420R (S3) Radiator design issue, regular failures???

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Jonathan Kay
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Can you add some photos of that hose and area, please.

Jonathan

CtrMint
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this large one

Caterham 420R S3 Lotus Toxic Green,  Caterham 620R S3 Exocet Red. Blog: https://www.caterham7diaries.com
timb2117
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Sorry I am a bit neanderthal, but from my viewing of the OP photo, it needs;

1. The right angle bracket which is welded onto the chassis cutting approx 5mm back from the right angle bend.

2 . This tab inverting and welding back on to the same spot.

Result no rad movement up or down, the bobbin is doing its job, no clearance issue for pipe inlet.

Jonathan Kay
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Tim:

I think that the alterations that you are suggesting have already been done, although by bolting rather than welding. 

Jonathan

Jonathan Kay
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"I noticed this evening there is still a significant amount of vibration being absorb by the rad, not from the chassis mounts, but the large diameter stiff hose at the top.  Holding that you can feel most of the vibration at tick over in that hose, rather than the chassis.  I'm wondering whether I should try and swap to a silicon hose, maybe cut the stiff hose and use an insert to extend into a silicon hose, which might suppress more of the vibrations."

Thanks for the photo.

Is that long fat hose ordinary black rubber throughout? 

If you remove one end does the other end sit nicely for length: so that it isn't compressed when connected at both ends?

Is the smaller hose running across it at the bend bearing on it?

Jonathan

PS: I've looked at the usual suppliers of silicone hoses for something like a bellows section but not found anything yet.

timb2117
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Sorry Jonathan it just looked from the photos in the OP that the upturned bracket was touching the inlet pipe and the bolt head was within 1mm of the rad tank, negating the bobbins action. Whereas the photo you have just above shows same alteration bracket clearly missing both areas and the bobbin can work well.

Anyway hes getting you on the case so that will see it solved :)

Best regards Tim.

CtrMint
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HI Jonathan, 

Thanks for the support. 

"Is that long fat hose ordinary black rubber throughout?"

Yes it's a stiff thick walled rubber hose all the way to the back of the engine near the submarine.  It's surprisingly hard for a coolant hose.

"If you remove one end does the other end sit nicely for length: so that it isn't compressed when connected at both ends?"

I'd say no, there is some additional length present, around 2cm of excess, so a little tricky to trim.  Making it too short might cause the hose to get dangerously close the belt too.  I can see your thinking, but given the stiffness of the wall I'm very doubtful reducing the length would render that much of an improvement.

"Is the smaller hose running across it at the bend bearing on it?"

Yes but and I know it's not scientific but from touch there doesn't appear to be any noticeable vibration coming from that hose.

I've found this sort of hose'

https://www.carbuilder.com/uk/28mm-id-x-225mm-long-vulcoflex-flexible-coolant-hose

There's also a number of options from Viper

https://www.viperperformance.co.uk

https://www.viperperformance.co.uk/silicone-hoses_10226_ultra-flex-hose-750mm-long.html

I'm not sure if my modification to the bracket is the fix, even if it is, I can't believe the level of vibration is good for the rad, so making an improvement here, has to be beneficial.

Caterham 420R S3 Lotus Toxic Green,  Caterham 620R S3 Exocet Red. Blog: https://www.caterham7diaries.com
Blue7
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The existing hose seems to be very close to the bonnet, but the Car Builder hose should certainly reduce vibration.  What puzzles me is why other 420R owners aren't having similar problems, or maybe they are?

CtrMint
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Based on PMs I received over Instagram when I posted about the rad failure others are experiencing similar problems.  

Also there's the ongoing discussion about the radiator quality, maybe the rads are better than thought and a contributing factor is the hose.  It's overly stiff and doesn't naturally fall into the required position.  It's design to meet the radiator further in the middle, hence why it appears to sit close to the bonnet.

Of course I might be chasing something that doesn't exist.  Having had a couple of issues, which CC put down to bad luck I'm trying to minimize any potential.

At the moment I'm thinking about cutting the hose under the plenum, adding an insert and then running a flexi hose to the radiator.

Caterham 420R S3 Lotus Toxic Green,  Caterham 620R S3 Exocet Red. Blog: https://www.caterham7diaries.com
John Vine
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...and a contributing factor is the hose.  It's overly stiff and doesn't naturally fall into the required position.  It's design to meet the radiator further in the middle...

I think that is exactly the problem.  Your top hose is designed for the earlier rad, and that enforced extra bend means the hose is under permanent tension.  This is the original design:

 

The hose is made of EPDM rubber, very tough but not very flexible.

Of course, the proper solution is for CC to offer a hose tailor-made for the new-style rad.  I'm a bit surprised that they haven't done that already.

JV