Mariner 3.3 cooling blocked

[Wilson]

Almost no water coming out through small exit pipe, just occasional drip.
Have tried running in fresh water to clear salt and squirting de-scaling fluidback down through tube but no success.
Anyone have any ideas as to most likely cause. I have heard pump failure is not common so it seems like salt build-up somewhere.
Alternatively a steer to a decent shop manual on-line would be apreciated - one that covers dismantling rather than routine user maintenance and operatiing of engine.

Any advice would be much appreciated.

 

[kirielad]

Hi,

I have a similar (might even be the same) engine, a 3.5 Tohatsu which has a small flexible pipe down the side - probably same location as yours. Unless the engine is running faster than 1/4 throttle it only ever drips (becoming more of a trickle at higher speeds).

If the engine isn't getting unduly hot, and you can see some water 'spitting' from the backwards facing ports about half way up the leg from the prop (though even this isn't always easy to spot) I would say that its running normally IMHO.

Don't know of an online Workshop manual source I'm afraid.

Rob

 

[JasB]

Uncanny, my Evinrude 6hp has what can only be described as a feeble dribble of output water which is hot, but not too hot to touch.
Is the temperature of the output water a safe way to judge the cooling of the engine?

 

[William_H]

High JasB the Evinrude should have a decent flow if it is anything lke mine. It is worth removing the gearbox/pump from the leg. If only to ensure screws are not corroded in. Beware of snapping them off.
I found if all is well in the engine head that a garden hose pushed onto the bottom of the pump outlet engine feed tube (about 8mm copper tube runs down inside the leg/ exhaust space) will produce good flow from the tell tale. Most of the water comes out into the exhaust space again.
I have had trouble with corrosion blocking the copper tube several times.
You should remove and check the thermostat housing and it is not difficult to remove the cylinder head to check water ways. (yes I reused the old gasket)

When the bottom end is off it is easy to dismantle and check the pump. I have fitted a new pump kit which includes a new housing impeller and side plate a while back.
Yes if you see steam coming out of the tell tale then it is too hot. Should be luke warm.
I did a whole speal about this engine (1980s) a while back which may be help full.(if you search) olewill

 

[gandy]

I've sent you a personal message. Look for the flashing envelope near top left hand of the screen.

 

[VicS]

Re: Mariner 3.3 cooling blocked/ Evinrude cooling

At the risk of high jacking someone else's thread you should take the symptoms you describe with your Evinrude seriously. Tthe first step would be to remove the lower unit to replace the pump impeller but also do as William H suggest and attach a hose to the water pipe and try and flush water through.

However I would not mind betting that the cause of the problem is that corrosion around the rubber grommet at the top of the water tube has squeezed it over the top of the tube so severely restricting the water flow. It'll stop altogether before long!
It is a recurring problem with these and similar engines which if ignored will cause severe over heating and consequent damage.

If you have a long shaft engine you must remove the extension with the lower unit to begin with or you risk damaging the whole water pump.

If you want full chapter and verse please feel free to PM me.

 

[VicS]

I have This site noted for Mercury and Mariner manual down loads. Click on "download center"

 

[Lakesailor]

You and Kirielad both have blockages building up.
I had the same with a Tohatsu (same motor). Remove the cover and the pipe can be removed to check for blockages. The pipe in itself being blocked is not an indication of cooling problems, but if any water that comes out is uncomfortably hot to the hand or there is steam or hot water spitting out elsewhere, then you have blockages.
Provided the impeller is OK (behind the prop) you need to take off the head.

You can see the build up of crud in the water jacket which all needs scraping out. This jacket is fed and emptied by two small holes from the water channels under the plate on the right of the pic, which is the leg/powerhead joint. You must remove this (and may break one or two studs, so be prepared to drill out the remaining piece and freshen the thread with a plug tap)

The arrows on the left show the channels which need cleaning out and the arrows on the right show where the small holes that feed the water jacket are. I actually used a reamer and slightly enlarged them to avoid further problems. But as long as they are clear it should be fine.
This transformed my motor from a steamer which would only operate for about 3 minutes to a smooth runner that will go for ages and the water runs clean and cool.

You can just see the pee stream against the leg (urgh)

 

[aitchw]

My Merc 4hp 2 stroke used to suffer the same problem and a bit of flushing through did no good but the engine ran sweetly enough. In the end it was suggested to me to poke a bit of wire up through the external telltale pipe while the engine was running and low and behold the flow escalated to a steady stream. This was 2 yrs ago and it is still fine. Try it, it could just be the outlet that is partially blocked.

 

[Lakesailor]

As Vic says it'll be the little grommet. Vic helped me fix mine via the wonder of t'internet.

As he says, if it's a long leg you must split the spacer from the bottom of the leg before trying to remove the leg from the powerhead as you will crack a casting trying to pull out the pump.

This pic is of the grommet at the point it enters the exhaust tube/powerhead flange. As you can see not much water will go through that

It's not as bad as it looks and everything cleans up beautifully

 

[VicS]

[ QUOTE ]
As he says, if it's a long leg you must split the spacer from the bottom of the leg before trying to remove the leg from the powerhead as you will crack a casting trying to pull out the pump.

[/ QUOTE ] Not quite the point I was trying to make. You must split the joint between the leg and the extension not between the extension and the gearbox.
You should also do that before removing the power head, at least even if you did manage to get the power head off with the lower unit in place I doubt if you would get shaft, water tube and gear shift rod all back in place by trying to reverse the procedure on re-assemly.

 

[kirielad]

Beg to differ as;

Engine is only 18months old, has only had light use (to and from mooring) and gets fresh water flush every time it comes ashore (in one of my clubs outboard flush tanks).

I haven't noticed any difference in flow rate from when I bought it brand new.

 

[Lakesailor]

Suit yourself.

 

[kirielad]

Sorry - didn't mean to be dismissive of your experience, and I probably engaged keyboard before brain - was just a bit surprised that a new(ish) engine could develop that problem quite so quickly. Did you notice your engine getting hot?

Rob

 

[Lakesailor]

Yes, in my instance it certainly wasn't a new engine and it did overheat. As you can see in the pic there should be a healthy pee stream if it's in good oreder. perhaps if it's always been like that there's been a kink or restriction in the rubber pipe from new. It may just be your outlet from the pipe is blocked which won't have any effect on the overall performance of the cooling, the majority of the water goes down the exhaust tube.
However it's really easy to jigger the impeller blades, it's only the tips that do any real work, so it's worth checking, or for the price of an impellor, replacing it, as it's really easy to get at.

 

[Lakesailor]

I didn't make my self particularly clear there. You're right and that's what I said, but it is ambiguous.

 

[snowleopard]

I gave my Mariner 3.3 its pre-season wake-up this week. While running in a dustbin of fresh water the water came out drop by drop - that most definitely isn't how it's supposed to be. I removed the rubber hose so I could get at the spigot on the block directly, then prodded around with a bit of wire. After a bit of jiggling I was rewarded with the normal steady jet of water.

 

[JasB]

I have no problem with splitting the leg as I created this frankenstein motor from a long shaft Johnson (Kaput engine) and a short shaft evinrude.

BTW, it appears I have a damaged thermostat, stuck open, but maybe not far enough open. time for another test run

 

[Lakesailor]

Have you seen the price of the thermostats?
We did replace it, but it makes you think.........

 

[steve_cronin]

I\'m wondering...

.. as to how you ever let it get in that state in the first place.

Don't abuse this "kirielad" he seems unusually mechanically sympathetic to me.

Copious fresh water flush and "Stop on Oil" is what 2T OB maintenance is all about, IMO.

Steve Cronin