Water pump issues-at a loss

[LatLong]

I've got a 1994 Suzuki DT25C and it's not pumping water. I've checked the impeller- very slight bend at the very end of the vanes and they still spring back when pressed on. I've checked the thermostat in a pan of water- opens at about 120 degrees. I've checked the passageways with compressed air and everything is clear. So by all rights it should pump water.

I ran it tonight after getting the carb kits put in(runs like a champ now) and I let it idle for a couple minutes. I kept checking the temp of the head by holding my hand on it. When it got to hot to hold my hand on it I shut it down. I pulled the thermostat housing, thermostat was open, but bone dry.

I also pulled the lower unit, again, and there wasn't any water, that I could tell in the pick up tube and inside the water pump housing was pretty dry. In fact it looked like some rubber marks on the inside of the housing from the pump running dry.

What gives with this thing?

[Surface Tension]

What are you running the water to?

I'm suspecting your using the flush port which you shouldn't use.

Use muffs.

If your using a barrel of water that water level has to be 6" above the cav plate.

[LatLong]

I've used a barrel and muffs. I put the muffs over the screens on the lower unit. If i'm looking at it correctly the flush port has a screw in it. It's by the fill hole for lower unit grease.

[jentz]

Drop the lower tape a hose to the water tube while the tube is inserted in the engine head,Turn the water on.If there is no circulation the rubber gromet on the head that seals the water tube is most likly tweeked and pushed into the head blocking flow.

[SkunkedAgain]

You didn't mention it, so I'll just ask if you checked the screens to make sure that they aren't caked or blocking water flow.

[LatLong]

I'll try the hose taped to the pickup tube when I get home this afternoon. I blew air up the hose when I had the thermostat out and I felt airflow, but I'll check it with water.

I have checked the screens on the lower unit. Once when I inspected the impeller the first time and again last night. After I took the LU off last night I put the muffs on it(after taking the water pump and plate off) and I could see water flow in the lower unit below the pump.

[jentz]

This statement you made> I let it idle for a couple minutes. I kept checking the temp of the head by holding my hand on it< That should be the way any engine runs,To hot to hold your hand on for more that a second or two.,What makes you thing theres no circulation??Maybe no water comming out the telltale?If thats true have you tried to clear the hose from its outlet right into the water jacket>Maybe even remove the water jacket cover and see whats in there.I use a hand held inferred thermometer on the head to determine running temps when a telltale doesn't flow.

[LatLong]

I just tried the hose hooked up to the pickup tube. I have water flow up to the head and out the indicator hole.

I don't thing there is flow because the inside of the water jacket was bone dry after running it. No water coming out of the indicator hole or the upper exhaust holes.

[jentz]

You may need the whole water pump kit,Not just the impellor.The housings do go bad from wear,especially if ran in shallows.grit is like sand paper.I just reread your post.Your using the old impellor??? Their cheap in comparison to a overheated engine!!!

[LatLong]

Yeah i put the old impellar in. I just bought the boat and i'm on a real tight budget and i've already spent a fair amount getting it running. It looked in good enough condition for a little while. On to the good news. I just ran it for about ten minutes and it was pumping. I took the plate and gasket off and there was a fair amount of crud under the gasket. I scraped that clean and reassembled. Does it make sense that this could have been causing a loss of suction?

When i order a pump kit i'll order the housing too.

[boatfixer]

Yes it makes sense. At some point it picked up that crud ( or over a period of time ) and either blocked or impeded the water flow.

If you do encounter what you think is overheating, using a laser type thermometer is the best way to verify actual block temp. Touching the block is a good way too, you should be able to touch it without getting burned. However the bad thing about doing that way is...well, getting burned if it is way too hot!! Ill kinda slap it real quick at first and remember to do it very soon after starting it. If it heats instantly, that's a good sign something ain't right.

If you have one of those thermometers or can borrow one, check the temp after its warmed up to temp, see if you're in that 120 range and then feel block.

[LatLong]

I think the crud under the gasket had to the problem. After scraping the sealing surface and reassembly it started pumping water right away. I took it out for the maiden voyage today and it ran great. It pumped water out the indicator the whole time i ran it. Now i just have to break the boat in with catching some fish!