engine overheating

[sailaway]

I have an 1986 m-25 engine it usually runs 165 -170 this wk we were a 1 wk trip in lake erie the water temp is 79 degree. my engine temp went to 180 on the long days. I also lost about 4 oz of antifreeze everyday. I am wonder if the heat exchanger is bad. I check all the normal things engine strainer baskets. water flows seems ok Charlie

[Ron Hill]

Sail : It's easy enough to take out the HX and pressure check it, clean it out, get some new end caps and reinstall!

A thought

[KWKloeber]

charlie

my 2" Hx developed a pinhole between the sides at about 15 years (lake erie water,) and replaced w/ the 3"  You can sometimes smell antifreeze in the exhaust if there's enough leaking thru. 

you might try filling, running up to temp/coolant pressure, shutting down, and later draining the aqualift to see if any antifreeze was pushed into it after shutdown while the block was still under pressure.  You can also check the system by pressure checking the coolant side with the Hx in place, just as you would with an auto radiator (pressure checker on the coolant cap,) or by applying pressure to any of the coolant hoses/pipe fittings.)  you only need 5-10 psi, not major water pressure to check it.  Can be done with a gauge/water hose, or even a bicycle pump.

kk

[RV61]

Charlie,
These are the same symptoms I had leading up to the water pump bearing failure on the internal water pump. I was was hitting 180 to 185 after about 3 hours once the lake water warmed up and would have to back down to cool off. I would also loose antifreeze more than normal. Once I put the new pump on in it has never gone above 160. May want to check if pulley on the pump spins freely with no friction and no play. Ask Turning Point if he had same symptoms leading up to his pump going out.
Something to consider.

[Ken Juul]

Auto Zone and I think Advance Auto parts stores have tools they loan.  The Radiator pressure tester is one of them.