4 or 5 hp Force Headgasket Part# Confusion

[Klink]

I have a 1989 Force 5 hp with 2.00 inch bore and I'm having a difficult time finding out what the correct part number is for the head gasket. You see, in 1990 Force changed the bore on the 5 hp to 2.125 inch bore, yet Mercury shows the same head gasket for both. I got the part and it is for a 2.125 bore, (the gasket ring is 2.155), being bigger than my 2.00 inch bore cylinder (my original used head gasket off the engine is 2.03 I.D.), this new gasket sits on the outer edge of the cylinder wall with practically no gasket separating the ring from the cooling water passage. I talked to Mercury Marine customer service 920-929-5040 and pointed out to them that they are specifying the same head gasket F712529 for 2.00 and a 2.125 engines, which makes no sense. The person answering agreed with me and thought that was odd, which does not help me any.

Does anyone here a Force 4 hp, they built it up to 1987, and I'm wondering if it is 2.00 bore, because it does show a different part number for the head gasket than the one specified for the 5 hp (which is too big for my 2.00 in bore 5 hp) ?

P.S.- other than the ring size problem, the gasket F712529 is also visible thinner than the one I took off the engine, the F712529 is .030, and the one off the engine is .050. I installed it anyways, but could not get it to stop leaking water. With clean threads I torqued it in specified order, in increments, and to spec per the Force service manual 130 in lbs. It did not seal. I tightened it a tad more, nothing, and so on till I got to 180 inch lbs., nothing, still leaked. It had no sticky seal material on it, so maybe next time I will try with Permatex #3. However, this most definitely is not the right head gasket for a 2.00 bore engine.

Maybe the 1987 4 hp Force was also 2.00 inch bore and that is the head gasket I should order? (head gasket F521529 which is listed for at least the 1983-1987 3.5 and 4 hp) ? What is the bore of the 1983-1987 3.5 and 4 hp?

Hoping the combined experiences of the members have gone through this before and can tell me what the correct head gasket number is?

 

[Klink]

UPDATE:

I found a 1982 Chrysler Outboards sales brochure at http://www.chryslercrew.com/ and it confirmed that the 4hp is exactly like my 5 hp: 4hp at 5250 RPM, 4750-5750 RPM, 2.00” bore x 1.59” stroke (5.0 cu in (82cc). Will try the part F521529 to see if it is it.

 

[Klink]

Bad news, Mercury tells me that head gasket F521529 has been superseded by the F712529 mentioned above. So Mercury is specifying the same head gasket F712529 for 2.00 and a 2.125 engines, all of which makes no sense.

If anyone has a F521529 (or the Chrysler part number it was used on the Chrysler 3.5 and 4 hp from 1979 till 1987) let me know.

 

[Klink]

No Title

Like I said, in 1990 Force changed the bore on the 5 hp from 2.00 to 2.125 inch bore, yet Mercury shows the same head gasket for both. I got the head new gasket F712529 and it is for a 2.125 bore, (the gasket ring is 2.155 inch bore cylinder (my original used head gasket off the engine is 2.03 Inch I.D.), this new gasket sits on the outer edge of the cylinder wall with practically no gasket separating the ring from the cooling water passage. See the pictures attached.

The first picture shows the gray F712529, the bigger ID 2.125 inch on top, with the smaller 2.00 inch bore head gasket below it, see the two rings.


The second picture shows the smaller original 2.00 head gasket, the black one. Notice the bulge in the black gasket material just 1/8" outside of the ring, that is the cooling system water passage area mark. If I were to install the bigger I.D head gasket, there would be no gasket material between the ring and the water passage, in other words I'd loose practically all of the 1/8" of gasket outside of the ring. Is this OK, to have salt water in direct contact with the metal ring? and also a hollow gap between the cylinder head and the cylinder head (because the bigger ring does not seal the fist 0.100" of the head).

 

[Klink]

Finally after one week the pictures are uploading on iboats.