200 Black Max Low Water Pressure

[TNRoostertail]

Well we got 200 black max on the gambler. We installed a new water pump kit and everything sealed and bolted up like it was supposed too. For some reason the pisser isn't doing much at idle and upper rpms are just bringing 5psi. It was like this before the install, I thought a new water pump would remedy it. Need help lol, thanks guys

[TNRoostertail]

Also just noticed alot of water coming g out of the upper 2 exhaust ports on the mid. Idk if that helps diagnostics

[Merc 2.5]

Did u check poppet? I'd just replace it and test stats , if that don't do it gonna have to pull powerhead and clean adapter plates

[TNRoostertail]

Will check that, thanks Merc

[TNRoostertail]

Ok so we took the poppet valve off to see if there were any flow coming through to the power head. We ran the motor for less than 10 seconds and there was a decent stream of water coming from the rear hole where the poppet valve was. I wouldn't say it was shooting out just a decent stream. There was still water blowing out the upper 2 exhaust holes though. Then put the valve cover back in without the valve to see if it helped. It seemed to help some so we decided to look at the thermostats. It doesn't have any t stats in it, but that wouldn't affect flow to the gauge or the pee tube would it? The pee tube is just dribbling at idle and at 3k rpms just has the idle stream imo. Thanks guys.

[Merc 2.5]

For it to work correct and build pressure it needs the valve and stats only other thing to do is check adapter plates for a clog but that usually cause a spike n pressure. I say clean it all real gud put it back and try again , u need new tho and stats. It's like fuel diaphragm. dont take much mess em up. Also check seal in block that poppet slides in

[Merc 2.5]

Ur not gonna get a great stream on hose either , mine pumps great but on hose stream ain't as strong

[99fxst99]

I used to run out of a shallow creek and would pick up small debris that would jam the poppet valve resulting in low water pressure.

[TNRoostertail]

Well after looking at what I think is the correct poppet valve kit Poppet Water Valve Kit R: 803062T1I have determined that the poppet valve in this motor is very incomplete. Its missing the spring and other parts.

[Merc 2.5]

No spring? Thats a problem

[Motv18]

Also check the squeez part is in the pump. Since you mentioned replacing the pump. It changes the pump from centrifugal to positive displacement.

Also sound like an adapter gasket leak since mentioned the water out of the relief.

I think you should have more then 5psi with thermo out but not sure how far no springs would drop it or how big the water flowing from relief is since it can hold 12+ with the popet and temps open normally with springs in.

One problem at a time though

[TEXAS20225]

sounds like you have a motor with previous cooling problems stats gone poppet twerked on . in experience is a killer on outboards:nonod: did u just get this motor

[TNRoostertail]

Yeah Tex we needed something to run on the gambler while we build the promax back up. We lake tested it and also ran compression test. It just doesnt have enough water pressure.

[TNRoostertail]

What temp stat should we install? And tex I see your point on possible troubles. But if it's a low water pressure issue I would think it has to be fairly simple (I'm not as good as you guys so dont roast me lol) as this isn't a radiant type cooling system. Were not getting any spikes do to a leak down on a cylinder.

[Merc 2.5]

Stats 143. poppet can cause low pressure. especially with no guts in it. I think tex was getting at , what made previous owner start screwin with the system? Was it over heating so he tried this and that. then maybe sold it

[TNRoostertail]

Gotcha, yeah it needed a water pump kit and he prob just skipped that lol. Were located a poppet kit and new stats, going to get those in this afternoon then report what we find. Just trying to get the ole gambler back fishing while we spruce up the promax.

[TEXAS20225]

Yes thats what i was getting at no disrespect intended as its very common for someone to not be able to cure a heating problem so get rid of it pass it on. i remember once i built a 200 efi that just would not cool off matter what i did and i sold the motor before i knew it would not cool off. the guy brought it back and i completely disassembled the motor down to bare block put it back together twice i wound up giving the guy his money back it set for about a month after i reassembled it then a guy from Oklahoma bought it but he had his own lower unit and this was sold as power head i put it on for him and never heard from him again till 4 years later when he sold it to a guy and the new owner called me asking what all was done during rebuild. i never found out what made it heat up it was different mid section and lower unit though the two things i had eliminated from the search Go figure

[TNRoostertail]

Lol right on tex, I have had engines like that. Rebuilt a kz1000 once and could not get that rascal to keep time. Used solid cct's tried everything. Sold it to a guy and turned out factory sent me the wrong chain lol. That taught me to start counting my links. And I didnt take your comment as disrespectful at all my man. I appreciate any info you can lay down.

