Is it running hot or too hot

[Bill kubiak]

97 merc 2 stroke 4 cylinder. The water squirting out the pee hole is very strong, but very hot, almost steaming hot. This motor does not have a thermostat housing, can this be normal.???? this is the 40 hp

 

[hotrod53]

My 1977 merc 500 pee water is pretty warm coming out. I wouldn't say that it is steaming, but definately noticeably warm in temp.

 

[roscoe]

Sounds too hot to me.

What is the model number of your motor?

 

[Bill kubiak]

Don't have the model number but I do have the serial number (OG554810) 40 hp, 4 cyl, 2 stroke, oil injected

 

[alldodge]

Appears no where in the manual so far as temp or amount of water it should be putting out. Just says there should be a good steady stream or water. Did find a specification table listed below; provides pressure numbers but does not specify how to get the readings
http://boatinfo.no/lib/mercury/manuals/30-40_2cyl.html#/276

 

[Bill kubiak]

Not Sure what to make of that, the water is so hot I cannot keep my hand under it, perhaps there is some blockage behind the side panel or on the head panel, anyone have any idea wheat I will see if I remove either of those.??

 

[Bill kubiak]

Appears no where in the manual so far as temp or amount of water it should be putting out. Just says there should be a good steady stream or water. Did find a specification table listed below; provides pressure numbers but does not specify how to get the readings
http://boatinfo.no/lib/mercury/manuals/30-40_2cyl.html#/276

Have not had the time over the last many months to look at the motor, But here is what I just did, fired it up and sure enough the pee stream is strong but it gets so hot, and so fast it will burn my hand. I removed the side exhaust panel and the cylinder head cover panel, unfortunately 3 bolts in the head broke off. The innards that I can see are as clean as a whistle, almost new looking. I am trying to figure out what the water flow is, what I mean by that is, the water comes up from the pump and goes where? and then where does it go, how does it get around the cylinders, I have several holes between the cylinder area and the exhaust area for water to pass and then it is channeled behind a gasket and down to the mid leg and overboard. There is a panel behind the electrical trigger box and I don't know if there is water channel there of if there are water lines behind it, can anyone help me out please, I know it should not run this hot?
This motor does not have a thermostat and I have no idea what or even where a poppet valve is or where it would be located.

btw I tried to remove the broken bolts with penetrating oil (PB Blaster) and big vise grips, all I did was damage the remaining threads. I have a map gas bottle setup and was wondering???????? Gonna need help there too now

 

[60sboater]

I read here or on another Merc site recently not to try e-z outs but to drill them out after center punching to help the bit run true.

The good stream and too hot temp seem odd. I had a no pee at low rpm (fine at higher revs) on a 9.8 and replaced the impeller (which was almost new). there was a rubber insert missing from the wp cartridge. Have not run it yet. The stream was not too hot unless the revs got too low and then it would turn to steam.

 

[enginepower]

Water coming out will probably be around 140+ after it's warmed up. This would be equivalent to some pretty hot water coming out your home faucet. Yes, your body will tell you don't keep your hand in that water or you may get a burn. If you are seeing steam with that, you have exhaust leaking into it or it's too hot. Get a hold of infrared hand thermometer and check block temp if you think it may be overheating.

 

[Bill kubiak]

SO far I discovered what 60'sBoater found EZ Outs do not work, I did center punch one after grinding it flat with my Dremmil to find the center better, those bolts are tough, I ended up using bigger and bigger drill bits and finally had to re tap it, was a bear to do, that was the one that almost broke off flush. Need some ideas how to get the remaining broken bolts out.

