Need a little help with a Merc OB cooling system question

[tumblebug1949]

Today I started a 1999, 40hp 2 cycle Tracker (Mercury) motor while it was in a tub of water. I let it run for about 10 minutes so the mix using seafoam I had added to the fuel tank would get through the carb. and into the cylinders.

This is a 1999 Sun Tracker Fishin" Barge Pontoon boat I just got and this is the first time I have started the motor because it has been very cold here in Indiana for the past few weeks.

My last outboard was a 150hp Johnson. When it squirted water it had a strong!!!! solid stream squirting out the back. This 40hp Merc is more of a spit & sputter which is passing water but there is certainly not what could be called a stream of any kind. I held my hand in the spitting water several times and there was very little heat to the water although the water in the tub was really cold. Instead of a single round hole to allow water to exit, the Merc has three pea sized square holes so I guess it is not supposed to squirt like my old Johnson. I don't want to damage anything but am not sure if this amount of water is right or if an impeller replacement is called for. Any comments on this would be appreciated.

If you need additional info, just let me know. I will be checking for comments off and on.

Thanks for your time
Tom

 

[tazrig]

Re: Need a little help with a Merc OB cooling system question

Keep in mind you 150 is more than 3 times the motor that your 40 is so it needed a lot more water to cool it. (hence a stronger steam) As far as your impeller goes you should replace that every 2 years regardless of how much the motor is used as the rubber degrades over time. The same way you should replace the gear oil once every season as it picks up impurities and degrades. It doesn't sound like you have any problems with the impeller now but if you haven't replaced it in the last 2 years do it any way. (good preventative maintenance)

 

[Bosunsmate]

Re: Need a little help with a Merc OB cooling system question

it should be coming out in a noticeable manner thats why its called a telltale.
I agree with tazrig that you should change the impeller.
If you are running in a tub make sure the water level extends well past the place where the LU drops (normally at the anti-cavitation plate).
Ive seen people use a tub and the water level is about 8cm above the anti cav plate yet they arent getting water pumping, they needed water about 20cm above the anti cav to pump and that was for a 30hp.

When the motors not moving there is no forward movement feeding the water up the intake pipe, at rest the boat sits lower in the water and thus the water level rises up the intake pipe. This stopped position is what you have to replicate in the tub, a water level much higher than the running position.
I wouldnt be surprised if the impeller is in a weak state now if it wasnt submerged for those ten minutes.
Do you remember where the water level was approximately?

 

[tumblebug1949]

Re: Need a little help with a Merc OB cooling system question

Hey Bosunsmate, I had plenty of water. it was 5 or 6 inches above cav plate. And at least a foot above inlet holes in lower foot. I just got this pontoon and motor the other day and I am not sure how old the impeller is. I know the gear oil was changed. The prior owner said he changed it every fall.

I have not had a boat for 10 years and never a Merc outboard. I do not have the maintenance manual so I don't really know where things are at on the motor. I am almost betting that I was not looking at the tale tell but was looking at an exhaust port when I was mentioning the three small square ports. From looking at the diagrams on a parts list, I have decided that the tale tell outlet is on the lower housing just to the right of the lid latch when looking from the rear. I do not know if this motor has a thermostat but if so, it probably did not get warm enough to open and let water flow. I It was probably 40 to 45 degree water in the tub and I only let the engine run a short time. I could put my hand on the piston housing and it was not hot at all.

If you could, would you verify where the water outlet is? nd is it a single round hole?

Thanks Tom

 

[tazrig]

Re: Need a little help with a Merc OB cooling system question

The tell tale is usually exactly where you described. just under the lower cowling of the engine block housing off to either the left or right. I didn't know how experienced you were so i didn't want to tell you to put your finger on the piston housing for fear the fly wheel would take it off but if that wasn't hot than the engine is getting plenty of cooling and you're fine. I would still change the impeller though, especially if you don't know for sure when it was last changed. They last until they self destruct and leave you stranded so for the small expense of replacing it now and then again every 2 seasons you will avoid a whole bunch of future trouble.

 

[tumblebug1949]

Re: Need a little help with a Merc OB cooling system question

Thanks Tazrig. I am not that savvy about boats and especially about mercs. I just did not think about a thermostat but Now I am fairly sure that is it. I was looking fora good stream and when I did not see one, I shut her off. It ran some but not enough to heat up. I will get a kit for the impeller and get it changed. From looking at some parts lists, I can see they made a lot of different 40hp Mercs so I will need to figure out which one I have. One last question for now if you don't mind. At the console, on the side of the throttle arm, beside the button that allows you to give it gas but prevents the shifter from changing gears, there is a small red button that says "RUN or OFF". What is that. I have not seen a switch there before. Or not on my old Johnson.


Thanks again for the help.

