No water flow 1984 40hp mercury

[jdavis7873]

I am at the end of my very short mechanical aptitude with my motor. Last time I took it out, there wasn't any water flowing out of the pee hole. no big deal, I assumed it to be the impeller. took it off, inspected it and everything was in good shape. Just to be sure, I replaced it anyway. It didn't help.

With some good advice from a local mechanic he told me to check to make sure the thermostat wasn't froze up. Much to my surprise, it wasn't froze up, THERE WAS NOT THERMOSTAT IN THERE. I know this isn't great, but it also isn't the end of the world. I had a car that we kept the thermostat out of for a while and it didn't hurt anything, but I will get one for it. While I had it apart though, I tried to run both water and compressed air into where the water flows. There was very little(basically none of either coming out where the fuel pump/pee hose is. Thinking there may be a block in the line, I took each of the lines from the pump off and neither were blocked, I also blew threw the fuel pump and there wasn't anything there.

I know there has to be something blocking this, but I have no idea where now. When I did put a little air pressure in there and sealed up everything else real good, I noticed a little water coming out the spark plug seat in my top spark plug...

This got me to thinking bad thoughts... Would this likely be blown head gasket or maybe even a cracked head? Upon further inspection, I noticed that the threads were starting to rust.

Is it time to put this motor out of it's misery, and sink for a crappie brushpile?

 

[WrenchHead]

Re: No water flow 1984 40hp mercury

Me thinks you nailed it!!! You should never have water coming out from around a spark plug hole. Pull the head and check the headgasket -- then you'll know whether to replace the headgasket or shoot the motor between the eyes. Good luck . . .

 

[jmburock]

Re: No water flow 1984 40hp mercury

This is a common location for water leaks in mercury outboards. The gasket for your water jacket cover is deteriorating. First place it leaks is the circle around the spark plugs. The big problem here is getting out all of the bolts intact without breaking bolts. The gasket itself is only $10. If you have a freshwater only motor you should be o.k. If you run in saltwater, get ready for a slew of cobalt bits and Heli-coil kits. I broke 8 out of the 14 bolts on my cover and spent several weekends drilling out the old bolts, and Heli-coiling. Make sure you have a torque wrench and the bolt sequence for putting the cover back on. My torque was 18 ft-lbs, with a bolt sequence starting in the center of the plate and working outwards, ending at the top 3 bolts.

 

[jdavis7873]

Re: No water flow 1984 40hp mercury

Well,
Thinking that maybe I'd cracked a head gasket, I borrowed a compression gauge and both cylinders are getting right at 150lbs. I spoke to someone who told me they thought that the water is somehow clogged, possibly with remnants from one of the times my impeller got shredded. I'm going to try to run water in the pipe leading up to the block by clamping off an old water hose and seeing what happens... Any other suggestions?

Thanks for the comments so far.

 

[Starcraftguy1]

Re: No water flow 1984 40hp mercury

You know,I have a 1995 Mercury 40 hp 4 cylinder.My motor did not pee when I first got it.Check out all the lines going to the pee hole,mine had a couple of leaves stuck into it.My gasket leaked water around the gasket,at the rear spark plug,after unplugging the line,it stopped,and runs great to this day.Check out everything that you possibly can before you go spending a bunch of money for someone to say to you,what you knew all along.Good luck.

 

[Bob_VT]

Re: No water flow 1984 40hp mercury

Mercury outboard used a water jacket...... the sparkplugs are actually screwed right into the block and there is no head gasket to speak of.

If the water gasket is breaking down you might have a piece clogging the flow from the inside.

The only good news I can give you is "most" of those small bolts have a spot behind them to get a nut if you need too. It seems like alot of work but it is worth it if the leak is bad.

Try running a piece of trimmer string into the hose for the telltale to see if it clear.

On mercs I like to install a pressure gauge instead of the telltale and I can keep an eye on the pressure while I am operating instead of having to turn around.