Rotax 912 coolant radiator

[rodgerc]

At only 132h my genuine Rotax radiator has sprung a small leak. 
 

I’m curious to know if anyone has had experience with the aftermarket alternatives that sell online for around AUD$90, or other options?

[Marty_d]

I bought and fitted one, but haven't yet started the engine - so not much use to you.

Also interested in opinions though.

[facthunter]

You can repair some leaks with resin in the Matrix if you know what you are doing. Nev

[danny_galaga]

For what it's worth, my Bushcat uses Setrab coolers, from Europe. I think you could probably get them from performance car shops. As far as I'm aware, there has been no issues in any Bushcat. They aren't dirt cheap, but $90 sounds TOO cheap for an aircraft. Not sure of specific prices but I bet Setrab are cheaper than something with a Rotax sticker on it 😁

Edited Tuesday at 03:59 AM by danny_galaga

[facthunter]

EVERYTHING is. Look up Heat exchangers to see what's available. I've  seen Chinese stuff  that's superior to the others.  Nev

[rodgerc]

OK….Time for an update.
 

I’ve back-ordered a genuine Rotax radiator with BF Imports. The genuine item price quoted was around $350, which is cheap compared to the item that is installed in RANS RV-12iS’s, that is around US$800. (Vans have a service bulletin on their RV-12iS that requires changes to the mounting due to many failed radiators)

 

I’m going to mount the new one (when it arrives in a few weeks) with some vibration isolators that will go between the M6 mounting bolts and the Adel clamps attached to the engine mount. 

[danny_galaga]

Thats good news. That price seems quite reasonable, similar in price to Setrab. Mayb Rotax radiators are made by Setrab 😄

 

Ha. Setrab cost MORE! Mind you, i think its a bigger radiator. This is what goes in the Bushcat:

 

https://www.efisolutions.com.au/setrab-proline-std-oil-fluid-cooler-series-9-405mm~143016?srsltid=AfmBOoqZPRFVrt9dpFfaFCFrdlBTnnYo5pnc6ENs5a8rG0fEtEJMOTWS

Edited Tuesday at 10:23 AM by danny_galaga

[skippydiesel]

There seems to be a small confusion in this thread between Radiators & Oil Coolers.

 

Radiator - Name commonly use for coolant heat exchanger

Oil Cooler  - Name commonly used for - you guessed it, oil heat exchanger.

 

In both cases they are air/liquid heat exchangers (there are liquid/liquid heat exchangers). 

Many similarities however, their design differences tend to reflect liquid viscosity and expected temperature & pressure ranges.

Not saying that the one heat exchanger design, could not be used for oil or coolant,  however I have never seen this and I would suggest that the targeted liquid is more likly to be efficiently cooled eg Danny-G's Setrab example looks to me to be an Oil Cooler., while Rodgerc's is a Coolant Radiator😈

[danny_galaga]

53 minutes ago, skippydiesel said:

There seems to be a small confusion in this thread between Radiators & Oil Coolers.

 

Radiator - Name commonly use for coolant heat exchanger

Oil Cooler  - Name commonly used for - you guessed it, oil heat exchanger.

 

In both cases they are air/liquid heat exchangers (there are liquid/liquid heat exchangers). 

Many similarities however, their design differences tend to reflect liquid viscosity and expected temperature & pressure ranges.

Not saying that the one heat exchanger design, could not be used for oil or coolant,  however I have never seen this and I would suggest that the targeted liquid is more likly to be efficiently cooled eg Danny-G's Setrab example looks to me to be an Oil Cooler., while Rodgerc's is a Coolant Radiator😈

In the case of my Setrab, it can be used for either. No confusion from me 😇 

[skippydiesel]

6 minutes ago, danny_galaga said:

In the case of my Setrab, it can be used for either. No confusion from me 😇 

Yes - as I acknowledged BUT how effective is the Setrab in BOTH roles???

 

Seems to me that if an oil cooler can be used as a coolant radiator,  then this would be common practise - last time I looked its not.

 

I would like to know the technical reasons why not.?????

 

I am sure there are Forum members who would be fare more qualified to debate this  than me😈

[onetrack]

Oil coolers are constructed to withstand much higher internal pressures than radiators. Oil pressure can reach 90 - 100psi (620-690kPa), but cooling systems rarely develop more than 16psi (110kPa).

 

Accordingly, cooling system rubber hoses are relatively light construction, whereas any rubber hose components in lube systems, are very robustly constructed.

 

In fact, it pays to eliminate rubber hose components in lube systems, if at all possible, as they're a major source of failure and resultant emergencies and often, serious engine damage.

 

There's also the viscosity and heat-transfer properties of oil and coolant to be considered. Oil is very viscous and flows a lot slower than coolant, and coolant has an improved film transfer coefficient when it comes to heat transfer. Simply put, coolant disperses heat much faster than oil.

 

Oil coolers contain fluid passageways that are larger in dimensions than radiators, thus if they're used for coolant, the coolant is in contact with a reduced surface area for heat dissipation, and therefore your cooling rate for coolant is lower than for a radiator.

 

Edited Wednesday at 02:21 AM by onetrack
addendum...

[danny_galaga]

1 hour ago, skippydiesel said:

Yes - as I acknowledged BUT how effective is the Setrab in BOTH roles???

 

Seems to me that if an oil cooler can be used as a coolant radiator,  then this would be common practise - last time I looked its not.

 

I would like to know the technical reasons why not.?????

