78 merc 1400

[angelvigil03]

Hi, I'm looking for information a old 78 merc 1400. I bought a 95 smokercraft pontoon boat and it came with this motor and an old merc control. Everything seems to be in good working condition. I'm am currently trying test the water pump. However there are no water inlets to inject a water supply. I only have a flush plug. How do I test the water/cooling system on this unit ?

 

[MTboatguy]

Probably going to get more action on your questions if you post them in the Mercury section of the website, as far as checking your waterpump, either pick up a set of water muffs, or put it in a test tank.

 

[Chris1956]

A 1978 Merc 1400 probably did not have a flush plug from the factory. Those were on older motors. Look for the holes, slightly above the prop center, but in the front 1/3 of the gearcase. That is where the water enters. It should exit via the grates on top of the antiventilation plate (horizontal plate above the prop).

 

[angelvigil03]

Thanks, a lot I appreciate the replies. Yeah this motor isn't compatible with the ear muffs. Took the motor to the lake and tested it out. Water pump looks good and motor runs good. Only issue was rough shifting ? Chris if I wanted to I could hook up a hose fitting to the FLUSH plug. That's the only spot I see but wasn't sure. Definitely don't have the normal water ports

 

[mr 88]

If this a prop driven motor it uses ear muffs. I have two and that is what I use.Use them to flush your motor.As far as the shifting goes ,is it in your engagement ? If so you can adjust your linkage. These motors like to be shifted from neutral into gear crisply,not slowly.

 

[angelvigil03]

Ok here is a picture of my motor and close up of my lower unit. I'm thinking its an older lower end on this 78 merc motor. The serial number on the motor is definitely a 1978 1400 / 140 hp merc. I'm thinking the flush plug is where I can run the unit with a water attachment. Just want to make sure before I do. Appreciate your help and knowledge.

 

[angelvigil03]

The only place I see a possible water port is on the Trim tab. I attached pic below

 

[Chris1956]

So you do not have about 4 holes directly up from the front of the "bullet" shaped gearcase? Take a close up picture of that area, where all the black paint is chipped off..

I have heard that there were some Mercs with low water pickups, but have never actually seen one.

 

[angelvigil03]

Yeah definitely no water ports there. I attached a pic. Where in the heck is this things water ports ? Low water pickups ?

 

[emckelvy]

Someone butchered-up a very old L/U and installed it on your 140hp. Circa 1962 or so. The trim tab is hollow and the water really does intake thru those holes.

The screw you identified as the flushing screw can be used to supply water to the powerhead. Just don't run the engine when you're doing so. Merc made a special flusher fitting that screwed into the threaded hole and had a hose fitting at the other end.

That L/U really isn't the right one for your motor and you might consider finding a newer one, once you see if the powerhead is any good. Best bet is from around '76 up when Merc upgraded the driveshafts to stainless or stainless-clad in the water pump area. The older driveshafts (such as the one that's on there now) were made of carbon steel and would rust away in the seal area under the water pump. Then you'd get water in the L/U.

HTH & G'luck..............ed

 

[angelvigil03]

Hey thank you very much. Your knowledge is greatly appreciated. I've been trying to do research on the old mercs and there just isn't much out there. I'll be looking for a new lower unit. I have one question. Can it be off a 1150 or does have to be from a 1400 motor ?

 

[MTboatguy]

There are actually quite a few lower units on ebay that will work for your motor.

 

[emckelvy]

Any Inline Six L/U in the horsepower range of 90hp-150hp, from '72-up should have a 2:1 gear ratio and would bolt right up to your motor.

Older ones (from around '65) would probably fit but there could be issues with gear ratios and driveshaft-to-crankshaft sealing method; you'd have less fitment hassles by using one from '72-up.

Merc changed the gearcase design in '79 and there were a number of improvements. The updated gearcase will bolt right up to your 140hp; if you can find one of those at a good deal, it's the one to get.

HTH...........ed