[TNRoostertail]

Ok guys, installed new poppet kit, new stats. Water pressure did go up as the water pressure gauge is now holding about 2.5 at idle. But we noticed water leaking out of the motor mount. My gut tells me all the water isn't making it into the engine from the pump. Here is a video for you guys.
https://youtu.be/EVLrd1fy5XI

[TNRoostertail]

More pics, looks like water is getting all in the driveline.

[Merc 2.5]

2.5 at idle is fine. sounds like u got that part. Now time pull power head , new adapter plate gaskets and use little sealant round the mounts , sumbody has had powerhead off , maybe they put solid mounts in and didnt seal good

[Merc 2.5]

Split the plates clean EVERYTHING new gaskets and sealant round mounts. U b gud. Check lower crank seal n bottom of block. Make sure its ok to

[TNRoostertail]

Took the adapter plate off and found rtv under the gasket. This may be the leak, the gasket was bubbled up all over.

[Merc 2.5]

Ya looks like sumone Putin solid mounts. Solid mounts have a tendency not to seal good and leak , I had take mine back apart for same reason after I installed em. U will always have some water come out exhaust relief in mid but It prob wont b that much if everything sealed good , so dont freak if keeps blowing water out

[Motv18]

Might want to inspect the lower crank bearing. Check the one way lip and such for blowout and in that area for corrosion.

It shouldn’t do anything but if pressure got high enough water can force itself into weird spots.

[Merc 2.5]

It may just b pic but r those the same size?

[TNRoostertail]

Yeah there the same size, they are completely coated with rtv. Were cleaning them now, there is rtv everywhere. So just to make sure, I just need to put rtv around the outside sealing surface of the mounts? Not actually coat the mount right? Thanks guys.

[TNRoostertail]

Here is the gasket. Has rtv all over it.

[Merc 2.5]

Just a small thin bead around front and back of the mount, that way when plate goes on , the rtv will touch alway around. But dont need coat whole thing. Do a dry fit 1st tho and make sure everything its bolting up nice and square. Other than mounts. everything else should go back together dry , so u dont take risk suckin all that junk up in a passage. Clean clean clean, if u got big piece glass and sandpaper. I'd do figure 8s on it with the plates ,

[TNRoostertail]

Right on, good info merc. I am cleaning everything up, I k ow this is just a "get by" motor but I cant stand it not being right. Probably didnt have to but I'm cleaning up mounts and everything. Here is a before and after of the mount so you can see how.much crap was on them. Idk how in the world you could bolt this back up and think everything would be ok.

[Merc 2.5]

Ya sumbody prob got em used and throwed em in there with crap already on em. prob a ****ty job cleanin old gasket. Look like a hurry up and use rtv so maybe wont leak haha
Also that "get by mota" mite suprise ya. the 2.4 200 good mota. I just sold one and it was strong, hell we got a member here. went from a 2.4 220 to 2.5 promax. and I think he said he gained 2 or 3 mph with same prop and setup. Just food for thought. I like them ole motas. Is urs a virgin chrome ? All 6 still chrome?

[TNRoostertail]

Brother idk about the cylinders, haven't even looked yet lol. Had good compression so we left her sealed.

[Merc 2.5]

Just curious as most the 2.4 200 runnin round with steel sleeve, which is perfectly fine. Just thinkin u mite have a original with 6 chrome sleeves. Its aluminum coated with chrome. A magnet wont stick to it. Either way. No need pullin heads to check tho. So did u have to order gaskets?

[TNRoostertail]

Well they only had the upper gasket, lower will be in tomorrow. Ran all the numbers on everything while we were there. Turns out mid and lower are out of a early 90's 150 with the newer trim setup. The powerhead we believe is a 1984 200, it does have a 2.4 exhaust setup as well and they didnt make a 2.4 150 in 1984. So it's a freankenmota lol. I thought you couldnt bolt a 2.4 to a 150 mid but iirc they went to 2.4 on 150's later on. Idk its confusing lol. Thanks everyone for your help, going to get it buttoned up tomorrow and see where she is. Can anyone think of anything else it could be while we have everything apart? So far : new water pump, new poppet, new stats, will have all new gaskets on mid. And everything has been a kit, so o rings are good to go as well.

