Rc8 thermostat

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J

J Cianflone

Does the Rc8 have a thermostat if so where is the darn thing??
 
J

J Cianflone

Thanks Jack

Thanks Jack> It appears you are the most knowledgeable one on the Rc8. I am new to the Rc8 as I acquired my 1980 H27 in November. I am familiar with the boat and deisel as my gramps had the same boat for a number of years. I have a problem with the temp gauge on the switch panel of the Rc8. It is telling me my engine is running hot although I can put my hand directly on the engine block when the needle on the temp guage is pinned past the red. I swapped the impeller. I did indeed have to change the bolts on the pump housing. Water is moving through the engine and out through the exhuast. Any ideas???
 
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Bob

Renault Temps

What is the water temp where you are motoring? I find that I run mid to 2/3rds on the dial range in the cool season with water temps in the 60's but as the summer progresses I hit the edge of the red.... If it hadn't been that way for several years I'd be nervous and I'd be lying if I said I don't get nervous anyway hehe! Degreasing the engine is imperative for cool running in the July/August months! Bob
 
J

J Cianflone

water temp

The water temp in florida is about 82 degrees now. My needle jumps past the red after 5 minutes under power. Plenty of water moving through
 
J

Jack Laird

No temp prob.

I must assume that you are switching the switch to the down position after starting the engine. Thats the switch in the upper right corner of the control panel after starting the engine. For some reason the water temp gage dosn't work if its in the up position with the engine running.
 
J

J Cianflone

Learn something everyday

After starting the engine, switch(top right) is in up position I have always left it there(up) I should throw that switch down after I get her started?
 
J

Jack Laird

Yes please down to run up to start.

Note what this does to your temp. gage. Ahhhhhhh now its in the green. Enjoy.
 
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JoeGooch

No Thermostat, No Problem

My l980 27 Hunter Renault has no thermostat and no heat problem. However, the hot wire to the control panel goes to the on switch for starting the diesel; it also then feeds the rest of the panel including the temp guage when it is in the on position. The way the temp guage works is that it has a positive charge on one side and the other side is connected to the sending unit on the engine for a ground. The ground has varying degrees of ground depending upon the temp of the engine and that is why the temp guage reads different temperatures. I do not see how it can work with the start switch switched to off because there would be no positive charge to the temp guage; for example, my guage just flops around when the switch is off. When the switch is on it doesn't read any temperature because the engine is "cool" as it should be. If water is surging through the engine and you can place your hand on it, it is running cool; that is as it should be. This little diesel is the simplest engine and absolutely dependable; I recommend that you make a start rope because of battery failure or loose wires sometime might keep you from starting it with the electric starter. A good stiff pull with the throttle open a bit and she will start chugging away. Remember that this is the engine that "takes a lickin and keeps on tickin". Good wind, Joe
 
J

Jack Laird

Sounds like a Hunter wireing problem

When the switch is in the up position the temp gage is in the red always. When in the down position in the green, middlw of. Guess I don't understand it either. Just know that water is comming out the back, the engine isn't hot as its just been started. You guys must be real men to start that thing with the rope. Wow i'm impresed. Seems like each Hunter has its own differences. For example I've never seen another with an interior like mine. I've had it 17 years and I'm the second owner, so.
 
J

JoeGooch

Mercury or wire thermostat

Jack, Glad to get such a quick response. As to the wiring of the panel on the 27 Hunter and thermostat, if the thermostat is a mercury filled thermostat it makes no difference whether or not the electric switch is on because the mercury switch would act like a thermometer. A wired switch with a sending unit must have a charge on one side of the temp guage for it to work in order for the sending unit to ground it through the temp guage. And, at least I am working with guages and sending units that are 20 years old. But, without another source of power to the positive side of the temp guage, I do not see how the guage can read anything. And, the only hot wire coming to my control panel is on the start switch, so when the switch is off there is no power to the panel for the temp guage or for the alternator to charge. I am now tempted to take the sending unit out of the block and put it in a pot of hot water to see what it does. If I have time, I'll get back to it and see. Meantime enjoy the "cool" little engine. Joe
 
J

Jack Laird

Maybe!!

Maybe my sending unit dosen't work at all. Think that more work is in order. I'll also dig out the wireing chart for the H27 and see what I can see. Lets get to the bottom of this. I know that my engine dosn't run hot but is the gage good?
 
J

Jack Laird

More Info.

According to the good book the normal temp on this engine is 120 F. Also note that the engine probe is six volt with a 12 volt receiver this is so the gage will report mid scale when normal temp is experienced. Tech Notice # 2992 1 June 1980. More to follow I hope.
 
Dec 2, 1999
15,184
Hunter Vision-36 Rio Vista, CA.
120F?

this does not even seem reasonable. Gonna overheat quick in 100F ambient air temp and 86F water temp.
 
J

Jack Laird

That's the book answer

Now we all know that Hunter didn't have all the answers, well I guess Renult didn't either. I did check the wireing diagrams and you guys are correct. Only with the switch up (on) will the gage work. OK then why is mine in the red all the time? Maybe its the sender is bad or the gage is bad. But I get deflection on the gage but only from on and off. What we need is a way to test the sending unit. Any ideas? Tomorrow morning I'll pull the starting panel and check that the wireing is as advertised in the book. Think that I'll also disconect the wire from the gage and see if that's significant in lieu of the of on switch. Ho Ho won the club race tonight didn't have much time to check wireing. Ideas please. More to follow tomorrow, I hope.
 
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JoeGooch

The Hot Water Test

Jack, One way to check the sending unit is to remove it from the engine block and place it in different degrees of water. If all is well the guage should move accordingly; this assumes that one side of the guage is activated or has a hotwire to it. To check the guage remove the wires; attach a hotwire clip to one side of the guage and ground the other side; the needle should go over all the way, one way or the other; if you reverse the hookup the needle should go the other way. The sending unit partially grounds the guage as the water temperature changes and it grounds more or less. If all fails, a generic mercury type direct temp guage might be put in but with that engine running so cool that a hand can rest on it, it probably is not worth the effort or cost. Will keep checking to see the results. Joe
 
J

Jack Laird

Responce to JoeGooch

Will try as you suggest will pull sending unit tomorrow morning and see if clean, etc. will also check gage with hot wire. Gage at present shows needle in center of green with no power and in center of red with power even when engine off overnight.
 
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