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5 year rubber alternatives

seagull

Well Known Member
My 5 year is coming up. I already have teflon fuel and oil hoses. The things I see on the list that I will need are;

267-789, carb rubber flange, I see one from JBM that is cheaper, any reviews?
861-116, carb diaphragm, do these go bad?
922-250, coolant hose 17mm, where is the cheapest place for this? How much is required?
922-192, coolant 90 degree, I have not found an alternative to Rotax.
230-910, intake manifold O-Rings, Mc Master Carr 9263K656
950-143, brass gasket, what is this for, does it go bad?
881-920, O-Ring set, where are these used, what are the sizes?

opinions / recommendations welcome.
 
I used 5/8” heater hose for my coolant hose replacement at the suggestion of one of the ROTAX course instructors. Three and a half years (ver 300 hours) and no problem.
 
For the molded hose, try high temp silicone molded heater hose. Pegasus Racing and others have it in 1'' diameter and you can cut it to fit. Works well with Dexcool.

Tom
 
Maybe we can make a BOM for the coolant hoses.

If I remember correctly, you need one molded hose.

17mm = 0.669”
5/8” = 0.625”

Pegasus Racing Supplies:

SHL16-BLUE
Blue Silicone Hose, Straight, 5/8 inch ID, 1 Meter Length $27.29


E90.16-BLUE
Blue Silicone Hose, 5/8" I.D. 90 degree Elbow, 4" Legs $12.49


SHL25-BLUE
Blue Silicone Hose, Straight, 1 inch ID, 1 Meter Length $31.49

Looks like 17mm Silicone heater hose can be sourced from MiniMania

Heater Hose Silicone 17mm Bore, 36 Long Red

Part No: C-GRH1008RED $39.01 3 Day Shipping ~ $10
 
Jim,
Is the silicone superior to the OEM?
Will it last longer than the expected 5 years?
Will the stock clamps work? i know some silicone cuts easily.
 
This thread is timely - I will do my 5-year coolant hoses at next Annual Condition Inspection.

I think silicone is probably superior to black rubber hose. I Googled silicone heater hose Vs. black rubber... Silicone hoses benefit from superior flexibility compared to rubber. They maintain this flexibility over their lifespan unlike rubber hoses. This reduces the risk that your hoses will split, harden, or become dry rotted. Silicone hoses last practically forever and might possibly outlast your car.

Check out this thread... https://vansairforce.com/community/showpost.php?p=1350979&postcount=362. Honda 1.8L being installed on RV-6A.
 
I would like to hear from someone that has used the silicone. Logic tells me it would be better. I can't pull this ship to the curb as easily as the car if I blow a hose.

Scott,
Do you have any input on this topic?
 
Can anyone give me the dimensions, length of the legs, on the water tube 922-122. This is the 90 degree bent hose that can't be replaced with bulk hose.

The silicone 90 hose I am looking to buy has a 1" radius vs the shallow bend the Rotax hose has. Is there any reason this wouldn't work?

I am trying to avoid removing the cowl.
 
Thanks,

Yes I meant 922-192.

The silicone one, also available in black.

50325246341_7a88a254d3_c.jpg
 
Silicone is a good material and lasts well. It is soft, though, so tight hose clamps can damage it and it is not as abrasion resistant as epdm.

Tim
 
Mike----I have to disagree. The 912ULS uses the VA216 return hose, the 912IS uses a VA138.
The VA216 is a -4 with a restrictor for carbureted applications. The VA138 is a -6 without a restrictor for the injected models. Yes, both are teflon, and NOT service life limited. Yes----be prudent, and inspect them for outside damages.

Tom
 
All the critical hoses have now been replaced, The blue are silicone for the coolant.

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https://hpsperformanceproducts.com/

HPS 1" ID Blue High Temp Reinforced Silicone Heater Hose Tubing, 25mm ID Part Number: HTHH-100-BLUE

HPS 5/8" ID, 10" Leg, Silicone 90 Degree Elbow Coupler Hose, High Temp 4-ply Reinforced, Blue, 16mm ID Part Number: HTHH-062-BLUE

HPS 5/8" ID Blue High Temp Reinforced Silicone Heater Hose Tubing, 16mm ID Part Number: HTHH-025-BLUE

HPS 1/4" ID Blue High Temp Reinforced Silicone Heater Hose Tubing, 6mm ID Part Number: HTHH-025-BLUE

Do not use worm clamps on silicone hose they will damage the outside. I used this type for the 1” hose, they have an inner band to protect the hose and are spring tension to keep constant clamping force. McMaster-Carr 54205K17

The vans spring clamps fit on the 5/8 - 16mm silicone hose except the 90 degree one, it is a slightly thicker wall, get these clamps instead. Constant-Tension Spring-Band Clamps for 1-1/16" OD Hose and Tube. McMaster-Carr 7329K16

These same size hoses come in black, blue, red, clear.
 
Began ordering silicone coolant replacement hoses yesterday to comply with the Rotax's 5 year rubber replacement. (Actually found green silicone coolant hoses that should compliment the green valve covers and green painted air shroud over the cylinders).

