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1987 Mercury 175 Question(s)

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blandy

New member
Hello All, I just sold my 87 sea ray (100 hp) and am looking for something with a bit more power. So I’ve checked out a checkmate in my neck of the woods several times, and I’m looking to pull the trigger, but wanted to check in with some knowledgeable folks first as the boat has an issue or two with the engine.


The boat itself is a very clean 1979 18 foot Eluder. Great lines- very sleek looking.


On the back is a 1987 Mercury Black Max 175 HP V-6 2 Stroke.


The engine has 2 issues- overheating, and running rough.


Issue #1- Overheating. The owner states the boat overheats on anything above idle. This in indicated by the thermometer on the dash. Owner states he “never” ran it into the red, but who knows. To fix this issue, he has replaced impeller, water pump, Poppet? valve, and thermostats. Boat reads 15 psi of water pressure at idle and 30 psi when the throttle is advanced. Water is exiting the pee tube in the back.


Owner states previous owner had the thermostats (both of them?) removed.




Issue #2- rough start, idles decent, won’t accelerate past 1500 rpm. To me, it sounds like it’s missing on 1 or more cylinders. Previous owner has changed plugs, cleaned carbs, installed new engine wiring harness, new starter, new solenoid, new battery, compression on each cylinder is right around 130. Are there any common issues with this engine? Perhaps in need of a stator or something else?


Thanks a lot for the help, just trying to decide if this is the right one or if this is a project to pass on.
 
Can you do the work yourself to chase down all the demons?

Sounds like the problems were never diagnosed, parts were just swapped in some cases hoping that it would get better.

Maybe there is nothing wrong with the cooling system - almost everything has been replaced save the gauge and it's sending unit by the sound of it. But maybe the water channels are clogged up and who knows if it has been overheated more than once.

The won't accelerate could be the stator, powerpack(s) or a number of other "not so cheap" fixes.

For me the boat would have to be in pristine shape and I wouldn't place a lot of value in the motor in it's current state when figuring a fair price for the package. When a motor gets to be 30 years old almost any part of it can be a common issue.

Price out "what you think" may need to be replaced on this and decide if you want to spend that kind of money and time on a motor that was built when Ronald Reagan was President and it's not running properly at the moment after quite a few hundred bucks has already been spent trying to fix it...

And you say the boat itself looks good - is that "pretty" or you have really looked it over, down in the bilge etc.

A "I got it for almost nothing" project is great if you are so inclined but if you are looking for something for "right now" I would be looking for something that doesn't require (unknown) service at the moment...
 
Thanks Galamb! I appreciate the insight. The owner is asking $1500, I was thinking of offering $750- and assuming the motor may be shot. There is a shop by me that charges $99 to diagnose the issue(s), perhaps they can find a solution to the issues. I was quoted anywhere from $2500 to $6000 to buy a new (used) engine for that boat. Hopefully, that wouldn't be the case- but I think I would have to go into the situation assuming as much. Thanks again.
 
Be verrrry careful as this is a chrome bore 2.4 motor and if cylinders are damaged you can drop a bunch of $$$$$$$ to repair.
These blocks need t-stats and cannot be bored!
 
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You should ask why the previous owner removed the thermostats, I would def not do that on a v6, it can easily cold seize, removing the thermostats cause the water to not reach all the channels, it needs that resistance to fill all the channels making sure the engine get sufficient cooling .....
 
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