Tell tale on 1999 40 3cyl merc

I bought a used pontoon with a 40hp merc on it. I failed to even think to check if it was pissing when I checked it out. When I got it home I started going through more detailed checks and found that the tell tale was just dribbling. I took the boat out and had dealer replace impeller due to the fact that I had no service records and the manual states that you should replace the impeller every 300 hours and the clock reads 520hrs. This way I get a baseline for this part. Anyway, there seems to be some question about whether the tell tale should pee right away or after it warms. I can not understand how a product could be designed to not show water flow due to the fact that even short run times with no water would wreck either the impeller if running dry or the block if allowed to get very hot.

Re: Tell tale on 1999 40 3cyl merc

Not familiar with your engine. Pee on the so equipped Mercs like I have, and have been around is plumbed off one of two places.

First is off the exhaust manifold cover. On the Left side of the engine, (port) "non curb side"....whatever works, is a large flat plate. That is your exhaust manifold cover. Inside is the exhaust from the cylinders then is a baffle, then is cooling water to keep the baffle cool and then is the cover. This manifold has to have fresh water continuously as hot exhaust is up against it as long as the engine is running.

Some engines, like mine (90 hp '02) have the pee plumbed off this plate. Real simple. A 1/8" nylon pipe ell/hose barb is inserted into the plate and a hose is attached. The hose goes directly over to the right/starboard/curb side of the engine in the lower cowl and terminates. This allows water to flow if the engine is running and it is immediate. It's on the right side as most boats with tillers or remotes are driven from the right side and it can be easily seen while under way.

The second option makes absolutely no sense to me but none the less Merc did it...I know of 1 150 hp plumbed as such....my sons; well it used to be till I changed it.

On the rear of the block, on later model engines....like from the '70's up, or whenever they redesigned the old 4 cyl original design, the engines are equipped with a thermostat and some/most also have an over temp warning system. The thermostat location is sometimes/most of the time/always accompanied by a high speed bypass valve. This/these valves are under an obvious cover on the back of the block, usually at the top and left. If your pee is plumbed off the thermostat the pee tube will be attached there right on top of the smaller of the two bulges.

With this system, the pee cannot originate until the stat opens....that's 143F internal block water temp. Then, as the engine warms up the stat opens and closes so the pee comes and goes till the stat remains open. In my opinion this system totally sucks but that's the way it is.

So the first thing you need to do in trouble shooting is to pop your cowling and look to see what you have. Then get back on here and I/we will direct you as to what to do.

Mark

Re: Tell tale on 1999 40 3cyl merc

It is not going to pee until the thermostat opens at 110 degrees. Is it happening?

What is your engine s/n?

Gerry

Re: Tell tale on 1999 40 3cyl merc

carholme said:

It is not going to pee until the thermostat opens at 110 degrees. Is it happening?

What is your engine s/n?

Gerry

Click to expand...

Carl, apparently they run smaller engines cooler. My 90 and son's 150 have 143 stamped on the pellet.

Thanks,
Mark

Re: Tell tale on 1999 40 3cyl merc

Yes Mark but this is a different engine.

See item 26.

Mercury, Mercruiser, Force, etc. - Cylinder Block and Crankcase - 40/50 JET 30 (3 CYLINDER) 2-STROKE

Gerry

Re: Tell tale on 1999 40 3cyl merc

carholme said:

Yes Mark but this is a different engine.

See item 26.

Mercury, Mercruiser, Force, etc. - Cylinder Block and Crankcase - 40/50 JET 30 (3 CYLINDER) 2-STROKE

Gerry

Click to expand...

Yepper. I guess the 110 means the opening temp otherwise why would they post the number.

Thanks,
Mark

Re: Tell tale on 1999 40 3cyl merc

My 2001 3cyl 40hp starts to put water out the pee hole almost right away but until it warms up a little it is more of a dribble.

Re: Tell tale on 1999 40 3cyl merc

Well, I got the boat back from mechanic. Serial #0G920159. The tell tale starts right away now. It appears to me that he drilled out the 1/16" hole in plastic bung to about1/8". The stream is strong and starts right away. I am not too sure if he just cleared a clog there were the water leaves cover or if he actually changed the impeller. Bill read that he did, so I guess I hope he did. I wanted the part changed even if the water was flowing as the part is a rubber like compound that if original would be 13 years old. I don't want it coming apart and fouling the plumbing. Anyway, the manual clearly states that you should replace after 300 hours. Given that a power head costs upward of $1500 I really don't want to go there.

Re: Tell tale on 1999 40 3cyl merc

I had a 2000 Merc 40 hp 3 cly. Mine dribbled all the time except WOT. Turned out the tell tale fitting had a little piece of plastic restricting the flow. Ran the correct size wire through it to clear and no problems.

Nick

Re: Tell tale on 1999 40 3cyl merc

Those engines are notorious for clogging the telltale at the plastic fitting where the talltale exits the engine cover. Carry a short length of string trimmer line to clear the tube and fitting if necessary. Regardless, that engine should show a stream immediately after starting.