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mdnanwelch7(at)hotmail.co
Guest

Posted: Wed Dec 16, 2009 1:55 pm Post subject: Rotax 912 Question

Bob C Rick  Lewis & others C

   I also have the inline coolant thermostat C for my GEO's coolant system.  I chose to use a complete system from a big engined road bike (Honda Interstate C IIRC C but I'm not exactly certain which brand).  I got the waterneck/thermostat housing (which is an inline arrangement) C the coolant recovery tank C the radiator C and the thermostatically controlled electric fan.

   One of the reasons I specifically chose this particular system is that the waterneck housing ALSO has the radiator cap C for easy fluid filling and monitoring.

   Now C for you folks that have Rotax 912 engines C you're likely going to stay with the factory parts C which is perfectly fine.  But C for those of us with "alternate" water cooled engines C you just about can't beat the selection of high quality motorcycle choices.

   Of course C you're going to want to do a lot of research first C and make sure you size the coolant system correctly.  In other words C make sure you get the equipment sized for your special needs.

   I got a package deal from a totaled highway cruiser (1400cc or so) (on eBay).  Radiator size was what the redrive maker recommended.  All the parts looked like they were less than a year old....price..about $45-$50 for everything C if I'm not mistaken.  It made for a very professional installation C if I do say so myself!!

   I haven't installed the electric cooling fan yet.  I'll monitor the temps first C then make a decision about the fan.  It would be an easy mounting job C since it came on that radiator C and then just wire it in.

   One more quick note;  an inline thermostat HAS to be properly located to do any good.  You can't just put it anywhere.  It needs to be as close to the block as possible.  The temperature sensitive side has to feel the heated block coolant in order to open.  If the thermostat sits away from the block C there will not be enough heat passing over the spring to open the unit! What you'll have is a hot engine with the thermostat acting like a plug in the system C and NEVER opening up.

 Mike Welch

 MkIII CX

 	  Quote: 	
		   Subject: Re: Re: Rotax 912 Question

 From: slyck(at)frontiernet.net

 Date: Wed C 16 Dec 2009 14:08:19 -0500

 To: kolb-list(at)matronics.com

 --> Kolb-List message posted by: robert bean <slyck(at)frontiernet.net>

 I have an inline thermostat on my suzuki. It has to be pushed into a chunk of (large) radiator hose.

 Carquest CTH31179

 This was the recommended way to go from the conversion redrive supplier.

 I had a problem initially as the volume capacity was too small.

 Carquest evidently had two suppliers for this part and the one I got first wasn't up to the task.

 I went back and bought another which turned out to have a larger opening which worked ok.

 BB

 On 16 C Dec 2009 C at 10:27 AM C John Hauck wrote:

 > --> Kolb-List message posted by: "John Hauck" <jhauck(at)elmore.rr.com>

 > 

 > 

 > 

 >> Here is a link to see one on a 912. You mount it on the left side before the radiator. No pressure problems. You can also use a Perma Cool oil thermostat for the oil.

 >> 

 >> http://www.flightdesignusa.com/dbimages/big_thermo.jpg

 >> 

 >> 

 >> Here are two pictures out of a manual.

 >> 

 >> --------

 >> Roger Lee

 > 

 > 

 > Roger L/Gang:

 > 

 > Looks like this thermostat will require a new coolant radiator tank to accept the bypass circuit? How much does Rotax want for the header tank with additional outlet?

 > 

 > Price of the BMW thermostat is reasonable C 18.95.

 > 

 > Had a couple Fiat Spyders that used the same thermostat bypass system.

 > 

 > The PDF files out of the manual for coolant and oil thermostats did not come through. Pages won't open.

 > 

 > john h

 > mkIII 

 > 

 > 

 > 

 > 

================

[quote] 

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John Hauck

Joined: 09 Jan 2006
Posts: 4639
Location: Titus, Alabama (hauck's holler)

Posted: Wed Dec 16, 2009 2:19 pm Post subject: Rotax 912 Question

 	  Quote: 	
		   I don't believe you need any different coolant tank. It is only a 

 difference in plumbing. If there is anyone around you with a Flight Design 

 CTLS you could stop by and take a look at theirs.



 --------

 Roger Lee


	




No Flight Designs in my neck of the woods.



