Coolant system pressure leak test

[ibjet]

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)

 

 

[Roger Lee]

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.

[ibjet]

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

[Roger Lee]

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.

[WmInce]

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

[Tom Baker]

Also check all the worm gear clamps on the 25mm coolant hose connections. Over the years they have been a constant source of small leaks.

[ibjet]

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 

[Roger Lee]

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.

[ibjet]

Next time I fly it, I will take off the cowls and do that thorough check out. Thx Roger.

[ibjet]

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. 

 

 

 

[Roger]

Where did you get the kit from?

[ibjet]

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. 

[Roger]

Thanks.

Thats way cheaper than the same kit at Harbor Freight.

[FlyRatz]

This little thing is cheap and does a great job detecting coolant leaks: UV Light

I recently bought three of them and I appended the topic: "UV Light leakage search" to the Rotax inspection checklist.

[ibjet]

I have been living with this very small leak for over a year now. I figured I would do more checking when I did my annual and as luck would have it, the leak just became much worse (lost about 3 ozs. on my last (short) flight. I had determined that it was coming from the rear of the engine and so I put my mini remote camera into that area and took a picture (posting here). It shows the bottom bolt of the coolant supply elbow (#19 in the exploded view, also posted here). It appears that it is leaking at or near that lower bolt.

The problem is that area is next to impossible to get to without pulling the engine. I guess I want to get capability to pull the engine anyway, so I'm picking up a 1 ton shop crane from Harbor Freight tomorrow.

Looks like just a new O ring and some polishing might fix it. I will look for some sort of goop that I can put on the housing just before re-assembly.

Question: Any of you fine gentlemen have any experience with a leak in that area? Any thoughts or comments would be appreciated! 

[Anticept]

That does look pretty miserable back there.

Was the coolant changed within the past few years? That stuff does turn acidic and can eat through the engine.

[ibjet]

I removed the radiator last year to boil it out. I spent quite a bit of effort trying to pin point my leak (it was a very small amount, about 1/4 ounce per flight). Finally realized it was coming from the area of the coolant pump, but waited until my tear down for annual to attempt to fix it. I thought it was a "water pump leak" like is common in car engines, but this looks like a plain old leak. In fact, I think that bolt did not get tightened correctly! I'll try tightening it before I remove it. Almost ready to pull the engine, excited to do that ('cause the 5 year rubber change will not be so scary after that, ha ha) . . .

[Tom Baker]

I think the bolt that is leaking is the one that is intended to use to drain the coolant. If it has maybe been apart before someone may have put a lock washer on it instead of the gasket ring. I would try replacing the gasket ring before pulling the engine. 

[ibjet]

The bolt with all the residue around it is #17 in the exploded view above. It is the lower bolt that holds the coolant return elbow on. Thanks for the comment, I will try to determine which is the drain bolt and have a drain pan in place. Also sounds very likely that a copper washer should be used there instead of a lock washer. There is a large O ring seal in that area that should keep that elbow from leaking, that's why I decided I really need to be able to see what is happening there and I'll probably paint on some kind of sealing compound there sparingly (Permatex type goop or something). 

I thought about removing my nose wheel assembly to try to gain access, but I decided I wanted to teach myself how to pull the engine. There really is not too much to disconnect to enable pulling it: 4 shock mount bolts, 2 gas lines, 1 electrical harness, 4 carb cables, 2 carb intakes, and the cabin heat flex tube. 

Advantage is that I will be able to really see what is leaking and clean it up really well and seal it up really well. And I can clean up the whole engine and the firewall area. 

If interested, I did a post on Engine Removal, you can see the shop crane, load leveler and the engine sling I am getting ready for this. http://ctflier.com/topic/5540-engine-removal/?tab=comments#comment-78544

Thanks Tom!

ET

[Tom Baker]

The washer (16) for bolt 17 is different that all the other washers. It is a copper gasket ring. That is the point where you are supposed to drain the coolant on a 912. On a CT it is really hard to get to. I have only drained from that point on one occasion. 

On pulling the engine, you can't pull it by removing the 4 shock mount bolts. You have to remove the 6 bolts and pull the whole mount frame from the firewall. You can then remove the frome from the 4 shock mount bolts. It will give you better access, but not great unless you remove the mount ring.

 

[ibjet]

Dang, now I'm pretty convinced that I have a lock washer where I need a copper washer. And I might be able to replace that washer and fix the leak! Also thinking that I might be able to gain access by removing the nose wheel (and I have a stand for holding the plane up just aft of the lower cowling. And, I need to remove my nose wheel to replace a brass washer I made with the correct plastic washer(s) that I bought from FD! Meaning that when I pull the engine, I still need to pull the nose wheel loose from the engine! Grrrr, hate making extra work for myself. 

I have to  go ahead and pull the nose wheel and see if that gives me enough room to get to that bolt. I will use my stand to hold the airplane up and then if I decide to go ahead and pull the engine, I will also pull the tail down against a padded stool with a ratchet strap. Might not use my shop crane and load leveler/slings yet! It's all good, I'll have it when I need it and I won't be afraid of the 5 year rubber change . . .

I'll show off my stand for holding up the front of the airplane, be glad to use it again . . . 

 

[ibjet]

Yesterday I raised the front of my airplane with my stand and I found that I could sit on a stool and reach that bolt with all the leak residue on it (from the right side of the airplane). By feel I inserted a 5 mm driver and ratchet and loosened the screw (finished removing with a 5 mm allen wrench). I did not get any drainage during or after removal of that screw. Sure enough it did have a steel lock washer which showed some rusting on the surface that was against the coolant elbow casting.

When I came home I searched on Amazon and found 6 mm copper seal washers. I have a bag of 50 on their way here by tomorrow for $6.99. What an amazing resource Amazon is!

Once I re-install that screw with the copper washer I will leak test (apply pressure) and see if it holds pressure/leaks at that elbow. I'll do at least one more post here of outcome . . . 

[ibjet]

I just realized that the screw I took out appears to be #20 in the exploded view above. And, if you look at my picture above you can see that the elbow points to the right side of the airplane, not the left (the elbow installation for a CTSW is rotated 180 deg. from that shown in the Rotax manual). Realizing this, I don't think the copper gasket washer will solve my issue. If not, I will go ahead and pull the engine. Fun, fun, fun, ha ha.