1986 Mercury Black Max 175 overheating

[tlwjkw]

"Small white waster included, seems to be a seat for the spring"

"I have big stainless washer that I dont see in my"

not used in yours...…….

[Dayton12]

Here is my update with a few questions, thanks any help. I thinking as others pointed out earlier that I might be restriction some where else. I hope not…
OK, ordered poppet valve parts as listed on mercury parts diagram as per my engine serial number. Was told it is a 1986 2.4 L. My engine has the Stamp 3 3/8 just to confirm other’s comments.

To date I have ordered two poppet kits. The first kit was for design one. That kit had extra parts and the wrong diaphragm- hard edge, mine is a soft edge.

I ordered the second kit based on the correct diaphragm part numbers and gaskets, making it a design two. But when design two kit arrived the poppet, grommet, carrier where two large diameters so I could not use. Seems mine is mishmash of design 1 & 2.

I just used two kits to get it right… I hope.

The BIG thing I noticed, my poppet never had the carrier and grommet, so maybe like others said, someone was trying to deal with the overheating by other methods… no thermostats, and with no carrier and grommet would not the poppet be open the whole time letting water pass through??

As for the water pump took it apart again and have attached pictures. Looks like a newer designed pump where the water slinger washer sits in its on compartment built into the water pump cover. Seems would be a better design. Book shows on top of the cover, but the cover was flat. See pics hope that explains. Impeller looked good - no wear and pliable. Does so have slight memory bend to the fins. The plates have no wear, slightly more shine to them

I hope to test the boat this week on the water, or could I run on muffs to get a rough idea what might happen with the water temp and pressure???

[Dayton12]

TEST UPDATE>>>>>> Results

Finally got the boat out. BTW, no one kit design I, II or III had the right poppet parts. Had to make from two kits, but think I have it right.

ON the the water here are the results.

Ran fine and actually better with T stats. and thought I had the problem solved.

Temp was fine until the engine RPMs were over 4000, then it overheated fairly fast. Not so much on the temp gauge, but the alarm then the temp gauge caught up. IN the past the alarm and temp gauge have been more or less in sync.

at 3000 the water PSI is about 20 , middle of the gauge, when at WOT the meter pegs. At 3500 sometimes the psi will drop from 28 psi to 22 or so. Not sure if the poppet is working properly.

Also when I have the boat up to 4500 RPMs it just dies, like a safety shut off, I dont remember this happening before.


Any comments, suggestions are greatly appreciated and thanks to all who have helped to this point.

[rock]

In post #2 I suggested a plugged adapter and it is looking more and more like it may be the issue. It's not that big of a deal but you will need to pull powerhead and split plates to see for sure. You will also need two gaskets. Remove 10 nuts holding powerhead and nut on shift shaft. Raise motor till long studs clear adapter then swing it aside. It should not be necessary to remove wiring, hoses, or cables unless they are too short. Adapter has 5 bolts to remove. Split plates apart and you will see an area where the exit water dumps and some fairly small holes. These holes often plug with sand or small pebbles and will not let water exit motor hence the high pressure and hot engine. Good luck.

Rock

[Dayton12]

Ok will do but a few questions.

I have cherry pickers will I need to remove the power head, I see the engine has a lifting tab on it.

Second, when my engine was cutting out, like a saftey cut off at 4500 rpm what is that most likely from, or is there indeed a safety cut off?

Thanks again to all............

[nitro_rat]

Ok will do but a few questions.

I have cherry pickers will I need to remove the power head, I see the engine has a lifting tab on it.

Second, when my engine was cutting out, like a saftey cut off at 4500 rpm what is that most likely from, or is there indeed a safety cut off?

Thanks again to all............

Lifting eye? You should get one of these:



Or one of these:

which doubles as a flywheel puller tool. Will make life much easier. I’m not sure what you’re seeing on the motor that’s a “lifting eye?”

There shouldn’t be any kind of “safety cutoff.” Some other problem. Possibly fuel, spark, or temperature related...

[Dayton12]

Do you have a reference numbers so I can find and buy.. Thanks....

[Bruce2]

Do you have a reference numbers so I can find and buy.. Thanks....

Google is your friend...

https://www.ebay.com/itm/Mercury-Mar...cAAOSw57xaiitl

[pjbrownva]

In post #2 I suggested a plugged adapter and it is looking more and more like it may be the issue. It's not that big of a deal but you will need to pull powerhead and split plates to see for sure. You will also need two gaskets. Remove 10 nuts holding powerhead and nut on shift shaft. Raise motor till long studs clear adapter then swing it aside. It should not be necessary to remove wiring, hoses, or cables unless they are too short. Adapter has 5 bolts to remove. Split plates apart and you will see an area where the exit water dumps and some fairly small holes. These holes often plug with sand or small pebbles and will not let water exit motor hence the high pressure and hot engine. Good luck.

Rock

Thanks Rock, (and everyone else). This thread is very helpful.

I have the exact same problem on an '89 V6 150 (started my own thread, so I won't hijack this thread).

I appreciate the description, including the the information on how many nuts to remove.

I have some questions, but I'll post them in my own thread. :-)


-Phil