Do you have a good url for the pdf files that show the coolant and 

thermostat installations?



I'm guessing, but they probably come off the 1" hose between the header tank 

and the radiator inlet with a T to the side barb on the thermostat, which is 

installed in the radiator outlet hose.  That would let the water pump 

circulate water, bypassing the radiator, and not creating additional 

pressure because of a restriction caused by a "normal" two opening 

thermostat housing.  That was my problem, water pump overpowering the header 

tank cap because the thermostat restricting flow.  I think my Cummins Diesel 

uses the same system to recirculate and bypass the radiator during warm-up.



If I keep thinking, I may have to splurge for the BMW thermostat, 18.95. 

However, would a 180F thermostat give me a minimum of 190F oil temp?



That was the problem with the engine oil thermostat.  Worked great up to its 

rated temperature, which was less than the 190F required to burn off 

condensation in the 912.



That is why I use the same system most of us use by adjusting temps with 

gaffer's tape on the radiator.  Only have to set the adjustment twice a 

year.



john h

mkIII

_________________
John Hauck
MKIII/912ULS
hauck's holler
Titus, Alabama

John Hauck

Joined: 09 Jan 2006
Posts: 4639
Location: Titus, Alabama (hauck's holler)

Posted: Wed Dec 16, 2009 2:22 pm Post subject: Rotax 912 Question

Mike W/Gang:

  

 Correct me if I am wrong.  I believe that is  why there is a bleed hole in the thermostat, to allow water to continuously  circulate so the thermostat can read the temp and react.

  

 john h - Got a good flight in this afternoon.   I feel better now.  Wind was agressive and hard to predict what it would be  doing for more than a few seconds at a time, especially on short, short  final.  This old pilot is definitely rusty.  The 912ULS is screaming  with the new Titan Exhaust System.  I am happy!

  

 mkIII - 2,983.1 hours

 912ULS - 414.6 hours

  

  

  

  

 [quote]      One more quick note;  an    inline thermostat HAS to be properly located to do any good.  You    can't just put it anywhere.  It needs to be as close to the block as    possible.  The temperature sensitive side has to feel the heated block    coolant in order to open.  If the thermostat sits away from the    block, there will not be enough heat passing over the spring to open the    unit! What you'll have is a hot engine with the thermostat acting    like a plug in the system, and NEVER opening up.

 

Mike    Welch

 

[b]

_________________
John Hauck
MKIII/912ULS
hauck's holler
Titus, Alabama

Vic Peters

Joined: 30 Oct 2009
Posts: 54
Location: Millinocket, Maine

Posted: Wed Dec 16, 2009 2:23 pm Post subject: Rotax 912 Question

Boyd,

 Does that mean you dont need a shut off to the main  radiator when you want heat?

 Would you get more heat or restrict normal coolant  flow too much?

  

 Vic

   [quote][b]

_________________
Vic
912ul Xtra
Maine
Too old to cut the mustard but not the cheese.

elleryweld(at)aol.com
Guest

Posted: Wed Dec 16, 2009 3:11 pm Post subject: Rotax 912 Question

Vic I am just installing a 12500 BTU heater in My Mk3 stop in and check it out

    

   Ellery

 

 

 

   --

mdnanwelch7(at)hotmail.co
Guest

Posted: Wed Dec 16, 2009 3:55 pm Post subject: Rotax 912 Question

John H C

  

   Yes C you are correct about the little bleed hole.  But C if you stick the inline thermostat too far from the block C you're going to get a "certain" amount of cool down.

   How far is "too" far C and how much cool down?  I'm not sure.  But C since this is "experimental" C I think a guy (or gal) would want to make certain their design worked as they planned.

  

   As an example of what I'm getting at;  normally C when you start your car/truck/tractor C the engine warms and then eventually the warmth gets to the thermostat C opening it up.  This is a fairly constant practice C and has been all worked out by the vehicle's maker.

   But let's say C for the sake of argument C you have to locate that thermostat 28" away from it's original mounting location.  Then the question is (not "do you feel lucky?"); No C the question is; how long will that small bleed hole take to get very warm coolant to the thermostat??  Might be too long.  Sure would be a pisser if it were. 

  

   As someone suggested about making the bleed hole larger C to allow for "extra" warm coolant flow C if we engineer a new system C we definitely want to make sure it works.

