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Water Temp shot up to 220 after being steady at 120 where to start? 1977 800 stern drive

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dwb1013

New member
Well.....We were having a nice first ride of the season (in july...long story) Boat is running great... Just replaced alternator so i am watching gauges......after about an hour i look down.....temp has gone from 120 to 220/230 in matter of minutes. I was idling at the time to go under a no wake bridge. i idled back to the launch and pulled it out. Boat continued to run fine.....temp did not continue to climb. I had to reverse at the launch cause of wind so I can't tell if i picked up some sea weed or something....but prop was clean...so i very much doubt it. I will refloat today and start and see where the temp goes. If it does what i suspect......and climbs again.....then the next question is where to start. It looks like to me we have two water pumps....one on out drive and one on motor.....which is most likely? how do I isolate the porblem to one or the other? How much hassle is it to change the outdrive water pump....do I need special tools? I can usually do most mechanical work if it doesn't get to techinical.....Frustrated and need some advice. I have gone through tilt motor problems....then to find out I had a bad alternator.....now this....All for a boat that has 160 orginal hours.....Not to mention that my "at home supervisor" aka the "wife" is starting to loose faith in the Cozy Lady....
 
Thermostat sticking? In my old 225 Buick, I had a piece of rust break off, and jam the plunger from letting the spring open the Thermostat. Only found it when I removed the Thermostat for inspection.
Engine got so hot, the paint on it was beginning to fry. Had to have friends pour water directly on the engine while hobbling in. Thank goodness for cast iron blocks, and heads. NO damage to the engine.
 
[FONT=Verdana, Arial, Helvetica][FONT=Verdana, Arial, Helvetica]First you have to know if you have good water coming into the boat.

Submerge the drive, and then wherever the raw water hose goes to say the t-stat or a heat exchanger remove it from that spot.

Then start the motor hold the hose straight up if you have 8-12 inchs of good water you good to that point.

You need do this for only 3-5 seconds quick shut off the motor.

Now say you got good water to the t-stat the you have to open the t-stat cover.

Me i would remove and replace or remove and leave empty the housing and close it up.

Run the boat if it over heats again then you know with no t-stat it's for sure a blockage down stream.

Then i'm betting the riser / elbow is clogged.

Now be aware a flapper / shutter could be blocking the exhaust. So if you pull the risers then look for them not there then you got to fish them out.

My own opinion i hate flappers and remove them. They cause alot of trouble and are just not worth it.

Say you don't have good water to the t-stat or exchanger then you know the problem is ether the hose is kinked inside the transom at the thru fitting to the drive.

Or the fitting on the outside of the transom that feeds the raw water hose is clogged, or the impeller went, or the water pump housing went.

Volvo says remove them if you have them and do not replace them if they go.

Good luck ![/FONT][/FONT]
 
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