Changing Thermostat on 2001 BF40 - and then the impeller

Hello again to all -

I was fishing in Port Canaveral the other day and again I saw that the tell-tale wasnt pumping water like i thought it should be - it seems to go from a good flow to a trickle - more defined at idle. When I bought the boat, I was told it had a 300 hr service done on it and I saw the repair invoice - the shop said they replaced the impeller and did normal service.

If I connected the boat to muffs, pee fairly strong - when in the water - not so strong - I also noted that the water was pretty darned warm when it was on muffs -

I had used wire and weed-eater mono to try to see if it would free the flow, I was able to put about 15 inches of weed eater line up there - and it worked 'ok' for a minute or so and back to the trickle......

I've read all of the advice from forum brethern and decided I need to jump in and start doing some things on my own. I decided that I would replace the thermostat and impeller - that way I know it's been done.

I ordered the parts - I got the impeller kit, thermostat and thermostat gasket. i researched and discovered the thermostat appears to be fairly easy to do - even with my limited skills -

This afternoon - I removed everything and discovered that there was slight corrosion (Crap) in the thermostat area - so I got the compressor and blew out the area - and from the tell-tale connector back up through to the thermostat area. (curious - is there something that could safely dissolve any of that corrosion that i saw without damaging anything or can I flush it with something to dissolve the stuff?) - Anyways - I put the new thermostat and gasket on and sealed it up. (I dont think I overtigtened the bolts when I sealed it up either and I checked for leaks.)

Boat fired up and it pee's pretty good.......i did the weed eater string again and it pees like a race horse - and the water doesnt feel as hot as it used to................then I saw a forum where someone said you can install the thermostat improperly and over heat your motor...........hmmmmmmmmm....not good - so how can u install it wrong - I looked at the old one - I simply dropped the new one in - and it seems to be working fine......is there a proper location or position it must be in? - i noted to 'marks' on the top of the thermostat - are they supposed to be indexed with something???

Well - my son-in-law is pretty handy and he has changed impellers in the past - I've got the instruction and manual to change it - and I will be doing that Saturday morning under his tutoring......I want to learn how to do it myself - but I want him there as back up to prevent me doing something wrong.....

Kind of fun doing these minor things by yourself - and saves alot of green......

I appreciate you all helping out folks like me.... but is there way i could have installed it improperly?? and is there something that I can use to dissolve all the stuff in the water passages?? - I read someplace to check the poppet valve - but I dont believe a 2001 bf40 has that feature - can find it in the manual......

thanks again all

Jeff

There is no poppet that I know of. As for the thermostat - as long as you do not put it in upside down, you should be good. Make sure you use a new cover gasket, so it does not leak.

I do not have a really good recommendation for you for flushing out the crap. Only once, did I need to flush out a 40 that was on a local fresh water lake, but had a lot of lime build up.

Ran it in a barrel of very dilute barrel of muratic acid. Ran it with the thermostat out....the water gets hot...so you have to watch the temperature. After about of 20 minutes of running, then running in fresh water, the thermostat housing looked clean as new. The lime was very thick and impeded the flow of water through the system, causing an overheat.

No more overheat.

If your buildup is salt, the acid probably would not work. I am sure others will jump in with flushing remedies for salt.

....or you could search the forum for flushing solutions.

Mike

Thanks for the info Mike - It didnt look like salt build up - the only time that boat has been in salt water was after i bought it - and i flush it religiously after each use.....the only owner prior to me was an older gentlemen who ran it/stored it in fresh water lake....with tannic acid content pretty high....

I heard that using a product called salt away (it's diluted 500:1 with muriatic and another acid) for 20 seconds, will eventually clean out junk over a period of time.....but nothing quick....

I'm going to get the impeller done this weekend and see how she goes.....

thanks again

jeff

Don't know a thing about the BF40. But on my bigger Honda, the water intakes occasionally get clogged with grass and other debries. Remove the intakes and check thoroughly. The inconsistency in the water flow from the telltale is basically telling you that there is junk floating around in your cooling passages, and it is not clearing on its own. You may want to remove that thermostat again, and work a garden hose into the opening, seal it with a rag, and flush it that way for awhile. Put a big bucket underneath to see if anything comes out of the water passages.

If you tkink that there is a salt build up, running the motor in a mixture of Dalt-Away with muriatic acid mixed in a large trash can will eventually clean it out. It takes awhile.

CHawk - Thanks for the information - I appreciate all the assistance provided -
I changed out the impeller yesterday - the old one looked brand new - so i guess the dealer actually did service it back in October - but this way, I learned how to do it all - the only trick was that damned shift linkage - that was a booger to undo.......anyways - the motor is peeing pretty good now - I will keep an eye on it -
If i see it acting up - i'll do the flushing with the rag.....and remove the intakes...and see what happens - but I am pretty impressed with it right now....

Again
Thanks to all

Jeff

Keep us posted on your progress.