  

 Mike W

 

  From: jhauck(at)elmore.rr.com

To: kolb-list(at)matronics.com

Subject: Re: Kolb-List: Re: Rotax 912 Question

Date: Wed C 16 Dec 2009 16:20:44 -0600



  .ExternalClass .ecxhmmessage P {padding-right:0px;padding-left:0px;padding-bottom:0px;padding-top:0px;} .ExternalClass BODY.ecxhmmessage {font-size:10pt;font-family:Verdana;}   Mike W/Gang:

  

 Correct me if I am wrong.  I believe that is why there is a bleed hole in the thermostat C to allow water to continuously circulate so the thermostat can read the temp and react.

  

 john h - Got a good flight in this afternoon.  I feel better now.  Wind was agressive and hard to predict what it would be doing for more than a few seconds at a time C especially on short C short final.  This old pilot is definitely rusty.  The 912ULS is screaming with the new Titan Exhaust System.  I am happy!

  

 mkIII - 2 C983.1 hours

 912ULS - 414.6 hours

  

  

  

  

  	  Quote: 	
		      One more quick note;  an inline thermostat HAS to be properly located to do any good.  You can't just put it anywhere.  It needs to be as close to the block as possible.  The temperature sensitive side has to feel the heated block coolant in order to open.  If the thermostat sits away from the block C there will not be enough heat passing over the spring to open the unit! What you'll have is a hot engine with the thermostat acting like a plug in the system C and NEVER opening up.

 

Mike Welch

 





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NeilsenRM(at)comcast.net
Guest

Posted: Wed Dec 16, 2009 4:48 pm Post subject: Rotax 912 Question

Mike

  

 I have a oil thermostat on my VW engine that looks like it  has a automotive water thermostat in it. The unit has four ports. When the  oil is cold the oil is allowed to loop back to the engine without going to the  cooler but some does go through the cooler. When the oil gets to app. 180-185  degrees the thermostat closes the internal loop back port. The design is fairly  fail safe but doesn't work as well as I would like in keeping my oil temps as  high as I would like. The unit is fairly cheep and might work for you as a  water thermostat if you had one for each head. Seems like it has 3/8 or 1/2 inch  hose barbs included with the kit. I don't remember the name or cost but the  units are sold by VW after market suppliers.  

  

 Some day I'm going to take the unit apart and go to a  automotive store with just the thermostat to find a higher temp thermostat for  it. I wrote the manufacture asking for a higher temp thermostat. No luck.  The oil temps rise quickly but only go to 180 degrees on a cool  day. 

  

 Rick Neilsen

 Redrive VW powered MKIIIC

 [quote]   ---

John Hauck

Joined: 09 Jan 2006
Posts: 4639
Location: Titus, Alabama (hauck's holler)

Posted: Wed Dec 16, 2009 4:49 pm Post subject: Rotax 912 Question

Mike W/Gang:

  

 Jack H suggested making the bleed hole larger, when  I was trying to explain the problems I encountered adapting an inline thermostat  on my first 912.  The reason for that was to attempt to overcome the  overpressure being caused by the restriction in the return line, the header tank  with cap, and the water pump.  I drilled larger holes to allow some water  pump pressure relief, but that reduced the thermostats effectiveness.  Was  going around in circles.  The orginal 350 Chevy thermostat got the temps up  fast, but the original 1/8" bleed hole wasn't enough to keep the water pump from  blowing water out the cap.  If I could have put the thermostat between the  water pump and the header tank, it would have worked perfectly.  If the  water pump had one outlet instead of four, I'd still be using the  thermostat.

  

 Today I could get a little over 180F engine  oil temp, and about 175F CHT, climbing wide open throttle to 3,000 feet  msl.  OAT was 50F.  Crusing 5,200 rpm showed 180F engine oil  temp.  Engine is running a lot cooler with the Titan Exhaust System.   This will work out good next Spring and Summer when the OAT is at the top of the  scale.

  

 I understand what you are getting at.  The  thermostat will react sooner the closer it is to the heat source.

  

 When we experiment we hope it works.  Usually,  we have to do a lot of trial and error exercises until we get it the way we want  it, or the way it should be.  

