1996 Mercury 150HP pee water ??? 2024

Hey all!

I recently bought a boat with a 96 Mercury 150HP outboard on it. When i run it or just fire it up in the drive way with the water hose the water from the pee hole is very hot. Hot enough for your hand to only withstand it for a couple seconds. The gauge is not showing overheating nor are any alarms going off. Is this normal or are my gauges and or over heating alarm not working properly? The previous owner showed me receipts for a tune up including new impeller, water pump and lower unit maintenance. Any help would be greatly appreciated.

You're really not supposed to run any OB, especially a V6 on the muffs long enough for the water to start getting really hot which it will if that's what you're doing. There's a big difference in the amount of water moving through the engine between an engine submerged in water vs having muffs on it. If you run that engine long enough that way, the overheat alarm will eventually kick in. I know that happens on my Yammie or any V6 I've ever owned.

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You're really not supposed to run any OB, especially a V6 on the muffs long enough for the water to start getting really hot which it will if that's what you're doing. There's a big difference in the amount of water moving through the engine between an engine submerged in water vs having muffs on it. If you run that engine long enough that way, the overheat alarm will eventually kick in. I know that happens on my Yammie or any V6 I've ever owned.

X2, boy if I ever agreed with a post this is it. More damage has been done to outboards on a muff than most would ever believe. Why would anyone want to even run one in the driveway is a mystery to me. If you just want to make sure it will start, just start it and then turn the key off. Don't run it on the muff.

Forgot to mention that it does it in the lake too. No alarms but what if the alarm is not working? Also, the boat sat in storage for about 1 1/2 years too. It is and EFI(electronic fuel injected) motor.

How about the thermostat?

Did you have this motor checked out by a mechanic before you purchased it? 

FYI, don't believe any statements or receipts that are stated or produced when buying an outboard. Get it professionally checked before any money changes hands.

Alarms can be and or disconnected at times.

Anyone can produce a piece of paper.

Just because you have a pee stream, it does not guarantee a working cooling system.

Tons of variables that can cause major damage to a motor. If not done , get it checked out.

While your at it, get the fuel delivery system checked. 

If you have a fuel delivery problem on a 2 stroke then you have an oil delivery problem.

You just cannot be too careful.

Good luck.

Well i got the receipt and called the shop and as far as i can see the work was done. Also, an electric fuel pump is listed on the receipt. No thermostats on there though. I called Mercury and they said the motor has 140 degree thermostats on it so the hot water is normal. I don't know what to do now!

Well if it concerns you that much, change out the thermostats with a lower temperature rating, or swap the gauge out to see how they compare. About the only thing that will change the temps (if )everything else is in order. Just remember, what is hot to your hand may not be hot to the motor. You can cool it down too much and do damage as well.

The guys that run the Optimax engines are well aware of an issue referred to as "cold seize".

Your electronics are programed to specific temp settings among other things. When you make one change it usually affects many others

Have you checked to see if one cylinder head is a lot hotter than the other? Could be one side or the other if there really is an overheat issue.

Just get it checked out and then you will know. Too many variables to try for an internet board diagnosis.

Jack will attest to the fact that I know absolutely nothing about outboard motors.  However, common sense tells me that any cooling water that runs through an internal combustion engine would exit the engine in a VERY warm state.  I have a Mercury 150 and holding my hand in the pee stream has never entered my mind, because I know that it will be HOT.  I know that my overheat alarm works because I've have experienced it after fishing in salad and slop.  Don't be overly paranoid about your engine and its pee stream.  Go out and enjoy your boat.

Maybe i am just looking for something to be wrong. The boat and engine are in MINT condition but it did sit for 2 years! The main reason i was shocked/worried is because my previous Mercury 50HP and 90HP and 115HP motors always had cool pee water. Guess i will run it and go from there.

Does your boat have a water temperature gauge and water PSI gauge? If it doesnt, get them installed. Do not wait for a alarm to tell you something is wrong. If you over trim your motor, you can lose water pressure.

