Suzuki DT4 cooling issue

[steve66]

Hi I have a cooling issue with my Suzuki DT4, It starts and runs very well, after a few seconds it pumps water well. Once ticking over for a minute or so the flow turns more into a spray and if I put it in gear it stops pumping completely. Put it into neutral , rev it and it starts pumping again. I have changed the impeller, (turned shaft clockwise when reassembling) new wear plate, driveshaft pump housing seal, removed the power head cleaned the water jackets ( they were not blocked) and rebuilt with a new base gasket. I have run it in a bucket with the water 3/4 way up the leg and slightly helps if I remove the grommet.
I am completely stumped. Any advice would be greatly received.
Steve

[Solarman]

What year/ model motor are we discussing here?

Post back when able.

[steve66]

Hi is a 1987

[Jimbo47]

Having the same issue with my DT4 after replacing impeller assy. Was told that there might be an issue with the exhaust leaking through a seal in the lower unit. Please let me know if you solve your issue

[Solarman]

Steve, Jim, on larger motors the exhaust can interfere with water pump function, and it sounds similar. The exhaust is under pressure (the faster the motor goes the higher the pressure), and if there are any grommets between water pump pick-up screen and the exhaust passage, those are the areas to inspect. If those grommets are loose, or burned replace.

I am not very familiar with this smaller motor, but trying to give you some ideas.

Good luck, post back on what you find out.

[Mattso]

I have a DT4 and have been reading multiple discussions on the cooling and peeing problem on the DT4 which mine also has. Last summer I took apart my newly purchased (used) DT4 to replace the impeller and noticed there is what appears to be a factory made hole! on the impeller housing just under where the tube attaches to the top of the housing. This would appear to allow all the pressure from the exhaust to be blown right down into the impeller area and thereby creating unwanted back pressure in the impeller housing. Has nobody else noticed this hole or is it just my motor that has it? This would explain everyone’s problem it seems to me. Anyway, I didn't have time to cover this hole to see if it would cure the problem but I will try it this summer. I’m pretty sure it is going to fix the issue. The problem also can be identified by removing your plastic gear shift linkage cover to relieve pressure and seeing if your motor starts to pee again. This will show you if it is an exhaust back pressure issue and if you should check to see if you have the hole in your impeller housing. If you have the offending hole, I would recommend using a stainless steel nut, washer and bolt with a countersunk head to fill it. By the way, I had just replaced the impeller gasket, water tube grommet, and shaft seal so exhaust wasn’t pushing through any of those. I could post a picture of the offending hole if anyone wants to see it.

[Murray]

Please post the picture. Good for future reference