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Merc 74 bravo 1 overheating

S

speedracer

New member
"87 sea ray pachanga 22, just

"87 sea ray pachanga 22, just bought it!!! Took it out for the first time--ran awesome, 68 @ 4600 RPM by GPS. The two times I opened it up we then went into a cove to hang out. The temp climbed to 220 until I (immediately) headed out of the cove back to a cruising speed when the temp dropped right back to 170. The only times it heated up like this was when I really opened it up then idled. When just cruising never heated up when back to an idle. First post--thanks ahead of time"
 
"You may have sucked something

"You may have sucked something (mud, sand, a plastic bag, a rag) into the water intake. I'd check the entire system out, just to be sure.

By the way, you were lucky! Mine did this to me a month ago and cost me an engine.

Jeff"
 
"OK guys--here's an update

"OK guys--here's an update. Go the lower unit off and 1. water's been in it, creamy colored oil. 2. The impeller looks great, all the fins are intact, found no chunks of debri that may signify blockage nor is there any distortion to the plastic housing. I also removed the pump case?, the black plastic piece found below the impeller, it looked fine, haven't gotten to the thermostat, will do that this evening. Here is the problem I am having now--these mercruiser retailers around me seem clueless as to the parts I need. Can someone tell me if there is a complete kit, otherwise clue me in on what is available to put back together what I have taken apart. Obviously I need gaskets for the impeller and the pump case? Is there a kit for putting the lower unit back together? Little help would be apreciated just so I don't get screwed."
 
"You have an oil seal leak som

"You have an oil seal leak somewhere in the drive.
Your best bet is to have it pressure tested to find out for sure what oil seal is leaking then go from there. BTW to replace the oil seals on either of the drive shafts, you'll need at the very least the special wrenches to remove/reinstall the bearing carrier(s). Also the lower unit and upper unit use different wrenches (about $70.00 each!)
Oil seal and gasket kits are available.
www.mercruiserparts.com has been very good to me.
I was (so far) very succesful in replacing the oil seals for the vertical shaft where it enters into upper unit. I did end up buying the wrench for the upper unit and took the chance that I wouldn't change the clearance or backlash in the gears, so I didn't bother messing with the special tools needed to measure it out. I simply put it back together the way it came apart using new gakets, o-rings, and oil seals.
I would have to guess that the vertical shaft oil seals are probably the most likely to start leaking first since the shaft gets yanked out and pushed back into those seals everytime the lower unit is pulled off. But, realistically, once one seal starts to go the rest are likely not far behind. Definately a pay now or pay later type deal.
One more thing: the replacement I got for what used to be two seperate seals (facing opposite directions) was one double sided oil seal. This may have contributed to my success since now the new seals are riding against unworn spots on the shaft."
 
"well, changed the impeller, r

"well, changed the impeller, ran the boat on muffs, OVERHEATED! changed the thermostat and the springs in the thermostat housing tee check balls, doesn't overheat....BUT...prior to the changes at cruising speed the temp ran about 140, with the changes at cruising it runs more like 155-160, any suggestions?"
 
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