1978 sea ray 240 da moneypitt overheating

[hucksterfool]

i just took my boat out usually runs 140 150 temp well today i looked down 220 240! I got it back to dock so i wasnt stranded out (only like a mile from dock) anyway i got to looking at it. temp is correct. i pulled thermo housing off, pulled thermo out . ran boat for a few secs with impellor line unhooked and is pumping decently so i think impellor is good but not sure how much force it should have. its a omc 800 outdrive. then i unhooked lines to both risers and ran boat and water was pumping out ok i guess faster when i ran throttle up. the temp stayed low tho like 160 with these lines off as soon as i reconnected the temp went back up. SO i oulled risers off and there pretty clean and clear ran hose thru and water flowed good. manafolds look basically clean. so i am at a loss. WATER pump on engine? impellor still bad not pumping hard enough? outdrive water or exhause blocked somehow? any ideas guys>?
risers are $$$$$$ and hate to waste if i dont need....

 

[BillyT0020]

Sounds like you have a stuck shutter in your Y Pipe. They are like a one way valve so water can exit through the prop but not come back in when you slow down and come off a plane. If this is the case it will block your hot water from exiting the boat which would not allow fresh cold water to enter. Thru Hull Exhaust would get rid of that problem :thumbsup:

You can check how much your impeller is pumping by unhooking the inlet line and catching the water in a bucket for exactly 15 seconds at 1000 RPMs. I think you are supposed to get 4 quarts but double check in the manual.

Good Luck!

 

[Vince_nj1]

Stuck thermostat?

 

[hucksterfool]

i took thermostat out already. Here are two photos of the riser and manafold. both are fairly clean..

 

[BillyT0020]

There's a good amount of surface rust on your manifolds, and those things usually rust from the inside out. You could have some rust blocking the internal passages that you cant see. I wouldn't rule them out completely.

I would check your Y pipe shutters and throw in a brand new thermostat and see if she cools down. If not, change the impleller since there cheap and should be changed every year anyway and check the tube going from the outdrive through the transom for kinks or blockage. Pull the tubes off the oil cooler and see if theres a block in there. If none of that works then it has to be the manifolds $$$.

 

[hucksterfool]

thanks for the info. i did take a garden hose and pump water into manafolds and was flowing great. i'll still the risers back on and run the boat with t fitting with garden hose suppying more pressure to see if she overheats that way. rule out the impellor ateast. i'll have to get the marine to pull her out so i can inspect the outdrive for issues and go ahead and change impellor. its a older omc 800 outdrive and finding parts can be tough

 

[BillyT0020]

Yeah I hear ya, I've had my boat pulled twice already this year! Check out your Y pipe while you have her out. Should be dry when its out of the water.

 

[stevea661]

Before you pull the boat try pulling the thermostat and running the boat with out it. Sounds like a bad thermostat to me. Also check at the sender with a IR thermometer and see if it agrees with your temp gauge. I think if you had a stuck or broken exhaust flapper you would be down on power, your exhaust would be restricted, worst case causing water to back up into the head from the blocked exhaust. I don't think this is your problem. You could have just sucked a plastic bag around your outdrive while running, that will shut the water flow down and cause it to over heat. Just some thoughts, I hope it's something easy, good luck.

 

[hucksterfool]

I took thermostat out already. i would agree with the flap issue because i do have power issues!. it will only go about 17 mph at full throttle!!!. I had a bad antisiphon valve fixed that used to cut out but now it opens up and seems like it has little to no power will barely get to plane. Maybe the flap is stuck.... thanks for the infoooo

 

[hucksterfool]

is the flap on the top of the outdrive when i can reach without pulling the boat out( reach with hand or jump in water and feel for it?) or do i need to pull boat out...?

 

[stevea661]

is the flap on the top of the outdrive when i can reach without pulling the boat out( reach with hand or jump in water and feel for it?) or do i need to pull boat out...?

I don't know what you have, mines an 86 omc cobra, there is a flap on each side of the exhaust in the wye pipe they are plastic with 2 ears and a rod going through across the pipe, I would check to make sure the overflow of the exhaust is above the water line before pulling stuff apart other wise water will come into the boat through the exhaust. If one breaks off it could block the exhaust.