Water Pressure

[ddaigle]

1989 evin 70 hp. This motor belonged to my dad and has been in salt water all its life, seldom if ever being freshwater flushed. Several years ago It had some overheating issues and the mechanic took the thermostat out and said he drilled some holes for extra cooling( I have no idea where). This motor has always ran great. I recently inherited it and tried to install a water pressure gauge. I got no reading off the gauge so I bought another new one and still no reading. I hooked it up per instructions to the peehole line- no good. So I drilled a hole in the thermostat cover and installed a fitting -still no reading. Has a new water pump and pumps water well. Where can I get a pressure reading?

 

[iwombat]

Re: Water Pressure

You should be able to get one off the indicator line, like you tried. Does it push water out the tell-tale hole?

 

[ezeke]

Re: Water Pressure

The tee that came with the gauge is supposed to restrict the flow to the tell-tale outlet enough to give you a pressure reading.

Where is the tell tale elbow fitting on the engine now?

 

[ddaigle]

Re: Water Pressure

Yes it does, it pumps out the tell tale and quite a lot out the two holes in the midsection, and out of the prop, just not with a lot of pressure. Probably because it has no thermostat and is a straight through system. Also, I say it has no thermostat but it looks like it has a bearing seal hammered into the opening to restrict the flow somewhat. Could I get a pressure reading if I tapped directly into the tube coming off the water pump?

 

[Silvertip]

Re: Water Pressure

With the engine running, pinch off the end of the tell tale line. See if that provides a pressure reading. If it doesn't, I'd be interested to know where the holes were drilled as that alone may be the problem. That engine didn't need any holes drilled. What it probably needed was a thorough flushing and a new thermostat and bypass valve. Do not run the engine without those parts as it will run too cool.

 

[ddaigle]

Re: Water Pressure

I even did away with the tee and hooked the gauge direct to the pee line with no result.

 

[ddaigle]

Re: Water Pressure

This motor has been running this way for probably10 years. I run it almost weekly, and I run it hard and it runs perfect every time. Its a mystery to me.

 

[ezeke]

Re: Water Pressure

Did you get any water in the air line to the gauge?

You might want to review OMC service bulletin # 2276.

 

[tashasdaddy]

Re: Water Pressure

there is a picture in this thread. http://forums.iboats.com/showthread.php?t=234569

 

[Silvertip]

Re: Water Pressure

Yes it does, it pumps out the tell tale and quite a lot out the two holes in the midsection, and out of the prop, just not with a lot of pressure. Probably because it has no thermostat and is a straight through system. Also, I say it has no thermostat but it looks like it has a bearing seal hammered into the opening to restrict the flow somewhat. Could I get a pressure reading if I tapped directly into the tube coming off the water pump?

With no thermostat or bypass valve how can you expect it to have any pressure. And no, tapping directly into the water pump outlet will not help either. Your cooling system is wide open -- it simply is not good for the engine.

 

[guy74]

Re: Water Pressure

If my understanding of the way the cooling water circultes in that type of motor is correct, with out a thermostat installed there would be no back pressure to register on your gauge. That is the problem you state that you have no pressure reading on your water pressure gauge, right? If you are worried about cooling, and want your pressure gauge to work I would think that you would need to install a new thermostat and bypass valve. Although running too cool isn't as hard on a motor as too hot, it still isn't good for the motor and will eventually kill it.

 

[ddaigle]

Re: Water Pressure

Thanks for the help guys, I had a feeling it was because it just blows water straight through the motor. But, as I said it has been like this for a long time and due to my dad's poor maint. it would overheat with a thermostat in it. It may not be as bad on it down here since the water temp. is usually in the 80's

 

[Silvertip]

Re: Water Pressure

Engines can cold-seize as well as from overheating or lack of oil. Cold seizing occurs when the pistons heat up quicker than the surrounding metal in the block. The clearance closes up and a plug (piston) that is now too big for the hole (cylinder) no longer fits.