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Oil Thermostat
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rholder(at)avnet.co.uk
Guest

Posted: Mon Jan 23, 2006 1:37 am Post subject: Oil Thermostat

I have fitted and test flown my oil thermostat. I fear

that it is faulty.



I was expecting that the oil temperature would go quickly

up to 80 or so and stay there whatever I did, unless I

went to a really hot place when the temp would go up.



I spoke to Steve Slade who currently owns G-MIKI the

microlight that Nigel Beale put the original thermostat

on, and on which the mod 10179 is based. He confirmed that

his plane temp goes to 80 and stays there.  he also said

that the original purpose of the mod was to get the oil

warming up quicker.



My oil did not warm up quicker. On take-off the

temperature rose to 95 on a very cold day (3 degrees),

then it dropped to 60 in the cruise. 60 is where it used

to cruise on cold days without the thermostat and with

almost all the radiator blanked off.



My feeling is that the waxstat in the thermostat is

opening too early and is not opening enough so that some

oil bypasses the cooler even at over 90.



Anyone got any suggestions ? I am contemplating ripping

the whole thing off and getting another one.



I relate the sad tale now in case anyone else has bought

the device and hasn't fitted it yet. The waxstat needs

checking (dump in a saucepan of water, heat slowly and I

believe it should start to expand at around 75 degrees and

be fully extended (12 mm ?) by 85).



If anyone has fitted one I would appreciate feed-back as

to whether their oil temp goes quickly up to 80 and stays

there !



TIA



Richard

G-OWWW High Cross

mikenjulie.parkin(at)btop
Guest

Posted: Mon Jan 23, 2006 2:20 am Post subject: Oil Thermostat

Richard,



Please don't shoot!!!  But I have to ask the obvious - you are sure it is 

connected correctly??



regards,



Mike



PS.  Is it OK to fit this Mod (PFA wise), or are you 'pressing to test'.



---

rholder(at)avnet.co.uk
Guest

Posted: Mon Jan 23, 2006 2:48 am Post subject: Oil Thermostat

 	  Quote: 	
		   Please don't shoot!!!  But I have to ask the obvious -

 you are sure it is connected correctly??


	


Bang Bang !



 	  Quote: 	
		   PS.  Is it OK to fit this Mod (PFA wise), or are you

 'pressing to test'.


	


Mod 10179 approved for "all of type" 



Richard

ami(at)mcfadyean.freeserv
Guest

Posted: Mon Jan 23, 2006 1:02 pm Post subject: Oil Thermostat

The temperature at which the waxstat opens is usually stamped on the end of 

the insert (located inside the thermostat).



Duncan McF.

---

rholder(at)avnet.co.uk
Guest

Posted: Mon Jan 23, 2006 1:17 pm Post subject: Oil Thermostat

Duncan McFadyean wrote:



 	  Quote: 	
		   The temperature at which the waxstat opens is usually

 stamped on the end of the insert (located inside the

 thermostat).


	


Yes, it may be. I will look at it when I strip it all out

again ! Would the waxstat go from closed to open in just a

few degrees - so if it is stamped say 80 it would start at

75 and be fully open at 85, or would it be even tighter

controlled than that ?



Thanks !



Richard

ami(at)mcfadyean.freeserv
Guest

Posted: Mon Jan 23, 2006 1:45 pm Post subject: Oil Thermostat

Yes they do (i.e. open very rapidly within a few degrees) around the 

temperature that they are 'rated' for, and close less rapidly. If you try it 

in water you'll see what I mean; an element rated at 80 will be doing next 

to nothing at around 78, then be fully open by about 82.

Having to dig deep in memory for this one!

If the temperature at any time exceeds 140 C then the wax element is 

permanently destroyed.



Duncan McF.

---

mikenjulie.parkin(at)btop
Guest

Posted: Mon Jan 23, 2006 1:55 pm Post subject: Oil Thermostat

Duncan,



If the waxstat fails does it fail open, closed or in the position where it 

failed.



regards,



MP



---

pete(at)lawless.info
Guest

Posted: Mon Jan 23, 2006 3:00 pm Post subject: Oil Thermostat

If this is the inline oil stat available from Think Automotive the

figure they gave me were starts to open 73 degrees fully open 79

degrees.



Pete



--

ami(at)mcfadyean.freeserv
Guest

Posted: Mon Jan 23, 2006 3:16 pm Post subject: Oil Thermostat

More often in the open position, AFAIK.

Cars with failed thermostats tend to run cold, rather than the reverse.



Duncan McF.

---

nigel_graham(at)btclick.c
Guest

Posted: Tue Jan 24, 2006 1:13 am Post subject: Oil Thermostat

Wax thermostats used in cars were notorious for failing closed (overheating 

the engine) since the wax capsule would split and the wax escape. It was the 

bi-metallic thermostats that failed safe.



