200 H.P Mercury Black Max Cooling issue/s

kcflan21

Cadet
Joined
Sep 5, 2009
Messages
20
Hello again everyone,

First, thank you for helping in the past. You guys have saved me more times than ....well than I have posted. Just reading others struggles have helped end mine (temporarily) and I thank you. I have an '88 (if I'm reading the serial number correctly... B264174) blackmax that isn't sending water out correctly at idle. Once passed 1/4 throttle (no RPM gauge, or pressure gauge, or speedo for that matter) and up on plane it is pushing out hard and true, but whenever at idle it doesn't. A spit every know and then but never a constant stream anymore. I've disassembled the t-stats, cleaned them, and checked in some rolling water and both opened and closed well. Cleaned and replaced...same thing. I had water coming out of the weep hole on my poppet valve cover. I ordered new replacement insides and am going tomorrow to replace. I also do get steam coming from the "pee hole" every now and again and/or the exhaust. My question is, based on some readings here, that although the diaphragm or something else inside the poppet may be damaged, that this occurring isn't consistent with the problem I'm having? I know the pump is working, my next guess would be the impeller not spinning freely to push enough water up at idle? I've never taken a lower unit off so that would be new and interesting for me. Any suggestions, advice, criticisms (i can take it), moving forward is appreciated. I've had since '09 and I feel like she'll run for awhile if I can get this cooling issue resolved.


Also,...sorry for adding multiple problems in one topic....anyone have a schematic for replacing the poppet or advice on installing the oil injection block off kit? The pump was always disconnected since I've bought it however it was tee'd together and is now leaking so I bought the kit. Thanks again everyone. I plan on tackling this weekend.
 

dingbat

Supreme Mariner
Joined
Nov 20, 2001
Messages
16,317
Eight years between water pumps changes is far too long. Water pumps need changed every 2-3 years if the motor is used or not.
 

CharlieB

Vice Admiral
Joined
Apr 10, 2007
Messages
5,617
Agreed. 8 years is a long time for an impeller. You should NEVER see steam from any motor. Most of the V6's the P stream comes only after the Stats open. At idle speeds the motor can run cool enough there is no P stream. I hate that and often dril a 1/16 hole in the flat of both stats to allow just a small amount of water flow so I can be sure there is flow.

A pressure gauge is very highly recommended for all v6's. It is cheap insurance and a great indicator of any water problem developing when it begins to show any abnormal reading.

Change that impeller and see if that cures your problem. Repost to let us know.
 

kcflan21

Cadet
Joined
Sep 5, 2009
Messages
20
OK great thanks guys. I'm going to get it and bring it home in a few. Any recommendations on brand or make for the gauge or impeller.
 

kcflan21

Cadet
Joined
Sep 5, 2009
Messages
20
Update. Ordered the Sierra water pump/impeller kit. Replaced the poppet valve...put it on the muffs and upon start I went from a spirt of water out of the weep hole to a constant strong stream?! I followed the schematic on how to put together, which is how it came apart, and just can't quite wrap my head around it... if it is put together correctly. No more time today and probably going to wait for kit to work on it again.

If somebody can correct me if I'm wrong but isn't the poppet supposed to stay closed under low pressure? So if my pump or impeller wasn't putting enough pressure it should have even less chance of coming through the weep?
 

racerone

Supreme Mariner
Joined
Dec 28, 2013
Messages
38,438
That hole in the cover is an AIR VENT it allows the diaphragm to move.----There is a water leak inside there.-----Take it apart and fix the leak point !!!
 

kcflan21

Cadet
Joined
Sep 5, 2009
Messages
20
Thanks racerone. I understand that if the valve is working / assembled correctly that there should never be water coming out of it. My question would be that if it is, do you know of anything other problem that could be forcing water out of it? I'm going to disassemble and reassemble again in the morning. TIA
 
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