suzuki dt 85 overheating

[artistdesigned]

Bought the motor a month ago. Seemed to run fine when tested on land. took it out the other day on a 17' Glasspar seafair and ran it at full throttle for ten minutes at 30 mph and the buzzer sounded. I looked back at the motor and it was steaming pretty heavily.
Shut the motor off and let it sit for a few minutes then started it at idle to cool the motor. The steam went away but as I headed back in at half throttle I noticed a small amount of steam coming out the exaust hole but no alarm. The tell tail sign was pissing with good preasure, pretty hot but withstandable. So Anyway i got home did a compression check all cylinders around 135psi., thermostat OK,
dropped lower unit broke 3 seized bolts, SWEET!, cant wait to tap those. water pump fine. Any ideas where to go from here. Oh the motor runs pretty rough at low rpms. runs smooth at higher rpms.
Thanks,

 

[deejaycee_2000]

Re: suzuki dt 85 overheating

Welcome to iboats ........ the exhaust hole should be sputtering out heaps of water while running not only the pee hole ..... change the impeller anyway even if it looks ok, and you will have to flush the motor out with a compressor to clear all passages if there is a obstruction somewhere .....

 

[artistdesigned]

Re: suzuki dt 85 overheating

Thanks for the reply, water does come out the exhaust and the prop, I wouldn,t
say heaps though, How should I flush the motor with air and water.
thanks,

 

[artistdesigned]

Re: suzuki dt 85 overheating

Ran a a garden hose into the intake while lower unit is off on full preasure and I pugged up the over flow and pee hole lots of water came out the exhaust.
I repeated this a few times with a bucket under it and noticed a total of maybe
a 1/4 of a teaspoon of sand. It Didn't actually seemed plugged though.
On Another note: I checked my GPS noticed I put 35 calm ocean miles on a full tank of oil and now its down to 1.2. Thats seems to be very liitle oil consumption. The boat was ran mostly half throttle. Anymore info would be great!

Thanks,

 

[deejaycee_2000]

Re: suzuki dt 85 overheating

How much fuel did you use on your 35 miles? You need to roughly work out the ratio of fuel to oil used on your trip to determine if you used enough oil or not it should be between 50:1 to 75:1 ...... also take out the thermostat and ran the hose in there ....

 

[artistdesigned]

Re: suzuki dt 85 overheating

Thanks, I will try flushing from the thermostat, Is possible or a likely scenario the motor could be overheating from gas rich or lean, oil, timing, I was also wondering how difficult it is to do the head and exhaust gaskets. I will try to rule out the simple things first but advice is appreciated.
Thanks,

 

[deejaycee_2000]

Re: suzuki dt 85 overheating

running rich or lean won't cause the overheating, getting no oil will, but the type of overheating you are describing point to water flow ..... the head and exhaust gaskets can play a role in this yes .... it happens that people use the gasket maker and then block some of the passages in the process ....

 

[artistdesigned]

Re: suzuki dt 85 overheating

Thanks for the replies, got it all back together and took it out on the bay today and no overheating, Yey!. The water coming out of motor felt pretty warm but I think it will be alright. Now my next issue is getting it to run smoother. Idles OK, studders and runs like a two legged dog trying to accelerate. Once it makes to mid range and full throttle runs fine. Its just bit above idle speed where it runs really rough. The fuel bulb holds pressure and gets hard, I replaced the spark plugs, not sure if I am supposed to gap them or not. I am guessing its the carburetors, I saw in another posting someone is having the same problem and mentioned "sea foam" as a fuel additive. I would like to avoid a rebuild on the carbs. It looks like a pretty intricate job, and I am sure Ill end up with a few extra parts.
Any ideas is greatly appreciated
Thanks,

 

[artistdesigned]

Re: suzuki dt 85 overheating

Oh forgot to mention to ask, I live in San Diego, and the water at its coldest in the winter is around 54 deg. F. Summer months around 70. Is it OK to run with out the thermostat.

 

[deejaycee_2000]

Re: suzuki dt 85 overheating

It is never really ok to run the motor without a thermostat, otherwise your motor can cold seize ..... is your thermostat not working ....... yes you should gap the spark plug, not sure of your motor's gap but there should be a sticker on the cowling somewhere ...... you can run fuel additive with the fuel as it will straighten out the rough idle you have ...... the air/fuel screw should be turn outwards 1 & 1/2 turn from soft stop .....

 

[artistdesigned]

Re: suzuki dt 85 overheating

Thanks for the help, So I added Pri-de fuel additive and took a second look at the spark plugs noticing one plug was a #6 and not an 8. So replaced the spark plugs went out on the water and the motor ran great for awhile. I ran 60 miles and the motor seemed
to run smooth at low rpms and had much greater throttle response. as I was coming into port though at 5mph it seemed to run rough again. When I got home and inspected the motor.I noticed a ton of salt residue coming from the thermostat and dripping all around the plugs, Oops forgot the gasket sealer!
So I figured maybe water was shorting the wires or plugs. I pulled wires and plugs, didn't see any moisture in the wire cavity, but one plug was a lot more brown around the electrode insulator. Any ideas?
Thanks,

 

[JUSTINTIME]

Re: suzuki dt 85 overheating

brown is better than black