I have no idea how this oil 'stat fails but would guess closed.



Nigel

---

ptag.dev(at)tiscali.co.uk
Guest

Posted: Tue Jan 24, 2006 7:43 am Post subject: Oil Thermostat

Hi! Nigel

I've been keeping "schtumn" because I'm not a Rotax Buff. BUT.... this

thermostat idea on oil systems gives me the creeps what if ......!

Much better to focus on a pilot control facility like metering the oil

to the cooler by pilot controlled valve. I know this is something else

to constantly do but you should be always "heads up " on P's and T's

anyway.

I have a system of P1 controlled oil to cooler metered or even off

completely and the engine still gets full flow supply at all settings.

I rarely need to engage the cooler but I have an all air cooled engine.

Regards

Bob Harrison G-PTAG Europa MKI Jabiru 3300 



--

nigel_graham(at)btclick.c
Guest

Posted: Tue Jan 24, 2006 9:21 am Post subject: Oil Thermostat

Hi Bob,



I was watching this thread with interest. The thought of a thermostat on an 

oil system that relies entirely on crankcase pressure for the return (912/4) 

scares the willies out of me too!

As I understrand it, the Rotax oil thermostat by-passes the radiator but 

maintains circulation, unlike the car water system that stops (reduces) the 

flow.

If I were going to control the oil temperature, I would have a 

temperature-transducer controlled vane adjusting the airflow through the 

radiator - not the oil........much less risky.

Sounds like a mission for Mark Burton (should he choose to accept)!



Nigel



---

rholder(at)avnet.co.uk
Guest

Posted: Tue Jan 24, 2006 10:05 am Post subject: Oil Thermostat

Hi team



I am reporting back after further investigation.



To Nigel Graham, the crankcase pressure does return the

oil to the oil tank. Wierd but it does work. However the

oil cooler is NOT in that return. The oil cooler is

between the oil tank and the oil pump, which SUCKS from

the tank, through the cooler. The oil thermostat provides

a by-pass of the cooler - and indeed as the cooler

provides significant restriction to the sucking the

by-pass might well provide MORE oil to the pump. If the

thermostat failed closed then there would be plenty of

oil, but it would get hot rapidly.



I reported on Sunday about my experience. My oil went to

95 in a climb to 2500 feet and then down to 60 in the

cruise on a very cold (2 C) day. Neither was what I was

expecting and so today I ripped the thermostat out,

dropping only a small amount of oil on the hanger floor 



I checked the installation and I was happy I had done it

right.



So I brought the wax-stat home and put it in a saucepan on

the AGA. Eventually I found a Celsius thermometer and

tried it. Then I put an elastic band on it to provide a

return spring force. It worked exactly as I expected -

opening at about 73 and being fully open at 80. As per spec.



So I did some thinking, and drew it past Simon Nash who

has part-installed his. We decided that it is likely that

the sealing of the ports in the thermostat has been

compromised by the required drilling out of the ports to

10 mm. If in the hot position the disk that seals off the

by-pass doesn't quite block it off then oil will prefer to

go the by-pass route and not go via the cooler.



I have a "cunning plan" to check on this and I will report

back soon after it is installed and tested. It should

prove the problem of heating up too much in the climb. The

cruise coldness may be a by-product, but I can live with

that for now as it was a VERY cold day when I test flew

it, and I had no baffles whatsoever on the radiators.



In the mean-time - I would recommend anyone who has bought

one of these thermostats to avoid drilling out the ports

until I report back. Or if you have done two ports then

DON'T do the other two.



Another lateral thought - does anyone know if oil coolers

ever have a required direction of flow ?



Richard Holder, who can envisage installation, and then a

further removal and re-installation. In the brrrrrrrr cold !



G-OWWW, High Cross

rholder(at)avnet.co.uk
Guest

Posted: Tue Jan 24, 2006 10:55 am Post subject: Oil Thermostat

josok wrote:



 	  Quote: 	
		   Hi Nigel, Bob,


	


 	  Quote: 	
		   OA, the German Rotax dealer has as a Rotax addon an oil

  thermostat available. This is a thermostat with 4 ! 

 connections, and only changes the oil flow through the 

 radiator or direct. So, if this thermostat is closed, 

 the oil pressure does not even have to deal with the 

 resistance of the radiator.  If this thermostat would 

 hang closed, you would notice a rise in oil 

 temperature, if it stays open, oil would not reach a 

 sufficient temperature.  IMHO, a manual operated flap 

 or anything that adds to (this new-by) pilot workload 

 is more error-prone.


