Re: 2000 mercury 150 xr6 tell tail not peeing please help
Tony, A lot of those V6 motors will not have a telltale, until the thermostats open. On a flusher device, the thermostats may never open. Does water exit the gratings above the antiventilation plate and thru the prop? If so, it is pumping water.
These water pumps are high volume, low pressure. When functioning correctly they will produce a tell tale stream within 10 seconds of start-up. The thermostats pass water to the tell tale via a small weep hole and do this in the closed or open position. There is sufficient volume to produce a strong tell tale at all temperatures and above approx. 1500 RPM when the poppet valve opens.
Having water flow out the prop or the vents on the lower unit is not an indication that the cylinder area of the block beneath the heads is filling. One of the most common failures in these motors is the lack of cooling water in the cylinder area of #2 cylinder which is the last cylinder to be filled.
If the water pump is producing adequate volume at idle and the poppet valve is open because of improper installation, you may not have adequate restriction to fill the upper cylinders and produce a tell tale stream. You would still have plenty of water at the prop but at low RPM's you would overheat. This is also why the the temp senders are located in the upper two cylinders of the engine.
The two primary causes are improperly constructed water pumps and poppet valves during the rebuilding process. There was a period when a certain manufacturer produced poppet valves with an off center diaphram retaining screw. These poppets would hang in the grommet on the block.
My suggestion is that you remove the water pump and poppet assy's, disassemble and the reassemble as per the diagrams and instructions in the Mercury Shop Manual. Also make sure that the thermostat grommets are correctly installed as some aftermarket brands were made in such a manner that installing them upside down would block the weep hole.
I should also mention that the exhaust plate receives cooling via the weep holes in the thermostats in the area of the exhaust relief. If there is an inordinate amount of steam comming from your exhaust relief port then you liekly have a cooling issue.
You should also check the water pump tube to ensure it's seated correctly in the exhaust plate and that the correct pump to tube sleeve is being used.
If, when you rebuilt the water pump and poppet you did not see anything that stood out as worn or damaged your problem is likely elsewhere. On some of these motors, baffles were placed in the block area beneath the heads. These helped retain cooling water in the heads. I've never seen them self destruct but I've been instructed that they can and when this occurs you could experience upper cylinder cooling issues.
