Coolant loss

Having dramas with disappearing coolant from my 914 , changed every hose replaced the clamps with the spring type , then don a 14 hr trip , all good , flew up to tilpa from echuca, about 2.5 hrs , bottle empty, filled it up , came home this morning, 3.5 hrs , headwinds, bottle empty, driving me nuts, is there a chance it’s leaking past the water pump seal, not a easy fix, read somewhere it can leak in the cold weather, can’t see any visible signs, anyone come across this?

 

 

Pull the cowls off and ground run it. Once it's up to temp you may be able to see the leaks.

 

If it's leaking past the pump seal you will see it at the weep hole at the back just in front of the water pump on the bottom.

 

Check your cap is sealing properly and that the elbows in the heads aren't weeping. Check your bottle overflow in case it's syphoning.

 

Important to get temps up so the system is pressurised, otherwise you won't see the leaks unless there is evidence of coolant inside the cowl.

 

 

rhtrudder - Usually, any coolant leakage past the water pump seal leaves a visible trail, after it's dried. Have you considered that a head gasket may be leaking coolant into the exhaust?

 

Have you considered doing a static cooling system pressure test to see if there's a pressure drop, and to see if you can spot any leakage? (while the system is pressurised).

 

 

rhtrudder - Usually, any coolant leakage past the water pump seal leaves a visible trail, after it's dried. Have you considered that a head gasket may be leaking coolant into the exhaust?

 

Have you considered doing a static cooling system pressure test to see if there's a pressure drop, and to see if you can spot any leakage? (while the system is pressurised).

I believe the heads are sealed and can’t leak and there are no head gaskets , but l will look into it,

 

 

Pull the cowls off and ground run it. Once it's up to temp you may be able to see the leaks.

 

If it's leaking past the pump seal you will see it at the weep hole at the back just in front of the water pump on the bottom.

 

Check your cap is sealing properly and that the elbows in the heads aren't weeping. Check your bottle overflow in case it's syphoning.

 

Important to get temps up so the system is pressurised, otherwise you won't see the leaks unless there is evidence of coolant inside the cowl.

Thought maybe be able to pressure the system through the barb under the cap , it should pass through the valve in the cap and then hold pressure , does this make sense

 

 

rhtrudder - Usually, any coolant leakage past the water pump seal leaves a visible trail, after it's dried. Have you considered that a head gasket may be leaking coolant into the exhaust?

 

Have you considered doing a static cooling system pressure test to see if there's a pressure drop, and to see if you can spot any leakage? (while the system is pressurised).

My experience is ground based engine cooling systems - head gasket leaks do not usually allow coolant into the exhaust system -rather high temperature gas (burnt fuel) gets into the cooling system vaporising coolant & pressurising the system causing rapid "boiling" & loss of coolant.

 

Your second suggestion is a sound one but may not work if engine & cooling system only leaks when system is at operating temperature.

 

[

 

 

Pull the cowls off and ground run it. Once it's up to temp you may be able to see the leaks.

 

If it's leaking past the pump seal you will see it at the weep hole at the back just in front of the water pump on the bottom.

 

Check your cap is sealing properly and that the elbows in the heads aren't weeping. Check your bottle overflow in case it's syphoning.

 

Important to get temps up so the system is pressurised, otherwise you won't see the leaks unless there is evidence of coolant inside the cowl.

All good suggestions - almost all leaks will show a "tell tail" IF the recommended coolant & correct coolant concentrate to high quality water ratio has been used (50:50).

 

Question: when Rhtrudder filled up "the bottle" did he use the Rotax recommend Castrol coolant or plain water ???

 

 

"the bottle"

 

Plastic bottles do become porous , & leak only under pressure.

 

spacesailor

 

 

I believe the heads are sealed and can’t leak and there are no head gaskets , but l will look into it,

That is 100% correct. The heads are the only bits with coolant passages and there are no head gaskets.

 

I use Evans waterless, it doesn't leave much visible if it leaks in flight, but is easily seen during a ground run, also has a distinctive smell. Another giveaway.

 

 

All good suggestions - almost all leaks will show a "tell tail" IF the recommended coolant & correct coolant concentrate to high quality water ratio has been used (50:50).

 

Question: when Rhtrudder filled up "the bottle" did he use the Rotax recommend Castrol coolant or plain water ???

Been using a red coolant, looks the part, put water in at tilpa, that’s all l had, engine ran a bit on the cold side on the way home

 

 

Been using a red coolant, looks the part, put water in at tilpa, that’s all l had, engine ran a bit on the cold side on the way home

It was red nulon

 

 

"the bottle"

 

Plastic bottles do become porous , & leak only under pressure.

 

spacesailor

I don’t think there is any pressure in the bottle

 

 

I don’t think there is any pressure in the bottle

The overflow/recovery/expansion bottle is NOT pressurised

 

It was red nulon

Have no experience of Nulon (red or otherwise) coolant leaks however the Rotax recommended Castrol Radicool concentrate (not pre mix) leaves a "chalky" residue when it leaks.

 

I would strongly suggest you flush your engine cooling system and refill with the recommended coolant at the recommended ratio (1:1) of concentrate to "pure" water.

