90 200 GT Johnson not pumping water

[89 Sprint]

I just bought a bassboat with the motor and first thing I did was change the lower unit oil and water pump impeller. It was pumping water when I test drove it, but now with the new impeller, it will not pump any. Took the thermostats out (Just for now to eliminate them). With the lower unit off, I put a hose to the water tube to the engine and water flows through fine,but the pump will not pump it through. Did not use new seals on anything becouse the shop told me I would not need them. Going to buy a new pump housing tomorrow, but cannot figure it out. Please Help!!!

 

[JB]

Re: 90 200 GT Johnson not pumping water

Yo, sprint. If you curl the arms the wrong way when you install the impeller, some engines will strip all of them off with the first turn of the crank. Another possibility is that the key or pin that locks the impeller to the driveshaft slipped out while you were reassembling the lower end.<br /><br />Good luck.<br />JB

 

[89 Sprint]

Re: 90 200 GT Johnson not pumping water

Should have mentioned I have had the lower unit off 3 more times since I put the new impeller in. Those were two things I thought of, but no such luck. Key is locking it in place, and impellers fins are folded back: not forward. Has me completely stumped. Thanks for the reply though. Any more thoughts?

 

[Dunk]

Re: 90 200 GT Johnson not pumping water

Are you absolutely sure you are getting the water pipes in the holes on the pump housing when you go up with the gearcase. Make sure the copper is solid in those pipes. Grease the tips of the pipes before you install. Those pumps will pump water just being near it. I got a 90 225 Rude and with the Tstat caps off she'll throw water 6-7 feet out her about 2 seconds after you start it.<br /><br /> This has nothing to do with your problem but have you updated your thermostats on that engine? If she has the white Tstats in her you need to do this. The new ones are black. These plastic housings are not really the tstats. The tstat is called a vernatherm and it's inside the white or black plastic housing. The problem is the rubber gromets that these plastic housing slide into get swollen. These gromets are in the engine block. At under 1800rpm these plastic housings stay in the block. At over 1800 the water pressure pushes them out of the block and water free flow through the engine. This is why those plastic housing are screw mounted into the rubber diaphrams. If they stick in the gromets the engine will run hot at over 1800. She should idle between 155-175 at idle, but over 1800 she should drop down below 145. Mine runs about 135.

 

[89 Sprint]

Re: 90 200 GT Johnson not pumping water

Thanks for the info on the t-stats. I was wondering how old these are, mine are black and do not look very old. Went to three shops this morning and they all told me the same thing, about the water tube. One shop would'nt even sell me a $70 pump housing saying that he was positive it is the water tube. Thought I checked it but am going outside to put it back together again,(after taking it off 4 times I left it off this time). Thanks for the info, will let you know how it turns out.