nsformula

thanx again for the replies,



Unless I have the hoses on backwards[again] which, I am sure I don't, there should be no reason not to get initial prime, regardless of what is
happening forward of the pump in the rest of the system.
This thing is melting impellors at startup, not after running for a period of time.
It does not suck to muffs in tight and continues to blow by water once running.
There only one water pick up.
I have had the boat for 6 years and it is always stored on the trailer and had been run on the muffs many times with no
issues. Something has changed in the last 2 years, sometimes it's ok, sometimes not.

I will take the intake hose off and make sure it is not collapsing inside as well, it is 20 years old, ordered the Merc muffs , impellor and housing.
I won't have time to fool with it again until the week end.

BUP

iTrader: (9)

YOUR POSSIBLE PROBLEM. read the service bulletin link below and your boat does not have to be saltwater used for this to happen. It really happens in saltwater a lot easier but It happens in freshwater / brackish water as well.

http://www.boatfix.com/merc/bullet/90/90_14.PDF

BUP

iTrader: (9)

here is an image what it can look like at the inner transom assembly. A company calls this Bravoitis. This same company is listed in the buyer beware section up here so you can form your opinions if you wanted to use their stuff or not for this, if in fact is your problem. Not sure but worth a check for being your problem.

The Mercruiser service bulletin above is the same problem as what Merc is referring to..

http://amarket.com/images/bravocorrin.jpg

nsformula

[QUOTE=BUP;4306540]here is an image what it can look like at the inner transom assembly. A company calls this Bravoitis. This same company is listed in the buyer beware section up here so you can form your opinions if you wanted to use their stuff or not for this, if in fact is your problem. Not sure but worth a check for being your problem.

The Mercruiser service bulletin above is the same problem as what Merc is referring to..


Thanx again, that looks nasty.

I am checking/changing the hose anyway so I'll check that as well

nsformula

Just to finish this thread....
I took the impeller housing, impeller, hose, and nipple/spigot off the drive to check everything.

Oddly the impellor was not burned up this time., but the impellor and housing and hose were dry as a bone, no water had been circulating.
I can only assume the silicone I coated the impellor and housing with saved it for the short time it ran.
The tube inside the drive was clean and corrosion free and the hose from the drive to the housing is in good condition and reusable.
I back flushed the drive from inside to be sure there was nothing plugged up and it ran free.

So I put it all back together with a new impellor and housing and ran it with the Merc muffs, the round cup one with the rod and lock clip that runs thru the
drive.

Voila, ran perfect.
Again, I can only assume the muffs I was using [the ones linked in the first post] were not working for me.
Seems to me the cups were hard rubber and combined with cool temps were not pliable enough to be drawn in to the contour of the drive
and seal the water flow without drawing air.

Anyway, I hope it is as simple as that and that I don't waste any boating time fooling with this issue.

HTRDLNCN

My problem,,did everything you did,,always same result,,
would run perfect then burn up half the time when I would put it in the water..
Finally figured it out,,where I launch I have to pull off trailer with drive raised
so I dont hit bottom,,the crappy hose in the transom assemble would close off
when I lifted the drive.. Replaced it with a hull mounted pickup and
never a problem again..

BUP

iTrader: (9)

and that's why I posted the MUFFS to use for Mercs - never had a problem with them and I own 8 of them. back in the day really needed all 8 of them. keep them out of the weather and sun ( room temp is best ) when not in use and they will last a very long time.

nsformula

Wow, never thought of the drive angle but I only had an issue on the trailer and the drive is always trimmed up.

I think the muffs are my issue.

nsformula

[QUOTE=BUP;4308151]and that's why I posted the MUFFS to use for Mercs

Yipper, never would of thought the type muffs was the culprit, but for me anyway, you were correct.

Drew555

Do you have a sea strainer? In most cases if you have a sea strainer there is water right by the pump and at least gives it a fighting chance by pulling water right away getting the impeller wet buying a few more seconds before meltdown . Not sure if this was mentioned yet I did not read all the post. Hope it helps