How much coolant water should be coming out of my outboard?

M

matnoo

Well-Known Member
Joined
6 Jun 2006
Messages
171
Location
Solihull, W.mids
www.faceparty.com
(about the 10th post about this damn thing)

Ive now got my 4hp Merc 40 running as sweet as a nut!

Only thing is that there is very little water coming out of it. I'm not running it for long, as I dont want to risk overheating it, but a splutter of water and some (exhaust?) gas is coming out of 4 holes half way up the shaft.

Its not really a lot, maybe an egg cups worth every 30 seconds.

But then again its only a small engine... I cannot find any way of cleaning the water filter or checking the impellor as i cant find either!!

What would you do?

1. run it for 30 mins to see if it overheats
2. dismantle the whole thing and find the cooling system, risk and risk screwing it up/not being able to put it back again!!
3. somthing else...

cheers for all the help on this guys!

Mat
 
Re: How much coolant water should be comming out of my outboard?

Usually the cooling water pisses out of a small hole under the power head. There should be a hols approx 3 mm diameter facing down and a bit out.

Normally a continuous flow expected, unless mercs are totally different.
 
Re: How much coolant water should be comming out of my outboard?

Yep, it has problems.

The generally accepted method of ensuring the engine is servicable for another season is to replace the impellor.

Buy a workshop manual from Ebay (On CD) for a couple of quid if you want the full info, otherwise pop it to a dealer for a good check and service.

Replacement usually involves removing the foot of the leg from the engine, as the impellor is shaft driven just above the gearbox.

Water should be coming out at quite a rate, like a pint or two a minute by my reckoning!
 
Re: How much coolant water should be comming out of my outboard?

All outboards have water injection in the exhaust manifold in the head they then expel the cooling water through the exhaust pipe otherwise the heat can damage the lower crank seal, the water pump cover if plastic, this exits under water, the exhaust holes in the leg are because at idle there isn't enough exhaust pressure to shove the seawater down the leg allowing the exhaust to exit underwater. The telltale is just that, it confirms that there is water being pumped around the engine, on a lot of recent engines it only spurts water when the thermostat is open so it appears to stop and start as the stat cycles.If you don't have a stat then it could be a sign that your impellor is worn or you have a restriction somewhere, its worth poking the nozzle with wire on all engines regularly as salt tends to block the pipe when it dries out.
As a rule you should be able to keep your hand on the top part of the cylinder head with it being too hot to touch when the engine is working, if its too hot to hold then you have a cooling problem.
 
If it has a telltale then a good steady stream of water should come out. If it does not then the first thing to do is check the tell tale right through for blockages.

If there is no telltale then you'd expect some water to be coming out via the exhaust relief port in the leg.maybe just a few drops.

The water pump is located in the top of the gearcase so to access it that has to be separated from the leg.

If you spit on the cylinder head and it sizzles it's overheating but if you can touch it and keep your finger there for a couple of seconds it is most likely OK

Exploded diagrams on the Crowley marine website may be useful but if you intend doing the pump impeller a manual would be advisable
 
On my Merc 2.3 I had similar problems. If you poke a piece of wire through the nipple to which the tell tale pipe is attached you should be able to dislodge any blockage. If the engine has been running too hot or it has not been flushed regularly it could be that the coolant galleies in the head are choking up with salt. If this is the case (plenty of coolant appearing at the tell tale but still running hot) then the only remedy is to remove the cylinder head and clean out the galleries in the head and cylinder. It is not a difficult job but you will need to fit a new head gasket. If, after clearing any blockage of the tell tale you are only getting a dribble of water, either your pump impeller needs renewal or the cooling passages are heavilly choked. Replacement of the impeller is relatively straight forward but fiddly, especially lining up the gear linkage rod as you are refitting the gearbox to the bottom of the leg.
 
I'd put the impeller well down on the list of suspects. My Merc. 2.2 telltale dried up a couple of years ago, just the odd wisp of steam. The cure was to remove the cylinder head to get access to the cooling jacket, which on this model, is just a groove concentric with the bore, around which the water flows. This was chock full of crud, probably salt and corrosion products. A few minutes cleaning, reassembly with the old gasket, and its been OK since.
 
Re: How much coolant water should be comming out of my outboard?

[ QUOTE ]
All outboards have water injection in the exhaust manifold in the head

[/ QUOTE ] Sorry that is a sweeping statement that is not true. Certainly not so with my Evinrude although the manifold is water cooled.
 
Re: How much coolant water should be comming out of my outboard?

Water coming out of those 4 holes is good I would think, indicating that water is coming through the engine and into the exhaust section, most of which will go through the normal exhaust run. I'd run it for 10 to 20 mins at around 1/4 revs, and do the finger on the engine test, you may not have a problem at all apart from a blocked tell tale. I’d hesitate to take the head apart until you have done this test, risk of snapping bolts is usually high on outboards especially if they are not new.
 
My Merc 4hp 2stroke has a short rubber hose protruding from under the bottom of the housing. I had the worry of restricted flow from it when I first acquired this engine s/h. It would flow OK for a minute or two and then reduce to a drip or slight trickle. All mine took to sort out was a good flush through running in a bin of fresh clean water and a poke around with a piece of wire up the tell tale outlet. After a few minutes of both there was a good steady flow which has continued thereafter. What appears to happen is that a skin of deposits builds up which is enough to inhibit the pressureless flow.
 
My new (ish) suzzy 2.5 does not have a tell-tale, the odd splutter from the 2 exhaust holes half way up the shaft is all you get. I don't know your motor, but did it ever have a tale-tale? Presumably you have been working on it from your question..

I only mention this as some replies seem to suggest all engines should have a tell-tale and clearly they do not. I would hate to see someone new to outboards panicking for no reason.
 
Is part #29 in the picture below the telltale. If so it apears to have some form of check valve fitted to the end #30.

click on the pic
 
You must log in or register to reply here.

Share this page

Top