I see the rubber hoses on either side of the carburetor balance tube are also on the 5 year replacement list.

The Lockwood site shows that hose as having a 11mm ID ... so wondering if anybody has found a good source for 11mm ID black silicone hose to replace Rotax's rubber hoses on the balance tube? It appears 11 mm (.443") ID or 7/16" (.438") is an oddball size as the web sites I've been searching seem to skip from 3/8" ID to 1/2" ID.
 
Are you talking about the balance tubes coming off the carburetor? 11mm ID sounds too big for that hose.

You don't want to use silicone near gasoline, the gasoline will swell it up and make it useless.
 
Are you talking about the balance tubes coming off the carburetor? 11mm ID sounds too big for that hose.

You don't want to use silicone near gasoline, the gasoline will swell it up and make it useless.

Your right! The balance tube is subjected to fuel vapors ... silicone hose would be a poor choice for that hose. Guess I was having a "senile delinquent" moment and caught up in an ordering frenzy..

Happy flying,
 
The short run (2”) at each end of the balance tube doesn’t seem like an issue for silicone.I wouldn’t put it in, but I wouldn’t lose sleep over it if I had. I’d just put it on the list to replace next annual.
 
I am using a vinyl tubing from the aviation department at Home Depot. The length is about 10" and runs from the carburetor vent to the air cleaner.
 
My Rotax trained A&P has suggested waiting on the five year replacement while monitoring condition of hoses. He says hoses will show signs of deterioration and are braided to prevent blow-out. He manages a fleet of trainers with Rotax 912ULS engines.

Are any RV-12 owners taking this approach as well? Thanks for your input.

Steve
 
Steve---they will deteriorate from the inside out. Hard to see without taking them off. Gates part number 27005 is 7/16 fuel rated.
Tom
 
Might not blowout, but how big of a fuel or oil leak are you willing to deal with before it finds you. Remember firesleeve makes it hard to assess hose condition.

Having experienced a fuel pressure sensor line failure in a Piper, I don’t press my luck with such a trivial expense/work effort like hose replacement.
 
Cold Leak Tendency w/ Silicone Hoses?

I have a question for folks using silicone hoses for 5-year rubber replacement. A friend advises me of a phenomenon called “cold leak tendency” when using silicone hoses on large diesel truck engines. Apparently, it’s pretty common. Anybody notice this problem when substituting silicone hoses on the 912ULS?
 
Another question... When using High Performance Silicone Heater Hoses do you reuse existing Rotax hose clamps or buy new?

Here's what I'm planning:
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I replaced most of my ROTAX spring clamps with screw type. A few don’t have enough clearance to adjust in place, so I left the spring clamps in those spots. Mine have been in place 4 years since there replacement. I did get a little movement on the screw at the first annual after replacement. Probably the rubber compressed and deformed a little. Subsequent annuals have shown no further adjustments.
 
The spring (also referred to as constant tension) clamps are used for a very good reason on the Rotax engines.
All of the fittings the hoses attach to are made of aluminum. Aluminum has a rather high thermal expansion coefficient.
That means with temp changes, the fitting will be expanding and contracting within a fixed diameter clamp if screw type clamps are used. Over time this can compress the hose enough that leaks start to develop because the clamping pressure of the clamp has actually reduced (that is why with the passage of time, this type of clamp is often found a bit loose).
The constant tension clamps can expand and contract slightly with the hose and fitting, so the integrity of the seal is un-effected

This is why people that know, have switch to using constant tension clamps on Lycoming engines, even though screw clamps have been traditionally used for many decades.
 
So, if you use Flexible Hose Clamp Plier to gently remove existing clamps do you think clamps can be reused safely?
 

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I posted the hoses and clamps here;
https://vansairforce.net/community/showpost.php?p=1470744&postcount=17

Depending on the hose you use you may be able to reuse the Rotax clamps. The 90 degree hose I got was thicker wall so I needed a bigger spring clamp from McMaster Carr, #7329K16.
You MUST use constant tension clamps or expect leaks, The spring clamps look cheap but they work good.

Don't use worm type screw clamps on silicone, the "worm" thread eats into the silicone and will tear the hose. There is a special type that has an inner band to protect the hose AND spring tension on the screw. It uses Belleville washers on the screw to maintain constact pressure during thermal expansion. McMaster-Carr #54205K17. I use these on the 1" hoses.
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Piper J3; “cold leak tendency”, I don't have any leaks after 125 hours.
 
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The 912ULS uses 17mm coolant hoses. Most folks use 5/8” heater hose when doing 5-year rubber replacement. A 90-degree molded hose is required in one of the eight cylinder head locations.

On the accompanying schematic drawing – can someone tell me which location requires the molded elbow? It appears to be the top left forward cylinder. It looks like all remaining hoses are fairly straight or have large sweeping bends.
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Just finished a hose replacement with the 5/8 silicone heater hoses. It is the top right cylinder to #3 that needed the 90 degree coupler. I was directed to get the 10 inch 90 degree and then trim to fit. The only other caveat was the hose needed bigger spring clamps. All the other replacements used the original spring clamps.
 