Tom

 

[tazrig]

Re: Need a little help with a Merc OB cooling system question

Thanks Tazrig. I am not that savvy about boats and especially about mercs. I just did not think about a thermostat but Now I am fairly sure that is it. I was looking fora good stream and when I did not see one, I shut her off. It ran some but not enough to heat up. I will get a kit for the impeller and get it changed. From looking at some parts lists, I can see they made a lot of different 40hp Mercs so I will need to figure out which one I have. One last question for now if you don't mind. At the console, on the side of the throttle arm, beside the button that allows you to give it gas but prevents the shifter from changing gears, there is a small red button that says "RUN or OFF". What is that. I have not seen a switch there before. Or not on my old Johnson.


Thanks again for the help.

Tom

You will need your serial number to determine which impeller kit to get. then go here:

https://webapps.brunswick.com/literature/literatureSearch.do

You should be able to look up the part number from there. as far as the red button goes, I would need to see a picture to be sure but it sound like some type of safety kill switch so you don't accidently start the motor with people in the water. You would need to flip it to on to start the motor and off to kill it?

 

[Bosunsmate]

Re: Need a little help with a Merc OB cooling system question

Hi Tom.
It may be the thermostat being blocked by sand debris or waterweeds or something but even if it is closed as cold you should still get a telltale after that amount of time. The bypass normally connects to the peehole too. Even cold engines with thermostats pee water out straight away after start up because if they didnt no one would know they arent working pumping water until its too late. (unless you have a temp guage or automatic overheat shut off).
Check to see if you have a poppet valve too, if that sticks open it wont be enough pressure to pee out the telltale at low revs.

 

[Bosunsmate]

Re: Need a little help with a Merc OB cooling system question

Yep Tom it will be a single hole, if its pumping out exhaust gas and not water somethings not right.

 

[oldman570]

Re: Need a little help with a Merc OB cooling system question

You might have a blockage in the tell tail also from bugs or dirt. A piece of weedeater sting pushed up the tell tail hose while the motor is runnig should clear that blockage. Only other way the tell tail could be blocked is if dirt or part of a old impeller is blocking the tell tail fitting on the inside of the water jacket/ exhaust cover on the motor. JMO
Oldman570

 

[Maxz695]

Re: Need a little help with a Merc OB cooling system question

Water will very soon after running spit a spray of water out of the rear ports of the engine as it is fed by the base plate under the engine. It takes several seconds to fill the cavities of the block with water before you see any tell tale stream. The driveshaft turns the impellor in the water pump any time the engine is running Not just in forawrds as someone described to you. That is false. The cold may be affecting the rubber impellor, and or may have even cause the fins to break off. As suggested a replacement if unsure of when it was last changed is highly recommended. I wouldn,t continue to test until this is done as any broken fins will end up in the water ports and block the stream of intake and it may take dismantling of the engine to remove the fins and clear the passegases. After replacing the impellor retest to see if you have a good stream out of the tell tale. Feel the side exhaust cover and it should be cool to the touch. If it is hot then you have internal blockage or stuck T stat or popit problem preventing the circulation which will lead to overheating the engine. JMO

 

[tumblebug1949]

Re: Need a little help with a Merc OB cooling system question

OK, I spent a while looking at this motor and as far as I can see, there is no outlet for a tell tale (anywhere). Not from the lower engine cover to the cavitation plate. The only outlets at all are at the very top of the lower foot where the motor housing tapers down to the lower unit. At that point, opening straight to the back is an indentation with three square openings in it. I take it to be for exhaust but it also spits out some water when the motor is running. No stream but a light sprinkling of water. Now, by tag from manufacture it is a 1999 40hp Mercury. Serial number is almost impossible to read. It says Max rpm 5250, ELPI "I think". The engine cover is labeled Tracker by Mercury The pontoon boat is in the barn and so it is difficult to get a picture or it would have already been posted.

This is a 1999 Sun Tracker. I wonder if I can contact Sun Tracker and get information on the motor?

Any help would be appreciated,
Tom

 

[Maxz695]

Re: Need a little help with a Merc OB cooling system question

Some engines do not have the TT as you indicate. Do you have a working temp gauge on it? If there where a TT it would be on the rear cover of the egine somewhere. This is a 70 HP just to give you an idea of where it might be located if there is one. View attachment 180385 as yu described it has 3 ports and my midsection has 2 It is definitly possible your engine does not have the TT. As you sated it is a tracker motor. I saw one from a distance yesterday. They may have just blocked off the TT and the indication water was being pumped would be through the ports. That doesn,t much help when an engine has a circulation problem and you would have to constantly monitor the temp gauge while boating.

 

[tumblebug1949]

Re: Need a little help with a Merc OB cooling system question

I agree. I am sure the three square holes I mentioned are for exhaust and it spits enough water that if you hold your hand about 5 inches from it with the engine running, it gets wet. But, no solid stream.