Yeah it has both and neither is indicating any issues. I will probably swap out thermos with new ones and take it out for a test drive. My local marine shop has nothing but @$$ #@*^@ working there! They never give a straight answer and are very rude. Plus i don't have the $115 per hour charge they want!

Another suggestion i got was the poppet valve? Anyone know where i can get instructions on how to replace this myself?

It's round

Located low on the drivers side of motor

Pull the cover and clean it.

It is nothing more than a bypass. At times the thermostats cannot cool an engine when opened completely.  The poppet valve allows additional water circulation to aide in cooling.

The poppet seats have been known to float out of the block. Check to make sure this has not happened.

Like said above...  hot to your hand and hot to a motor are very different.

If it eases your mind at all, my 1994 merc 175 does as you describe... and has since the day I took it home, brand spanking new.  At idle, the stream gets hot and fairly weak.  When you are underway, it gets stronger.  At full throttle if you look back, it's very strong.

All the older mercs I have been around are similar in that regard.

the first thing I would do is have the oil injection turned off and mix your own oil.  I just had my 200 merc sieze up because of the tube though which the oil runs though break.  Now it is costing me almost 6k to fix. 

jenga

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Like said above... hot to your hand and hot to a motor are very different.

If it eases your mind at all, my 1994 merc 175 does as you describe... and has since the day I took it home, brand spanking new. At idle, the stream gets hot and fairly weak. When you are underway, it gets stronger. At full throttle if you look back, it's very strong.

All the older mercs I have been around are similar in that regard.

Thanks flechero, it does put me a little at ease. I am getting new thermos tomorrow and will go from there. jenga, my oil injection system seems to be working fine. I would hate to remove it if it is. Is this a common problem or what?

Okay, i removed the thermos and they look pretty corroded! I stuck them in hot water and they opened up fine though? Also, there is no seals/gaskets for the thermostats, is this right? I though all thermostat assemblies had to have a gasket/seal. A marine shop told me that there computer was not showing that motor to have seals but i didn't believe them.

Mine was working fine as well.  A few weeks ago I asked that same question on this web site and I had a bunch of people tell me to have it disabled but it was to late it already siezed up.  I now have to have a reman powerhead assembly put in.  I told my mechanic that I will mix my own gas from now on and I won't have that problem.  It takes more time but so what better then having to go through this again.  trust me disinable the oil injection ask anyone.

Jenga

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Mine was working fine as well. A few weeks ago I asked that same question on this web site and I had a bunch of people tell me to have it disabled but it was to late it already siezed up. I now have to have a reman powerhead assembly put in. I told my mechanic that I will mix my own gas from now on and I won't have that problem. It takes more time but so what better then having to go through this again. trust me disinable the oil injection ask anyone.

Jenga

I have heard a lot of horror stories on the oil injection! What all is required to eliminate it?

Well hold on a minute there partner.  If it ain't broke, don't fix it.

Water coming out of the peehole should be warm, if not hot.  So long as the water temp gauge looks good, you're good to go.

It should be a strong stream.  If not, replace the impeller (and inspect the housing while you're at it, you might need to replace that too).  That said, water pressure should be your main concern.  Low pressure = higher temps.  It should be at least 15 psi.  I ALWAYS replace the impeller ever 2 years as a standard maintenance precedure, even if the psi is well above 15.

As for oil injection - you said your motor is a '96, right?  If it was going to have any injection issues, it would have had it by now.  If it's working fine for you, then don't mess with it. You could be opening up a bevvy of problems by switching now.

From what you've said, it sounds like the engine is in good condition.  Do the normal maintenance work (oil, spark plugs, etc.) and enjoy! 

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Well hold on a minute there partner. If it ain't broke, don't fix it.

Water coming out of the peehole should be warm, if not hot. So long as the water temp gauge looks good, you're good to go.

It should be a strong stream. If not, replace the impeller (and inspect the housing while you're at it, you might need to replace that too). That said, water pressure should be your main concern. Low pressure = higher temps. It should be at least 15 psi. I ALWAYS replace the impeller ever 2 years as a standard maintenance precedure, even if the psi is well above 15.

