HELP Coolant Tank - Intermittent leak bottom hose connector.

Hi all,

HELP!

I'm sure most of you will have read my tale of not getting to Macon because of coolant bottle failure and the 'coolant cooler pipe' leaking.

Just to recap, last year, amongst other works I had a new silicone coolant hose set fitted by John Law and over the winter I fitted a new aluminium alloy radiator and completely flushed the cooling system filling up with Renault Type D coolant, all good and no problems over the last 800 + miles driven.

Since the Macon issues I have since changed the expansion bottle for a Crown one as recommended but what I am getting is an intermittent leak from the bottom hose connector, the one underneath the bottle which is the most difficult one to see and access...this is driving me potty as it doesn't happen every time I use the car.

I have removed the expansion bottle some 5 times now. In fact I bought two Crown bottles and have also changed the bottle in case there was a problem with the bottle but no difference.
I put the old bottom hose back on in case the silicone one was faulty but still got a leak so I had the silicone hose pressure tested by a helpful local garage, it was fine so I've put the silicone hose back on and I changed the jubilee clip for a new one and all seemed OK.

Yesterday morning I went on a 20+ mile run fast, slow and in traffic no problems at all, no leak.
Yesterday afternoon I drove into Andover and back, 16 miles,checked under the back of the car, drip, drip, drip .

Last night removed the bottle again and fitted TWO new jubilee clips to this connector, went for another 10 + mile run and it 'seems' OK now but I can't think for the life of me as to why this connection should leak intermittently.

I'm guessing it must be down to pressure give the bottle, hose and clips are all new so I am also replacing the coolant bottle cap. This is about a year old but I have ordered a new one from Renault that I can pick up tomorrow night just to eliminate any problem with the cap itself.

After that I'm not sure what else I can do, I'm plain out of ideas!.

I'm 'hopefully' going to La Vie en Bleu on Sunday staying in Tewkesbury at the Premier Inn Saturday night. it would be great to get there and back with no more leaks.

Can anyone advise me what else I can do or if I'm doing anything wrong. Any advice greatly welcomed.

Cheers, Barry.

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I think it sometimes depends where the jubilee clip is in relation to the "flare" on the bottle.
I am told that the clip should be butting up to the flare. I think you put the clip on gently, tug the hose so that the clip snags on the flare and then tighten it up.
See you at Prescott.

I had problems in the past with two different diameter hoses on the A310 that leaked at the ends even with double jubilee clips positioned adjacent to the flares. The cause was that the inside diameters of the hoses were not quite small enough. The hoses would push over the pipe flares with some resistance but weren't 'tight' enough on the plain section of the pipe stubs behind the flare. However much the jubilee clips were tightened, the hoses still leaked.

I replaced the hoses with ones the next size down on inside diameter which solved the problem. The inside diameters of the hoses needed to be just less than the outside diameters of the pipe stubs behind the flare.

I can't think of a reason for your intermittent problem, in my case the leaks were there all the time.

The original OE clip was not a jubilee type clip but one of those that had two tags which had to be squeezed together to release the pressure on the hose. The big advantage of those was the pressure exhibited by the clip was uniform right around the hose and even more importantly around the pipe that the hose was fitted too. Although ... in theory ... a special tool should be used for this type of clip, I have always used a mole wrench to squeeze the tags together. Once squeezed together, the mole wrench held the clip open for easy removal and fitting.
I agree with the others in that I also think the jubilee clip is your problem. In high pressure conditions, the choice of clip is important due to the radius of the part of the adjuster that sits against the hose. If it is too big, that part of the clip sits flatter against the hose and does not apply consistent pressure around the pipe, and as you tighten up, the clip is pulling the flexible hose up towards the metal radius and could be distorting the hose against the static pipe.
In this case, because of the flare on the reservoir's pipe, the clip's size, in order to get it over the flare whilst loose on the hose, it is likely to be a bigger clip than is necessary. Although awkward to fit, it would be better to fit the clip after the hose has been attached to the pipe, as once fitted and squeezed down the radius of the clips adjuster (where it is sitting on the hose) will be more suited to the diameter of the pipe.
Another thing I always do with water hoses, is lightly smear the inside of the hose, and pipe, with silicone grease. This has a number of advantages. It helps seat the hose whilst tightening up the clip which stops the hose bunching up where the clip is being drawn into its adjuster. It also helps seal the joint, and as silicone grease does not deteriorate, it helps in the eventual removal of the hose, as once the clip is undone, a gentle twist of the hose and off it slides.
The only thing that might worry you is that once the clip has been done up, you still may be able to rotate the hose ....... don't worry, that often occurs on larger hoses, but it will be sealed.
Obviously you need to check it out .... like you would anyway, But I have been doing this on all my coolant hoses at least for 30 to 40 years and have not a failure ..... yet.
One word of warning though ........ never do this on fuel lines ...... silicone adhesive or grease do not like petrol.

