High Oil Temp Anomaly

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Dee

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Currently I have 4 hours on my new 1/2 VW 45hp Hummel engine. With the first 1.5 hours flight time during much climbing (touch-N-Go's) and some rpm’s around 3000, I got no indication of high oil temp (temp was in normal range of 210-220F). Today’s flight of 1.5 hours with virtually the same weather temp and cruising at only 2600 rpm, I suddenly got an oil temp of over 250F. The question is . . . What do you think might have caused my oil temp to suddenly climb to over 250F ? Possibly oil foaming ? The oil level is maintained at 2 quarts.[FONT=arial, helvetica, sans-serif]
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[FONT=arial, helvetica, sans-serif]My Hummel engine has a Zenith carb with oil tubing coiled around the intake manifold. If high oil temps persist, would you recommend a) simply adding an oil cooler (heat exchanger) or b) removing the oil tubing around the inlet and then adding an oil cooler ?[/FONT]
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[FONT=arial, helvetica, sans-serif]Also, [FONT=arial, helvetica, sans-serif][/FONT][FONT=arial, helvetica, sans-serif]Should I be using an oil with a non-foaming agent? I’ve heard that this is advantages. What oil is best for the 1/2 VW engine?
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[/FONT][FONT=arial, helvetica, sans-serif]Also, I have the Zenith carb idle jet set at 1-1/2 turns open and the main jet set at 3 turns open (getting black spark plugs). What is the best jet setting for the 1/2 VW engine?[/FONT][FONT=arial, helvetica, sans-serif][/FONT][/FONT]
 

Hot Wings

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We need more data. Pictures are good

Oil - run what Casler recommends. He built the motor and this removes one variable.

"Suddenly"? As a noticeable spike during the flight or just that it was noticed on this flight? In either case double check the temperature sender against it's ohm/temp specifications. This removes another variable.

Jet setting? All engines are different. Even if they are identical at the core they get operated in different conditions, like base altitude, normal temperature, humidity and cowling configuration. This is just part of owning and operating an Experimental airplane. Spark plug color and EGT are the 2 most common parameters used to adjust mixture. An add on O2 sensor works too. Even an old school narrow band is a valuable tuning tool. Colortune is another, but it's not the best choice near a rotating prop. :whistle:
 

N8053H

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On my 45hp half I would also get black plugs. I started running LOP on taxi or anytime when on the ground and my plugs then stayed nice and clean. After 100 hrs flight in a year my plugs looked brand new like they were just installed.
As to oil temps, mine never did run high oil temps, but I did have a cooler mounted under the engine. It had a flap or door that could be opened or closed to stop the airflow through it. It all ways stayed closed except when it got to around 100 degrees outside.
 

Pops

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To me normal temps is not 210-220 degs for long engine life for a VW where the oil is used to cool a large percentage of the engine. I'll take 185-195 degs/
 

Rockiedog2

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Shouldn't need a cooler. Check the gauge. Mine has run that high on high ambient temp days. Use Mobil one with zddp additive. Run it some more and see what does.
 

Dan Thomas

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If it's an electric oil temp gauge, it might be a bad engine-to-airframe ground. In certified airplanes this sometimes occurs. The alternator is grounded to the engine, and in some airplanes it also has a ground cable to the firewall. If any part of that ground path gets loose or oil-contaminated, the ground current from the alternator tries to find some easier paths. One of those is though the oil temp sender, which is grounded to the engine, and the alternator's negative ground output forces electrons into the sender, through it and to the gauge in the normal direction of electron flow. That tricks the gauge into reading higher. Cessna had a service bulletin advising installing a small (18 or 20 gauge) ground wire from a point near the sender to the gauge case to prevent erroneous readings. A better approach is to check the entire ground path between engine and airframe. Bad grounds only get worse. The engine gets harder to start. In extreme situations, the ground current can run through engine control cables and fry them.
 

Dee

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Thanks for the information and suggestions. Scott Casler has also suggested that I may need an external cooler and that there's no need for a special oil.. I have a cooler on order and plan to install it and changes the oil to a zddp oil. Then I'll see if this improves the situation. Thanks again.
 

Dee

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Messages
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Location
Baton Rouge, LA, USA
On my 45hp half I would also get black plugs. I started running LOP on taxi or anytime when on the ground and my plugs then stayed nice and clean. After 100 hrs flight in a year my plugs looked brand new like they were just installed.
As to oil temps, mine never did run high oil temps, but I did have a cooler mounted under the engine. It had a flap or door that could be opened or closed to stop the airflow through it. It all ways stayed closed except when it got to around 100 degrees outside.
What is "LOP" . . . Thanks
 

Rockiedog2

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Thanks for the information and suggestions. Scott Casler has also suggested that I may need an external cooler and that there's no need for a special oil.. I have a cooler on order and plan to install it and changes the oil to a zddp oil. Then I'll see if this improves the situation. Thanks again.
The reason for the synthetic is it will stand higher temps than regular dino oil so while you're figuring it out you'll have a little extra pad. Or go ahead and run straight dino during break in and go syn after about 50 hours if you like; the dino may break in better. I don't know what cylinders you got. If you go synthetic after breakin you should get about 100 more rpm out of it, it takes power to pump oil
Don't take my word for it but I think if you research you will decide to run zddp. Or you can ask the experts here. I'm not one of those.
I got an oil cooler here; tiny little devil that I think was intended for a Harley Sportster. Got it in here thinking I would need it and it's still in the box. No need. Mine is no cowling Legal Eagle.

