[Search for users] [Overall Top Noters] [List of all Conferences] [Download this site]

Conference vicki::boats

Title:	Powerboats
Notice:	Introductions 2 /Classifieds 3 / '97 Ski Season 1267
Moderator:	KWLITY::SUTER

Created:	Thu May 12 1988
Last Modified:	Wed Jun 04 1997
Last Successful Update:	Fri Jun 06 1997
Number of topics:	1275
Total number of notes:	18109

982.0. "Old Merc outboard leaks water" by MSEDEV::ARSENAULT () Thu May 21 1992 15:20


I've got an old 50hp Mercury (model 500) which is in real rough shape.
I don't know what year it is, but I know its old because its original color
was white.  I've heard that Mercury changed its colors in the 60s, any
confirmation?

Anyways, I think I've got a dilemna.  I'm not even sure the condition of the
motor since it currently leaks water big time.  I removed the head, and soon
discovered just how much I didn't know about this motor.  The head?  Well,
actually, it's a cover for the water jacket and has nothing to do with the
cylinders except that it supposed to provide a tight seal to allow water
flow.  Unfortunately, it appears as though it corrided due to salt water.
Bascially, there should be a wide ring around each plug (its a 4 cylinder)
as this surface provides a tight seal when the cover is on and tighted.
But, it's corroded so much, that it leaks right past the gaskets and would
most likely foul the plugs as water would shoot right out at it.

I'm not sure of the material this water jacket/outer cylinder is, Aluminum?
Cast?  but I'm wondering it this is a lost cause?  If I got someone to build
up around the edges to provide a new flat surface, would it last?  Is it
worth it?  It doesn't appear as though the seal would have to hold any
significant pressure.

Has anyone seen this or have any experiance?
Hm, does anyone have an older 50hp Merc for sale?

thanks for your thoughts...
-(dan)

T.R	Title	User	Personal Name	Date	Lines
982.1	AUTOMOTIVE MACHINE SHOP	MR4DEC::DCADMUS	happiness is a bigger boat	`Thu May 21 1992 16:00`	9
	Can you get the cover off?? if there is enough material left,andy automotive machine shop should be able to machine it down enough to get a good flat surface Dick
982.2	Aluminum rods did the trick	MSEDEV::ARSENAULT		`Wed Jun 03 1992 10:36`	3
	I finally got the heads fixed by someone handy with a torch. It actually ended up to be an easy alum. weld job.
982.3	Water blockage? Thermostat?	MSEDEV::ARSENAULT		`Wed Jun 03 1992 10:47`	18
	Now that I've fixed the water jacket from leaking, I'm still left with a circulation problem. I believe (not exactly sure) that the water and exhaust should both be exiting from the prop and from the exhaust port found on the back of the lower unit. However, it doesn't look like ANY water is exiting from this exhaust port. I ran the motor for about 10 minutes and it ran well, I stopped it after suspecting the problem. I checked the water pump and it looks brand new. It was suggested that possibly the thermostat is defected, but I can't find it? I bought thus repair manual, and unfortunately, its not worth 2 cents, never mind the 25 bucks I paid for it, yes I got soaked. Any experianced Merc's out there? 1963 Merc Model 500 4 cycl, 50hp thanks -(dan)
982.4	An ongoing battle	GOLF::WILSON	Stop the Killer Fees	`Thu Jun 04 1992 11:48`	34
	Dan, I was going to offer this suggestion before you had the repairs done, it looks now like I should have. Early model Mercs were not very salt tolerant to begin with. And any motor that has seen enough salt and neglect to have holes corroded clear through a water jacket, is going to be an ongoing battle to get it running and then keep it running reliably. What you had fixed was what was visible from the outside. Chances are, the internal water jackets are heavily corroded and/or blocked with salt and corrosion. There may be other holes that already have or about to pop through, leaking water either to the outside, or into the crankcase or a cylinder. There may also be blocked water jackets which could cause some very hot spots in the block while running. If you're determined to get this baby running, remove the powerhead from the tower housing, and check the inlet where the water tube feeds into the engine block. This is usually the first place where enough salt and corrosion builds up to stop the water flow. If you get things flowing properly, it may work fine. But you probably won't want to rely on this engine to take you 10 miles offshore. On the other hand, you may not even have a problem. If you were able to run the motor a full 10 minutes as you say, there was either some water being pumped or the motor should have been in the midst of a MAJOR melt down. A water cooled outboard will overheat very badly, to the point of self destruction if it runs 10 minutes without water. It could be that your motor is pumping OK but water just isn't exiting where you think it should. Try running it again and watch the engine temp. Except for the exhaust port covers, you should be able to hold your hand on just about any other part of the engine while it is running. Check for hot spots which may indicate blocked water jackets. good luck. Rick
982.5	How about a thermostat?	MSEDEV::ARSENAULT		`Thu Jun 04 1992 13:13`	16
	Hi Rick, Thanks for the suggestions... Last weekend I started to disconnect the powerhead from the tower, but I stopped as I soon realized that this was not an EASY task. However, maybe this is the only way as you suggested. As I mentioned, this motor really did run good for the time I kept it alive. Therefore, I havn't given up yet. I still have a question though about the thermostat. Do you think this motor has one, and if it is defective, could this stop the water from exiting from the exhaust port? thanks again...