NA broken coolant hose? help

15mx5 · Post by **15mx5** » Mon Feb 16, 2009 12:30 am

Hi all,
I have a 92 NA with 160,000kms on it, went for a 400km drive a while ago, found the hose under coil pack spraying out coolant after arriving home, it's coming out of the red circled area in the picture. Has anybody had this happen before? Any help would be appreciated. Thanks

Habanero666 · Post by **Habanero666** » Mon Feb 16, 2009 1:37 am

Hi there, yes, this was the first hose to leak on my vehicle. The next thing to do would be to renew the whole cooling system if your vehicle is a 1990 model with the original hoses etc. Sounds over the top I know!
To save major carnage I got all the hoses, thermostat and coolant additive through the local Mazda dealer and a new Radiator from SilverdaleRadiators in Auckland. Speaking from experience I would replace the engine management coolant temp sensor too. And NO I don't work for Mazda parts Dept! Total bill is around$5-600 if you do it yourself.......or take the risk and keep replacing the hoses as they perish... choice is yours.

Euen · Post by **Euen** » Mon Feb 16, 2009 9:32 pm

If you do it yourself, be very careful removing the heater hoses from the stubs poking through the firewall. They crush very easily and are quite difficult to reshape. Once you have the correct new hoses, the easiest way to get the old ones off is to cut them with a sharp craft knife.

If you have access to a bit of rubber grease, it makes reassembly a whole lot easier, but only use a very light smear.

15mx5 · Post by **15mx5** » Mon Feb 16, 2009 11:36 pm

thanks 666 and euen, you all seem to have done this yourselves, is it going to be a big job(labour/hours wise)?

Euen · Post by **Euen** » Tue Feb 17, 2009 11:06 am

I agree with Habanero that if you are going to do hoses, then do them all. If one has gone then the others won't be far behind.

The job is more fiddly than difficult. There are 4 small hoses that feed to the throttle body and oil cooler (under the inlet manifold), 2 of which are a real pain to replace. I haven't done a radiator on a 5 so can't comment on the difficulty or otherwise of doing that.

Without knowing your skills under the bonnet it would be hard to predict how long it would take but I would expect that if you have all the parts you need it should be possible to complete it in a weekend at a reasonably leisurely pace. It would probably pay to get a manual as well.

Good luck.

WideOpenThrottle · Post by **WideOpenThrottle** » Tue Feb 17, 2009 12:57 pm

Another trick which is easier & safer is to cut all rubber & plastic hoses with sharp pruning clippers-no chance of slipping & cutting the wrong things.

poison · Post by **poison** » Wed Feb 18, 2009 9:35 am

It’s better to pull off the hoses before cutting too much off as the ends get rusted on.

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sprsta · Post by **sprsta** » Wed Feb 18, 2009 7:24 pm

radiator is no problem, just acouple of bolts securing it to the rad support, should be easier to replace than getting some of the hoses off. if your doing an auto make sure you take one of the trans lines off at the rad and the other off at the metal pipe so you can join them to recirculate, you wont have to put so much trans fluid back in.
we do this if we have to take a rad out and then need to drive up to the paint shop without a radiator

15mx5 · Post by **15mx5** » Wed Feb 18, 2009 9:58 pm

Damn, i knew this would cost me...
My mechanical skills are limited to changing light bulbs, so DIY is out of question for me.
Thanks all.
It's going on trademe now, anyone want a 92 manual with 16xxxx kms for cheap?

Post by **zorruno** » Wed Feb 18, 2009 10:25 pm

I think some people forget that others are sometimes on a budget... and don't require chromed engine bays & steel reinforced silicon piping

You don't have to replace your whole cooling system. My 94 has had exactly two cooling system leaks. Certainly annoying, but I wasn't about to change out my whole system because of it.... or sell my car! If something looks particularly worn, I'll change it, or replace it if it breaks.

Mine leaked in the same pipe as yours a number of years ago (except on the firewall side) - from memory I cut the hose off and shortened it until I got it to my mechanic who ordered the replacement 'shaped' hose. The other leak was the elbow at the front of the block in the middle of the belts (the metal join had corroded).

Actually both happened on MX5 events, and one was a 'Track day'...

cheers

poison · Post by **poison** » Wed Feb 18, 2009 11:22 pm

If you are worried about your hoses, just wait till the system is cool and given them a squeeze, If they are crunchy then a swap is a good idea, if not too bad and still a little soft then they should be fine.

Anyway the small hose is no biggie. After 15 years all the hoses can become brittle and can burst. Usually it's the main radiator hoses, but any can go at any time. You will need to get one of these from Mazda, and if you have basic tool skills can do it yourself.

When the car is COLD!!!! drain the fluid from the bottom of the radiator (there is a small Phillips head screw), use rubber gloves if you have some. It is toxic so don't get it in your mouth or eyes. Drain into a tray, will be about 4 litres in there. Remove the radiator cap to make it come out quicker. It's good to replace the fluid every couple of years anyway.

Use pliers or vice grips to squeeze the little metal clamp back at each end of the hose. And pull them back along the hose.

The hoses often rust on so you may need to use pliers, a knife or screw driver to get the old hose off with a bit of wiggling and twisting.

Stick the new hose on (with the clamps).

Do up the screw on the bottom of the radiator and refill the system with coolant. Check the coolant after a day (only when car is COLD).

Hose should be only $25 or so at a guess, but Mazda is Mazda

and if you don't want to do it yourself I'd say it's a 30-45 minute job for a half decent mechanic and an hour for a Mazda specialist

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poison · Post by **poison** » Thu Feb 19, 2009 12:00 am

Do not sell because of one hose, most of us are car fanatics and look towards overkill, as Z said it's just one hose. Any car you buy in the world will have something fail.

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Stevo · Post by **Stevo** » Thu Feb 19, 2009 7:40 am

Exactly what Poison just said. Its just a hose which is generally a piece of cake, I have not done one on the MX5 yet but any handyman should be able to do it in an hour. No need to do the whole system, thats an overkill. cheers stevo

15mx5 · Post by **15mx5** » Sun Feb 22, 2009 10:25 pm

Thank you all for the suggestions.
I've decided to sell the car, I have neither the money nor the time to have it fixed. Byebye twisty roads pleasure, hello wobbly suv...
hope to come back in a NB

Fletch · Post by **Fletch** » Wed Mar 18, 2009 9:43 am

A frequent cause of that particular hose starting to leak coolant is if your CAS O-ring is leaking engine oil down the back of your head..... the oil breaks down the rubber fairly quickly...

To check, just reach behind the head (engine cold, of course) and feel for a greasy mess under the CAS....

The O-ring is cheap, and nearly as easy to replace as the coolant hose.... and removing the CAS will actually make replacing the hose easier, so you may as well do it all together.

Fletch.