Overheat Warning On 210 Merc Sportjet- Need Help!

[Downunder]

I've put a new Merc 210 Sportjet powerhead into my Seadoo Sportster and the continuous warning horn always seems to come on after about an hour of running. It's normally under load or at low- medium power settings. Shutting the engine down for 5 minutes and ideling in to the ramp also results in the horn starting up again about 1 minute after start up.

Are there any suggestions on what I can do to diagnose the difficult problem. Does anyone know whether there is a water pump (other than the water forced up by the jetdrive impellor) or a thermostat that needs checking?

All I can think of is either a blocked line (I have checked all the lines I know of and confirmed water running from them during opertation) or a faulty warning system (a dangerous assumption that I am avoiding).

I would appreciate any help from anyone that knows a bit about this engine. I just don't want to take anyone out in the boat anymore as I can't get too far from the ramp just in case!! Thanks

 

[Don S]

Re: Overheat Warning On 210 Merc Sportjet- Need Help!

There is no impeller pump in the 210, the water does come from the jet pump.
The first thing you need to do is a pressure test and see what you have.

 

[achris]

Re: Overheat Warning On 210 Merc Sportjet- Need Help!

Shouldn't this be in the "PWC Forum"?

 

[Don S]

Re: Overheat Warning On 210 Merc Sportjet- Need Help!

Shouldn't this be in the "PWC Forum"?

Not really Chris, it's a Mercury Outboard powerhead and a Mercury jet pump that the powerhead is mounted on. Just happens to be in a boat by a manufacturer know for PWC's and Snowmobiles.
SeeDooDoo also had some boats that weren't considered PWC's. Seating for 4 etc.

 

[Downunder]

Re: Overheat Warning On 210 Merc Sportjet- Need Help!

Hi Don. Thanks for the good advice. I have a copy of the manual and was also thinking the pressure test you mention would be a good next step. I will now get on to this when i'm back in town next week and post the results.

Yes the boat's an 18 footer certified as a seven seater, and as you mentioned the powerhead is the same as a Merc outboard. Regards Trent

 

[Downunder]

Re: Overheat Warning On 210 Merc Sportjet- Need Help!

I have pressure tested the water through the engine. Rather than buy the expensive kit recommended in the manual I made up my own using a copper elbow, 1metre of tubing and a air pressure guage. The readings I got were a bit lower which may or may not be due to the apparatus. (The width of the tubing was approx 4mm). The readings were idle = 0 and 5 1/4 rpm= 8psi. However the overheat doesn't normally come on when ideling.

I have found that by disconnecting the fuel sender that the warning doesn't seem to come on. I aim to confirm this next time I take it out for a long run in the water.

Any advise on my findings in the meantime wiould be greatly appreciated!!

 

[Dale002]

Re: Overheat Warning On 210 Merc Sportjet- Need Help!

Partially clog hose and or partially bad Stat. Check the pickup opening for debri