Cooling Systems drips

[Dave S]

Good afternoon,

I have about 50 hours on the 912ULS in my kitfox and am having a little trouble keeping the cooling system drips at bay.

Where I am getting the drips is at the aluminum "T" s - which patch in for the heater - both on the 1/2 inch fitting for the heater and on the 1" connection at the heater "T".

The 1" hose and aluminum "T" s came from skystar, just before they flushed themselves in the bankruptcy. The clamps are the traditional screw drive clamps common on auto radiator hoses.

There are no leaks at the lines on the engine going to and from the cylinders and none at the fittings going into the heater core, radiator or engine. (Note - the cylinder fittings use spring clamps and the heater fittings have nice sharp barb fittings - unlike the aluminum "T" s which are fairly rounded.)

What I have done is incrementally tighten the clamps on the "T" s, hoping that eventually this will stabalize the problem, however, no luck so far. Also - There is no sealant on any of the connections.

I am wondering if there is some basic incompatibility between the hoses, clamps and heater "T" s - but that is only a wild-elbow guess on my part.

Anyone else had any issues with this type of problem? If so, what works?

Sincerely,

Dave S
St Paul, MN
K7-Trigear
912ULS warpdrive

[Peteohms]

I just renewed all my coolant hoses and had to tighten many of the hoses over a week or two. Used 2 screw type hose clamps on a couple to stop the drips.

[darinh]

Dave,

I had a few leaks in the same place (on the tee's) using the standard screw-type hose clamps also. I ended up replacing the clamps with others from McMaster Carr that are also screw type but they are smooth interior (the worm drive doesn't cut the hose) so you can crank them down without worrying about cutting the hose. Now no more leaks. I can't remember what they are called but if you go to www.mcmaster.com and search for hose clamps you will find them.

[Dave S]

With the recent below zero F weather and having replaced both the radiator and all hoses last fall, I found myself dealing with coolant leaks again on the 1" radiator hoses. Also switched from the Evans coolant to 60% dexcool.

After much observation, diddling, studying, it appears the problem is caused by component shrinkage due to extreme cold and since the hose clamps don't change, allows a leak to occur as the other components shrink with the cold. While I found it is entirely possible to (experimentally) eliminate the drips by overtightening the clamps that is not an option I care to practice as the hose can be damaged from such things.

The local Fastenal store catalogs constant pressure clamps similar to what Darinh mentioned that he got from Mcmasters. Got 10 of them today. Attached is a photo of the CP clamp and standard clamp for comparison. The manufacturer is Ideal (same as who manufactures standard clamps) described as #16 ( for 1") Series 47 - 13/16" to 1 1/2" HD Constant pressure hose clamp. As the photo shows, they have 6 belville washers and a smaller flat washer at the end. Tightening compresses the belville washers which allows for automatic adjustments with temperature changes, I was really looking for some spring clamps like the ones Rotax uses on the small cylinder head hoses but could not fnd anything the right size. A Spring clamp is also a constant pressure clamp but should be cheaper (if one does not buy it from rotax) - but no joy. On the Ideal Constant Pressure Clamps the band is 9/16" wide so a little wider than a standard clamp. The band also has an entirely smooth inside surface so the hose does not end up getting shredded by the spiral slots.

They are a little pricey - $7 each with tax.

Don't have then installed yet but hope to get out to the hangar real soon.

Dave S
Kitfox 7 Trigear
912ULS Warp Drive

[kmach]

I put what looks like to be an identical constant tension clamp on my coolant radiator 1" "in" connection last fall. I had a small drip when the temp went down to - 5 F or so. That clamp seems to have fixed the issue ! They are expensive as well as heavier.

I did find 1" auto spring clamps and changed all the other 1" and as well as the 17 mm connections to spring clamps at the last 5yr rubber replacement with good results = no drips , except for that one connection at the radiator when it got real cold.

I got all of the non rotax size spring clamps at Den Paul auto parts. In Canada

[Av8r3400]

I just put a piece of cardboard under mine. I have spring clamps (OEM) but it doesn't matter. It still drips when it's real cold, no matter what.

I have a Harley, too. So I guess I'm just used to it.

[Dave S]

Larry,

I have a couple friends with Harleys........they tell me if there are no oil drips.....it means the crankcase is empty....now you have me worried if the kitfox ever quits dripping coolant

DS

[colospace]

Any of you experimenters tried the Gates PowerGrip SB Clamp? It's a thermoplastic band installed with a heatgun. According to the Gates' material, it "clamps better" and is good for temperatures from -40F to 302F.

[SkyPirate]

I made my "T"'s and I went a little bigger then the ID of heater hose ,..a little coolant dip with the end of the hose and slide it on,..I bet I could almost not even use a clamp