merccruiser I/B water pump

[danman321]

A newby here,
Got a Tige with the 5.7MAG MPI direct drive set up. First start up of the year I heard a intermittent "clanking" noise that sounds metallic to me. Two shade tree mechanics and I all agreed it was coming from the water circulatory pump on the engine. So we pulled this off for inspection and repair. Alas we found nothing wrong with the water pump. So my questions are:
1) What you think the noise could be
2) when reinstalling the water pump, is it necessary to prime the system before re-starting to protect the impeller from being run dry? If so, how is this best accomplished?

thanks in advance for your help

SkiOn,

danman321

 

[HT32BSX115]

Re: merccruiser I/B water pump

Howdy,

You most likely have a Bravo pump on that engine. Since the pump is usually mounted below the water line, it primes almost immediately.

If you want you can put a little Dawn or other dishwashing detergent on the impeller to "lube" it for the first startup. You can also use a little vegetable oil.....just about anything works.... once the engine runs all of it is quickly washed out.

Just make absolutely sure you get the inlet and discharge hoses back on correctly and you get the impeller vanes bent in the right direction.(although if they're not they'll probably go in the right direction on the first turn!)

Since you have the pump out, it also might not be a bad idea to check your oil cooler heat exchanger for previous impeller remnants and other debris.

Cheers,


Rick

 

[TilliamWe]

Re: merccruiser I/B water pump

'intermittent "clanking" noise that sounds metallic to me'

Exhaust shutters

 

[HT32BSX115]

Re: merccruiser I/B water pump

Yeah....I didn't give my opinion on the noise


I'd probably get one of those "Steth-A-Scope" things and listen that way. It's very hard to find noises like that without one....

You could also probably just use a piece of hose and put one end up to your ear and the other to the engine components you're checking...

 

[danman321]

Re: merccruiser I/B water pump

Thanks for your replies. Rick, I don't have the impeller out (changed that last year) but have the water pump off. the one mounted on the front of the block. It is my impeller that I am trying to keep from frying itself if it starts up dry. The oil and dawn ideas are good one, thanks for those. The exhaust flappers have been mentioned before, so I will get it back together and take another listen with the stethoscope.

thanks,

dan

 

[gadget73]

Re: merccruiser I/B water pump

Pull the belt off the circ pump and try to rock the pully. Last time I had one of those go bad, the bushings wore out and the shaft would wobble. It was making clacking sounds. While you have the belt off, spin the other stuff on the front of the motor. Could be a bent alternator cooling fan ticking on something, a bad tensioner pulley (if equipped), or something else.

 

[nazz2005]

Re: merccruiser I/B water pump

Wow i got the same problem, at first i thought it was engine, but then my boat mechanic said it was the circulating water pump. now after reading this im nervous as it migght not be that. I heard about the exhaust shutters before. im so curious to figure this out. Yea its like a clakiting noise and sounds like metal.

 

[gadget73]

Re: merccruiser I/B water pump

Those shutters do make all kinds of racket, but its at the back of the motor, not the front. A stethoscope or even a broom handle will tell you where the noise is coming from. If its the shutters, you'll find the clacking in the pipe coming up from the transom, just below the lowest rubber joint. If its the circ pump, the noise is up front. Just be careful where you put your hearing device, don't want to get it caught in moving parts.

 

[Don S]

Re: merccruiser I/B water pump

'intermittent "clanking" noise that sounds metallic to me'

Exhaust shutters

It's a MIE (Straight inboard) no shutters.

 

[danman321]

Re: merccruiser I/B water pump

So now what? If direct drive does not have the shutters, what is the next best thought. I checked everything that the Belt passed over or around and came up empty. I guess it is broom stick (stethoscope) time???