VP aq125a/270 overheating issue

[JAL51974]

this is a 1985 Bayliner Capri and I have done a lot of maintenance over the 20 years I have owned it. I am getting ready to sell it and this overheating started. It doesn't overheat on the hose with muffs, it runs fine on the lake at idle speed. I probably ran it in idle speed for 45 minutes without problem. Once it goes up on plane it overheats with the higher RPMs and going down to idle RPMs it cools off again. I had a problem with it last summer, going too shallow in a very muddy river and ended up taking most of the cooling hose/pipe/HE apart to clean it thoroughly and reassembled it to get the mud out of everything. Replaced the impeller and inspected the raw water pump inside which looked ok. I needed a new HE strainer housing due to a crack in the lower part where it bolts onto the water tank and did that.

I thought it might be the water neck fitting on the OD, I replaced that 19 years ago, when it only overheated up on plane. To test it I pulled a vacuum from the copper tube at the engine to the OD and covered the water neck with shaving cream- no actual signs of the cream sucking in with the vacuum.

I am puzzled. There is also antifreeze green color, under the strainer in the HE housing which shouldn't be there since this is the water coming from the lake to "cool off" the heated water from the engine. And the antifreeze part of the cooling system is low on antifreeze too.

what should I examine next? Thanks in advance.
Joe

 

[Scott Danforth]

Look under the drive where the hose and fitting is on the H-frame. Replace the fitting, pull the drive and replace the O-rings that seal the H-frame pivot shaft

 

[JAL51974]

I was thinking the same thing Scott, but when I pulled the vacuum from the inside engine compartment on the copper piping, I put foamy shave cream on all the fittings and gaskets, and there was no apparent leaking with the suction. maybe that fitting is corroded slightly and I don't see the leak?

But the mixing of antifreeze into the raw water strainer housing has really got me puzzled. I thought that the antifreeze cooling the engine block is a sealed system, with the raw water from the lake cooling it down as it goes through the cooling parts, then raw water exits into the lake through the leg.