Cooling system on 1990 Suzuki DT15c

[simplystressed]

Hi all - today I had the motor running in a tub of water and it took some time but I ended up cleaning quite a bit of sand out of the telltale hole. I did however notice this:

After I shut it off and start it again, when idling it takes quite a while for the water to start spitting out of the exhaust and the telltale.

Is it normal for no water to come out until the thermostat kicks open? The water is quite hot when it first comes out and cools off as it flows for a while. Just want to make sure this model is supposed to do this.

thanks.

SS

 

[deejaycee_2000]

Re: Cooling system on 1990 Suzuki DT15c

no that is not normal ..... there is obviously alot more sand in there, the water should start pumping out straight away after the motor starts .... you will need to take the thermostat cover off and flush through there .......

 

[simplystressed]

Re: Cooling system on 1990 Suzuki DT15c

Would I need to replace the gasket? For some reason I thought I heard some Suzukis don't pump water out of the telltale until it reaches the tstat opening temp.

Anyhow so looking here http://store.brownspoint.com/pdf/DT15c(89-97).pdf on page #3 I just pull 19, 20, 21 and 22 out and flush some water through there?

thanks! SS

 

[James R]

Re: Cooling system on 1990 Suzuki DT15c

Good cooling is essential to an outboard.
If you have sand in the system the impeller is probably shot and the housing and plate is probably scored. Potential for a blown motor. The Suzuki pumps provide a strong telltale as soon as the motor fires.
Need to pull the lower unit and service the pump. With the lower unit off you can do a better flush both ways to clear any sand and debris.

 

[simplystressed]

Re: Cooling system on 1990 Suzuki DT15c

Good cooling is essential to an outboard.
If you have sand in the system the impeller is probably shot and the housing and plate is probably scored. Potential for a blown motor. The Suzuki pumps provide a strong telltale as soon as the motor fires.
Need to pull the lower unit and service the pump. With the lower unit off you can do a better flush both ways to clear any sand and debris.

Better to be safe than sorry. I'm going to take the t-stat out and clean/test it tonight, but I'm pricing out the impeller kit and tstat and I'll get it tuned up. Runs nice and I want to keep it that way.

So the telltale should always have flow even when the motor is cold on these models?

 

[deejaycee_2000]

Re: Cooling system on 1990 Suzuki DT15c

Yes that is correct, I agree with James, with the lower unit off aswell you can flush it even better both ways ....

 

[simplystressed]

Re: Cooling system on 1990 Suzuki DT15c

I took the thermostat off last night to flush that section out and one of the housing bolts broke on me inside Got the telltale hole flowing better though.

The other two came out but all three were corroded. I'm going to take it to a shop and have them replace the thermostat and get an impeller kit with the housing etc.

 

[deejaycee_2000]

Re: Cooling system on 1990 Suzuki DT15c

Always frustrating when that happens, always lube it well with WD 40 about 30 mins before trying to loosen bolts, now you need to drill out the old bolt and re-tap it ...

 

[ebsworj]

Re: Cooling system on 1990 Suzuki DT15c

The same thing just happend to me on the same motor! But my thermostat was totally melted inside and I broke 2 bolts off.. arggh! Has anyone had any success in getting these bolts out? They must be realy corroded!

I tried a left handed drill bit and that didn't work. Should I take it to a machice shop? Are these good motors?

 

[deejaycee_2000]

Re: Cooling system on 1990 Suzuki DT15c

You can take it to a machine shop, it will take very quick for them to do it .... or you can try doing it yourself ..... but probably better to let someone do it that knows how .....

 

[ebsworj]

Re: Cooling system on 1990 Suzuki DT15c

Here's an update on my 2 broken off thermostat bolts:

I just got my motor back from the machine shop today, the bill was 1 hour or around $100 but they were able to get both out cleanly and even save the original threads. So I'm happy.

He said the aluminum just about melted to the stainless since it got so hot. I've ordered a new thermostat, spacer and gasket... will let you know how it turns out.