[Merc 2.5]

Did u replace seal in block for poppet? I know it's a bitch to get out

[TNRoostertail]

Did u replace seal in block for poppet? I know it's a bitch to get out

Yeah, it did suck. It's made of a harder plastic like material with the notched o ring inside it and was in there.

[TNRoostertail]

Soon as we get this done I'm going to get my lil 2.0 done for my lil boat ;p

[TNRoostertail]

Ok got out mid and ph gaskets in. Installed all new gaskets, new hardware in places old hardware looked bad and this is the result. Much better tale tale flow, and it's just on the hose. Does this look good to you guys?
https://youtu.be/b6iOKH8mWqE

[Merc 2.5]

Perfect. Pressure needs b no more than 15lbs wot. also water flow out exhaust relief slowed down to
Ole mota sounds pretty gud

[TNRoostertail]

Does sound pretty good.

[rochelle howell]

Excellent thread. Good pics, descriptions, videos. Thank you, gentlemen.

[TNRoostertail]

Well we took her out, water pressure is real sporadic. It will jump between 5-15 and were getting an alarm pretty quick. When we get the alarm the tale tale is still spitting water good. Any ideas

[TNRoostertail]

We can sit still and idle for 15 minutes but as soon as we get on plane underway the alarm under the dash goes off

[Merc 2.5]

It looked like it was surging. so u got a heat alarm?

[Merc 2.5]

Ok usually a blockage in adapter will cause a spike n pressure, 20+lbs. What poppet kit u buy? Where did motor come from? Salt water?

[TNRoostertail]

Were not getting a spike really merc, it's just jumping to 15 or less. Bought the quicksilver poppet kit, dont have number on me. No saltwater. The alarm was going off before too but I thought low water psi caused it

[Merc 2.5]

Seems me like there still a clog. Bit maybe its sumthin else. I wanna say any clog b a spike n pressure , if poppet not sealed gud it will b little low , the "surge" I seen. like poppet opening and closing. Ur 100% sure everything went back rite with the pump? Hey s&f. am I missing sumthin I'm tellin him , would a clog n head cause lowish pressure?, rooster. Was the old pump intact. ot was there any pieces missin?

[TNRoostertail]

Old impeller was intact, just hard and starting to crack. What wasnt intact was some if the poppet valve and the spring.

[TNRoostertail]

Were going to get it back home and take the poppet valve off and back flush it.

[Merc 2.5]

Definitely go back over poppet, maybe take stats out just to try, or test em n hot water with a food thermostat in water, double check water pump, if that dont fix , gonna gave start lookin for blockage , b gud back flush it from copper tube goin to lower. Will need take it off tho and get his pipe.on tube

Did ALL the water pump parts go back in and go back correct

[TNRoostertail]

All parts did go back correctly. I turned shaft clock wise when installing top half of water pump cover. Did everything as right as I know how to. Nothing looks wrong with it now. I am thinking it has something in it rattling around intermittently clogging the passages in the block, like part of the puppet valve that was missing.

[Merc 2.5]

Pull stats leave covers off. Pull poppet leave it off pull lower flush from copper tube

[TNRoostertail]

Pull stats leave covers off. Pull poppet leave it off pull lower flush from copper tube
Right on, were gonna try that tomorrow, will it hurt to back flush it from the tstat holes?

