Mercury XRI 150

[edward859]

Hey everyone I have a problem with my 95 Merc XRI 150 not peeing right out the tell tale when at idle. When I have the muffs on and at idle it just spits and sputters out water at random, it doesn't stay a solid stream for more than 2 seconds. Now when I take it out on the water at higher rpm and full throttle it stays a solid stream, but when I stop and idle spits out water at random. The things I have done are installed a new impeller, changed the two stats and checked the lines for block edge. I don't think anything could be blocked if it pees solid at higher rpm and full throttle. Has anyone else ever had or heard of these symptoms and know any other steps to try I'd appreciate the help thanks.

 

[Texasmark]

Re: Mercury XRI 150

Apparently this is a new problem? Is your pee tube plumbed off your tstats?

No - yes: The stats, one per side as you know, start opening at 143F. The water in the block has to rise to that temp for that to happen. Takes time and for that time you have no or a pinhole outlet of water (small hole in the top of some stats) from the stat, hence no pee.

As the engine heats to 143, the stat cracks open and lets out a little water, some of which comes out the pee tube as spurting. If you are at idle and at cooler water temperatures, about the time the stat cracks open, it shuts back down due to the influx of cold water; pee stops. etc, and etc, till the water heats and stays above the opening temp of the stat.

At about 2500 rpms (planing speed??) the popoff valve is forced off it's seat by increased water pressure/volume from the impeller and ram induction from the lower unit water pickup ports if around planing speed or beyond. Once the PO valve is off it's seat, being a steady stream and a much larger port, the pee volume is large and solid.

Mark

 

[Chris1956]

Re: Mercury XRI 150

What Mark was trying to say is....the telltale is downstream of the thermostats. On the flusher device, at idle the thermostats may not open, and you will not have a telltale. If the thermostats open and close due to low speed and cold water, you will see spurts in the telltale. At high speed the thermostats will always be open and you will see steady stream. The poppit valve is not connected to the telltale, however, it only functions at high RPM, when the thermostats are usually open.

 

[Texasmark]

Re: Mercury XRI 150

What Mark was trying to say is....the telltale is downstream of the thermostats. On the flusher device, at idle the thermostats may not open, and you will not have a telltale. If the thermostats open and close due to low speed and cold water, you will see spurts in the telltale. At high speed the thermostats will always be open and you will see steady stream. The poppit valve is not connected to the telltale, however, it only functions at high RPM, when the thermostats are usually open.

Thanks Chris. I got that tangled up with my 90. The last time I was into a 150 in that area was my son's engine. I didn't like the pee having to wait on the stat so I replumbed it off the inlet to the popoff. Worked great. Had water in just a few seconds so I knew in a heartbeat that my water pump was functioning. Figured if the stats failed I'd get an over heat warning. My 90 is plumbed that way (immediate water via the exhaust manifold) and works great.

When I first bought my engine I had a stuck shut stat. First time out below 2500 had an alarm. Above and all was quiet. New to me engine and had to get home and read up on what was going on.

Mark