As for oil injection - you said your motor is a '96, right? If it was going to have any injection issues, it would have had it by now. If it's working fine for you, then don't mess with it. You could be opening up a bevvy of problems by switching now.

From what you've said, it sounds like the engine is in good condition. Do the normal maintenance work (oil, spark plugs, etc.) and enjoy!

I REALLY want to enjoy it Glenn, just being cautious. The impeller was replaced in Aug and has not really been used since. So were the plugs, fuel/water sep, lower unit oil and now the thermos are in too. But my PSI gauge is showing only 3psi at idle and the stream of pee water is weak to non existing until you run at higher speeds? Could the psi gauge be faulty? Can a bad poppet valve cause all this too? I HATE OUTBOARD MOTORS!!!!

Yup, a bad poppet valve could cause it. But keep in mind it's going to be around 5psi at idle, so 3 isn't THAT bad.  If it's above 15psi while running on plane, you should be fine.

Example:  My motor had a clogged poppit valve (dang sand dunes!).  Idle psi was ok.  The pee pressure was a little weak, but wasn't too bad.  However it wouldn't go above 10psi, even at WOT.  Clue train!!

Cleaned the valve, and the stream was stronger at idle (@5psi), and it shot up to 24psi at WOT. 

One other thing to check is the hose connections for the pee water.  Just trace the hose back from the hole and make sure they're on nice and tight.  I'd even pull the hose loose and blow through it to make sure it's not obstructed.  Unlikely for sure, but since you're there...

And pull the screen off the intake and take a look inside with a flashlight.  Even stick your finger in there and check for any obstructions.

Where is the intake screen located Glenn? Also, do you know of any instructions on replacing the poppet and what all parts are included in the system? I cannot find it on my motor. THANKS A LOT

I don't know your motor specifically, but the intake should be in the lower unit.  Mine are attached with allen bolts. I have an '03 Yamaha HPDI.

Same with poppet valves - mine is a pain in the butt to get to.  It's 45 mins of taking things apart to get to it - and that's if you know what you're doing!  I presume yours is easier.  Maybe somebody here knows specifics.

I thought about it overnight, and remembered one time not only was my poppet clogged, but the line from the intake to the valve was clogged as well.  Compressed air did the trick in that case.

And just to be clear - your poppet valve could be operating normally, but might be clogged.  Or it might simply be a blocked line.  I wouldn't replace the valve unless I knew it was broken.

How are you fellows getting a water pressure reading?

PSI gauge on most. I got the poppet valve off and all gaskets are wasted and spring is corroded. Will replace and crank er up again.

Alright i got pretty much everything out that needed out except for the intake screen. I have looked everywhere for it and cannot find one anywhere! Where is the intake on a 96 150 HP EFI? Is the intake the holes where the muffs go over? If so there are no screens there. Anyone???

Yes, it's where the muffs go over.  I would think there should be screens there, as they're supposed to help keep junk out. 

While you have the poppet valve apart you might want to check the diaphragm very carefully for pin holes. It is very common for it to have them. As I stated above, check to see if the seat has floated out of the block. It happens so look for that.

Jack

Never tried this, but don't know why it wouldn't work, just to check.

Catch the pee water in a container and put a candy thermometer in it and see how hot the water coming out is. It should be slightly cooler than the thermostadt setting.

cwb60

Mine has no screens nor has any other Mercury outboard that i have owned. I called Mercury marine and they said that most if not all Mercs do not have them. I checked my bros 2006 Merc 200hp and a friends 2002 150HP and they have no screens either. Anyone know more about this? I went ahead and bought the whole poppet kit to be safe. It was only $25 anyways. I will be testing it all out in the water Wed so we will see.

