94' DT25 cooling issues

[Idaho suzi]

Hi There,

I’m having problems with my Suzuki DT25 (’94) and was wondering if I could get some help. I bought it used last fall and used it in late fall and early spring with no problems and the previous (original) owner said that he never had it in saltwater. But a couple weeks ago…

I was out trolling in my boat for a while and the kid was getting a little antsy so I powered up and got up on plane and went into a cove about a quarter mile away. When I stopped I noticed a burning smell and the pee stream was inconsistent (we had been trolling around in circles and I didn’t smell anything so I’m pretty certain the burning smell started after I was up on plane). So I shut down and paddled most of the way back to the launch but did power up for short periods operating at just above idle. I was operating at just above idle b/c there wasn’t a consistent pee stream at idle but it was consistent at slightly higher RMP. The outflow was hot, it didn’t scold me but I wouldn’t want to keep it in the stream for very long.

I installed a water pump rebuild kit this weekend. One of the vanes of the impeller was broken but the part that broke off was in the water pump housing. The parts matched up like a couple of puzzle pieces so if anything did go into the cooling system it was very small, dust or grain of sand size at most.

I ran the motor in a trash can (it was clean) and it took a little while for the stream to start and wasn’t all that consistent at idle and after a while it got really hot to the touch, not scolding but not comfortable either.

Does the water temp seem reasonable to you? What is the expected operating temp?

Does anyone have any idea what might be going on and what I can do to diagnose the problem?

[keakar]

you should remove and blow clear any water hoses for the tattle tail in case it has trash in it. put an air hose on the hose fitting in the block and blast it clear as well (if you don't have an air compressor use a small wire) then remove the lower unit then take out the thermostat and back flush the water jackets by sticking the hose in the thermostat hole and let it run on good hose pressure for 5 or ten minutes then switch and hook the hose to the bottom water tube and let it flow out of the thermostat opening to clean it all out good then put it all back together and recheck how it runs.

that's about all you can do to flush out the water passages short of taking the motor apart.

[Chris P]

As far as I know, it shouldn't be hot enough that you wouldn't want to put your hand in it. It should be bathtub-warm in my opinion.

I have a 9.9, and if your telltale is similar to mine, it doesn't take much to cause the stream from the telltale to turn into a dribble from a strong stream. You can try wiggling some wire up the telltale to see if that helps (18 gage) or some weedeater cord (do this while running the engine). Check the thermostat to make sure no tiny bits of impeller are stuck in it as well.

I had to clean out my telltale by taking the cylinder head off to access the back of the telltale. That helped.

Having a compressor helps too.

Make sure you tightened all the bolts to torque specs and that no grommets or gaskets were damaged in the process of redoing the water pump. It's amazing how easy a tiny grommet can tear during re-install...

One thing I find handy is a laser temperature gage so when I run a motor in a tub and there is a cooling problem, I can monitor the temps at the cylinder head to make sure nothing goes above 200F.