Roger Lee Posted December 1, 2010 Report Share Posted December 1, 2010 Coolant flow route. Coolant flow route.pdf Link to comment Share on other sites More sharing options...
Tip Posted January 7, 2011 Report Share Posted January 7, 2011 My '08 LS and my friends '07 SW both drip antifreeze during the cold winter months in the hanger. Both have done this since new and the dealer said that the hoses loosen up in cold weather. Have any of you cold weather guys found and fixed this problem? Link to comment Share on other sites More sharing options...
Tom Baker Posted January 7, 2011 Report Share Posted January 7, 2011 My '08 LS and my friends '07 SW both drip antifreeze during the cold winter months in the hanger. Both have done this since new and the dealer said that the hoses loosen up in cold weather. Have any of you cold weather guys found and fixed this problem? Go through and tighten all the screw clamps. It seems to me that when I switched to Dexcool the drips went away, or really slowed down a bunch. It may just be that I had already tightened the clamps enough. Link to comment Share on other sites More sharing options...
Roger Lee Posted January 7, 2011 Author Report Share Posted January 7, 2011 Hi Tip, Here are the two most common places for a little drip and it can be found on new as well as used. If you have a continuing low level in the coolant reservoir and can't find a leak then tighten the coolant hose clamps. It leaks around them while under pressure and blows off or dries up before you will ever find it. First take the cowl off and take a screwdriver and tighten every coolant screw clamp on the cooling hoses. There are only a few. This should be done every single inspection. after the 3 inspection they should be good to go from then on. the second place this can happen is the water pump seal on the back bottom side of the engine. If you see a table spoon or so no big deal and could be normal. If it is coming out of the water pump seal in a large puddle it is time for a new seal. (PITA time) You can tell if it's the seal because all the puddle will be on the floor at the back of the engine and if you lay on your back with a flashlight and look up you'll be able to see where the coolant is coming out the weep hole. The leaks in our plane is usually loose hose clamps 95% of the time. Link to comment Share on other sites More sharing options...
Tip Posted January 7, 2011 Report Share Posted January 7, 2011 Tom and Roger, Thanks for the reply. I think it is probably the weep hole as it drips out the back of the cowling and only does it in extremely cold weather. I had tightened up the clamps last winter. It leaks very little. Link to comment Share on other sites More sharing options...
Tom Baker Posted January 8, 2011 Report Share Posted January 8, 2011 Tom and Roger, Thanks for the reply. I think it is probably the weep hole as it drips out the back of the cowling and only does it in extremely cold weather. I had tightened up the clamps last winter. It leaks very little. Tip, mine dripped from the back, but was the hose clamps. There are several to tighten up. My biggest problem was around the thermostat on my LS. Link to comment Share on other sites More sharing options...
Jeremy MacGregor Posted January 8, 2011 Report Share Posted January 8, 2011 I agree that the clamps loosening, especially the standard worm drive ones used for the radiator or thermostat are certainly prone to leaking. However like Roger said a thurogh tightening should certainly remedy this. The constant pressure clamps on the cylinder heads themselves should certainly not loosen up thou. One thing you need to keep in mind is that when your aircraft is at operating temps, your coolant system has an internal pressure of just under 1.2bar or about 17psi so any substantial leaks in the system would quickly cause coolant evacuation. The exception to this is in the case of the operator using Evans NPG+ waterless coolant, Since Evans is not waterbased there is very little expansion inside of the system which translates to average operating pressures of about 3psi.The question I have is how much coolant are you loosing while the aircraft is sitting in the hangar? Dex-cool in particular should be the more prone to leaks because of the added system pressure but if your loosing coolant while the aircraft is in storage then system pressure should not play a major factor. One common problem that is more related to water pump design, is leaks from the weepage bore on the rear of the engine. The shaft on the coolant side of the pump uses a ceramic seal that is lubricated by the coolant itself and actually requires the coolant to form a proper seal. When the engine hasnt been ran for a while these two ceramic disk can dry out and develop a slight leak, not usually more than a few drops during start up till the seal has had a chance to relubricate itself. If you happened to use tap or bottled water instead of distiller water in your coolant than minerals will tend to collect in this area and basically hold the two disk slightly apart also causing a leak, most of the time a good flush and replacing the coolant can remedy this but in select cases the seal may néed to be replaced. Not Fun $$$ !!! When this area leaks the coolant will end up on the floor ( it doesn't take much ) because the pump is positioned more or less over the opening on the lower back of the cowling. Link to comment Share on other sites More sharing options...
Roger Lee Posted January 8, 2011 Author Report Share Posted January 8, 2011 Like I mentioned tighten all coolant hose clamps for at least three 100 hr. inspections. 95% of the time it's a weeping hose by a screw clamp. As the hose gets smashed down over time the the clamp ends up exerting less circumferential pressure around the hose to seal it. So they need to be checked every so often. Eventually these will only settle so far then any hose compression at the clamp will for the most part cease. many times it's hard to find the exact weeping hose because it only happens under pressure and the hot engine and ram air flow through the cowl make it very hard to find. I tighten every coolant clamp at every inspection. They are always loose the first inspection and only some are loose the second. The black constant compression clamps on some of the coolant hose compensates for any change. Link to comment Share on other sites More sharing options...
Roger Fane Posted January 9, 2011 Report Share Posted January 9, 2011 but in select cases the seal may néed to be replaced. Not Fun $$$ !!! Sounds like it might be a good idea to replace this seal when the engine is off at the 5 year replace all rubber time? Link to comment Share on other sites More sharing options...
Roger Lee Posted January 9, 2011 Author Report Share Posted January 9, 2011 Hi Roger F, This water seal is ceramic and can have a minor drip sometimes. Rotax knows this and it's not a problem. To replace this is a major ordeal. (PITA) You have to pull the back of the engine completely off , press the seal out carefully, then putting the new one in careful not to destroy the new seal or the electrical housing. Only Heavy Maint. shops can do this and I bet most would be afraid to touch it since you can mess something up here fairly easy. This is rarely done so not many people have actually done one. Link to comment Share on other sites More sharing options...
Tip Posted January 9, 2011 Report Share Posted January 9, 2011 Our leaks only occur when the temperature is well below freezing, probably below 20F. Link to comment Share on other sites More sharing options...
Runtoeat Posted January 11, 2011 Report Share Posted January 11, 2011 Tip, I'll go with the "tighten the clamp" group. The last two winters my SW has developed coolant drips when temps drop. I see a little wet spot on the floor at the rear of my front wheel pant. It was coming from a loose coolant clamp on the coolant hose running from the expansion can on the top of the engine. This leak dripped on the lower cowl, ran downwards and rearwards and dripped on the floor. When cold weather starts make it a point to snug up all clamps to fix the problem. Link to comment Share on other sites More sharing options...
Jeremy MacGregor Posted January 14, 2011 Report Share Posted January 14, 2011 Personally, I wouldn't change the seal if your not having leaking issues. Get in the habit of flushing your coolant system with the mixed coolant every 2yrs and you should never have to worry about it. It is not a common failure if your maintaining your coolant system properly. With the engine off the aircraft your looking at about 4 hrs of work and that's assuming you have all the tools and a very familure with the process, ignition housing removal, seal replacement, proper prep for reinstallation. It tends to be tedious and not something most mechanics volunteer for unless necessary. Link to comment Share on other sites More sharing options...
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