Tiffany Cobb

bundy_harry · Postby **bundy_harry** » Sun Nov 28, 2010 1:47 pm

Howdy All,

I am new to all things MX5 and must say that I am thoroughly hooked - I should have bought one of these years ago in stead of messing around with Landcruisers...

Allow me to introduce you to my MX5 Tiffany Cobb, although I call her "Blu" for short...

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This is a nice little car I picked up for a song on the Central Coast of NSW. "Blu" is a 92 red NA6 with air conditioning - she had only done 155,000km when I found her.

Since I bought her back in August, I have added a Black Hardtop, have acquired some parts from MX5 Mania and some other bits and pieces from the net, to be added over time...

At some stage in her past she has had a punch in the nose, i discovered this in the form of her over heating at highway speeds, so I acquired a tome of knowledge, got underneath and had a look around. Fortunately I have another NA floating around that I could use as a guide to what may be missing. I found there was no airguide in front of the radiator and no engine under tray. The MX5 i was using as a guide has been setup to race so I setup about having another engine under tray fabricated from its own as a template.

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A new air guide was acquired from the Mx5 Centre and 5 clips used to attach it to the front bar were acquired from the Mazda dealer in Penrith.
All was fitted yesterday afternoon and a spirited drive up Springwood Rd followed to see if I could get it hot.

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My drive was a partial success. I had set out to improve the Air Flow into and around my radiator. I no longer have an issue with heat at Highway speeds however for short intense "spirited" drives up hills I still have a serious problem. I could the engine boiling before I got to the top of the hill however when I stopped (engine still running) the recovery was much quicker than with out the air guide installed.

My hypothese is that now that I have returned the vehicle back to its basic 'spec' that the performance of the radiator (OEM Original) is marginal at best. I dont believe the water pump is at fault as performance at highway speeds is now satisfactory.

My Plan is to upgrade the radiator to and ASI or cooling pro radiator, replace all the cooling pipes with those good looking blue pipes from Mania, flush the water galleries on the motor prior to removal and install some high density foam around the radiator to force more air into the radiator at all speeds...

cheers
Harry

Hammer · Postby **Hammer** » Sun Nov 28, 2010 3:25 pm

Welcome. I see you've started the mods already. :mrgreen:

Old Dude · Postby **Old Dude** » Sun Nov 28, 2010 5:41 pm

Welcome Bundy_Harry, and a very nice looking Tiffany Cobb she is. :beer:

Cheers
Dale

Guran · Postby **Guran** » Sun Nov 28, 2010 6:22 pm

Welcome aboard! Lovely car you have there. But I'm biased! (check my garage thread - our cars are almost twins :lol:

)

bundy_harry wrote:My hypothese is that now that I have returned the vehicle back to its basic 'spec' that the performance of the radiator (OEM Original) is marginal at best. I dont believe the water pump is at fault as performance at highway speeds is now satisfactory.

I don't think that's your problem. My NA6 is stock and regularly cops a thorough workout on the track and on mountain passes. The stock radiator is fine under this treatment. Your radiator might be partially blocked and you could get a radiator specialist to test it for you. I noticed that the front of the bottom tank on your radiator is white in colour. It should be black - the white colour is a sign of heavy degradation of the plastic. Mine looked the same when I had it replaced recently. A new aftermarket radiator from Mania costs $280.

Or it might be a dodgy thermostat which has failed in the "closed" position. It's easy to remove and you can test it in the kitchen. Hang it in a saucepan of water with a thermometer, heat it up and watch for it start opening at 80.5-83.5C, fully open by 95C with maximum lift of 8.5mm. If it's not working properly, fit a new one and try it out again.

Or your waterpump could be on the way out. It spins faster at higher rpm, plus there's more airflow through the radiator from the front intake. Both effects would mask the overheating problem at highway speeds. Hopefully this is not the problem because it costs ~$1000 to get it fixed (might as well do the timing belt at the same time since it needs to come out to access the waterpump).

If your radiator and heater hoses are hard and brittle, then you should definitely replace them before they spring a leak and you cook your engine in the process. A set of stock hoses cost about $160 from Mania.