  

 john h

 mklIII

  

  

 [quote]      As someone suggested about making    the bleed hole larger, to allow for "extra" warm coolant flow, if we engineer    a new system, we definitely want to make sure it works.

 

Mike    W

 

[b]

_________________
John Hauck
MKIII/912ULS
hauck's holler
Titus, Alabama

Roger Lee

Joined: 10 Jan 2006
Posts: 1464
Location: Tucson, Az.

Posted: Wed Dec 16, 2009 4:57 pm Post subject: Re: Rotax 912 Question

John,



Here are a couple of pictures. Two of the coolant thermostat and one with an oil thermostat. These only go to 180F and won't take an engine to 200F. 180F is about the highest on the market. The tape is less expensive and you can tape until you get your desired temp. These are not cheap either.

Oil Thermostat.jpg

Description:

Oil thermostat

Filesize:

364.84 KB

Viewed:

19758 Time(s)

Coolant thermostat 1.jpg

Description:

Coolant thermostat

Filesize:

287.08 KB

Viewed:

19758 Time(s)

Coolant Thermostat.jpg

Description:

Coolant thermostat

Filesize:

443.11 KB

Viewed:

19758 Time(s)

_________________
Roger Lee
Tucson, Az.
Rotax Instructor & Rotax IRC
Light Sport Repairman
Home 520-574-1080 TRY HOME FIRST
Cell 520-349-7056

herbgh(at)nctc.com
Guest

Posted: Wed Dec 16, 2009 5:04 pm Post subject: Rotax 912 Question

Mike



   Which engine and are you running it stock?  Herb ( with 5 geo engines...three and four cyl...)   



 

 At 05:49 PM 12/16/2009, you wrote:

 [quote]John H,

  

   Yes, you are correct about the little bleed hole.  But, if you stick the inline thermostat too far from the block, you're going to get a "certain" amount of cool down.

   How far is "too" far, and how much cool down?  I'm not sure.  But, since this is "experimental", I think a guy (or gal) would want to make certain their design worked as they planned.

  

   As an example of what I'm getting at;  normally, when you start your car/truck/tractor, the engine warms and then eventually the warmth gets to the thermostat, opening it up.  This is a fairly constant practice, and has been all worked out by the vehicle's maker.

   But let's say, for the sake of argument, you have to locate that thermostat 28" away from it's original mounting location.  Then the question is (not "do you feel lucky?"); No, the question is; how long will that small bleed hole take to get very warm coolant to the thermostat??  Might be too long.  Sure would be a pisser if it were. 

  

   As someone suggested about making the bleed hole larger, to allow for "extra" warm coolant flow, if we engineer a new system, we definitely want to make sure it works.

  

 Mike W

  

  [b]

Dana

Joined: 13 Dec 2007
Posts: 1047
Location: Connecticut, USA

Posted: Wed Dec 16, 2009 6:05 pm Post subject: Rotax 912 Question

At 06:49 PM 12/16/2009, Mike Welch wrote:

  	  Quote: 	
		  ...if you stick the inline thermostat too far from the block, you're going to get a "certain" amount of cool down.

   ...say, for the sake of argument, you have to locate that thermostat 28" away from it's original mounting location.  Then the question is (not "do you feel lucky?"); No, the question is; how long will that small bleed hole take to get very warm coolant to the thermostat?? 	


 This has nothing to do with Kolbs or even Rotaxes unless somebody wants to try something really different, but a few years back I owned a couple of Fiat Spiders.  Rather than the conventional thermostat in the cylinder head they had a rather strange 3 way thermostat mounted in a junction of three hoses.  With the engine cold, the coolant circulated through the thermostat and directly back to the engine.  As it warmed up, the flow gradually got diverted through the radiator and returned to the engine via a fourth hose... there was a tee on the cylinder head where the thermostat would normally be; one hose went to the thermostat and the other to the radiator.  I presume this was to allow the entire engine to warm up more evenly than it would if there was no circulation, or circulation through only a tiny bleed hole.  The only drawback was that the thermostat was a rather expensive $30 deal instead of a cheap $1.99 plus a gasket.  I do know that they changed it at one point to a more conventional thermostat in the cylinder head, but it must not have worked as well because after a year or two they changed it back to the 3 way version... I had the 3 way on my 1971, a standard thermostat on a 1974 parts car, and the 3 way again on a 1977.