 

[simplystressed]

Re: Cooling system on 1990 Suzuki DT15c

Here's an update on my 2 broken off thermostat bolts:

I just got my motor back from the machine shop today, the bill was 1 hour or around $100 but they were able to get both out cleanly and even save the original threads. So I'm happy.

He said the aluminum just about melted to the stainless since it got so hot. I've ordered a new thermostat, spacer and gasket... will let you know how it turns out.

Good luck...mine has been working fine since i got the bolts out and new ones in...remember to coat the threads with hi-temp anti-sieze!

 

[ebsworj]

Re: Cooling system on 1990 Suzuki DT15c

HI SimplyStressed: Could you tell me what size prop you have on your motor? The one that came with mine is almost destroyed. I need to find a new one but I'm not sure of the standard prop.

I do know that I want to go fast and it will be on a small boat rated for 10hp so I might increase the pitch a little but a starting size/pitch would be useful.

Also does anyone know if other brands will fit? No one carries Suzuki around Seattle. I do know it takes a 10 spline.

 

[simplystressed]

Re: Cooling system on 1990 Suzuki DT15c

Order right off here they are $50 and free shipping! (Well except for me in Canada )I'm gonna order a new one today I think.

Mine is 9 1/4X9 stock...you could buy mine

I'm going to a 4 blade 8'' pitch prop because my boat is pretty heavy. You need to stick in the right RPM range though don't want to overrev her.

 

[simplystressed]

Re: Cooling system on 1990 Suzuki DT15c

Hey ebsworj check to make sure your motor's A/V plate is level or slightly higher than the bottom of the boat as well! The shortshaft DT15C (at least mine) is actually 17'' so it was a little long for my 15'' transon and I needed to raise up the transom a bit. Helped signifigantly both in takeoff and top end.

 

[ebsworj]

Re: Cooling system on 1990 Suzuki DT15c

Hey ebsworj check to make sure your motor's A/V plate is level or slightly higher than the bottom of the boat as well! The shortshaft DT15C (at least mine) is actually 17'' so it was a little long for my 15'' transon and I needed to raise up the transom a bit. Helped signifigantly both in takeoff and top end.

Hi, Thanks for the tip, I did notice she's a little longer than my old mercury 9.8. Another update on my thermostat... I just got a new thermo, gasket and the spacer from the internet but when I went to put them all back together one of the threads in one of the drilled out bolt holes blew out. I couldn't get it tight enough to not leak when running.

But it ran enough to test it... I just took it back to the machine shop to have them tap the holes one size bigger. Hope it works and that I didn't buy a anchor weight of a motor.

Another question for DT15C owners. What is the wire coming out of the front of the motor? Is it a charging wire for a battery?

 

[ebsworj]

Re: Cooling system on 1990 Suzuki DT15c

I blew out tons of sand and part of an old head gasket after I pulled the head it was easier to blow out sand from the passages. It pumps great now even with the old impeller.

My question now is how hot is normal for the tell tale water on this Suzukis? I measured it at 105 to 115 degrees pumping strong the whole time in a a water barrel. This seems twice as hot as my other motors.

Is this normal?

 

[simplystressed]

Re: Cooling system on 1990 Suzuki DT15c

I think it has a 60 degree Celcius thermostat in it - someone would need to clarify though. And yes that wire is a 12V charging wire.

 

[ebsworj]

Re: Cooling system on 1990 Suzuki DT15c

Yes mine has a new 60c thermostat in it which is 140 F. Just seems too hot to me when I put my hand in the tell tall stream, sometimes too hot to put it there. My Johnson, Yamaha and Mercury motors are not even as close as hot. Anyway, I haven't run it after the new head gasket (on my boat) I have run it in the barrel. Well see.

I tested the wire and didn't get any voltage, maybe mine's broken? I did look online and couldn't find any info on how much voltage it's supposed to put out.

 

[James R]

Re: Cooling system on 1990 Suzuki DT15c

The cooling systems are a heat exchange systems. This means that if the water going in is warm then the water coming out will be proportionally warm. Use a temp gun at the head to check the temp. Up to 140 is good.
If you run a Suzuki on muffs the cooling does not work as well as in a tub or pond. Also water in a tub gets heated by the exhaust.