cooling 1999 6hp evinrude 4 stroke

[Michawilden]

Hi All,

I have a 6 hp 4 stroke outboard which has problems cooling. Replaced the impeller ( original), the gommet and the gasket between the stainles steel plate and the housing.
I got some flow from the pee hole but no where what it should be. It starts of realy strong for one second and then starts hesitating and end with a weak stream.

I checked if the system is clogged somewhere by removing the lower unit and adding water trough a garden hose and than I will get a strong pee from the tell tale. But not with the brand new impeller.
Is is possible that the exhaust forces all the water out of the lower unit? I am quite stumped here. Never had this problem.

 

[flyingscott]

is the key in the impeller?

 

[Michawilden]

yeah

 

[flyingscott]

yeah

Did you double check the tube is in the housing?

 

[Michawilden]

Yess, tube is in the housing and the gommet is new.

 

[KJM]

Is it possible there is something stuck in the water intake passages below the water pump?

 

[Crosbyman]

Is it possible there is something stuck in the water intake passages below the water pump?

possible... but rare
is this a salt or fresh water engine ?

tired sending a monofilament up the pee hole while it trickles water or a strong air blast to dislodge things ??

tried spinning the drive shaft & GC impeller alone in a deep bucket to see if the pump puts out lots of water ?? how is the pump base plate wear

 

[Michawilden]

I have blasted some air in the intake but could not see anything there. When I put some water in there form above it flows out easily. I will try to remove the screen next.
The motor is a fresh water motor. If I rotate the shaft with a drill it pumps out water but just a couple of inches. It is definively not shooting out.

The plate has some wear, same as the housing. But not more than I have seen before on good working pumps. Is it possible that the housing warps when bolted down?

 

[racerone]

That water pump was first used on the 1980 model 7.5 HP 2 stroke.-----There is nothing wrong with the design of the pump.----Find the real issue here.----Water in your test bucket is 20 cm above the impeller ?

 

[Michawilden]

Is is deep enough. Filled it up to the lower cowling. I will buy a new wear plate and housing. And try again.

 

[KJM]

Double check that key in the impeller, can't really think of anything else...

 

[Michawilden]

Well, It pumps a little. That should indicate that the key is in place right?

 

[KJM]

Well, It pumps a little. That should indicate that the key is in place right?

Not sure, but those impellers are pretty tight on the drive shaft and maybe turning some even without the key locking it in place? Not sure, just surmising....

 

[Crosbyman]

It starts of realy strong for one second and then starts hesitating and end with a weak stream.
If I rotate the shaft with a drill it pumps out water but just a couple of inches.

I can't say if water should shoot out with the drill but at least it does flow out and that water column should eventually make it to the engine passages,

it seems it does based on your first comment but then begins hesitating...

this may indicate some form of floating obstruction is woken up by the water flow.

it may be time to back probe the pee hole with a smaller pliable piece of mono or wire while the stream is weak .

remove the thermostat cover and see just how much watrer does reach the PH thermostat passage. Most water bypasses the thermostat anyway
but you should see plenty reaching the thermostat ,

next may involve PH removal to inspect passages more closely. :-(


and... worries aside what temperatures do you see on the PH ...have you tried touching or using a IR gun to measure the temperature ??

 

[Michawilden]

Oke, some months later and still no luck.

I changed out the wear plate underneath and the stainless housing but the problem changed.
I have already removed the thermostat in order to check if I have flow.

I mounted the wear plate, stainless impeller housing, gaskets ( below the wear plate and below the impeller housing), a new key and a new gommet. I did not check with a drill due to a shortage of time.

Motor started as normal. After a couple of seconds I got flow quite some from the exhaust relief at the back. But no flow at the tell tale and no flow at the thermostat ( I removed the cover).

I did not have the time to remove the lower unit again but I think I miss alligned the copper tube.

I am starting to suspect that the copper tube is maybe broken somewhere or is not sealing at the powerhead but my firt guess now is a missalignment or which causes the entire midsection so fill up and flow out of the relief port.

I will keep you guys posted and I will try to get an IR gun. But PH gets quite hot after some time. ( to hot for my hand )

 

[Crosbyman]

does your pump have some kind of relief vent hole that if blocked can impair the pump,s operation.. not saying yours does but check anyway see warning on older style impellers

you replaced the impeller (original) does that mean you replaced the "original" impeller or does it mean you used an " original" like OEM vs chinese

some cheap impellers have been known to separate from their brass liner !!

did you apply sealant on the rims of the stack of gaskets and plate ?

 

[Michawilden]

I do have the vent hole but it wasn't clogged. Installed new factory OEM impeller.
Today I had some time so I checked the alignment of the cooling tube but it was inside the gommet so I don't think the leg was entirely filled up.

I almost instantly get water from the relieve valve. Not from the tell tale or at the thermostat housing.
If I put my hand on the relieve valve, the water will go up to the thermostat housing and then to the tell tale ( but just drips)
Before the tell tale the hose goes through the float bowl and than the exhaust tube.
Could be that there is a crack in the exhaust tube. Next I will put on the garden hose again and try to see what happens. Previous time I got flow from the tell tale with the garden hose

 

[Crosbyman]

back to step 1... you have a cooling problem...did you measure the temperature of the PH with a IR gun...

how is the PH to the touch ? warm very warm untouchable steaming hot ?

or are you basing your suspecuions due to the missing tell tale only ?

 

[Michawilden]

No, not only the missing tell tale.
The powerhead gets to hot to touch and it begins to steam vapor after a while.
First I thought it might be the thermostat so I inspected that.
Running it with the thermostat cover off no water appears there.

Altough quite some water apears at the exhaust relief at the back. But Im not sure if water should come out of it while I dont have water at the thermostat.

But, I think you are right to go back to step 1.
I wil check the impeller housing again and see if I can get water if spin it with a drill

 

[Michawilden]