	


 	  Quote: 	
		   Regards,

 

 Jos Okhuijsen


	


Is that OA the dealer ? I thought the dealer was

Franz-aircraft, who do indeed have an oil thermostat. Not

approved here, but it works in exactly the same way as the

one that is approved.



They also have a water thermostat and we have no

equivalent of that approved ;-(



By the way - the oil going through the oil cooler (and the

thermostat) is not under pressure, it is being SUCKED into

the engine from the tank by the oil pump. Do not put the

oil cooler in the oil line between the sump and the oil tank.



Richard

ptag.dev(at)tiscali.co.uk
Guest

Posted: Tue Jan 24, 2006 1:18 pm Post subject: Oil Thermostat

Ok Jos thanks for that, However what if the cooler breaks and you start

loosing oil (I had that problem but only on a half hour flight!) With

mine the cooler is in circuit only a miniscule period of time so a leak

would be kept to the absolute minimum when you landed you'd get to

notice before the "donkey" packed up aloft !



I've just seen Richards message as to where the cooler on the Rotax is

situated so similar may apply except it would be pulling air in ......

don't you believe it IMHO oil would still p.... out !

Regards

Bob Harrison  G-PTAG Europa MKI/Jabiru 3300



--

ami(at)mcfadyean.freeserv
Guest

Posted: Tue Jan 24, 2006 2:56 pm Post subject: Oil Thermostat

Bob,

The recent problems with leaking joints on the Rotax-supplied oil coolers 

(MPD issued by PFA) resulted in air leaking in and loss of oil-circuit 

priming, not oil leaking out.



Before you you respond (!), don't forget that Jab's (particularly the less 

smoothly running 2200) have suffered numerous oil cooler circuit failures on 

a number of aircraft types (Rans S6 and Renegade to name two).

This is has a lot to do with the oil cooling circuit running at full system 

pressure.



Duncan McF.

---

Gilles.Thesee(at)ac-greno
Guest

Posted: Tue Jan 24, 2006 3:22 pm Post subject: Oil Thermostat

 	  Quote: 	
		   If this thermostat would hang closed, you would notice a rise in oil temperature, if it stays open, oil would not reach a sufficient temperature.  IMHO, a manual operated flap or anything that adds to (this new-by) pilot workload is more error-prone.



  



Hi all,
	




Although the following doesn't apply to a Europa, it may be of interest 

regarding Rotax 914 setups.

In our project, we decided to make a cowling from scratch, and I had the 

opportunity to design a radiator duct with cowl flaps. A short summary 

of the design principle can be viewed on my "wind tunnel" web pages.



The airplane has been flight tested from -14C to +37C with perfect 

ease of temperature adjustment. Operating the cowl flap is a breeze, and 

you always have a few minutes to adjust temperatures to your taste 

within 5C of target.

We had considered using a thermostat, but whereas it solves the 

temperature issue, the drag is always high. On the other hand, drag 

decreases when you close the flap.

Besides, if the thermostat fails in the by-pass position, the 

temperature rise will be fast and very harmful to the engine.



 From the messages about blocking the radiators, or adding thermostat to 

cowl flaps, I have the feeling that the cooling of Europas could benefit 

from this little research work.



FWIW,

Regards,

Gilles Thesee

Grenoble, France

http://contrails.free.fr

pete(at)lawless.info
Guest

Posted: Tue Jan 24, 2006 3:27 pm Post subject: Oil Thermostat

Evening All



Think Automotive sent me a drawing of the oil stat with some hand

written annotations.  As well as the temperature figures they clearly

marked flow from and to the engine and flow to and from the oil cooler.

On the diagram if you hold the stat so that the 2 screws that hold it

together have their heads at the top, then turn it so that the higher

pipe it to the right.  Now the right hand pipes are engine and the left

had pair the cooler.  Looking at the diagram the other way round would

have oil pressure pushing up the diaphragm and potentially opening the

stat.  I will send a TIF of the diagram off forum.



Regards



Pete



--

ami(at)mcfadyean.freeserv
Guest

Posted: Tue Jan 24, 2006 3:46 pm Post subject: Oil Thermostat

The heated and expanded wax causes the thermostat to open against spring 

pressure. As the wax cools, the valve is closed by the spring pressure, not 

"suction" of contracting wax, which would probably cavitate anyway.

As such, when the wax is lost there is nothing to push the valve open and 

the spring returns it to the closed position, so failing in that position.



I agree that the older mechanical versions fail closed.



The Mocal version of oil thermostat bypasses the cooler when "closed".



Duncan McF

---

ami(at)mcfadyean.freeserv
Guest

Posted: Tue Jan 24, 2006 4:01 pm Post subject: Oil Thermostat

You can find that diagram at 

http://www.xse.com/leres/ss/images/mocal2.pdf



Duncan McF.

---

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