water pressure needed to cool

[papastoy]

Dhadley or anyone , is it possible that by removing thermostats I have increased the flow at the pisser but the voltage regulator is not being properly cooled. Would an overheating voltage regulator give erratic RPM readings. Engine is a 1993 Evinrude 225

 

[Dhadley]

Re: water pressure needed to cool

Welcome!!<br /><br />Absolutely!! Without t-stats its very likely the block is not filling the water to the top. Without water at the top of the block, the cooling fins of the reg/rect are in air. If the reg/rect isnt cooling properly it may not function properly.<br /><br />It is possible for those reg/rect to fail in such a way as to catch the wiring on fire. I'd put the t-stats back ASAP. The motor should idle better with them in -- not to mention with them out it takes a real long time to come out of QuickStart -- if at all. Shifting it at those rpms can take a toll on the gears quickly.

 

[rabidfish]

Re: water pressure needed to cool

Ditto: It's a common misconception that "cooler" is better. A good rule of thumb is: only run without thermostats when your life is in peril. Overheating voltage regulators can do all sorts of silly tricks, usually right before they ignite!(or at least smoke alot) Otherwise what Dhadley said is right on the money!

 

[papastoy]

Re: water pressure needed to cool

Dhadley Rabidfish or anyone, I have just changed the impellarproperly done I believe - whole pump was done a year ago, all hoses are clear, with thermostat housing open the water gushes, with thermostats out , - the stream at the telltale is strong like a merc. I have tried 3 or 4 nearly new thermostats identical to what was in before. My problem has to be lack of pressure, what could be wrong with the pump or could there be something causing a lack of pressure somewhere along the route the water takes. Remember with the t'stats out the engine pisses like a horse so water does seem to be able to flow all the way through. How do you tell if thermostats are operating properly, I have the plastic black encased vernatherms with the rubber diagphram.

 

[Walker]

Re: water pressure needed to cool

Is your motor overheating????

 

[Dhadley]

Re: water pressure needed to cool

Lets start from the begining. <br /><br />First -- a 1993 225 does not use the vernatherm you describe. Lets look at the model number so we're all on the same page. <br /><br />Second -- lets answer Walkers question. Is it overheating? You didnt mention if it was or not, you simply asked if it was possible for the reg/rect to overheat without t-stats.

 

[papastoy]

Re: water pressure needed to cool

Dhadley & Guys the model number is AE225 TXETX and the serial # is G02951696.<br /><br />The engine does not overheat at idle with thermostats in although there is no flow at the telltale but does overheat at cruise. With both t'stats out it does not overheat at idle or cruise but tach becomes erratic after a few minutes of cruise. The black plastic cased vernatherm must have found its way in when t'stats were changed a year ago but I now know from a parts manual I just saw today that they are not original t'stats. The original t.stats are not available down here. Maybe this is the problem as I have changed 3 tachs and the voltage reg in the last 6-12 months and have never been able to figure out why my V/R was destroying tachs.

 

[Dhadley]

Re: water pressure needed to cool

Ah! OK the model number is for a 1993, good info.<br /><br />By any chance is there a little round valve hooked to the throttle arm on the starboard side of the block? With several hoses attached?

 

[pjb]

Re: water pressure needed to cool

Yes there is , the hose that goes to the telltale opening in the cowling comes from it as does another hose with a T junction and the water feed to it is from the starboard side thermostat housing. If its not the thermostat maybe the pump is not generating enough pressure or there is a leak in the water pipe in the casing where it connects under the power head.

 

[Dhadley]

Re: water pressure needed to cool

OK, someone has put a 1992 or older powerhead on a 1993 mid section.<br /><br />Describe exactly what happens at cruise speed. Does the horn come on indicating an overheat? We assume so as you say the motor does not overheat with the t-stats out.

 

[pjb]

Re: water pressure needed to cool

At cruise with tstas in, there is no flow at the pisser and it will overheat in a few minutes - no alarm functioning any more but temp runs up to 180 and climbing. Pressure guage reads 3 0r 4 instead of usual 10 or 12. With tstats out lots of flow, no over heat (tried it for 15 minutes) but after a few minutes running the tach becomes extremely erratic. I believe we have got to look at the water pipe in the casing where it connects under the engine mounts to see if there is corrosion or blockage . What do you think and what are the things to look for if we do this

 

[Dhadley]

Re: water pressure needed to cool

Did it ever work correctly?

 

[pjb]

Re: water pressure needed to cool

Yes for the last 2 years but I have changed a few tachs in this time which may have been due to the V/R runnuing hot. As of now it overheats with thermostas in at cruise and with them out at cruise engine runs fine but tach is erratic and as you say this is a\bad idea for several reasons.

 

[Dhadley]

Re: water pressure needed to cool

OK, so it never really did work correctly. You may have to make some cooling mods as this powerhead (with its cooling design) was not intended to be used on this mid section. <br /><br />I know you say you have the overboard indicator. Are you refering to the hose thru the pan or the indicator in the middle of the exhaust relief holes? Or do you have both?

 

[pjb]

Re: water pressure needed to cool

Dhadley, if you see my other post (which we should now close ) you will see we put on a whole new leg ( around 2002) yesterday. I have one hose that goes from the round valve hooked on the throttle lever to the exit hole on the cowling and another hose from same place that goes to 2 places a) a plastic nipple at the right lower side of the block and b) to a long hard cased tube that loops all round the base of motor and just sits in the cowling. Please let me know if any modifications are neccessary with this set up or to get the V/R to cool better

 

[seahorse5]

Re: water pressure needed to cool

OK, I just read this thread for the first time, after I was following and responding to the "engine overheats with thermostats" thread.<br /><br />Your '92 and earlier cooling system uses water pressure against the rubber diaphragms to hold the thermostats against the engine block (rubber grommet seal) to make the engine run warm at lower speeds.<br /><br />As the throttle is opened, the water valve on the throttle lever diverts the water pressure from the diaphragms to overboard. The thermostats then come off the rubber grommets and water flow unimpeded thru the cylinder block, letting the motor run cooler at high speeds.<br /><br />I believe part of your problem is the plumbing on the water valve. Disconnect your throttle cable and all the hoses. Blow thru the water pressure hose from the adapter plate while the throttle is closed, and the air should go thru the hose to the thermostats. Keep blowing as you advance the throttle, and the air should then start flowing out the overboard water hose, and you should also be able to blow air from the thermostat hose to the overboard hose.

 

[seahorse5]

Re: water pressure needed to cool

I just thought of something else to check. Make sure there are no transducers, speedo pickups, thru-hull fittings, or hull strakes within 14" of the propeller centerline. Anything within those 14" disrupts the water flow into the gearcase inlets and causes areated water to flow thru the motor, which can result in improper cooling.

 

[Dhadley]

Re: water pressure needed to cool

If youre using the overboard indicator like on the 92 and earlier there will be a hose thru the pan. If you use the 93 and newer adaptor plate the is an indicator between the exhaust relief holes. If you do indeed have 2, I would try closing one. You may be losing too much water.<br /><br />I would also verify that you have the hi volume pump.