Mariner 3.5hp Outboard, 2 stroke

[xcw]

I have recently serviced my outboard, new impellor, plug etc and it starts and runs beautifully. The only thing I have noticed is that there is no water coming out of the piddle hole at tick over and it appears that steam (smoke?)is coming out. When I increase the revs there is a good constant flow of water and I have run the engine on the inflatable under load and there is no sign of overheating. I wondered if the impellor is not bedded properly and not turning at low revs. Any ideas gratefully received?

 

[VicS]

Steam coming from the tell-tale indicates inadequate water flow
Smoke / exhaust gas indicates total loss of water flow allowing exhaust gas the blow back through the cooing system

I think you will have to revisit your work on the water pump. Check everything is correctly installed and bolted together properly.
Check the impeller drive key is in position . Did you fit the correct parts ( did you compare the new impeller with the old)
Check the seal between the water tube and the pump housing and the other seals in the housing .

Hopefully you did not disturb the seals at the top of the water tube or you will have to pull the powerhead to check .

 

[Mark-1]

+1

Since it's recently been apart taking the gearbox off to have a look should be trivial. There's no alternative.

I suppose 30 seconds with a cocktail stick might clear a blocked tell tale but since the problem goes away with revs it seems highly unlikely the tell tale itself is blocked.

 

[seumask]

Does the tell tale trickle once the pump has primed the system? ie after revving it does the stream disappear again? If not all good.
If you really want to know the state of salting up you need to remove the cylinder head and have a look at the water jacket. Its pretty easy on these little motors , 4 bolts surrounding the Spark plug. You'll probably need a new head gasket as well.

Having said all that if your happy its cooling well under load, I would not bother with taking the head off, it sound fine.

 

[Mark-1]

Does the tell tale trickle once the pump has primed the system? ie after revving it does the stream disappear again? If not all good.
If you really want to know the state of salting up you need to remove the cylinder head and have a look at the water jacket. Its pretty easy on these little motors , 4 bolts surrounding the Spark plug. You'll probably need a new head gasket as well.

Having said all that if your happy its cooling well under load, I would not bother with taking the head off, it sound fine.

The tell tale doesn't tell you much about blockages in the head, it's a hole near the entry point of the water tube up the leg. It could still flow freely if the engine cooling channels were totally blocked.

Before removing the head I'd try flushing with vinegar or similar first.

However, in this case it seems far more likely the problem is with the new impeller or the fitment of it which is exactly what the tell tale is there to detect. First job has to be to take a look at that IMHO.

 

[rogerthebodger]

I had a similar issue with a Suzuki 16hp 2 stroke no water but exhaust gasses from the tell tail but no overheating.

I found a hole in the in the bottom of the power head allowing the cooling water to exit the power head and pass down the gearbox control leg access and not down the leg exhaust part of the leg.

 

[Caraway]

Take the power head off the leg. Carefull not to break the bolts. There are channels along the cylinder barrel and into and around the head that get choked up. The holes from the cyclider block to the head are particuarly prone to blocking. They are all open and easily cleaned once the power head is off the leg.

 

[Mark-1]

Take the power head off the leg. Carefull not to break the bolts. There are channels along the cylinder barrel and into and around the head that get choked up. The holes from the cyclider block to the head are particuarly prone to blocking. They are all open and easily cleaned once the power head is off the leg.

This came on straight after an impeller change and the symptoms can be totally explained by a problem with the impeller or fitting of the impeller.

So the first step is to check the impeller.

Separating the leg and powerhead is for later when a good few other things have failed.

(IMHO)

 

[Laysula]

Check your impeller, have you bought the right one? . The mariner 3.5 is a fourstroke. The mariner 3.3 is a two stroke. Have you bought the correct impeller?

 

[Dellquay13]

If it is the 3.3hp f/n gear no reverse, it’s a tohatsu model also sold as mercury and Johnson. I had the white Johnson one. Some makes call it 3.3, some 3.5hp.
Check you fitted the impeller blades pointing the right way, if they are bent the wrong way there will be very little water flow and accelerated impeller wear. I would replace it again if I had ran it under load the wrong way round.
With the pump cover off and with the driveshaft pulled up into gear, twist it to see which way the prop turns the right way for forwards and that the impeller blades are then curving back behind the direction of turn, not towards it.

 

[xcw]

Many thanks everyone for your most helpful responses. Yes I did fit the correct impellor. I will strip it down again and check everything is fitted correctly.