I checked for a local dealer and found one that is close. I called him and he would like me to bring it over when we get a decent day weather wise. He seems very interested and willing to do what ever he can to help. That seems like the best route to go.

Do most folks like a tub of water to test an engine or are the muffs better?

The muffs would seem to be more convenient if spilled water were not a problem.

I want to thank everyone for their assistance.

Tom

 

[Maxz695]

Re: Need a little help with a Merc OB cooling system question

The tub is always a better option (Noise LOL) Neighbors probably hate me running in muffs. It (the tub) gives it a more realistic running environment as opposed to forced water through the ingine that impeads the actually pumping of the impellor. Just a few reasons I,m sure there are dozens. Muffs are great to have with you at the ramp (If water is accesible like mine to flush the engine after boating.

 

[tumblebug1949]

Re: Need a little help with a Merc OB cooling system question

I have not got the exact model Number yet but have it narrowed down a lot. Mercury only made (4) 1999, 2 cylinder 40hp motors.

I looked for the number on a freeze plug but found nothing, not even the plug.

Thanks everyone for your help. If you think of anything else, let me know. There is a printed sticker on the top of the motor that gives the Part number and some other info about spark plugs and gap. Maybe the local merc dealer can figure it out. When it quits snowing.

Thanks all

 

[carholme]

Re: Need a little help with a Merc OB cooling system question

From the 1999 40hp, 2 cylinder service manual:

The Outboard serial number is located on the lower
starboard side of the engine block. A serial number
is also located on the starboard side of the swivel
bracket.

Note: The engine block one is the freeze plug.

Note: The one on the swivel bracket is just a stick on plate.

If it is a 1999, the s/n should look like this:

0G762300 thru 0G961499

Gerry

 

[River_Lizard]

Re: Need a little help with a Merc OB cooling system question

Tom,

As far as the switch by your throttle....it should have a coiled cord attached to it that you can hook to your lifevest while you're underway. It's a safety system in case you get thrown from the seat, it will automatically kill the engine. The last thing you want is a run away boat with no driver because most outboards will crank to one side and the boat will start doing circles around the area where the operator was thrown into the water....not good! It's something like this: Seadog Universal Kill Switch - iboats But the link also includes the switch.....yours may take a certain style of clip for the kill switch, check with the dealer when you take your pontoon in for the outboard.

I took my wife out in my old Fisher w/40 Merc and during the time out on the water it seemed that she bumped or messed with that switch and I didn't know it. 1-1/2 hrs later and 2 trolling motor batteries drained, we got to the ramp, due to the engine not wanting to start. Took it to the shop......first thing they did was ask me if I checked the kill switch.....Geeeeeeeez!!! :facepalm: Went home and asked my wife if she messed with a cord by the throttle...."Oh...you mean that coiled red one? Yeah, I bumped it and I heard it click!
So if you're ever out on the water and your engine won't start.......check the kill switch. :lol:

 

[Maxz695]

Re: Need a little help with a Merc OB cooling system question

And change it if it,s even a bit worn as it will also short out the ignition.

 

[tumblebug1949]

Re: Need a little help with a Merc OB cooling system question

Thanks for all the info. I will check for the freeze plug tomorrow. I am not sure where the swivel bracket is located. I checked on a parts diagram and can see what it looks like but I still can not place it. Now the stick-on label that is attached in the area where the mount attaches to the transom is there but it is not readable. I can read slight portions. It appears to have an "1" then an "F", then the bottom section of several numerals seem to be a 6 or 8 but it is too light to make out. I had looked for the freeze plug on the side of the engine but did not see one. I will look again tomorrow. I am curious about this swivel bracket but will need to know what an more important where it is.

Thank you for your help.

River Lizard, I am familiar with the safety shutoff you are mentioning because my old 150 Johnson had one. I will try to add a picture of this little red button that is on the side of the throttle arm but I don't think it is that safety switch. On a Johnson, it is a push button that the little pressure cap holds down until you pull it off. I have in the past, shifted to neutral and stood up with out removing the clip from my vest and it shut off the motor.

This is a small red switch but like a little toggle switch. It is labeled "Run" and "Off" but there is nothing that hooks to it that I can see. A picture will help identify it I am sure. It is just not easy to get it right now. It is supposed to be 5 degrees in the morning so it may take me a day or so.

This model number has me confused right now. My motor is a 2 cylinder. Per the Merc model number list, there are only (4) models of the 40hp that have 2 cylinders. someone else might verify that for me. I am new at this. I can read the label enough to see that the HP is 40 the weight is 187 and it is labeled as "ELPI". I know it has to eject the cooling water through the exhaust because there is no other outlets on the motor for water to come out of. And, when I had it in the water tub and idling, it was spitting water out.

I will continue the search tomorrow.

Again, thanks everyone for the help.