Thanks for info. Do you know spec for spring clamp? Working size?

I posted all this information on page 2 #17. Here it is again.

https://hpsperformanceproducts.com/ click on "silicone heater hose"

HPS 1" ID Blue High Temp Reinforced Silicone Heater Hose Tubing, 25mm ID Part Number: HTHH-100-BLUE

HPS 5/8" ID, 10" Leg, Silicone 90 Degree Elbow Coupler Hose, High Temp 4-ply Reinforced, Blue, 16mm ID Part Number: HTHH-062-BLUE

HPS 5/8" ID Blue High Temp Reinforced Silicone Heater Hose Tubing, 16mm ID Part Number: HTHH-025-BLUE

HPS 1/4" ID Blue High Temp Reinforced Silicone Heater Hose Tubing, 6mm ID Part Number: HTHH-025-BLUE

Do not use worm clamps on silicone hose they will damage the outside. I used this type for the 1” hose, they have an inner band to protect the hose and are spring tension to keep constant clamping force. McMaster-Carr 54205K17 go to here; https://www.mcmaster.com/clamps/ type in the search "54205K17"

The original vans spring clamps fit on the 5/8 - 16mm silicone hose except the 90 degree one, it is a slightly thicker wall, get these clamps instead. Constant-Tension Spring-Band Clamps for 1-1/16" OD Hose and Tube. McMaster-Carr 7329K16 go to here; https://www.mcmaster.com/catalog/127/338 type in "7329K16"

These same size hoses come in black, blue, red, clear.
 
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Thanks for info. Do you know spec for spring clamp? Working size?

If you get the HPS 90 degree hose I specified, the 7329K16 clamp is a perfect fit. These clamps do not have a lot of range, they are designed for one diameter only while giving just enough squeeze tension.

The HPS 90 degree hose is only slightly larger in OD than the OEM hoses. The OEM clamps could be opened far enough to fit but they would not clamp properly if you did that.
 
Jim,
I used everything Seagull provided in the post and it went well. Getting off the original stuff was the challenge. I ended up cutting off most of them.
 
There are hose removal tools that are basically awls in various geometries that break the adhesion between the fitting and the inner wall of the hose, but some cutting was needed when I did my first replacement.

For those of you using silicone hose: are you planning on avoiding another replacement in 5 years? It’s not clear to me that is possible.
 
There are hose removal tools that are basically awls in various geometries that break the adhesion between the fitting and the inner wall of the hose, but some cutting was needed when I did my first replacement.

For those of you using silicone hose: are you planning on avoiding another replacement in 5 years? It’s not clear to me that is possible.

Silicone is the preferred choice in race cars, obviously i am not flying a race car:)

I will see how they look after some time, I expect they will outlast the rubber. Silicone does not do well with abrasion, If you don't have anything rubbing on them or abuse them on the outside you should be fine.

In any case the silicone replacement was cheaper than Rotax hose.
 
I made a management decision today while installing new Silicone High Performance Heater Hoses. Rotax uses a molded hose for the top #3 cylinder in order to route around the ignition modules. I’m sure the reason for using a molded hose is because reinforced rubber hose would kink if bent in a 90- degree radius.

So, today, instead of using a molded hose, I installed a straight piece of silicone hose. The hose does need to turn 90-degrees in direction but the bend radius is very large. The Silicone High Performance Hose is more than flexible enough to accomplish this bend without kinking. The installation is nice and clean.
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I installed a straight piece of silicone hose. The hose does need to turn 90-degrees in direction but the bend radius is very large. The Silicone High Performance Hose is more than flexible enough to accomplish this bend without kinking. The installation is nice and clean.
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I seriously considered doing the same but instead stayed with the preformed 90 degree silicone piece.

Be careful that when the hose gets hot that the pressure of the bend causes it to kink and impede the cooling to that cylinder.

I had thought of using an internal spring that would prevent kinking but was’t sure if it would make the coolant flow slower to that cylinder.
 
I seriously considered doing the same but instead stayed with the preformed 90 degree silicone piece.

Be careful that when the hose gets hot that the pressure of the bend causes it to kink and impede the cooling to that cylinder.

I had thought of using an internal spring that would prevent kinking but was’t sure if it would make the coolant flow slower to that cylinder.

I am reconsidering this based on your reasoning. I didn't want to install the molded elbow because the radius bend is so small. I can't find a large radius bend molded elbow so I will be installing the smaller radius elbow and just be happy knowing safety is not compromised.

Seagull - Thanks for stating point of view. Always welcome...
 
This looks like a good solution... Heater hose 5/8 exterior spring with spine to hold shape of hose for custom bending of straight hose.
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Seagull - did you remove the springs from your old hoses and install in new silicone ones? Is it ok to put metal springs in silicone hoses (are they tough enough?)

Also, did you safety wire the 54205K17 clamps at all or do they stay tensioned in vibration on their own?
 
I reused internal spring

On my upper radiator hose, I removed the spring from my original build and reinstalled it in my new silicone hose. Did anyone else do likewise?. It was a bear to get in.
 
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