As for the cooling yes it is really hot, so hot that there is steam coming off the water as it pees out. I am gonna pull the lower unit and connect a hose to the coolant tube, add some water pressure to see where the water goes first. So far I have passed a drill bit thru every water passage hole I could find between the cylinder and the exhaust ports, I noticed that the factory machining of the holes left some burrs here and there which I have cleaned up also in the exhaust side I see many areas that have little, (for the lack of the correct word pimples the size of a grain of sand). My days of auto hot rodding tells me to smooth everything out for better exhaust flow. After carefully spending last evening reading the manual about rebuilding the powerhead I saw something interesting I never thought about. Since each cylinder has 3 exhaust holes and I can see the rings between them and I had been spraying them with PB blaster from time to time. Anyway the manual says to take a small flat screwdriver and very carefully push on each ring to see if it springs back, this will tell you if it was broken during reassembly, I guess it will also tell me if a ring is stuck if it will not push in.

Also not 100% sure yet but I can see two lines behind that trigger box and I think they are both fuel lines, one is called an equalizer and it has a check valve (have no idea what it equalizes) and the other is the main fuel line between the two carbs, I will have to remove the oil tank and starter to double check.

I do have a water dribbling down on the right side from the area between the powerhead and the mid leg while it is running, indicating a leak in there somewhere. The only place I can thing it might be leaking is the gasket between the two. I bought a new gasket but I really do not want to pull the powerhead just to change a gasket, Any thoughts on that????

 

[mlbinseattle]

Unfortunately, you'll probably need to pull that powerhead to change those gaskets. The bolts are torqued in three stages (1/3 full torque value, 2/3 full torque value, and then full torque value), at least on the older Mercs, and if it's anything like mine, you won't be able to get a torque wrench and socket in there for the bottom bolts. This applies to all covers from what I've read. You'll need to check the service manual for your year Merc to know for sure. Also, I feel your pain about the snapped head bolts. (Read my thread about gaskets and you'll see what I'm talking about.) I don't know about your year Merc, but the older ones have a head cover gasket and a water jacket cover gasket. Mine was leaking, as well, and I'll need to change those gaskets ... and drill/tap some head bolts. Oh, the joy of having an older engine.

I know, on mine, the water from the pee-hole was hot ... too hot to keep my hand in the stream. As long as the correct temp plugs are used and there isn't any pre-ignition happening, then it's probably not getting too hot. Those combustion chambers get pretty hot, and it doesn't take much to heat everything (including water that's flowing) around it. On mine, it's probably as hot as the hot water out of my hot water heater. Enough to get scalded real good.

 

[Bill kubiak]

I had a johnson 25hp on a small boat and the pee water was warm, not hot and it had a thermostat in it. Mine does not have a thermostat, I did see something about a poppet valve, but I have no idea what that is or where they might even be located.
My wife was tightening the 8 nuts and bolts today that hold the head to the mid leg and she said I was missing one bolt in the forward left side and she was right, damn that might be my leak.

 

[mlbinseattle]

From what I understand, a poppet valve acts like some sort of water pressure regulator. At low RPM's, it's closed because of low pressure, and the cooling water gets circulated through the engine. At higher RPM's, pressure increases, the poppet valve opens at a pre-determined pressure, and the excess water bypasses the cooling system. Also, from what I've read, they get "fouled" with dirt or get stuck closed causing the engine to overheat at low RPM's. Sounds like it could be your problem if you have one on your engine.

If you don't have a service manual for that engine, you should really see about getting one. It will save you some future headaches. I was actually able to find the one for mine online and for free. I like free.

Kudos to the wife for finding the missing bolt/nut!

 

[Bill kubiak]

If you look back at the page AllDodge posted it talks about a poppet valve opening on engines without a thermostat on 94-97 engines. Mine is W/O and it is a 97?? I find nothing in my manual about a poppet valve in the cooling system, the only thing I find about a cooling system is how to change the impeller, I also got my manual for free on line, perhaps I am missing a section on cooling.

 

[mlbinseattle]

Hmm. My manual is for engines made from '65 through '89 and covers the entire horsepower range. The powerhead section mentions a thermostat and a poppet valve ... actually shows an exploded view pic of a cover with a thermostat and poppet valve. I haven't seen anything like that on mine, so I assume it's for a different year or different size engine. That may be the case with yours, too. All I apparently have for cooling is an impeller, as well.