 

This ill not fix an existing leak but may give you an indication of where its is AND returns your engine to the Rotax standard.

 

 

That is 100% correct. The heads are the only bits with coolant passages and there are no head gaskets.

 

I use Evans waterless, it doesn't leave much visible if it leaks in flight, but is easily seen during a ground run, also has a distinctive smell. Another giveaway.

Just curios - why use Evans ? It expensive, can not be topped up with water in a "get you home" scenario and has a slightly lower thermal efficiency than the alternative recommend Castol glycol coolant mix.

 

 

The overflow/recovery/expansion bottle is NOT pressurised

 

Have no experience of Nulon (red or otherwise) coolant leaks however the Rotax recommended Castrol Radicool concentrate (not pre mix) leaves a "chalky" residue when it leaks.

 

I would strongly suggest you flush your engine cooling system and refill with the recommended coolant at the recommended ratio (1:1) of concentrate to "pure" water.

 

This ill not fix an existing leak but may give you an indication of where its is AND returns your engine to the Rotax standard.

Thanks for that, l will change over , is it available at most auto shops

 

 

Thanks for that, l will change over , is it available at most auto shops

Hi RR Note the max is 50/50. Ratio must be less than 50% radicool to the water mix. Have a good read of the instructions. (don't exceed the 50% ratio of radicool.) Cheers

 

 

Glycol is not as effective at removing heat as straight water is. Evans is less efficient also but won't boil and create hotspots or corrode alloys.. Water + suitable salts (NOT common salt) are more effective, but that gives you no antifreeze protection and you would quite often need it if you don't spend all your time in the tropics. at low cruising levels. Concentrates give mixing ratios on the container. Use de ionized water. Nulon green is 1:2 ie one part in 3..Available nearly everywhere.. If you are pressuring the system when running it's a bit hard to tell where you are getting it from. The usual way to check is apply pressure ( with the right handpump) to it and leave for a while The first thing I would check is the rubber in the cap and the condition of the cap itself and the bit of the radiator it fits in. The overflow container doesn't get pressurized and requires the outer sealing rubber thingy, And the small length of rubber pipe to seal to bring the overflow back into the radiator when it cools. Nev

 

 

I think the red nulon is more anti corrosive but not as much anti freeze which l thought was better suited, did use de ionised water, thanks for all the advice and l will have to look a bit harder

 

 

Either would be OK . (Not mixed tough). The Particular green one I use is a long life one. (concentrate). Nev

 

 

Either would be OK . (Not mixed tough). The Particular green one I use is a long life one. (concentrate). Nev

Is it possible for the non return in the cap leak , it seems like it doesn’t hold any pressure , l guess that would overfill the bottle and then draw it back , engine ran cold on the 3 hr trip but l did notice the temp gauge varying up and down slightly, can’t see any sign where it leaked but l guess the blast from prop wash would clear that away

 

 

Just curios - why use Evans ? It expensive, can not be topped up with water in a "get you home" scenario and has a slightly lower thermal efficiency than the alternative recommend Castol glycol coolant mix.

It was recommended to me, so I gave it a try when I first got the machine going. I had no coolant temp sensor initially as well, only CHT, that has since been changed.

 

Had no reason to change it yet (200hrs in 13 months) as it generally runs quite cool even when it's 40°C OAT

 

I have already made the decision to replace it with my preferred coolant and water if I need to change it.

 

According to the Evans people, it can be mixed with water for a "get you home" scenario.

 

 

I think the red nulon is more anti corrosive but not as much anti freeze which l thought was better suited, did use de ionised water, thanks for all the advice and l will have to look a bit harder

May be true but not what Rotax recommend - if you would like to check for yourself and you dont have a manual you can view it on the Bert Flood web site.

 

 

Is it possible for the non return in the cap leak , it seems like it doesn’t hold any pressure , l guess that would overfill the bottle and then draw it back , engine ran cold on the 3 hr trip but l did notice the temp gauge varying up and down slightly, can’t see any sign where it leaked but l guess the blast from prop wash would clear that away

The "radiator" cap on the Rotax is designed to hold pressure to a certain point and then release coolant into the "over flow" tank/bottle. The cap is also designed to allow coolant to flow back, as the system cools down (in cruise/decent & engine off) the coolant is then drawn back into the cooling system. That's why you only fill your overflow between 1/4 & 1/2 to allow room for the hot coolant to be temporarily stored (if your overflow fills to the top excess fluid will be dumped.

 

If you have doubts about the condition of your radiator cap - purchase a new one (much cheaper from your Ducati Motorcycle dealership)

 

 

According to the Evans people, it can be mixed with water for a "get you home" scenario.

 

I find that to be very doubtful advice - there are strong warnings against any water residue, in the cooling system, when using Evans.

 

 

evans web site info

 

.

 

With Evans waterless coolant, the likelihood of coolant loss and the need for topping up are greatly reduced. In the event that there is significant coolant loss from the system during operation and no Evans waterless coolant is available to fill the system, water or water-based coolant may be used. However, repairs should be made as soon as possible, and the system should be drained, purged and re-filled with Evans waterless coolant.