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Coolant system pressure leak test

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By error I ordered the wrong radiator cap (the old 13 psi version) but I thought it might eliminate my slow coolant leak. Well, that was a pipe dream, ha ha. 

Still have the leak and I want to pressure test my system so I can isolate the leak. I have an idea of how to make up a pressure test system. But, I'm wondering if anyone has found a standard pressure tester or pressure test adapter (I have the standard Stuart tester). 

Anybody already been there done that?

Thanks in advance good people!

ET

(Ed Tichenor)

 

 

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Hi Ed,

Check right around the 90 degree aluminum coolant tubes on top of each head. Look right where the tube screws into the flange. If they aren't clean and have some residue then you may have found your problem. These are only threaded in place and sometimes the Loctite breaks down. Also put a wrench on the fittings on the coolant radiator. They may be hand tight, but wrench lose. Make these tight. A 7/8" wrench works. I never have to pressure test to find a leak. They should be viable and there isn't, but a few places to leak from.

If the leak looks to be at the back of the cowl and at the rear of the front tire then it is the water pump seal. This can leak 1-3 table spoons of coolant during cooling cycles due to differential metals and the ceramic seal. this is normal. It may come and go. If you have a big puddle then it would need replacement.

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YOU DA MAN Roger!!! Thank you!!! I have some drips on the lower cowl, left side, close to the firewall. It happens over time after a flight. My pressure test adapter is a pretty simple idea. Maybe I'll do a drawing to share here. I just hate that I need to pull the cowling and try to catch it leaking while it's hot. 

But, thank you so much for the ideas Roger!!!

ET

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This sure sounds like the normal heating and cooling cycle at the coolant pump and drips through the weep hole. I get calls on this all the time. It happens more often as weather cools down. If it's just a tablespoon or two I don't think you need to do anything and it may be very limited and not do it all the time.

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9 hours ago, Roger Lee said:

Check right around the 90 degree aluminum coolant tubes on top of each head. Look right where the tube screws into the flange. If they aren't clean and have some residue then you may have found your problem. These are only threaded in place and sometimes the Loctite breaks down. Also put a wrench on the fittings on the coolant radiator. They may be hand tight, but wrench lose. Make these tight. A 7/8" wrench works. I never have to pressure test to find a leak. They should be viable and there isn't, but a few places to leak from.

If the leak looks to be at the back of the cowl and at the rear of the front tire then it is the water pump seal. This can leak 1-3 table spoons of coolant during cooling cycles due to differential metals and the ceramic seal. this is normal. It may come and go. If you have a big puddle then it would need replacement.

 

5 hours ago, ibjet said:

YOU DA MAN Roger!!! Thank you!!! I have some drips on the lower cowl, left side, close to the firewall. It happens over time after a flight. My pressure test adapter is a pretty simple idea. Maybe I'll do a drawing to share here. I just hate that I need to pull the cowling and try to catch it leaking while it's hot. 

But, thank you so much for the ideas Roger!!!

 

7 minutes ago, Roger Lee said:

This sure sounds like the normal heating and cooling cycle at the coolant pump and drips through the weep hole. I get calls on this all the time. It happens more often as weather cools down. If it's just a tablespoon or two I don't think you need to do anything and it may be very limited and not do it all the time.

All the more reason to keep that engine compartment very clean and pull both cowls for (first flight of the day) preflight inspections.

JMTC

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Update: I decided to get a universal pressure tester, found it for only $59. 

Roger - my coolant reservoir is down about 1/2 inch from 2 flights. It had been staying almost unchanged even during early summer. I fixed one leak, added a new clamp on the right side. Stopped getting drips running down my exhaust pipe. Then, soon thereafter, I started seeing drips on the left side, added a clamp, stopped seeing drips there, but still loosing some coolant. 

Anyway, I just want to be able to pressure test it. I'm a tool guy, ha ha. I'll do another post once I try it. And, after my next fight, I'll pull the cowling and put cardboard under the engine. And inspect of course. And look at all the points that you fine folks have mentioned.

Thx,

ET 

Universal radiator leak tester.jpg

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If you are getting leaks from under the clamps on the 17mm hose then the clamps are more likely positioned too far back from the flared end on the metal tubing. Move the clamp up by the flared end , but not on top of it. Then check the 1" (25mm) coolant hose wormdrive clamps for tightness. Rarely does a Rotax just leak coolant except for that 1-2 tablespoons amount I told you about at the coolant pump weep hole during its cooling and heating cycles. This may start and stop any time and there is no real way to predict either other than it tends to do this in colder weather.

The only other place to get a leak that tends to be hard for people to find is where the 90 degree aluminum tube screws into the flange that the 17mm hose attaches to. If you see any discoloration or moisture around the joint. Take it off and fix it.

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Update: My last couple of flights I have lost no coolant, yaaaaaa! But, I'm still running the 13 psi cap and I won't keep that when summer comes. 

That pressure test system that I bought was a disappointment, none of all those test adapters fits. The problem is that Rotax designed a none standard cap. But, I took the closest test adapter, took it apart and put my old Rotax cap on it! 

Now I can pressure test my system at 17 psi ??? (1.2 bar). 

If any body wants to do this, I'll give you a run down. I thought that tester was pretty cheap, just checked and it was $59.XX. It is a very nice set. 

A guy has to have lots of tools, right???? ha ha. 

 

 

 

Rotax radiator pressure tester.jpg

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I ordered it from eBay. Here is a link:

https://www.ebay.com/itm/14Pc-Radiator-Pressure-Cooling-System-Kit-Leak-Tester-Water-Tank-Adapter-w-Case/292249477094?ssPageName=STRK%3AMEBIDX%3AIT&_trksid=p2060353.m2749.l2648

I had to machine the bottom register of the pressure test adapter to about 1.060 dia. (it was about 1.100 dia, the Rotax reservoir filler neck that it must fit in is about 1.080 dia. but not very round). I used my mini milling machine as a lathe to do this turning. But, you could spin the part with a drill motor and grind off the material with a dremel motor with their cut off wheel. Then you could file the edges smooth with a file while still spinning with the drill motor. You can see by the picture above which one of the pressure test adapters I used. There is only one that looks like that. 

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