In 1996 there was no screens on the lower unit That lower should be a XR6 case or some call it the 200 case.Glenn gave you some good advice.Now you say that there is corrosion In your popet valve and thermostats!That tells me that it has been run in saltwater replace the popet take the boat out and run it As long AS YOU HAVE 12PSI AT WOT YOU ARE GOOD. I think on the starboard side of your motor on the head you will see a Brown and blue wire going to a sensor on your head that is your over heat alarm you can unplug that and ground it and you should here your alarm go off.Now on the other head is your temp sensor it has a brown wire the only good way to test it is to compare it with another gauge Now between the heads is you divider plate at the bottom there should be a plug or a fitting with a rubber hose that is attached to your bottom cowl that you can hook a hose to and flush your system If it only has the plug in the plate you can take that out and get some adapter's and hook a hose to it that way and sometimes when a impeller is destroyed Little pieces of impeller get into the water passage's Of the divider plate and cause low water psi and the only way to fix that is to remove the plate and clean out the passages manually I know this is long and I hope Im not confusing you These are just some of my experience's And I dont want you to Trash your motor If i can help Pm me your number and Ill call and try and help you out

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In 1996 there was no screens on the lower unit That lower should be a XR6 case or some call it the 200 case.Glenn gave you some good advice.Now you say that there is corrosion In your popet valve and thermostats!That tells me that it has been run in saltwater replace the popet take the boat out and run it As long AS YOU HAVE 12PSI AT WOT YOU ARE GOOD. I think on the starboard side of your motor on the head you will see a Brown and blue wire going to a sensor on your head that is your over heat alarm you can unplug that and ground it and you should here your alarm go off.Now on the other head is your temp sensor it has a brown wire the only good way to test it is to compare it with another gauge Now between the heads is you divider plate at the bottom there should be a plug or a fitting with a rubber hose that is attached to your bottom cowl that you can hook a hose to and flush your system If it only has the plug in the plate you can take that out and get some adapter's and hook a hose to it that way and sometimes when a impeller is destroyed Little pieces of impeller get into the water passage's Of the divider plate and cause low water psi and the only way to fix that is to remove the plate and clean out the passages manually I know this is long and I hope Im not confusing you These are just some of my experience's And I dont want you to Trash your motor If i can help Pm me your number and Ill call and try and help you out

Man that is awesome of you fishn hard! PM sent

One thing I might agree with (and it's really minor), is that if the water pressure is too high, the water can pass through the motor too quick to actually transfer any heat. Some people stretch the poppet valve spring just a little to increase pressure but ... 12 psi sure is a good number. If anything, you've gained a wealth of knowledge about your motor and it's workings. Good luck with it.

I was asleep when I wrote that. DISAGREE with ... DUH. If the water pressure is too high it can actually make the motor run hot. The rest I THINK I got right. Woo Wee ... sleep don't fail me now.

When I mentioned screen I was not referring to a wire mesh. Maybe a bad choice of words. There is a plate just inside the entry openings. Sorry for the confusion.

I have a lower unit sitting here that I am going to put seals and bearings in this morning. I will try to take some pics during the tear down and post them up if that will help you.

I have sent them to Long Mike asking him to put them up. All my family has up here is fr&*^%$g dial up.

140 Water is pretty hot to the touch. Before I spent unneccessary money I'd catch a sample and check the temperature with a thermometer. If the temp of the sample is 140 or less you should be just fine.

I have all kinds of issues now guys! I put it all back together today and decided to run it with no  thermostats to clear the passages out. I cranked it up and water is only coming out of the passenger side head! Water will only come out of the driver side if i rev the engine? The driver side head is getting hotter than the passenger side too. Than i put the thermostats back on and the motor wouldn't even turn over. I put the key to the on position and alarm check beeps than nothing!. Not even a noise from the engine. All fuses are good and battery is charged. I AM DONE WITH BOATS!!!!!!

It has been crazy at work sry I didn't get to call you but i will tomorrow we need to talk

Thanks for the help fishn hard! Most of the issues have been resolved...................for now!

Your welcome just call any time you need help!! that goes for the rest of you guys  :)

Finally took er out on the water today. PSI is at 14-15 at WOT. Temp looks good and she topped out at 67MPH. Only one issue left that i can see. After a couple minutes of wide open throttle the motor just shuts off! No alarms no overheating or any obvious issues. If i crank it right back up it goes again just fine. After a few minutes it seemed to stop doing this a bit. Is this because the engine is been sitting a long time or what. Maybe a fuel issue or bad battery? Anyone?

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