Another overheating prob.

[BoatDestroyer]

i'm sure everyone gets tired of reading about overheating problems. <br />but anyway , this one has me stumped. <br />first , she's a 1986 mercruiser 350-260 <br />i've pulled both manifolds and checked and they look like new , no rust or corrosion , new impellor and housing , new belts , pulled all hoses and checked for obstruction , i'm baffled<br /><br />ok , now the problem , i put her in the water , and she runs fine , idles at 800 and the temp stays at 135-140 , as soon as i get on plane the temp starts going up past 170-180 , and i drop off plane and the temp goes back down , if i rev it up in neutral , 2500-3500 r's , the temp drops FAST , it seems because of that the manifolds are flowing e-nuff water , the circulating pump is turning , water is flowing from the exhaust (hose fed) , i have great pressure at the water pump from the drive ( took hose off water pump ) <br />the only flaw that i can see is that i need the lower unit re-sealed , i have water mixing with gear oil , but i dont see how that effects the engine. <br />thanks in advance

 

[Wart T]

Re: Another overheating prob.

restriction somewhere. You sure you have the right riser gaskets and are you sure they are installed properly?

 

[Blk-n-Blu]

Re: Another overheating prob.

BoatD, Remembering water boils at 212 degF does the motor actually go that far. From what Ive seen on posts a lot of motors are running 20 or more degrees hotter than the thermostat rating. <br />What thermostat are you running? Get a cooler one.<br />Look here for more info:<br /> http://www.marinemechanic.com/site/page85.html <br />Good Luck

 

[BoatDestroyer]

Re: Another overheating prob.

really dont want to take it that high , water might boil at that point , but metal warps at alot of different temps. <br />with a 145 thermostat , i know that 180 is too high , i'v been boating for many years , and have always been bale to keep temps in the 150-160 range.