 

I am sure there are Forum members who would be fare more qualified to debate this  than me😈

Right now I have to put tape on it to keep the temperature up. So I guess it's not too bad at its job 😇 

[facthunter]

 Some oil cooler were near round and soldered copper honeycomb, I doubt solder tanks or radiators are permitted today. Oil cooler ones would take more pressure and be more solidly Constructed. Water types for OIL avoid as they won't be expected to take the Higher Pressure. Other wise no issue. They are ALL heat exchangers. You can have LIQUID /LIQUID and GAS /Gas as well.

[skippydiesel]

2 hours ago, danny_galaga said:

Right now I have to put tape on it to keep the temperature up. So I guess it's not too bad at its job 😇 

I didnt not suggest using an oil cooler, for a coolant radiator, would not work, only that it may not be the best design for the job.

 

Oil coolers usually ;

• Are of heavier construction, than needed for coolant - in aircraft all unnecessary weight is usually avoided
• Have smaller ID inlet/outlet pipes - this may result in the need for pipe reducers, more weight & complexity

 When perfectly satisfactory dedicated Radiators & Oil Coolers are available,  I wonder why you or is it the kit supplier, would choose to do this??😈

[facthunter]

There's a vast choice and you make an informed decision or just buy what was there if it works OK..  I don't think there's a  debate to Have. Walk in and say "Have you got something LIKE THIS in stock?". Mention it's for an aeroplane and they will tell you to go elsewhere..  Nev

[danny_galaga]

1 hour ago, skippydiesel said:

I didnt not suggest using an oil cooler, for a coolant radiator, would not work, only that it may not be the best design for the job.

 

Oil coolers usually ;

• Are of heavier construction, than needed for coolant - in aircraft all unnecessary weight is usually avoided
• Have smaller ID inlet/outlet pipes - this may result in the need for pipe reducers, more weight & complexity

 When perfectly satisfactory dedicated Radiators & Oil Coolers are available,  I wonder why you or is it the kit supplier, would choose to do this??😈

I didn't randomly choose that radiator.. people much smarter than me, aeronautical engineers, chose that part number. Now I look at it, it seems bigger than the standard Rotax jobby. Considering that it's a low n slow plane from a hot country, and the particular location of the radiator, I'm guessing they crunched some numbers on a variety of options and this one did the job for a reasonable price 😇 

Edited Wednesday at 07:56 AM by danny_galaga

[facthunter]

The best type of oil cooler is one that bolts straight onto the crankcase. SOME engines just don't need them. Nev

[skippydiesel]

23 hours ago, danny_galaga said:

I didn't randomly choose that radiator.. people much smarter than me, aeronautical engineers, chose that part number. Now I look at it, it seems bigger than the standard Rotax jobby. Considering that it's a low n slow plane from a hot country, and the particular location of the radiator, I'm guessing they crunched some numbers on a variety of options and this one did the job for a reasonable price 😇 

Oh well there you go - I wonder why Rotax have stuck with the more conventional (PN 997083)  ???😈

 

[facthunter]

It's certain that the speed of the Plane would affect the radiator you use. Also the Power output of the engine.. and the ambient air temp where you might operate.  Shutters or Cowl Gills anybody?  Heat and drag control.  A hotter running motor is more efficient in a technical sense. Then there's the Quicker warm up, and the under cowl temps after landing. Nev

[danny_galaga]

42 minutes ago, skippydiesel said:

Oh well there you go - I wonder why Rotax have stuck with the more conventional (PN 997083)  ???😈

 

I reckon maybe that one is for general low wing plane use, and slow draggy planes like mine are best off with something a bit different 

[skippydiesel]

15 hours ago, danny_galaga said:

I reckon maybe that one is for general low wing plane use, and slow draggy planes like mine are best off with something a bit different 

Speculation: For Rotax 9 powered aircraft, high / low / rotating, the Rotax radiator is the norm - Your dual purpose oil/coolant, the exception. Nothing wrong with that of course😈

[danny_galaga]

1 hour ago, skippydiesel said:

Speculation: For Rotax 9 powered aircraft, high / low / rotating, the Rotax radiator is the norm - Your dual purpose oil/coolant, the exception. Nothing wrong with that of course😈

It's much the same size in the similarly performing zenith and savannah 701. What's your theory then, since the radiators are roughly the same price? Seems to me a slow aircraft could do with a larger radiator. Maybe you ought to write to the bush plane manufacturers and tell them they've been doing it all wrong 😇 

Edited 1 hour ago by danny_galaga

[skippydiesel]

2 minutes ago, danny_galaga said:

It's much the same size in the similarly performing zenith and savannah 701. What's your theory then, since the radiators are roughly the same price? Seems to me a slow aircraft could do with a larger radiator. Maybe you ought to write to the bush plane manufacturers and tell them they've been doing it all wrong 😇 

I have never suggested you (Zenith et al) are wrong, only that the approach is somewhat unconventional. I like unconventional, especially when it works. Despite this I am not a fan of "reinventing the wheel" for no apparent gain.

 

I still wonder at the choice, given the diffrent viscosities of oil & coolant (water) and I assume the Setrab heat exchanger has been optimised for oil (it looks like an oil cooler).

 

In addition, the Rotax 9 coolant system will have 25 mm OD hose connections , so at some point reducers will have to be fitted to get down to the Setrab inlet/outlet dimensions - added weight, more joins ????😈

[facthunter]

When it's aircooled you don't Have all this problem with rubber PIPES, coolant and pressure caps, pumps and leaks. (dare I mention). Then you can FLY in the AIR. Nev