F4 water issue

[saltchuckmatt]

Hi, I have a 2000 Yamaha four horse four stroke. Doesn't seem to be peeing much water but runs fine, at least off the boat and in a tank. Do these motors not run much water out the telltales? Went ahead and pulled the lower unit thinking the water pump was spun and everything looked brand new. Put it back together which by the way wasn't very easy, I sure prefer evinrudes for doing that little job, but that's just a side note. So does anybody have an older four-stroke 4 horse that not much water is coming out of the pee hole? I pulled the hose off the thermostat while it was running and there was a pretty good amount of water. But that hose doesn't go directly out the back like I'm used to it goes back into the block. When I blew air into that hose I got lots of bubbling below the water down near the prop so I'm wondering if that pee hole just doesn't show all the water or if something else is messed up like the draw tube or something. This is a tough one I'm sure but if anybody knows what's going on please let me know. Be interesting to know where the water is circulating through that particular motor. Thanks in advance.

 

[mike_i]

I don't understand what motor you have but without seeing the water coming from the motors pee hole there's no way anybody can tell you if it's good or bad. Can you post a video? My Yamaha F150 doesn't pee much. The mechanic told me the motors run on high water volume under low pressure so I assumed it's normal what you're describing but can't say for sure without seeing your motor peeing.

 

[saltchuckmatt]

Top of my thread says 2000 Yamaha 4 hp 4 stroke. Not sure what else to say. That being said, I now have a theory. The stainless cup that the impeller site in, does that have to be in a certain position? I watched a YouTube video and it looked like maybe the hole in the top has to be located a certain way. In the omc ones they only go in one way. Maybe you ever put that one in put it in wrong therefore limiting how much water goes through it. If someone knows than please let me know. Thanks

 

[boscoe99]

The four stroke Yams are weak pissers. Nature of the beast.

 

[mike_i]

My ignorance, I haven't heard of a 4hp. The stainless cup only fits one way in my motor.

 

[saltchuckmatt]

My ignorance, I haven't heard of a 4hp. The stainless cup only fits one way in my motor.

So your cup only fits one way in the plastic water pump housing? Please clarify. That's the way the evinrudes 6 to 8 how are but not sure on this outboard. Also, what motor is yours?

 

[saltchuckmatt]

The four stroke Yams are weak pissers. Nature of the beast.

Is that true? Because when I look at YouTube's of that engine, when they complete the replacement they seem to pee pretty well. Mine looks like a combo of water and mist or possibly steam.

 

[99yam40]

if you replace the pump housing, cup, impeller and wear plate along with the gaskets and orings, and make sure the pipe sits in the bushings at pump and in powerhead, that is all you can do.
unless the pipe has a hole in it.
if you have air or steam coming out the TT, I would think head gasket maybe

 

[saltchuckmatt]

if you replace the pump housing, cup, impeller and wear plate along with the gaskets and orings, and make sure the pipe sits in the bushings at pump and in powerhead, that is all you can do.
unless the pipe has a hole in it.
if you have air or steam coming out the TT, I would think head gasket maybe

 

[saltchuckmatt]

On the first part I agree. I just pulled it back apart and the cup was correct....and it only goes in one way. Now the pump kit isn't new but it looks pretty good. Impeller knobs are still straight but she me wear on the plate. If it was an Evinrude it would still pump fine. So two things, hole in draw tube could be one but the motor shows no sign of salt damage. Compression and it runs perfect. I'm assuming with head gasket failure compression would not check out. Could I be wrong on that? Maybe the pump plate is to warn but I just don't buy it. I can see a weak stream but not one that sputters. I also don't remember tt being that hot. This one will burn your hand. Is the draw tube replaceable? Or do you have to tear the whole engine down? Thanks for your response by the way.

 

[99yam40]

I have never messed with a 4hp 4 stroke so not much help.
but I do not think the TT should be that hot, and should not be having air or steam coming out

leak down test might tell if head gasket is a problem

 

[saltchuckmatt]

I have never messed with a 4hp 4 stroke so not much help.
but I do not think the TT should be that hot, and should not be having air or steam coming out

leak down test might tell if head gasket is a problem

I agree on the TT results ( to hot and not a solid stream) though must not be steam because it looks the same at start up as it does after running but water starts out cool and then gets to hot.
I've done leak down tests on cars but the one time I attempted to do one on a small outboard I could never stop the engine from spinning when filling it with air. How do you do that?

 

[mike_i]

The water temp out of the pisser should basically the same temp as the water source. Now you say it's hot enough to burn. If you have steam or the water is hot to the touch you have issues. I'm assuming you're running the motor with ear muffs and not in a tank with the exhaust heating the water.

 

[saltchuckmatt]

The water temp out of the pisser should basically the same temp as the water source. Now you say it's hot enough to burn. If you have steam or the water is hot to the touch you have issues. I'm assuming you're running the motor with ear muffs and not in a tank with the exhaust heating the water.

Well TT that I have touched before, at least in my experience, will get warm or even slightly hot so not sure I agree with your first line but it should not get this hot. To reclarify, it doesn't burn my skin but it's hot enough that you don't want to keep touching it. Also, I am running it in a barrel at the moment but it holds lots of water and I've been doing that with small outboard my whole life. A lot of small outboards (remember this is a 4 hp) won't take muffs but this one might because how it picks up the water but I don't think that would change much. My bet right now is either pick up tube (not financially correctable) or internal like you said (gasket or case crack) or possibly thermostat. In my experience, the TT bypasses the thermo so not sure if the thermo is even something to consider. Correct me if I'm wrong. This damn thing has me perplexed!

 

[mike_i]

I flush my OB in a large trash can. The water temp only gets warms after running it for awhile and the source water in the tank gets warm from the exhaust warming it. The water in the tank is the same temp as the pisser water. Do you have an infrared thermometer to check the head temp? Is the pisser water hotter than the tank water? Any idea how old the pump is? If you don't know exactly how old the pump is I would replace it so you know you're starting off with good working parts.

 

[saltchuckmatt]

I flush my OB in a large trash can. The water temp only gets warms after running it for awhile and the source water in the tank gets warm from the exhaust warming it. The water in the tank is the same temp as the pisser water. Do you have an infrared thermometer to check the head temp? Is the pisser water hotter than the tank water? Any idea how old the pump is? If you don't know exactly how old the pump is I would replace it so you know you're starting off with good working parts.

I do have an infrared thermo. What should that read and where do I point it? In my day we used a wax stick up on the head. Pump wise, if you read above I checked it and even though it's used it looked fairly new. (Impeller fins are still mostly straight) I would rather not put anything more into it if it's toast....if you know what I mean.

 

[saltchuckmatt]

Has anyone ever or know how you might test a water pump draw tube (brass one) in an outboard motor? If it flops around in there is that an indication? Never seen them flop around in a Evinrude engine. Maybe in a Yamaha that is normal. Please respond if you know. Thanks.