dt 50 cooling problems

[Davesboat]

hi every one

I have a suzuki dt50 1983, running ok but when it at 5000 rpm the temp gauge goes to 125 degrees is this the normal operating temp.If I cruise about 3000 rpm gauge sits at 95 degrees. There is water coming out of exhaust on back of leg and tell tell dose flow but most of the time its just a trickle. If i clean tell tell then pumps lots of water. I felt the water on tell tell and its warm then goes cold so I assume the t state is working and felt the top of cylinder head and it was warm.

So not showing any signs of over heating as far as i can see, could it be a the temp gauge at fault? Is there anything else i could check /do.I have changed the impeller.

many thanks
DAVE

[artdf175]

This really sounds like a water pump failing
How long ago did you replace the impeller? And did you replace all the parts- -a full kit?
There have been a few situations where just the impeller was changed and subsequent overheating
Your temps? C of F ?
Degrees F they are low degrees C way over the top
Would certaininly check the thermostat normal should be around 140f (60C)
One exception--- looking at parts page I don't see a thermostat ??
Art

[Solarman]

Dave, this is an older motor, and I would first ask, if at wot do you have a good flow of water out of the exhaust on back of midsection and tell-tale? Is it possible you have good flow at lower rpms, and not at higher rpms? Then I'd ask if you have noticed any corrosion in the aluminum webbing (mating surfaces, where they bolt together) between exhaust chamber & water pump chamber, when you had the lower unit off to change water pump? These motors do create higher temps at wot, as well as higher exhaust pressures.

You could have a slight buildup of corrosion in water pas-sages around the cylinders (flush motor with vinegar or other corrosion flush solution in container for 1-2 hrs) or possibly exhaust pressures getting into water pump chamber and interfering with water getting to water pump (repair areas allowing exhaust into water pump chamber).

Also, it is possible your temp sending sensor could be out of calibration, but usually would become irratic at warmer temps.

Post back, and let us know.

[Davesboat]

hi thank you for the reply

spent time this weekend on boat, to start with, the tell- tale seems to be flowing well best its done for a long time gave it a good blow through and seems to done the trick. There is a flow of water out of the rear section of the leg runs down the leg and there is a spray coming from it as well, sorry just best way to describe it.Not sure how much water should be coming out. There is no signs of of corrosion on the cylinder head or exhaust. I changed impeller and plate (got a service kit from suzuki so plugs fuel filter and gear oil all done.)

I think I need to give this motor a good run and report back.Could the prop make the engine over heat (prop is a S1400 11 3/8 14p) WOT is about 5300 RPM

many thanks guys

Dave

[Solarman]

Prop relates to rpms, should not cause motor to overheat, and your 5300 rpms sounds fine for wot.

What Art suggested by complete water pump kit, was replacing the top housing as well. Sometimes old housings get worn, and do not send full pressure to the powerhead.

Corrosion in water pas-sages around cylinders in early stages might just partially slow down water flow, but it might be enough to allow motor to get too warm at wot.

The rest of what you have done seems fine.

Good luck, let us know how it's going when able.