Re: 1986 Suzuki DT 140 cooling problem.
Rear Admiral,
What I thought was crack in Block, turned out to be casting line. Replaced exhaust gasket at secondary inlet in gearcase, and problem solved. I had read about this gasket on other forums and thought mine looked OK, but wasn't.
Those of you who have cooling issues on Suzuki's with a secondary water inlet at prop wash, be BE SURE EXHAUST GASKET IS SEALING EXHAUST FROM PUMP HOUSING INLET!!!!!
Hi Andre,
Thanks for sharing your experience.
I have a 1997 model Suzuki DT140 (Last Carby model) that has done only 280 hrs.
The motor has been well looked after for the last 10 years, but spent a bit of time uncared for in salt water before we got it, to the point where the lower unit gear case developed a crack from corrosion between the case and the bearing carrier. I aquired a second hand gearbox from a motor that was on a house boat that has spent its life in fresh water which was found to be in reasonable condition.
Water pressure from the tell tale has been declining over the last few years, despite regular water impeller changes etc...especially at idle/ trolling speed / when docking etc which has been very frustrating...with overheat / water pressure alarms sounding only seconds after the motor is started, or when slowed from a higher speed. While running in gear, with boat on the plane the motor run extremely well, with no overheat problems at all.
I have just has new impeller fitted, along with replacement of drive and prop shaft seals and pulling/ cleaning / greasing of the bearing carrier, oil change etc by a local boat service workshop. (to prevent the corrosion mentioned above happening again) I did mention the poor looking condition of a rubber seal in the exhaust area of the lower unit to the shop mechanic, who mentioned that most of the motors this age have seals that look ratty like that, and to not worry about changing it as that seal has little effect on the operation of the motor, and they can be difficult to replace due to requiring removal on the high speed water tube, corrosing issues etc, so I decided to leave it as it was.... I now have second thoughts about this...
Upon re-installing the lower unit, there is now virtually no water pressure from the tell tale, and the overheat alarm comes on only a few minutes after starting (this is with the boat in the water, both idling and in gear reving to about 2500 rpm. There was what I thought was steam coming from the tell tale with the small amount of water that was there and shut the motor down immdiately, but after reading the posts above, I am now wondering if that was actually exhaust gas?
I pulled the thermostat cover, and the coolant water float switch & re-started the engine. Very little water and a bit of "smoke" (typical two stroke blue smoke) came from the now open thermostat housing, hopefully confirming that there is "just an exhust leak" happening like you have explained above....
I had done a compression test before I pulled the lower unit for the service mentioned above and all cylinders were within a few PSI of each other. I have not done one since, as the motor has not even run since then, only what I have explained above so I would assume all would be good with head gaskets etc,..
The exhaust gasket you mention, is it item #13-1 on fig 45 on the parts diagram pictured here?
If so, please let me know and I will order this part, pull the lower unit, replace it and try again.....
Not sure if it complicates things at all, but the motor I have is the XL version with an case extension that sits on top of the lower unit wich could also add extra "exhaust leaking" to the issue??
I have read about the water pressure "pop off" valve in these motors. I have never had this serviced / replaced, or even looked at it as the parts diagram shows that to acess it, would require removal of the powerhead.... And that is out of my ability while the boat is in the water! And as it is now, I could not even power the boat to the boat ramp to haul it out due to this overheating problem....
I have considered replacing this motor with something a little more modern, but due to its low hours, and the fact that it has been so reliable, if it is just a simple gasket that is casuing this issue, it would be great to get a bit more life out of it.
The boat does not see a lot of use anyway - approx 30 hrs / year, over outings at least every two months or so, and the fact of the shortage of income I just cant justify spending the money on a changeover motor right now...
Cheers,
Gary
