there are small gaps there).
I had a small water leak at the rear but when I nipped the bolts up after the first run, this cured it.

Michael barnfather

Jim,the steel heater pipe that runs under the in/man. is very prone to corrosion.If you have to replace it, you can use copper piping & the screwed fitting should be available at a plumbers outlet. A bead of silicone sealant on both sides of the gasket around the coolant holes is recommended.There seems to be a lot more plumbing for the heater with the Rover manifold. A jubilee clip not tightened fully ? My engine slopes from front to back, so it's difficult to say where any leak comes from as the coolant always ends up at the rear of the tray. Good luck, Barrie E
Barrie Egerton

Thanks to all. The concensus is that the composite gaskets are good, but still need sealant, as the tin gasket did.

I made up a rig for the compressed air line with a small valve & regulator, so I will check again this weekend to try to better identify the leak by pressurising the cooling system with air. Harder to find the leak, but less of a mess than filling with water & having it run all over the shop floor.
Jim Stuart

This thread was discussed on 17/02/2004

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