Water Pressure Relief Valve(popit)

[gvh]

I having Problems on my 1985 Mercury 150. It runs very hot with muffs on. The pee hole has very good pressure, but it also very hot after a minute of running. After this motor runs rough. Thermostats look good. but not to sure about the popit valve. Could this be the problem. Also there is a water fitting on the top of the block in the center rear, any idea's. Right now it is blocked off? 1985 Mercury 150 06619015 mod#1175725<br /><br />Also boat has been sitting for 6 months, and cylinder #1 plug is clean, others look black.<br />I know what that means, water getting into #1.<br />Is it posible that the motor is running hot do to a lean condition due to cloged carbs.<br /><br />Just bought boat, first time out the water pump went out. That has been replaced.

 

[trumanlake]

Re: Water Pressure Relief Valve(popit)

poppit valve only comes into play at higher rpm's UNLESS it is stuck open or has a hole in the diaphram. were there any water droplets on the surface of #1 plug when you removed it after it ran? would have to say nay at this point on carbs. water fitting on block should be for your water pressure gauge (which you should have or be purchasing shortly!!) back to #1 plug. same cylinder went down on my 200hp (85 also). blew head gasket. confirmed damage by removing exhaust cover plate, you can view side of piston from there. can send you a nice picture of a burnt piston! that should also be a chrome bore, any pitting you'll have to resleeve it no honing! let me know what you find.

 

[gvh]

Re: Water Pressure Relief Valve(popit)

Thanks, trum I'll look at that this weekend and get back with good or bad news.

 

[KCLOST]

Re: Water Pressure Relief Valve(popit)

Pitting vs Repair, is really a matter of how much. <br />I recently replaced a leaking head gasket on my 175hp (actually both), and every cylinder had a few very small pits in them. "Very Small" I might add, but they were present, even though only one cylinder was getting water into it. Anything larger than a pin head might be reason for repair, but less than that I think you'll be ok, especially considering the repair costs and the age of the engine. Compression was 125psi in every cylinder... <br />If the pits are so deep they have eaten through the sleeve, now that's another story...<br />Just My Opinion.

 

[Boston Habba]

Re: Water Pressure Relief Valve(popit)

Quote from Merc manual; "IMPORTANT: DO NOT mistake porosity for a damaged cylinder". Test by applying muriatic acid (hydrochloric acid or HCl). If it bubbles, the pitting is through to the aluminum head and the cylinder needs to be sleeved. If no bubbles, no worries.

 

[KCLOST]

Re: Water Pressure Relief Valve(popit)

"If the pits are so deep they have eaten through the sleeve, now that's another story..."<br /><br /><br />Thanks Boston, I always like a quote to back me up...