overheated,help!

[arquerogringo]

Today I took my boat out and overheated.<br />I do not have good info but will post it later if needed.I am at an internet cafe and did not know that I would find this forum this evening when I came here,so I did not bring the hard stats.<br />My motor is a Mercury 500,50 hp.Late 70s model,(ashamed that I do not know the exact year offhand)<br />This was the fourth time that I took it out.I use it in the sea and every time before I flushed the motor out with fresh water after use with the suction cup type attachment that was given to me by the seller.It struck me as strange that it always took a fair amount of time for the motor to start to "pee".Several minutes at least.<br />Today we take off,I don't look back and check the waterflow.We go a mile or so and my partner yells to stop.There is smoke,which is actually steam clouding behind the motor.There is no water flow from the hole,just steam.It appeared that steam was comming from the exhaust as well.And It felt that exhaust was comming from the water port.<br />After resting and cooling for a couple hours,(we went diving a bit),we limped it back to the dock(probably foolishly).<br />Any ideas what happened and what damage I may have done.<br />It started and ran fine otherwise.<br />Thank you,<br />Damon

 

[OBJ]

Re: overheated,help!

Hi Damon...wilcome to iboats.<br /><br />What probably happened is that your water pump impeller failed. If it took the pee hole a while to pee, then that would be a good indicator. Don't know how hot the engine got but it would be a good idea to run a compression check on the cylinders. Note that they are within 10% of each other. If you are going to do the work your self, get a service manual to guide you.

 

[tmcalavy]

Re: overheated,help!

Yep, time for a new pump and impeller. My 73 Merc 500 won't pee on the muffs unless I push the rpms up a little higher than idle. Always does it. They're a little lazy at idle I guess. Just to be safe I installed a temp gauge so I can watch the engine temp on the dash. Cost me about $60 and an hour of installation time. Others use a water pressure gauge instead of a temp gauge. Might consider either.

 

[NathanY]

Re: overheated,help!

You might want to run a compression test to see if you did any damage internally. Also look at your electrical components and see if any are melted. If it got hot enough to melt anything, the outlook for that motor is not very good.

 

[arquerogringo]

Re: overheated,help!

Thanks for the input everyone!<br />I saw a local guy that is a friend of my father in law.He showed us how to tear it down and he put a impeller in it for me.Sure enough solved the problem,she circulates now.I will do a compression test on it,although he said that it was unlikely that I damaged it as it starts like a champ and runs great.It looks like I got lucky and I really hope so.<br />He recommended that I go ahead and get the entire housing and base for the pump as well as all the gaskets asap,as there was an amount of damage to the plastic housing and the gaskets were starting to crack a little.He also showed me where I can install a sending unit for a temp gauge.He offered to do the work for very little or talk me through any of it if I want to do it myself.<br />He said the motor is old but a mule which is in great shape and if taken care of will last a lot longer.<br />good guy,huh,Does the advice sound good?

 

[andrewkafp]

Re: overheated,help!

Sounds good to me.<br />Not a bad idea to keep your eye on the pisser and maybe get a small Aux motor, so you don't have to compromise and damage the motor more while "limping" back.