I am rebuilding an old 1989? MCM165 4cyl Mercruiser engine. Followed Clymer's to the letter, engine turns over great, but no start. If I take a plug out, antifreeze shoots from the cylinder! What have I done wrong? Clymer's shows a diagram on how to configure the gasket to mount the resevoir to the exhaust manifold, leaving the front slot open between the two. Is this right or wrong? How could coolant from the resevoir enter the block? Any help would be greatly appreciated.David
Yes, you must install the gasket so that the slots in front are open, or you will be closing your resevoir from the rest of the coolant system.It is fairly easy for this riser to have a leak into the exhaust through either a gasket or from a bad casting. However, if you are having anti-freeze that "shoots out" from the cylinder you probably have a different problem source - like the head or head gasket, or a very large casting flaw in your riser or manifold.
When you seperated the cooling tank/riser combo did you check the mating surfaces for flatness, the manifolds for these 3.7litre engines do warp between riser and manifold and will allow antifreeze to enter into the exhaust side and on down into the cylinders, also did you have the head or deck on the block resurfaced if so then you should have had to correct the length of the cooling tube that goes from the block up into the head if its to long then you cannot get a positive seal on the head gasket thus a leak will occur, do a compression / leak down test and watch for any air bubbles coming up into the coolant tank, if so then its head, and for the cost of a riser gasket I would seperate the riser and check the surfaces with a strait edge and see if any light is passing through. Why was engine rebuilt was it a overheat problem?