Merc pressure/temp gauge?

[andrewkafp]

My early 80's 50hp Merc has a tube coming from the head and I think it's attached to a pressure gauge on the dash.<br />I assume it's for water pressure from the pump.<br />Along the line, it has what appears to be a car tube valve on a Tee piece. What is this valve for ? Is it to release any air that gets trapped in the tube ?Or to connect a pump to test the gauge ? The gauge seems not to work although the impeller is fairly new, water emitted is only warm and pressure from tell tale is very strong ..<br /><br /> http://www.myfishingpictures.com/img/004505.jpg

 

[andrewkafp]

Re: Merc pressure/temp gauge?

bmp

 

[andrewkafp]

Re: Merc pressure/temp gauge?

bmp

 

[corm]

Re: Merc pressure/temp gauge?

Hi Unicorn,<br />I passed on your post before but you have bumped enough. Th air valve is not std equipment, it must be there to back pressure the line. To drain salt water or clear the line so it doesn't freeze if you were here in Wi. I usually ues a larger dia hose for water pressure gauges than what comes with the kit. Take the hose off the back of the gauge and blow it with compressed air back to the motor to see that it is clear. If it is the pressure the gauge with 7lbs of air pressure to see if it works. The gauges are a bit tempermental. They only seem to work good for 5 yrs for me. Any way you can test it like I said. They are a good thing to have so you can tell what your pump is doing at all times. Some times you can trim off a bit of hose and reconnect it to make it work again. The hose colaspes with age and closes off the inside out it. Good luck.

 

[andrewkafp]

Re: Merc pressure/temp gauge?

Thanx Corm..<br /><br />Sorry 'bout the bumps.. But they DO work.<br />J.B. said it was OK. <br /><br />I'll give that a try. I thought, maybe the tee pce was inserted so that the tube could seperate when L/U servicing takes place.<br />I really haven't seen it work, then again it's not my main focus when using the boat.i tend to look at the Tell tale periodically instead.<br />I think I read that pressure gauges only really give a reading at higher RPM anyway an I do tend to drive like an old woman.

 

[corm]

Re: Merc pressure/temp gauge?

hehe, I've used the bump before,it works.<br />A good 15 lb gauge will work at low speed, but work best at low-mid to high RPM. I have a pressure gauge on all my boats except for one which hase a 9 lb fuel pressure gauge on it in place of a water one to get a better idea of the pump pressure. This gauge has a 270 degree face so it is real sensitive to change. I seem to have two speeds off and WOT. Unless the boss is along then I have to drive like you do

 

[andrewkafp]

Re: Merc pressure/temp gauge?

The boss is always along.. <br />and also has boat licence (We have to have them here) So as soon as it starts hopping over waves, the cold spoon is used..

 

[corm]

Re: Merc pressure/temp gauge?

Gee what a world,<br />Drivers lic to get to the lake.Trailier lic for the boat trailier. Boat lic for the boat on the trailier that is behind the car. Launch fee, not a lic but might as well be. Parking permit, is this a license too? Boat driver's lic so you can get away from it all and relax. Only to find out that someone has a lic that outranks yours, or is that a marriage license? I think I have a dog<br />lic tag on my colar. Sorry it is late here

 

[andrewkafp]

Re: Merc pressure/temp gauge?

Removed the cap to find a hollow tube. Pumped some air into it using a valved bike pump.<br />Checked gauge (Battery not connected) and saw no reading. I wouldn't have thought I would need voltage for a pressure gauge to work ?? <br />Conclusion. tube works.. gauge doesn't..I might remove a test/replace the gauge.<br />

 

[andrewkafp]

Re: Merc pressure/temp gauge?

BMP

 

[corm]

Re: Merc pressure/temp gauge?

Hi,<br />It is a direct read gauge (no power). I would take the hose off the back of the gauge and check the gauge there. The hose may have a kink or something in it. I would use an air tank to pressure the hose up for a test from the front to the back (motor) ahh stern is the correct term lol.

 

[andrewkafp]

Re: Merc pressure/temp gauge?

Good Tinken Corm... <br />Hence the high number of posts ...<br /> BTW The Cubic inch theory is starting to become a little inaccurate with these new WRX and BMW turbo buzzboxes <br />But with Boats.. it still applies.