Yeh if I were you I would do what Scott says too.
 

Pops

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The reason for the synthetic is it will stand higher temps than regular dino oil so while you're figuring it out you'll have a little extra pad. Or go ahead and run straight dino during break in and go syn after about 50 hours if you like; the dino may break in better. I don't know what cylinders you got. If you go synthetic after breakin you should get about 100 more rpm out of it, it takes power to pump oil
Don't take my word for it but I think if you research you will decide to run zddp. Or you can ask the experts here. I'm not one of those.
I got an oil cooler here; tiny little devil that I think was intended for a Harley Sportster. Got it in here thinking I would need it and it's still in the box. No need. Mine is no cowling Legal Eagle.

Yeh if I were you I would do what Scott says too.
Yes-- Talk to Scott.

If I do not warm the oil up before takeoff, at WOT on climb out the RPM will be down 50 RPM. When the oil temp come off the peg, and taxie to the end of the runway the oil temp will be OK to takeoff.
 

lr27

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Call me a pessimist, but it might be worth draining a bit of oil and seeing if there's any metal in it.
 

Rockiedog2

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Dee you got the motor with the little sump underneath? In case you don't already know there's an oil screen in there and like lr27 said I always check mine a few hours in on a new motor and change the oil...yeh it never hurts.
I dunno if Scott is still using the same breather setup I got but on mine if I put 2 qts in it will blow out about a half quart. On mine it goes all over the PIC left knee. Part of the fun. I only use 1.5 qt.
 

Daleandee

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If I do not warm the oil up before takeoff, at WOT on climb out the RPM will be down 50 RPM. When the oil temp come off the peg, and taxi to the end of the runway the oil temp will be OK to takeoff.
Engines have different requirements for oil temps. My hangar buddy flying a Lycoming powered aircraft sometimes heads to the runway shortly after startup, even in the colder weather. I asked why he doesn't warm the engine. He said Lycoming states that if the throttle will advance without stumbling it is ready to fly. He is correct: http://11hc.44rf.com/manuals/engine-prop/lycoming/aerosportspower-library/360_series_ops_manual/sec_3a-operating-instructions.pdf

On my Corvair the recommenced take-off oil temperature is 150ºF. I use that and it has worked well. Even on the full case VW in my previous Sonex I used to make sure the oil was quite warm as cold oil & WOT for take-off can cause some pretty high pressures and that's when things like oil filters and oil coolers like to go "bang."

Dale
N319WF
 

Pops

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Engines have different requirements for oil temps. My hangar buddy flying a Lycoming powered aircraft sometimes heads to the runway shortly after startup, even in the colder weather. I asked why he doesn't warm the engine. He said Lycoming states that if the throttle will advance without stumbling it is ready to fly. He is correct: http://11hc.44rf.com/manuals/engine-prop/lycoming/aerosportspower-library/360_series_ops_manual/sec_3a-operating-instructions.pdf

On my Corvair the recommenced take-off oil temperature is 150ºF. I use that and it has worked well. Even on the full case VW in my previous Sonex I used to make sure the oil was quite warm as cold oil & WOT for take-off can cause some pretty high pressures and that's when things like oil filters and oil coolers like to go "bang."

Dale
N319WF
On the later VW cases, the oil control valve close to the flywheel end is a high pressure regulating valve. I bought an adjustable screw cap and set the high pressure at 56 lbs. I had an oil filter split one morning before installing this. I use a full flow remote oil cooler.
Drill the allen head bolt for a safety wire.

https://vwparts.aircooled.net/Oil-Pressure-Adjuster-Kit-p/oil-pressure-adj-kit.htm
 

Daleandee

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On the later VW cases, the oil control valve close to the flywheel end is a high pressure regulating valve. I bought an adjustable screw cap and set the high pressure at 56 lbs. I had an oil filter split one morning before installing this.
I've still got one of those for a VW engine somewhere in the hangar.

William Wynne makes one for the Corvair engine: https://flycorvair.net/2014/09/03/adjustable-oil-pressure-regulator-2010a/

I don't use one. I was up flying tonight and my cruise oil pressure was 44 PSI at 186ºF. That's right where I like to see it. When it's cold the oil pressure can get pretty high until the engine warms up.

Dale
N319WF
 

Pops

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I've still got one of those for a VW engine somewhere in the hangar.

William Wynne makes one for the Corvair engine: https://flycorvair.net/2014/09/03/adjustable-oil-pressure-regulator-2010a/

I don't use one. I was up flying tonight and my cruise oil pressure was 44 PSI at 186ºF. That's right where I like to see it. When it's cold the oil pressure can get pretty high until the engine warms up.

Dale
N319WF
That is good, where I also like to see it. On the 1845 cc engine, the cruise oil pressure was 43/44 psi and the oil temps stayed in the 180's, highest oil temp that I have seen was a 100 deg day and a long WOT climb to a high altitude and it went to 192-195 temps. My hot idle oil pressure was 20 psi.
 
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