[Merc 2.5]

I dnt c y it would hurt nething

[TEXAS20225]

i just remembered a situation i had several years ago i installed a rebuilt power head on a customers stump which he claimed he just put in a new water pump , i sent him on his way he called a week later saying it was heating up just like before i asked before what??? he did not mention that while i was quoting him a price so he brought it back i took lower off saw nothing wrong i took it to lake it idled running cool but the minute i gassed it the heat gauge climbed with the speedo so i went back to shop tore out poppet ( i rebuilt it so i did not think that was it but u never know which old man is showing up for work at my house)nothing wrong there took out stats put in washers back to lake same deal back to shop pulled heads put hose diverters in it back to lake same deal back to shop took lower unit off again this time i took bottom half up i saw immediately that the base gasket was on backwards that cuts off about half of the water that should be coming thru so another deal of just not watching what your doing bites again maybe thats it good luck PS inspect the metal plates in your pump if do did not replace them you should because if they are scored very deep it will affect you performance

[Merc 2.5]

The base gasket could b it. I dont think it was doin this exact thing until he put it back. :confused:

[TNRoostertail]

The base gasket could b it. I dont think it was doin this exact thing until he put it back. :confused:
Right Merc, before we started we had zero water pressure at idle and maybe 3-6 at wot. Here is a list of what we have done so far following merc specs in the book. Water pump kit, poppet kit, tstats with new grommets, and mid gaskets. Now we have more pressure but its intermittent from 5-12 psi. It will idle decent but 5 seconds after you go wot and jump on plane it overheats.

[Merc 2.5]

Sure sounds exactly what bobby sayin (texas) also hes lot better at these than I am. So with that said. R u 100% sure the metal plate went back in right in water pump and if so.base gasket mite b upside down covering g wrong holes for flow. But fine at idle

[Merc 2.5]

If base gasket gets flipped it dont fit water passages just rite. It will "fit" both ways but only work 1 way

[TNRoostertail]

Im pretty sure, as I lined it out with flow path of the metal plate. Were gonna pull the lower tomorrow and flush it, I will check it again as I installed the new one like the old one came out. Maybe the old one was in wrong the whole time idk.

[Merc 2.5]

They metal plate is in water pump we talking bout , but base gasket is power head gasket we talking bout. Gonna need check that I'm afraid

[TEXAS20225]

no not the base gasket for power head but base gasket for lower half of water pump most people dont change that part of the pump for what ever reason but just the impeller and the two gaskets and metal plate if you pull up lower part of pump you will see the base gasket for thats part of the pump that what was backwards sorry for the confusion

[Merc 2.5]

Oops sry. I misunderstood

[TNRoostertail]

Ok guys, we completely redone the water pump new housing new seals new everything. The mid gaskets are all new. We flushed the engine. Dang thing still wont hold more than 5psi. Were lost and about over it lol. Anybody want to buy a black max lol.

[TNRoostertail]

Only thing that bothers me is how much water is coming out of the top 2 exhaust vents. This is a 200 powerhead, and the mid is a 150. Could the adapter plate be causing problems? Were lost

[TNRoostertail]

Here is a video
https://youtu.be/7_EcaIRitkA

[TNRoostertail]

Think we may have our answer, started looking at gaskets that were on the mid originally. They are 92 and up gaskets, this mid is an 86 according to the serial. The gaskets for the mid to powerhead are completely different in the pics I can find. So we have the wrong mid gasket. Would this cause our problem? Thanks

[Merc 2.5]

Yes wrong gasket will direct water to wrong spot. 5 psi at idle?

[TNRoostertail]

A little less Merc but close.

[Merc 2.5]

Mine idles round 1lb ,,sumtimes dont read in idle goin out no wake , at wot. U want no more than 15lbs. If ur 3-5lbs idle ur good

My guage could b off little but idle pressure should b under 5lbs

[Merc 2.5]

I think that's 1 reason I blew my 1st 2.4. I had way to much pressure and water didnt have time pull heat out of block

[TNRoostertail]

Well we got the new gasket on tonight that matches the mid. Psi is still low around 2-3lbs at idle. I will say this, when we run the throttle up it sucks the hose dry and doesnt give a good psi reading. It didnt do this before so were going to lake test and see what we have. Also ran compression test just to make sure we didnt have a bad head gasket etc.. Motor was from 117- 119 on all 6.

