MercCrusier 180 overheating

[capt. steve]

1987 180 MercCrusier Ser#ob678452. Closed cooling . Temp at idle 165 , under power 200+ , take it out of gear and idle up temp drops .Have replaced lower water pump ,Thermostat, clean& flushed heat exchanger, replaced exhaust elbow, replaced hose from transom. No oil in water , But small drops of oil in antifreeze. In process of replacing head gasket. Am I missing anything?

 

[Trent]

Re: MercCrusier 180 overheating

Yep......Small drops of oil on those engines usually means the inner seal on the waterpump has gone out. The waterpump is cam driven and over time they leak and the two waterpump seals need to be replaced. Normally not a head gasket problem when you have oil in the water. <br /><br />Wondering if you have replaced the heat exchanger to the bigger 4" one. The smaller ones caused overheating problems.<br /><br />Item #2 are the seals im talking about.<br /><br />

 

[elpaso]

Re: MercCrusier 180 overheating

At sterndrives.com in - how to do it section.<br />is a excellent artical on the leaking cam<br />seals problem.

 

[capt. steve]

Re: MercCrusier 180 overheating

Trent , I just completed the Head gasket and it was in bad shape. I have the 4" heat exchangers.<br />Would the two seals cause it to run hot?

 

[Trent]

Re: MercCrusier 180 overheating

No, The seals will not make it run hot. Another thing to check is to kick the drive to the side and look up in the gimble to see if the hose from the outdrive (looks like heater hose) is kinked. Same hose you replaced from the transom but outside the boat. Also check its fitting for damage. Did you replace the impeller only or the whole waterpump including wear plates and housing? Also you can do this trick. Replace the hose from the transom to the engine that you just replaced with a clear hose. At cruse RPM, If there are ANY bubbles in this hose your problem is in the outdrive and not the engine.

 

[capt. steve]

Re: MercCrusier 180 overheating

Trent ,<br /> I will try the clear hose trick. To check the hose at the gimble I will have to get it lifted out of the water Monday. I replaced everything at the pump.