Engine Cooling

[mbuller]

I recently purchased a Suzuki DT115 (1983 I think). After reading some of the postings on water in the exhaust, I've discovered that there is a thermostat in the cooling system. Can someone explain to me where the Thermostat is and how the cooling flow path works? I had some problems with no water from the "tell-tale the other day and thought the impeller might be disintegrating. I pulled the lower unit & the impeller is still in good shape. I also don't see any spray coming from the top exhaust port when I run it in the yard with "muffs". THX.

 

[jim dozier]

Re: Engine Cooling

If you went to the trouble of pulling the lower unit off you should have replaced the impeller, they aren't expensive and sometimes looks can be deceiving. The thermostat is located at the rear of the engine on the top of the cylinder head underneath a cap that is held on by 4 bolts. Water flows up the water tube from the pump, fills the cylinder channels and the pee stream. When the thermostat opens full flow is established through the head and out the exhaust relief holes in the back of the engine beneath the powerhead on the trunk of the outboard. If the thermostat gets stuck closed the engine will overheat. There are a number of other issues that contribute to overheating engines. Rule out the basics first. Be aware that the pee stream is only an indicator and the cooling system can work fine with it completely plugged up. However, if the cooling system is not working correctly a weak or non-existent pee stream may be an early indicator of trouble. Make sure the pee stream hole isn't plugged with crud. Stick the red tube off a can of WD40 up inside and make sure its clear. Remove and test the thermostat in a pot of water and make sure it opens at 50 degrees Celsius (122 degrees F).

 

[mbuller]

Re: Engine Cooling

Thanks. I still have the lower unit removed fully intending to replace it. Another question, should there be water coming out of the exhaust hole (I think you described it as just below the power head on the upper trunk)? With the lower unit off I put a nozzle in the water tube and watched water stream out of the pee hole but nothing out that upper exhaust hole.

 

[rodbolt]

Re: Engine Cooling

hello<br /> on the muffs you wont see water from the relief port. remember to tape up the sub water intake under the cavitation plate.<br /> good luck and keep posting

 

[jafa]

Re: Engine Cooling

Hi RB<br />Could you explain about taping the hole under the cavitation plate is it supposed to be covered when on muffs. Water pours out from there as soon as I turn the hose on.<br /><br />RH

 

[jim dozier]

Re: Engine Cooling

If you hook a hose up like you said and remove the thermostat (and put the cover back on) water will come out the exhaust relief holes and the pee stream. I believe (Rodbolt will correct me if I'm wrong) that the water won't come out the exhaust relief holes until the thermostat opens. It may be a good idea to do what's described above to verify that the cooling system is not clogged up.

 

[rodbolt]

Re: Engine Cooling

hello<br /> usually on the muffs you wont ever see water from the relief holes. it drains into the exhaust cavity. now in the water you will see it when the t-stat opens. on the dtno you can see it <br /> you can also make enough noise to aggrevate your neighbors. dont go looking for troubles <br /> install a new pump and t-stat. just remember to use the tape when using the flusher. if it stays cool for 5 min on the flusher try it in the water.<br /> goiod luck and keep posting and listen to what jimd is telling ya

 

[mbuller]

Re: Engine Cooling

Jimd & Rodbolt, <br />Thanks for your help. I'm having a little difficulty getting parts. I found out the engine is either an '81 or '82 instead of an '83. It seems '83 is were the cutoff year is for some of the dealers here. Is there an on-line or mail order place to get parts?

 

[jim dozier]

Re: Engine Cooling

Check out www.brownspoint.com as an excellent source for online parts. Also you can download the exploded parts diagram which is often helpful.