engine running hot

Stan V

Active Member
Joined
Jan 23, 2011
Messages
1,271
Location
Monticello, GA
Aircraft
Piper Arrow/RAF2000
Total Flight Time
450
Has anyone else had an overheating issue with their RAF? I've replaced the thermostat twice. I now have a stainless 172 degree Stant and it still runs at 200 degrees. I've done everything I can think of - flushed the coolant, etc. Has anyone gone to a larger radiator or added an oil cooler? This is a 2.2 FI engine.
 
The thermostat determines the minimum operating temperature, the pressure rating of the radiator cap determines the max coolant temp.
Most autos run at least a 7 psi cap, which places the boiling point of water at about 230.
Has it been determined that 200 degrees is objectionable?
I believe it is best to keep the oil temp at about 200 to keep the detergents working and the water vaporized out.
This is all my opinion only, I know this has been debated for years.
 
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Lee, I've got a 16-lb Stant cap on it now. Are you saying if I run a lower lb. cap, I can get it to run cooler?
 
Hey Stan, The 16 lb. cap just raises the boiling point of the coolant. The load on the engine and the sizing of the radiator more determine how cool it will actually run at.
I was just wondering if 200 was too high a coolant temp. That seems reasonable to me considering the load imposed on the engine.
I think the NASCAR guys routinely run 250 degrees.
p.s. I'd bet that a properly tuned and well running soob in an automobile will be running well above 200 on a hot summer day. Just loosen the radiator cap with a broom handle and see.
 
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I ran up to 200 today doing some high powered stuff but it didn't go over. When I trimmed out and stopped playing around I dropped back down to 160-180. Your yellow and green bug should meet right at 200. So I think you are good. Is it 200 just running trimmed out flight at cruise?
 
When I'm solo and trimmed out on a cool day, I'm still running 200 degrees. Whether it's a cool or hot day seems to make little difference.
 
Ah ok yea that's not right. Could also disconnect your heater core and run it back through the engine and see if that changes anything. Has it always been like that?
 
Brian - I have not taken the heater core out of the equation. I did install a bleeder tube on the upper heater hose in order to get all the air out of the coolant system. I've also been flying with the cabin heat fan turned on. There have only been one or two short flights I've made where the temp has run at about 190. This is a new engine and I worry about damaging it if I don't get it figured out. I've been running 90 octane ethanol-free marine fuel and added an octane booster. So I don't believe my fuel is an issue. When I talked to you in Florida you said you were running 87 octane on your 2.2FI, and it didn't seem to be causing you an issue. My manual calls for 93 octane unleaded, and they warn you about the damage that can be caused to the engine if you don't comply. So I've complied!
 
Oh yea. I remember you. I forget where you are from though. Elevation pretty much at 100-200 around here and I'm fuel injected. Never had a hiccup on 87 test. Wouldn't do it on carbed engine though. Follow the manual.
 
Get a laser temperture gun from your local auto parts store and have someone shoot the engine when you get the temperature up, it may be running cooler than you think. Last year I spent a lot of time and money trying to diagnose a hot engine. Changed thermostat, changed radiator cap, flushed the radiator, took the radiator off and had it cored out. Nothing worked, got a temp gun and had someone check it when it showed it was overheating, it wasn't. Bought a new sending unit, $9, that did the trick.
 
Thanks, Mike, great idea - I may not actually have a temp problem at all. I've already looked up the part number for the sending unit and hope to pick it up tomorrow. That was my next item to eliminate! I'll also see how affordable a temperature gun is. I'll try this next, since nobody appears to have gone to a larger radiator or added an oil cooler.
 
Make sure your running a 180 degree thermostat. That is what the repair maunal says use for that engine. Had a bit of a problem with my 1st RAF back in 2000. Comapny said they put higher degree thermostats in for some reason, forget what now. But when I found out what the book called for in that engine and put it the 180, no more trouble. Takeoff it would get to 199 then at cruise settle do to 180, on a hot day in the summer in Florida.
 
Stan,
In the summer I was running over 200 due to the 100 degree days.
Dolfin told me the old radiators were single pass & RAF changed them to 3 pass.
My gyro is a 1999 with EJ22 with a carb.
I took my radiator to a local shop & had them install 2 baffels to make it a 3 pass radiator, now it stays around 180.
 
I had. A problem when I first started flying mine. It ran in the 200 degree range. I bought some wrap for my mufffler. Wrapped it put two large hose clamps on top of it to keep the heat from my radiator. I don't see above 180'even in the summer. Good luck on your research.
 
rgraffeo said:
Stan,
In the summer I was running over 200 due to the 100 degree days.
Dolfin told me the old radiators were single pass & RAF changed them to 3 pass.
My gyro is a 1999 with EJ22 with a carb.
I took my radiator to a local shop & had them install 2 baffels to make it a 3 pass radiator, now it stays around 180.

Could youe xplain the single pass vs 3 pass?

Thanx....

Tommy
 
The radiator had the water entering the top & flowing straight down to the bottom through all the passages, only one pass.
We placed a plate 1/3 of the way on the top header & 2/3 of the way on the bottom header.
This forces the water to make 3 passes before it goes to the water pump.
A local radiator shop did the work & charged me about $50.
I hope I explained it good enough.
 
Had the same problem. After consulting the gauge maker, was told to ground the temp gauge by itself somewhere. The temp gauge does not like shared grounds. It can be on the same ground bar, just not attached to any other grounds from other instruments or radios. I went through the same drill.....new radiator caps, infra-red temp sensor, flushing the radiator, "Water-Wetter" and on and on. Moved one wire and the problem was solved.
 
The ground wire would be the easiest and cheapest fix, try it.
When I did my drop keel/engine I moved my radiator to the other side of the vertical engine mount bars away from the exhaust.
Always runs at 180* even when it's 104* here in Calif.
Good luck.
 

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Had the same problem. After consulting the gauge maker, was told to ground the temp gauge by itself somewhere. The temp gauge does not like shared grounds. It can be on the same ground bar, just not attached to any other grounds from other instruments or radios. I went through the same drill.....new radiator caps, infra-red temp sensor, flushing the radiator, "Water-Wetter" and on and on. Moved one wire and the problem was solved.

Hey Ken,
You showing up usually means you are usually up to something. Getting back in?
Larry
 
Hey Ken,
You showing up usually means you are usually up to something. Getting back in?
Larry

If my lotto tickets come through for me and I can afford to move back to San Diego..
 
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