 The engine was strange in other ways as well... Italians just don't approach machinery in the same way as do Americans or Japanese or even Germans!



 -Dana



 do not archive

 

 --

  A day without sunshine is like, night.    [quote][b]

John Hauck

Joined: 09 Jan 2006
Posts: 4639
Location: Titus, Alabama (hauck's holler)

Posted: Wed Dec 16, 2009 6:05 pm Post subject: Rotax 912 Question

Rick N/Gang:

  

 That's what my 912 was doing today.  Once in  the air the temp rose right up to 180 and stopped.

  

 I may try bi-passing the oil cooler by swapping  lines and see how she performs in this weather.  Never done it with the  912ULS, only the 912UL.  The ULS runs a lot hotter than the UL.  If  this engine doesn't run too high, that would solve my cold weather flying time  without installing a thermostat or taping the radiator.

  

 john h

 mkIII

  

  

  

  

 [quote]    Some day I'm going to    take the unit apart and go to a automotive store with just the thermostat to    find a higher temp thermostat for it. I wrote the manufacture asking for a    higher temp thermostat. No luck. The oil temps rise quickly but only go    to 180 degrees on a cool day. 

    

   Rick Neilsen

    

[b]

_________________
John Hauck
MKIII/912ULS
hauck's holler
Titus, Alabama

John Hauck

Joined: 09 Jan 2006
Posts: 4639
Location: Titus, Alabama (hauck's holler)

Posted: Wed Dec 16, 2009 7:00 pm Post subject: Rotax 912 Question

 	  Quote: 	
		   Here are a couple of pictures. Two of the coolant thermostat and one with 

 an oil thermostat. These only go to 180F and won't take an engine to 200F. 

 180F is about the highest on the market. The tape is less expensive and 

 you can tape until you get your desired temp. These are not cheap either.



 --------

 Roger Lee


	




Thanks, Roger:



I got the photos that time.  Still didn't show where they are bringing the 

bypass water from.



I'm going to stick with what I have.  Looks like this 912ULS is going to run 

about 20F cooler with the Titan Exhaust System.  May be able to get away 

with bypassing the oil cooler like I used to do on my 912UL.  If not, I'll 

go to the tape.



john h

mkIII

_________________
John Hauck
MKIII/912ULS
hauck's holler
Titus, Alabama

by0ung(at)brigham.net
Guest

Posted: Thu Dec 17, 2009 8:22 am Post subject: Rotax 912 Question

Boyd,  

Does that mean you dont need a shut off to the main radiator when you want heat?  

Would you get more heat or restrict normal coolant flow too much?  

   

Vic   	  Quote: 	
		   	
  

 	  Quote: 	
		  >>>>>>>>>>>>>>>>>>>>>>>>>>..  

   
	


That is correct,  I do not have a shut off in line with the main radiator.  

   

The radiator and the heater core are plumed in parallel  they both get the same differential pressure all the time.  In winter when I want heat I have to tape up the main radiator in order to keep the temps higher,   when I started this project I looked for an in line thermostat at  snowmobile shops, motorcycle shops, auto parts store, LEAF,    I had no luck finding one. That is when Leading Edge Air Foil  told me that there was no specific need to have a minimum water temp.  Thus no thermostat from rotax.      The BMW thermostat, 18.95. may be a perfect answer.   I would have a higher flow through the heater core  this would keep enough flow to reduce pressure build up from the pump, bring the heat quickly to the thermostat,  and the thermostat would replace the need for tape.   Just thinking out loud….    If you created a bypass from the extra opening in the BMW thermostat back to the outlet side of the radiator,   I am thinking you would want something to restrict the flow so when the thermostat opened the flow would be through the radiator and not the bypass.    Maybe a spring loaded check valve.   Or in my case the heater core.      

   

Questions:   Would the thermostat create too much restriction in an otherwise open circuit?  

                       do we know that the sizes are on the three openings in the bmw thermostat?  

   

Boyd Young  

MKIII  

   

   

       [quote][b]

Rick Lewis

Joined: 03 Jul 2007
Posts: 122
Location: Kingston, Tn.

Posted: Sat Dec 19, 2009 6:40 pm Post subject: Re: Rotax 912 Question

Thanks everybody for all the replys.  I've got a lot good information to run with.  



Rick Lewis

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