problem with Waterpump flow on a '67 Merc 500 50hp

[Starcrafted]

I have a 50 hp merc 500 '67 model and was wondering what kind of water flow I should get out the pee hole while the engine is running? it takes a while to flow anything after the motor starts and when it does spit water out its more of a dribble than a stream.
I replaced the waterpump last year thinking that may have been the problem but still no luck

Any thoughts?

 

[OCboat]

Re: problem with Waterpump flow on a '67 Merc 500 50hp

On my '68 Merc 650, it also takes a while for any water to exit the pee hole. If I leave it at low idle at start up, it hardly spits any water out. I usually bump the idle up to about 1,000 - 1,200 rpm to get the flow going and then back it back down to around 600-800 rpm. Maybe it takes a little higher rpm to get the water up around the motor and once it is circulating, gravity helps to keep it going.

 

[emckelvy]

Re: problem with Waterpump flow on a '67 Merc 500 50hp

The water telltale tube might be clogged; blow air back up the tube to be sure it's cleared. If that doesn't help you may need to pull the hose off the block and check for obstructions.

In extreme cases, the water passages inside the exhaust manifold are clogged and the only way to fix that is to pull the powerhead, remove exhaust manifold covers, clean out the clogged passages and reinstall cover with new gaskets.

As an alternative you might find another threaded plug in the block which can be substituted for the existing telltale outlet.

Many of these have a plug at the top of the block. Just remove the plug and install a 1/8" N.P.T. fitting for the telltale. Be sure to block off the old fitting in case there's still any water at all flowing from it.

Last ditch, if the back cover has a reinforced 'boss' in it you can drill/tap for a fitting there. Better if you pull the cover, so you'll know where you're drilling and prevent alum chips from falling inside the block's water passages. Just be careful, a motor that old is gonna have frozen cover bolts and you don't want to be breaking them all. Lotsa heat and PB Blaster.

Hopefully it's as simple as crud in the line, if not there ya go............ed

 

[Starcrafted]

Re: problem with Waterpump flow on a '67 Merc 500 50hp

Thanks for the tips! I'll check it out this weekend.