1979 Mercury inline 6 90HP Water problems

[Barry Prior]

I am a car mechanic for 25 Yrs so have great mechanical skills but only on 4-Stroke. Never toutched a 2-Stroke EVER.

I have a problem with the Tell Tail not producing enough water. I have stripped the pump section and found the rubber impeller to be knackered/faulty. Great I thought....... but when cleaning out the water ways with the hose from the tell tail, backwards I have found that the water seems to be going into the exhaust system and not directly out through the bottom. When I blow up the telltail I can hear the blowing through the top exhaust vents and when I put the hose up the water inlet as I have removed the propeller/Water pump bit the water dosn?t even get to the top of the engine to come out of the tell tail outlet. Ouch I am thinking please could you advise weather is it worth stripping the exhaust plates.

07748 655731 London UK

 

[Chris1956]

If you have all the pieces of the impeller, the motor is probably not clogged. On that motor, water goes up the 1/2" copper tube, cools the exhaust ports, flows up and over the block and falls down the outer exhaust cover and cylinder head water jacket. The telltale drains the cylinderhead water jacket.

Replace the impeller, wearplate and two gaskets flanking the wearplate. Make sure to install the watertube into the waterpump. There is a guide tube to help you.

Install the flusher, remove the wrap cowl and pull off the telltale hose, from the block. Run the motor. You should see a solid stream of water from the telltale elbow on the block. The telltale hoses clog easily., and give misleading indications.

 

[Barry Prior]

Thanks for that PANIC over..... dose the engine have to be running/warm for water to come out of the tellTail ? I've seen a video on Youtube with the hose striaght up the 1/2" Tube and with the engine running pouring out of the TellTail ? Is there some form of Thermostat ? ?

Thanks Again
Barry

 

[Chris1956]

No thermostat in that motor. Water should exit the telltale after 15 sec or so. The main water discharge is via the gratings above the anti-ventilation plate and thru the prop. If you have water exiting in those places, she is pumping.

 

[Barry Prior]

Thanks Chris. I have just received the Selco manual and ordered a new water pump kit so should be back in the water on the weekend. Whoop whoop

 

[Barry Prior]

Just to let you guys all know. I fitted the new water pump kit last year and all is working great. Getting 45Mph without any problem just need to play with the trim and bit of a tune up with the 3 carbs. Having loads of fun at present. Just got a bit of a low idle which stalls sometimes ? Ill get there

 

[Chris1956]

Those idle mixture adjustments need to be pretty rich to allow the motor to accelerate, as there is no accelerator pump. So set them to bet idle and start testing on the water. With a warm motor and fresh 50::1 fuel, try to accelerate. If she stumbles or dies, open top idle mixture screw 1.8 turn and retry acceleration test. If she still stumbles, open mid carb idle mixture screw 1/8 turn and repeat test. Next is lower carb, then test, then top carb and test...see the pattern?

 

[Barry Prior]

There is no problem with power just the idle now. Think I'm going to 'Fully' Strip the carbs and set float levels as I have 1 cab that leaks a bit(Over fueling) Are the mixture screws Fuel or Air. with cars some let more air(Bypass) in and some let more fuel in ?

 

[Chris1956]

The mixture screws are fuel screws. CCW turning makes the mixture richer. Initial setting is 1-1/2 turns open.

To set float height, Invert the carb bowl covers and bend the lower lever until the upper lever is parallel with the cover. Turn the carb cover over. Now bend lower lever until the distance between the two lever ends is 1/4"

Make sure the floats are hard plastic and the springs on their tops are in good shape. There are pinholes in the carb throat on the bowl side that must be clear for idle circuit to work correctly. It makes sense to replace floats, inlet needles and seats and all gaskets, when you strip the carbs.