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View Full Version : Merc T stat cure!!



MOP
08-03-2004, 09:31 AM
Most everyone has or is running the Merc ball check T stat housing. As we all know the ball checks supply water to the risers until the engine gets up to temp, once at temp all the water goes to the bottom feed of the manifold non to the riser through that circuit if properly working. The T stat has been a pain since its inception causing low speed overheats etc. For guys that installed headers it was even worse as most headers have only bottom feed. While installing the Gils I could see trouble was ahead, I contacted Doug Lovins who by chance was having trouble blowing circ hoses. He went to Gil they supplied an expensive fix, I found a very reasonable about 1/3 the the Gill cost T stat housing that will allow anyone to dump the flakey ball check unit. Merc is the only OEM that I know of that uses this trouble prone unit, take my word for it there is absolutely no reason not to just feed the manifolds from the bottom all of the time and eliminate the riser feed hoses. Check out CHV-29-80 it comes complete with the thermostat retail $65. Yeah so you won't have balls anymore, you not have T stat problems anymore either!

http://www.barrmarine.net/barr_misc/barr_misc7.htm

Rootsy
08-03-2004, 06:46 PM
Phil,

merc does not use the check balls anymore... not since sometime in the early 90's... they went to a 4 port housing. main inlet, outlet to the circ pump and 2 outlets (1 for each manifold) which feed into the bottom... i have never had an issue.. even at high rpm... flow balance on the other hand has been a slight pain but nothing really to worry bout..just don't lay your hand on the starboard riser.. and you can chill your beer on the port... there is NO blockage...

MOP
08-03-2004, 08:02 PM
Jamie I got this thing all fixed up, drilled and tapped for senders. Its a Barr unit quality of the iron is very good I will let you know how well I like it.
What I have done in the past with uneven flow is to put a restrictor washer in the riser hose right at the riser and shoved the hose back on, 3/8" hole has worked well. It just slows the flow at the riser the bottom flow keeps the temp in check.

Phil

Murphy
08-05-2004, 09:40 PM
Phil,

Sounds good. It sounds like this unit flows water even before the thermostat opens. How does that work? Also, I assume we'd want to go to a different riser gasket with the large passages on all sides versus the one with the small hole on the forward passage. Incidentally, on some of the older boats using the checkball housing, the riser has a 1" spacer/adapter that actually had the small hole cast right into the spacer rather than using a small hole in the gasket. I wonder how that would work.

Murph