Hi all,

Thanks for your help and advice. The odd thing is that pre Macon when I had the coolant leak I'm now beginning to think that my old coolant bottle was OK but it was the jubilee clip that was causing the problem, but I still cant understand why its been fine for nearly a year then starts to leak...!
John C I know the type of special clip you mean with the two tags on. When I changed the Heater Matrix those pipes had these clips on and I happen to have the special tool for these types of clips. So it looks like a high pressure issue which is why I decided to use 2 jubilee clips instead of one. When I fitted these I did fit the clips to the hose after it had been attached to the outlet pipe...maybe that will help!
Thanks also for the info on silicone grease I'll buy some of this as soon as I can.
I'm picking up the new coolant cap from my local Renault dealer tomorrow night so I'll see if they have any of the special clips in stock.

Cheers, Barry.

........ So it looks like a high pressure issue which is why I decided to use 2 jubilee clips instead of one.

Barry ..... I suspect you are doing this anyway, but if not ..... It is important to position the clips adjusters, as close to 180 degrees away from each other. This way you will have each of the clips adjusters weak points on the hose, being covered by the other clip ..... if that makes sense .....
John

Just try nipping it up a bit......but not too much .

If that fails then you could try shouting at it and tell it not to take the feckin "wee wee".

or wrap a load of ptfe tape around the tube to increase it's diameter a bit.
And some grease as JC suggests.
BTW, mine leaks too.

[mettersl]

You could or self amalgamating tape inside or outside to tighten up the native fit , that worked on a damaged radiator pipe on one of my cars.
As it cures and mould together it will bond onto the pipes around it.
The correct clips are probably a good idea too.
Lee

Hi all,
Well its now 9.45 pm and I'm just out of the garage, need to eat and have a shower.. The double jubilee clips spaced at 180 degrees didn't work so today I managed to buy some of the spring clips that JohnC suggested along with some silicone grease.
So removed the bottle...7th time now, clean everything up apply the silicone grease refit the hose put in the spring clip, top up coolant went for a run...drip. drip, drip. The I discovered a minute leak in the silicone hose...ah ha I thought...found the problem.

Let everything cool down, removed the bottle, 8th time, changed the hose for the original black Renault one which I know is OK, applied the silicone grease fitted the spring clip, topped up the coolant, went for a run...drip. drip, drip..

I'm ready to give in, last thing I can do is take my car to my friendly Independent Renault guy in Andover tomorrow morning, see if he can assist at all, failing that I'll be on the club stand in a Renault Laguna or as a spectator...

Hi Barry ...... I would be going out of my mind as well ....... it seems such an easy fault to find.
Just a couple of things ...... would it be possible after a run whilst the pressure is still there, to wipe the joint dry, and with a mirror try to see where the drip is originating from, or is it dripping too fast to do that ? .......... point two ... what coolant level are you filling the reservoir to ?
John

Hi Barry ...... I would be going out of my mind as well ....... it seems such an easy fault to find.
Just a couple of things ...... would it be possible after a run whilst the pressure is still there, to wipe the joint dry, and with a mirror try to see where the drip is originating from, or is it dripping too fast to do that ? .......... point two ... what coolant level are you filling the reservoir to ?
John

Hi John,

After my last run out I did look at the joint with a tiny mirror, tight squeeze as you know and of course the bottle and pipes are pretty hot. The coolant does appear to be getting past the spring clip and dripping from where the hose abuts the bottom of the bottle.,.maybe I need a slightly smaller spring clip?

I have Crown bottle fitted which had the min and max plastic thingy inside so I filled the bottle with coolant to just above the minimum level.

Cheers, Barry.

Hi Barry, thanks for your reply. Yes ... the unfortunate thing with these "Constant Tension Clamps" as I have just found out what they are called, they are designed each for a very specific size for hose, with very little tolerance. So unless one knows the size of the OE one, it is a little hit and miss to select the right one.
Your coolant level is fine ...... the only reason I asked is because I have found that if they are over filled, the coolant can splash up against the underside of the cap, and small amounts of coolant collects around the base of the cap having been pushed out, as the cap is maintaining the pressure. I did wonder if the coolant could be being pushed out and running down the bottle to its lowest point where you are seeing the leak.
Ah well ..... that's another idea shot out of the window.
If you can get a tighter clamp, that would be worth a try ....... perhaps one that when the two tags are pressed together, (opened to its fullest diameter) it just slips over the hose at its largest diameter over the flare. That's what I think I would be going for.
Anyway, let us know how you get on at the garage.
Cheers
John

Hi Barry,

Going back to my earlier comments, are the hoses a tight fit on the plain diameter of the tank pipe stub, behind the swaged section? Really needs a caliper measurement to check the hose is smaller id than the pipe stub od.