Mercury 200 HP Black Max questions...

Hey... I'm new to this site... but, it's AWESOME!! I have a Mercury 200 Black Max... Model #1200422GD Serial # OC150739 When I'm running above idle speed.. I have a good stream of water out of the "pee-hole". When I'm idling.. It comes out sort "erratic".. (stream, stop, stream, stop). When I run at high speeds for a long time.. the engine temperature (according to my gauge) stays in the "normal" range. When I come back down to idle.. the temperature gauge goes up and sometimes after extended periods of high RPM running and back down to idle speed... I get hardly any water out of "pee-hole" and sometimes even STEAM out of the hole!! You can hear the steam whisps while idling! Now... when I'm at home and I flush the motor using the muffs... I get a pretty good stream of water while idling... The temperature gauge is even lower... and there's a GOOD stream coming out of the center of the prop. There's also a good spray from the "exhaust nostrils" on the motor whether I'm on the muffs or under way. Some people have told me the water temperature I run in here.. (Gulf Coast Alabama.. sometimes 87 degrees F and UP in the summer!) is just not too cool enough for the motor to be properly cooled after high RPM running and then quickly back down to idle speed. Maybe the low water pressure and fairly warm (feels like bath-water!) water temperature can't cool the motor fast enough when returned to idle speed after a hard, extended running? If I keep idling at a "little higher" than idle speed engine speed... The temperature gauge will eventually come on back down to "more" normal. It has never over-heated... Just runs more warm than I'd like it to.. Especially after those hard runs. ALSO.. My motor has no thermostat... Hasn't had one for years. Would that make that much of a difference? ALSO.. When you first start it.. (In or out of water.. ON or OFF muffs.. I mean..) If you keep it idling.. It will idle all day long nice and cool.. It's only when you run it hard then come back to idle quickly does it run "sort-of" hot. Is all this normal for my water temperature I run it in? Sorry so it's such a long post.. Thanks for your help guys!!

Re: Mercury 200 HP Black Max questions...

I don't think your motor will cool right w/o the thermostats and poppet valve in place and working right. The water temp you're running in shouldn't make a significant difference in the temp your motor runs at if the cooling system is OK (good water pump, no internal obstructions, etc.) My 150's run around 135 to 140 no matter what the sea water temp is (50 or 80° F).

Re: Mercury 200 HP Black Max questions...

What is a "poppet valve"? Where is it on the motor? What does it do? AND.. How do I know if I have one and it's working right? Thanks!

Re: Mercury 200 HP Black Max questions...

The poppet is on the starboard side of the block below the switchboxes... <br /><br />Get the stats re-installed with all the proper washers. <br /><br />It's also good for you to know, that your temp. sensor is measuring metal below one of the top cylinders, Not Water... So your readings will be higher than most other motors..

Re: Mercury 200 HP Black Max questions...

Thanks for the info!! So, what's the deal with the steam whisping out of my "pee-hole" when idling after a high RPM run? Is my motor overheating? You can actually see and hear it "whisping" out. The temp gauge isn't in the "H" range yet. Also.. do I need a thermostat at all times? Thanks!

Re: Mercury 200 HP Black Max questions...

Without the thermostats and poppet valve, or some other method of slowing the water circulation down, the engine won't maintain the proper operating temp. If the thermostats and poppet valve have been removed and no other modifications made to compensate for their removal, put 'um back in.<br /><br />c/6<br />Hooty

Re: Mercury 200 HP Black Max questions...

With the poppet removed or stuck open, water will exit the block and go into the exhaust prematurely. It is designed to open only at higher rpms... If it is stuck open at lower rpms the water will exit the cooling system, thus no water flow out of the pee-hole, and you could overheat...

Re: Mercury 200 HP Black Max questions...

I get a pretty good stream of water while idling... The temperature gauge is even lower... and there's a GOOD stream coming out of the center of the prop. There's also a good spray from the "exhaust nostrils" on the motor whether I'm on the muffs or under way.

Click to expand...

If you are getting water out of the "exhaust nostrils" at idle speed or even up to 2000 rpms, your poppet valve is difinitely stuck open or removed... This would explain your higher temps just after you run it hard and return back to idle. Not enough water is cooling the block, due to the poppet not working. It's being exited through the exhaust.<br /><br />I would also recommend servicing the water pump also, if you haven't already...

Re: Mercury 200 HP Black Max questions...

You may want to get a shop manual and parts list ... they ID all the motor's parts. Try Mercury Parts Express on-line.

Re: Mercury 200 HP Black Max questions...

Man, you guys are GREAT!! We need more sites like this on the net. Thanks for all the wonderful help from anyone!! Have a great week!

Re: Mercury 200 HP Black Max questions...

I just did a water pump on my 225 Black Max and you can get everything you need in 2 kits from Mercury for about $85 and it only took about a hour or 2 to do. She also told me to put rtv sealer between the exaust port and the water pump area to keep exaust from leaking in on the water pump housing.

Re: Mercury 200 HP Black Max questions...

I have the same engine. Heating is an issue as well...except at WOT where she runs like hound. Am replacing waterpump, impeller, poppet....like a wise guy says on this forum..a manual is a great investment...

Re: Mercury 200 HP Black Max questions...

jscgdunn@telus.net said:

I have the same engine. Heating is an issue as well...except at WOT where she runs like hound. Am replacing waterpump, impeller, poppet....like a wise guy says on this forum..a manual is a great investment...

Click to expand...

hi new to this so here goes changed the water pump and i cant get the bottom of the leg back in seems to be some thing stoping it going in gust where the drive sharft slips in to the spline at the base of the engine can any one help

Re: Mercury 200 HP Black Max questions...

Wayne, start a new thread with your question, don't just jump into someone elses thead with your question, even if it is a 3 year old post. In no time no one will even see your question way down at the bottom or they will see it's a 2004 post and not even look.

And Welcome to iboats.