Dry Suzuki outboard

[Scunnered]

Hi
I have a 1996 Suzuki DT4 outboard that I keep as a spare and have started it for the first time in 2 years. Started on 3rd pull and seems to be running sweetly. Ran it on tick-over then on half throttle for a total of about 45 secs then noticed no cooling water coming out of the tell tale. I could however feel a regular and rapid series of puffs of 'air' coming out of the tell-tale pipe. This engine never put out much more than a dribble of cooling water, on one occasion ran for hours on end and seemed not to overheat. However I would appreciate any advice on what might be wrong and how to replace an impeller or any other fault that might be causing this problem.
Many thanks
S

 

[Cliveshep]

I don't know your engine so my offering is strictly generic!

Puffs of air is probably exhaust gases which usually disharge down the leg with the cooling water pumped around engine block and injected into the flow, which is why you get a tell tale water stream whilst the rest discharges under the cav plate where prop wash dissipates it. Kay - that's the how, now for the why - no water is not good news so - either waterways blocked up, feed pipe from pump to cylinder block inside the leg disconnected or broken/corroded, or pump impellor knackered.

First step is remove the leg. This is usually 3 or 4 bolts top of the lower unit or bottom of leg, plus any gear linkage to be disconnected either back of the leg exposed near the lower unit or behind an access plate. Doing this and the lower unit can be withdrawn away from the power head with the engine on a bench or tilted on the transom if on a trailed boat and leaving the powerhead and tilt/clamp and upper leg still attached to the boat. This will expose the drive shaft usually either fixed to the lower unit or sleeved over a stub drive out of the lower unit, and the gear actuator lever also coming out of the lower unit. Left in the leg should generally be the feed water tube which has now separated from the top of the pump. I say "generally" here! If not remove the upper leg section (4 bolts under the power head) and find out why not!

At this point you can connect a hose to the feed pipe and blow water into the engine, it should circulate and come back out again. If not - further investigation required. Does it have a stat, (is it working or not - heat in saucepan of water to check it opens), if stat fitted temporary removal might allow water to flow around block as a test waterways are clear.

Next check pump rotor/impellor. Pump is usually located (for engineering easiness) on the top of the lower unit with the main drive shaft from the gearbox passing through it. Again generally, on top of the little housing around the drive shaft coming out of the lower unit should be 3 or 4 screws, remove these and lift up the pump housing top cover. The impellor is now exposed and can be checked.

Frankly, if you've got this far I'd change it anyway. Reassembly is reverse of above. Also to check, grating/grill either side of lower unit in front of gearbox or back of gearbox which is where water gets to the pump in the first place. You can check this with impellor off by blowing water back down the pump water entry port when it is dismantled.

Also check gearbox oil, if milky remove pump lower chamber and dig out and change the oil seals around the main drive shaft, likewise the oil seals behind the prop are also easy to dig out without dismantling the gear box.

Hope all this helps. It's not hard, just going through all the steps of checks/service part changes. An impact screwdriver, the kind you wack with a hammer and which takes 1/2" drive sockets, can be very usefull in dismantling.

 

[Slowtack]

I have a Johnson 2.5 which is a rebadged Suzuki. Very little water flow untilo it heats up a bit, and even then not a lot. Works well though.

 

[JimC]

Check for blocked water passages in cylinder head (easily blocked by salt deposits). This frequently occurs on Suzuki 2/2.2 hp.

 

[Scunnered]

Many thanks for the advice. Can anyone suggest how I might clear out any salt deposits? Is there a chemical can use to dissolve them or is it a case of scrapping out parts that I can get a screwdriver/piece of wire into.
Thanks again

 

[maxi]

Citric acid will clear the salt deposits - if it can circulate through the chambers.

Remove the prop and then run the engine with the gearbox (waterpump inlet) immersed in a bucket filled with freshwater & a strong solution of citric acid.

Run for a few minutes and then leave for an hour or so - this will need lots of repetitions over several days !

Has worked well for me.