temp. for 1992 Mariner 150 Magnum II

[avian22]

WoW!

If 150 should be my running temp. I have a long way to come down. My gauge reads about 135-140 under 3000. When I "Put it down", it goes up to about 190-200 and stays there (never over heats). Weird! Gives me the feeling that it's about to start overheating, but never does. Maybe my temp. gauge (which is new) is not reading correctly.

I am going to change my t-stat (which hasn't been changed in over 5 yrs. And, I'm going to flush it with some "Salt-away" (salt remover).

Question: Is the "poppet valve" different than the T-stat or is it "part of" the T-stat?

[Blue197320]

they are 2 different things. the poppet valve goes on the bottom of the block on the starboard side. its about in the location where your harness connects to the motor. should be less than 15 bucks to buy a new one from boat center. the stats are a few bucks each from boat center. its kind of a pain to do the poppet on your motor because of the lower cowlings. i think you have the same thing as i do. it might be easier to split them at the bottom and get to it.

[Bigshrimpin]

poppet is the relief valve on the bottom right (electronics side)of the block. There are a few different designs.

[Fr. Frank]

I ran a '91 XR4 on my Seafari for six years. I had 135* thermostats installed in place of the original factory stats which actually opened at about 148-150.

I also moniter water pressure constantly. I also had a water temp gauge AND a cylinder head temp gauge for each cylinder head. (Not my idea, actually. The man who remanufactured my motor installed those.)

Result was fairly constant water temp of about 140* while on plane, regardless of how hard I ran it. More than once, I pushed 5200-5500 rpms for more than an hour of constant running, and temp still hung at 140. In contrast, the temp would rise to 145*-150* at idle to 1200 rpms, while maintaining 7-8 lbs of water pressure.

The poppet valve is vital to maintaining proper water pressure, which leads to proper temperatures. Doesn't matter how good your thermostats are if you aren't getting enough water flow to properly cool the engine.

I would do the following, in order:

• Check the Poppet valve for proper installation.
• Check thermostats for proper opening and closing
• Check water pressure. (should be 6lbs minimum to 18 lbs maximum)
• Check/replace water pump impeller and check water pump to inlet tube mating.
• Run motor for 1/2 hour in mild acidic solution in closed system (in a drum or tub) I use 1 gallon of muriatic swimming pool acid in 25 gallons of water.

Let us know.

[Blue_Heron]

In addition to controling water pressure, the poppet valve also bleeds air from the cooling system. Look at the diagram Bigshrimpin posted. The hose fitting that feeds the poppet valve is at the top of the block where air pockets naturally form when the lower unit takes a gulp of air. Purging air from the system is just as important as controling pressure and flow. Air pockets in a water cooled engine = hot spots. Hot spots create stress when a part of the engine undergoes thermal expansion at a rate different from the part next to it.

Likewise, the T-stats are important for keeping the engine at the correct operating temperature. The rapid heating and cooling that occurs when loading and unloading an engine with no T-stats, and therefore no temperature control, create stress due to repeated, and often uneven, thermal expansion and contraction. That can't be good.

I agree with all of Fr. Frank's recommendations, but I've never run dilute muriatic acid through my motors. The slightly acidic solution I run mine in is the Suwannee River.
Dave

[Fr. Frank]

I agree with all of Fr. Frank's recommendations, but I've never run dilute muriatic acid through my motors. The slightly acidic solution I run mine in is the Suwannee River.
Dave

That'll work.

Seriously. ONLY run an acid solution through your motor for KNOWN salt scale or salt gel build up - NEVER as a preventative measure. I have only done this after opening the water jacket and seeing salt build up present.