[Merc 2.5]

Ok rooster. I will say it again haha. That is perfect pressure for idle. What kinda pressure u lookin for at idle? More pressure isnt good. When u drop n lake and put in gear at idle it will drop little more but that's fine to. U have normal pressure:thumbsup:
Also when u do get to wot. U dont want more than 15lbs

[TNRoostertail]

Ok rooster. I will say it again haha. That is perfect pressure for idle. What kinda pressure u lookin for at idle? More pressure isnt good. When u drop n lake and put in gear at idle it will drop little more but that's fine to. U have normal pressure:thumbsup:
Also when u do get to wot. U dont want more than 15lbs
Right on, thanks Merc. Oh and I just meant low as in its just a couple lbs, not in a bad way lol. My bad

[Merc 2.5]

Right on, thanks Merc. Oh and I just meant low as in its just a couple lbs, not in a bad way lol. My bad


All good just tryin help. sounds like idle pressure is good good luck with test run

[TNRoostertail]

Well motor is still getting too hot. Idk what else to do unless the mid plate is wrong, or we have a problem in the heads.

[TNRoostertail]

Well I think I we got it. Took the power head off again because I didnt like the look of the mate up on the adapter plate. Our engine is a 2.4 200, adapter is 2.4 but the exhaust bracket that the tuner bolts too is not. I believe it's a later model 2.5, it doesnt line up at all with gaskets. How can I get my hands on a 2.4 exhaust plate? I dont need the tuner.

[Capt.Insane-o]

You can't put a 2.4 on 2.5 exhaust plate. There in is where your problem lies.

[TNRoostertail]

You can't put a 2.4 on 2.5 exhaust plate. There in is where your problem lies.
I took your advice on the 2.0, got me a set of 39's.

[Capt.Insane-o]

Not sure if I have pair of plates here at home to show the difference.

[Merc 2.5]

Not sure if I have pair of plates here at home to show the difference.

Are the older 2.0 plates same as 2.4?

[TNRoostertail]

We found a 89 2.4 mid local. It has the exhaust plate and tuner along with newer trim. I'm snagging the tuner, mid and trim my buddy is taking the plates. Should work out ok.

[Merc 2.5]

U dont want the 3 ram. Keep single ram if that's what u got

[Capt.Insane-o]

3 ram is much better for recreational purposes. Yeah you can't mismatch plates like that.

[TNRoostertail]

I have the single but I'm swapping to the newer boat and dont want the trim pump and all that stuff in my storage area if possible. It's a 17.5 boat and storage is limited.

[Merc 2.5]

I have the single but I'm swapping to the newer boat and dont want the trim pump and all that stuff in my storage area if possible. It's a 17.5 boat and storage is limited.

I'll buy the single ram clamp when ur done

[TNRoostertail]

Well merc turned out to be another single ram. I will holler atcha as I'm not taking it.

[TNRoostertail]

Ok we got the water pressure issue sorted out. On the lake now, holds 4-5 at idle and then a steady 15-20 wot. It's still overheating though. I'm pretty confident it's not a water issue now, the stats are opening and expelling hot water and pressure is very good. Could this be a timing issue? The guy that put this motor together before we got it obviously skipped some steps lol. What else could it be?

[Capt.Insane-o]

Do you have an infared temp gun?

[TNRoostertail]

Do you have an infared temp gun?
I have a laser if that will work. We use them to test heating water temps.

[TNRoostertail]

Just fyi, were using the buzzer and trying to put a hand on the hands to judge temp right now. At idle before we go out you can hold your hand on the head. After the buzzer sounds you cannot hold your hand on the head. Also it overheats very quickly, I would say 10-15 seconds after the hole shot it gets too hot.

[Merc 2.5]

Ya laser work fine

[TNRoostertail]

If we give up on this motor whats it worth to sell? We would be forthcoming with the overheating issue. Were just trying to get the gambler back in the water and now we have 2 engines with problems because the seller wasnt forthcoming.

[Capt.Insane-o]

At this age it should have had new head gaskets anyway, but 143 is very warm to the touch.

[TNRoostertail]

Yeah its warmer than that cap lol.

[TNRoostertail]

Ok so we finally caught the villain infesting the 2.4. We knew everything was right cooling wise so we took a deep breath and dropped the heads. We started to shoot it with a thermometer but knew there was nothing left but something inside the block. Two cylinders have bad discoloration and those pistons are starting to pit from heat soak. I believe the guy who put the engine back together with the wrong adapter plate must have not had an engine alarm and drove it like this for a little while or just ignored the alarm. So this motor needs rebuilt too. Lesson learned, anytime we buy any other engines a thorough evaluation will take place before we purchase. Wish more people would use manuals instead of just throwing things together. We managed to find a decent older 2.4 powerhead were going to look at to try and get us by while the promax is getting built. We will do a full compression test and thermal scan. I want to thank everyone for their help. We learned a lot from this little endeavor that will make future troubleshooting and engine buying easier for us. Plus we can now jerk a powerhead in less than 10 minutes lol.

