Mercury Mark 55 help please

[MercMe]

Hello I have a what is titled as a 1962 Merc Mark 55 thunderbolt. But I after did some research I found out they where made from 1955-1958. So I am not sure of the year hear is a picture sorry it not that great. So here is my question; (and please forgive my lace of proper term knowledge) this motor dose not have the two intakes on the side of it so you cant use rabbit ears on it. Just one large intake on the bottom. Is there an easy way to run this motor out of water for maintenance and winterizing? I think its too big to stick in a bucket.

 

[Willyclay]

Re: Mercury Mark 55 help please

My Mark75A had direct-reversing and that made running it in a barrel very inconvenient due the rapid ejection of the water unless I removed the prop. It has been a long time since I had that motor but I did run mine on the hose and will try to recall what connector/adapter I used to do it. Whatever it was went with the motor to a new home about 25 years ago. Sorry I cannot give you more info right now but you will understand better when you reach geezer status!

 

[Chinewalker]

Re: Mercury Mark 55 help please

Someone has repainted your top cowling, covering the decals, so I can't tell your model year by looking. Do you have a serial number handy? Maybe a shot of the face plate?

As for running out of the water, you can remove the prop and cobble a hose to the intake with a small toilet plunger adapted to a hose. Others have modified a traditional set of motor muffs to work on the under AV plate intakes.

 

[Texasmark]

Re: Mercury Mark 55 help please

Been a very long time but it looks like a mid-late '50's which had a "hand rail that completely encircled the lower part of the upper cowling. In later models they did away with all but the rear and even later, in about '89 when the new loop designs came on board removed it completely....really non functional as later on engines were seldom removed from the boat and it added weight and cost.

In those days, you undid the large electrical connector (plug) on the starboard side of the engine, twisted the wing nut holding your remote cable steering to the front of the engine, undid the transom bracket T handle (clamps), and with a person on either side, lifted it off the boat and put it into the shop's test tank....after you took the customer's prop off and installed the "spinning disc" test tank prop.

I don't remember and can't see, but your water intake is probably on the leading edge of the exhaust chute that sticks out the rear (triangular shaped looking from the side) just above and to the rear of the prop. There is a water pickup somewhere on that engine and that is probably where it is.

Back in those days, OMC had the same type of arrangement and surely there is an adapter that you can clamp onto the lower unit to introduce water for test purposes.

Suggest you go to the OMC site and ask around for an engine flush adapter for the 50's engines....bet you will get an answer for a part you can purchase today.

HTH,

Mark

 

[Willyclay]

Re: Mercury Mark 55 help please

Back in those days, OMC had the same type of arrangement and surely there is an adapter that you can clamp onto the lower unit to introduce water for test purposes. Mark

Mark, you and Chinewalker said enough to stimulate some dead cells in the empty space between my ears and, after a search of my workshop, I found one. I had it marked as a 1959 Johnson 35 application but I know it will work on others including the old Mercury's. I believe it was a Tempo product but that is a mute point since they have been absorbed by Moeller. Hopefully, the attachment thingie is working tonight.

EDIT: Two attempts at attaching a picture have failed. Will keep trying!

 

[Willyclay]

Re: Mercury Mark 55 help please

Will keep trying!

Strike Three! I must have a Setting wrong. Where's Woodonglass when you need him? Sorry, but you could send me a PM with your email address and I should be able to Reply with the pix attached. Will play around with the Settings some and keep trying.

EDIT: Size still matters! Hope the picture can be seen.View attachment 124502

 

[Chinewalker]

Re: Mercury Mark 55 help please

That's the OMC one, but of no use to the Mark 55. The Mark 55 has an opening on the underside of the AV plate with a small grate covering the hole. There was a year or two in the white Merc era when they had the pick-up on the leading edge of the trim tab, but not on anything from the 1950s...

 

[Texasmark]

Re: Mercury Mark 55 help please

Strike Three! I must have a Setting wrong. Where's Woodonglass when you need him? Sorry, but you could send me a PM with your email address and I should be able to Reply with the pix attached. Will play around with the Settings some and keep trying.

EDIT: Size still matters! Hope the picture can be seen.View attachment 124502

Well we tried!

 

[merc850]

Re: Mercury Mark 55 help please

Take the prop off, get a set of muffs that come apart remove the one with the water connection and wire it to the underside of the anti- cav plate under the metal water intake grill. Run water before starting engine.
Don't run the motor above fast idle (1800 rpm) with no load.
Did this for years on my '60 Merc 700.

 

[steelespike]

Re: Mercury Mark 55 help please

Just a side note.The Mark 55 was rated at 40 hp.
I believe the Mark 55 was based on the first year of production.
The 40 hp was 10 hp more than anyone else in 55.

 

[Texasmark]

Re: Mercury Mark 55 help please

Just a side note.The Mark 55 was rated at 40 hp.
I believe the Mark 55 was based on the first year of production.
The 40 hp was 10 hp more than anyone else in 55.

Yes Yes Yes. All my boating associates were running OMC 25,30 and 35's (engine hp increased over the years....35 was '57 to '59 time frame).

Here comes this guy (a friend of my dad's) with a Mark 55, 40 hp, Green on Chrome, on a 14' wooden boat that had a semi-v bow, then a step to a flat bottom aft starting about mid ship. He had 4 pipes from the deck connected to the air space where the semi-v abruptly stopped and the flat bottom commenced to allow air to fill the vacuum.

I was a young lad at the time but on a couple of outings with him we would fish the flats on the North side of Galveston Island, TX. Water was extremely shallow. He was running a 2 blade bronze prop.

Anyhew, he could punch that sucker out and we would hole shoot in a second or two and that engine would just sing, white foam everythere. Will never forget it, smooth water, sitting on the boat rather than in seats, wind blowing in your face, engine singing.....whadda deal

I bought the boat from him later and was my first boat....he kept the engine and put it on another boat.

Fond memories,

Mark

 

[shadowrider]

Re: Mercury Mark 55 help please

I have a Mark 58, which is 5 hp more than the mark 55 but otherwise same engine. There is a flush plug on the port side of the lower unit below the cav plate. Mercury made a flushing attachment that was used at that plug. Unscrew the plug, then attach the threaded flusher. The thread is 3/8-16, the plug is next to the impeller and it is safe to run the motor at idle with this device. I have done it many times. I made a flusher from a heavy brass garden hose nozzle. I turned the end down on a lathe and ran a 3/8 die on it. It was simple to make.