Mercury outbrive overheating

[DFH]

I have a 25ft Bertram fitted with twin Mercury outdrives 3litre mcm alphas with bravo outdrives 1990 (OC 764077)<br />One of the engines runs hot.I have carried out all the items listed below:there has been an improvement but it still runs about 30degrees hotter than the other engine.<br />A new exhaust elbow fitted and the flapper checked.<br />The exhaust manifold has been cleaned.<br />The head has been off and cleaned the valves checked.<br />A new impeller and a new engine water pump fitted.<br />The plugs are ok and the timing has been checked.<br />The problem is the same with or without the thermostat fitted.<br />The engine cools quickly if run out of gear.<br />The boat has recently been antifouled so there is not weed build-up.<br />I would be very grateful for any ideas.<br />DFH

 

[corm]

Re: Mercury outbrive overheating

How hot is 30 degrees hotter? match your sending units with a VOM, swap the gauges<br />to see if they read the same or different.<br />Let us know.<br /><br />------------------<br />...have fun...corm<br /><br />cubic inches = power<br />power = speed<br />speed = FUN<br /><br />Email me if you need to.

 

[DFH]

Re: Mercury outbrive overheating

One engine runs at about 190f the other at 200f to 210f it is definately running hotter.The manifold and elbow are much hotter to the touch that the other engine.<br />DFH

 

[corm]

Re: Mercury outbrive overheating

Have you had anything done to your props lately? What is the top rpm of the motor?<br />How is the fuelpump pressure,the one motor<br />may be a little lean. Pure speculation on my part. I'll look at some service aids tomorrow.<br />...have fun...corm

 

[MercilessMike]

Re: Mercury outbrive overheating

I have heard that these outdrive run hot, (BRAVO)I have seen on several websites that have a "shower" for the bravo drive, It attaches to your outdrive and cools it with fresh water flowing through rear cover and thus keeps outdrive cooler which in turn helps to keep engine temp down. A little on the high end for price,($350.00 US) but An ounce of prevention........<br /><br />Here is the link. http://www.performancemarine.net/performance/coolers.html <br /><br />Regards!<br />Yo ho ho and a bottle of rum....