Race Engine Problem

[stubaillie]

My 1972 2000 105 race engine is pumping water into the overflow bottle. This occurs when the engine is being used at speed (around 7000rpm).
About 2 ltrs. usually. The engine at that stage is hot but not boiling.
The obvious problem was the head gasket, I removed the head, had the head crack tested, skimmed the head and installed a new original Alfa gasket. Same problem!! Replaced the radiator cap with a 21-25lb cap and now air pressure remains in the radiator after still pumping water into the overflow bottle.The air has to come from somewhere most likley the combustion chamber. Has anyone experienced the same problem, if so what was you solution and maybe you might like to suggest an area I should be looking in .

[andyb6]

Where is the overflow bottle source? Could you post a picture of your engine bay? If your overflow is simply from the nipple at the radiator neck then it is only coming from bypassing the cap. If you have properly bled the air out of the system at the back of the head et al run it up to temp and pukes water, what happens if you don't replace the water? If it pukes out more water then the head gasket is still leaking and pressurizing the cooling system. If no more water comes out and the system equalizes you may simply have to add an expansion tank to help bled off steam at the back of the head.

Post pictures if you can.

[stubaillie]

The water then air is bypassing the cap via the nipple on the radiator however i think the combustion chamber is still leaking air somewhere ---however everything looks good, it may be the liners moving or something i havent thought about. Have just had a big weekend racing and i think the engine will have to be completely stripped to try and determine the problem. Wishfull thinking has encouraged me to post this note in the hope that i can get out of that.

[180OUT]

If you haven't done so already, add a can of "Alumaseal" to your radiator. It will sometimes cure a multitude of leakage problems that resist other methods.

[gtv27]

adding 'Silverseal' to the coolant also can help deal with minor issues and is not a bad idea for a new motor. Also, does it keep pumping out the water, or does it normalise after an initial 2l purge (ie suck it back in via a recovery cap once cool?)

[Alfar7]

At high RPM you could be loosing a little combustion pressure around the firering, but there should be some evidence of that. A simple cure like in the old CRS can solve that. (a small groove cut in the liner seal surface and head.
I agree with andy that the engine should not be raced withour vents in the top of the head.
Below is a full race modified 1750 head I have in the shop, showing vents between front & rear cylenders (and needs a home by the way! anybody need?)
Sorry for the diversion...

[raff_gta]

are they vents for the water galleries or the oil galleries?

ive got a semi race engine (used for track work and hillclimbs, but street too), should I do this mod to my engine?

[stubaillie]

The combustion leak was coming from the edge of the liner and head gasket. The soution has been to cut a groove in the top of the liner and press in a "ring " of stainless wire .008thick protruding .004 above the liner binding into the gasket when the head is torqued on.Im hopeing this will solve the problem. Next meeting is in 10 days so we will see.

[Gordon Raymond]

Nice catch! From my experience with the smaller 1300 & 1600 Alfa engines, while the SS "O" ring is nice, it's really not necessary if a grove is cut in the liner, .5 mm deep x .8 mm wide midway in the liners tops. A like grove is cut around the combustion chambers in the head, about 1/2 of the fire ring seal width, .8 x.8 mm. We used to cut these with a vertical mill. In use the fire ring displaces into these liner and head groves when the head is torqued. This is often more effective than the SS "O" ring as it is gapless, and once done will always seal the combustion chamber, as Richard mentioned. It's a one time only job.