[Merc 2.5]

I agree sumthin wrong. The pitting is normal for chrome bores

[TNRoostertail]

I agree sumthin wrong. The pitting is normal for chrome bores
Merc you were solid help through this thing man, we really appreciate it. I have built quite a few 4 stroke automotive engines so i can figure a few things out, but there are some key differences. Live and learn a lot lol.

[Capt.Insane-o]

Bores have pits or are the piston tops eroded? Chrome motors always have pits.

[TNRoostertail]

Bores have pits or are the piston tops eroded? Chrome motors always have pits.
Piston tops are eroded, but from a metallurgy stand point they look like they got a little hot. Plus there is discoloration in 2 cylinder walls, very dark gray coloring.

[Motv18]

With the water working, it was probably lean, dubble check the color isn’t ashy stained. But physical damage pretty much ends it till a piston swap

good of luck on getting her going.

[TNRoostertail]

With the water working, it was probably lean, dubble check the color isn’t ashy stained. But physical damage pretty much ends it till a piston swap

good of luck on getting her going.

Well the water wasnt correct when we got it, and the guy ran it quite a bit that way. Were estimating that's what created the hotspots. It's a shame to because it was exploding out of the hole and running like a 225.

[rochelle howell]

Did your block water diverters look to be in o.k. shape and in the right spots when you pulled the heads?
If it's not too much to ask, could you shoot a couple pics of your discolored / pitted chrome bores and diverter shape / locations in block? Thanks!

[TNRoostertail]

Here yah go, the camera isn't quite clear enough on some pics. In person you can definitely see the discoloration where the chamber was getting hot.

[TNRoostertail]

This engine was supposed to be in "good" shape. Guy said he just put it back together etc... We learned to always do a full work through from now on unless purchasing new or from a verified source. This engine was just meant to "get us by" while we rebuilt the promax. This engine was also 1500 bucks, and that's a good price imo for an older 2.4 that's running good.

[rochelle howell]

Might be my eyes, but I don't see any water diverters in there.
Maybe you pulled them out?
Hate to be a pest, but could you snap pics of both seperate sides of motor that includes all 3 holes with water passages?
Had a overheat problem on a motor kinda recently that turned out to be diverters, after I had replaced stats, poppets, grommets, pump and housing, water jacket gaskets, then finally head gaskets, where I found distorted diverters in the block passages.
Thank you, just curious.

[TNRoostertail]

Sure , at work will when I get home. Here is where my amateur status comes into play on outboard engines. What do the diverters look like? I dont think there were any extra pieces.

[rochelle howell]

Look like pieces of fuel line, inserted between cylinder and water jacket.452728452729452730Here's what mine looked like (distorted), and here's what I replaced it with. (Fuel line). They direct (divert) water to flow around cylinders to cool properly.In my kooky sideways pic, you can see the diverter in the middle, between cylinders, and also another one at the bottom of block, uh, to the right side of the one in the middle.

[tlwjkw]

"production" 2.0's, 2.4's, 2.5's dont have diverters.....

[rochelle howell]

So all those pics of 2.4 merc with diverters in block are "modified" cooling systems or race motors?
My bad.
Good to know, thank you!

[tlwjkw]

some add 'em to their stuff 'cause it can be beneficial but, yeah only came in ha hi perf blocks...….

[Merc 2.5]

When does it start to be beneficial Tommy? Over 8k? Can they be run on any cooling system?

[Motv18]

Looks like jets in backwards port and starboard, but not lean enough to be the heat problem.

The first piston pic where it’s busted up is probably causing silent knock (knock condition or ping you can’t hear) that will cause excessive heat.

Discoloring looks like scuffing, and is that oil or is the chrome cracked in that one pick. That will also cause excessive heat.

But since it it hasn’t been done ohm test the temp sensors to confirm their not bad. Not an pressing concern since you found physical damage, but might as well hit them up and take care of if needed while doing the rest.