Coolant Hose Options - Silicone vs Rubber

Roadrunner · Postby **Roadrunner** » Mon Dec 10, 2018 12:18 pm

Well, options and opinions....
I'm looking to replace all my radiator/coolant hoses soon. My top hose is brand new rubber. All other hoses as far as I am aware have never been replaced but "appear" in perfect condition so this would be more preventative maintenance than anything.

Rubber has never let me down so happy to replace with genuine rubber hoses, but,
Mazda has discontinued the bottom hose for the SE. It is available in Silicone though.

My concern with silicone is that from what I've read, it weeps (permeates) through the walls of the hose considerably quicker than rubber and some suppliers don't recommend silicone for street dríven cars due to this as the weeping is accelerated by constant heat up/cool down of a daily dríven car.
My other concern is tightening clamps down. Silicone doesn't flex like rubber and I'm worried about clamping down and crushing a heater pipe outlet etc or just never getting it to seal completely.

Has anyone had any issues with this? Is there an alternative to the SE bottom hose in rubber? Or am I overthinking it and should just get the MX5Mania silicone kit with their hose clamp kit and not look back?

Roadrunner · Postby **Roadrunner** » Mon Dec 10, 2018 12:39 pm

hks_kansei · Postby **hks_kansei** » Mon Dec 10, 2018 12:50 pm

Rubber all the way for me.

My theory is that the original rubber hoses did just under 20 years of service in my car without a hitch, and even then it was one of the tiny ones that blew on mine.

On top of that, generally silicone hoses are cheaper (well, retail anyway, not sure on wholesale), if they were as good or better, and cheaper, surely the OEMs would use them during manufacture.

In saying that, it also comes down to price.
I think my full set of Gates rubber hoses cost me about $500 (may have included labour? cant remember) when I had the whole lot done (every coolant hose, including the annoying ones for the oil cooler and the throttle body)

The silicone sets are about $150 from memory. So as long as they last more than 1/3 the life of the rubber ones you'll be ahead.

I just paid the extra since I really dont want to have to deal with them for another 15 years or so.
That, and I just dislike the shiny look of the silicone stuff, and how most of it has gross logos all over it.

manga_blue · Postby **manga_blue** » Mon Dec 10, 2018 6:28 pm

Only rubber for me too. If you can work out all the part numbers then a full set of genuine Mazda Made in Japan hoses from amayama.com is pretty cheap.

KevGoat · Postby **KevGoat** » Mon Dec 10, 2018 9:51 pm

Roadrunner wrote:Mazda has discontinued the bottom hose for the SE.

Is the SE hose different to the standard NB hose?

Roadrunner · Postby **Roadrunner** » Tue Dec 11, 2018 8:21 am

KevGoat wrote:
Roadrunner wrote:Mazda has discontinued the bottom hose for the SE.

Is the SE hose different to the standard NB hose?

Yes it is. Apparently if you use the standard NB lower hose on an SE it'll kink and restrict flow.

Ended up ordering genuine heater and bypass hoses, new clamps and all. Stuck on what to do about the SE bottom hose though.

Lokiel · Postby **Lokiel** » Tue Dec 11, 2018 10:34 am

Roadrunner wrote::
Stuck on what to do about the SE bottom hose though.

Do what I did, it's even better than OEM (see http://www.mx5cartalk.com/forum/viewtopic.php?f=57&t=76716&start=178):
1. Modify water inlet barb (aka mixing manifold) so that it angles downward diagonally behind A/C compressor
2. Find/modify a hose so that it runs under the A/C compressor and straight to the lower radiator barb (if you have the OEM radiator, the hose should be easy to find since you just need one that has a 90* bend with one short and one long end).

Our RHD cars don't need that convoluted lower radiator hose routing - that's only needed to avoid the steering wheel shaft on LHD cars.

Another advantage of the re-route is that it clears a lot of room down low for intercooler hotside plumbing.