Mercruiser 260 overheating

mykidsdad... thanks for the suggestion. The head gaskets were not removed, this motor was "rebuilt" i.e. re-ringed and head gaskets by a GM certified engine shop--I basically swapped the marine stuff + intake on it and dumped it in. I did install the intake, and spent some time looking at the gaskets there--they only go on one way and I made sure nothing was plugged. I think the main reason it gets so hot is because there's an exhaust passage through the center of the intake to heat up the choke.

Really whats left ?

Valves too tight can and will make a motor over heat.

But now we are into stuff that should have been looked at ?

Fresh rebuilt from michigan motors for a week we chased a problem hit 2000-2500 rpms and the motor would start to get hot and would just not run ..

For a whole week till my friend went into the house to take a dump and we were going back and forth i wanted to set the valves over and he said no he came out and i was just finishing.

Sure it was a mess and we hauled it to the bay and problem vanished.

Still running good 3 years latter or is it 4 .

Thanks for you reply. My 1988 Searay 230 WE is kind of over heating as well and with my very limited experience with boats, I am very interested in this thread.

The part I dont like was beating the therm out of the housing.Are you sure you have the correct therm housing in relation to the plumbing of the hoses? Thinking a clogged therm housing could restrict the flow. Only other idea is to remove the drive and put the hose right in the water inlet.Might isolate either engine or drive.

I am having the same issue, I read through the thread but seems that there was no final resolution. My engine runs fine at low RPM, once it gets to 3000 RPM the temp goes up to around 190, anything above that RPM it just keeps creeping up. I have replaced the re-circulatory water pump, the impeller and the seal which was bad in the upper housing for the water tube. This weekend I will remove the exhaust manifolds and check for blockage and disloged flappers. One flapper did blow out the exhaust but not sure about the other one. The motor was totally rebuilt spring of 2014 and ran good for most the season. When the overheating started we were sitting idling for an hour waiting for locks to open and have had issues since. There was alot of debris in the water but should not still be in any ports I wouldnt think. Still scratching my head on this one. Until I figure it out I got a 30 mph boat and that it but still gets me around the river.

Start a new topic this one is very old.............