Erratic Temp Gauge NC

kris · Postby **kris** » Thu Oct 13, 2011 4:38 pm

Hey guys,
Yesterday and today i noticed my nc temperature gauge has been very unstable. Normally it sits mid way and doesn't move no matter what. It now sits around 70% from MAX and has at times been only 2-3 bars shy of max temperature.
I have noticed that it climbs when going up hills and drops marginally going down hills!
When idling it occasionally climbs to 80%. Also, after turning the car engine off, a fan seems to remain on for awhile as though its trying to cool the car down- I can't remember this ever happening before.
I don't believe the air intake is blocked, nothing else seems to be a problem.
Any advice?
Cheers

JBT · Postby **JBT** » Thu Oct 13, 2011 5:03 pm

This thread may be helpful: http://mx5cartalk.com/forum/viewtopic.php?f=79&t=49246

kris · Postby **kris** » Thu Oct 13, 2011 6:16 pm

Hmm thanks for the link JBT...... oh boy........

Mr Morlock · Postby **Mr Morlock** » Thu Oct 13, 2011 7:44 pm

looks like a very useful diy. It seems the gauge is doing its job ie alert of overheating. I would be heading to a suitable repairer asap.

Sailor · Postby **Sailor** » Thu Oct 13, 2011 8:45 pm

Might sound silly Kris, but have you checked the coolant level?

kris · Postby **kris** » Thu Oct 13, 2011 9:10 pm

No I haven't checked the coolant level! Thanks Sailor I will do this ASAP.

Yes, i was looking through that guide.... I don't think my driveway mechanic ability is quite up to that level!

I will have to warn the mechanic prior, would they be likely to have the part available if necessary? I will call MX5 Mania, its also time for a service so i will try and get that done at the same time too.

Charlie Brown · Postby **Charlie Brown** » Thu Oct 13, 2011 10:31 pm

Kris,
I doubt that Mania will have a thermostat, they will need to get it from Mazda, cost is around $124.
It's cheaper to get one from Brian Goodwin but pay for fast mail. Don't use US Postal because it will take 5 weeks!!!
Check your fluid level first though.

Gmi · Postby **Gmi** » Fri Oct 14, 2011 12:27 am

Oh Kris ):!! Good luck with it man.

Charlie Brown · Postby **Charlie Brown** » Fri Oct 14, 2011 8:52 am

Kris,

Something I left out last night.

Your problem is the reverse to mine. Mine ran cold.

First check the fluid level then if that's OK, this is the check for your thermostat.

Run the engine until it's hot, turn it off and then feel the bottom radiator hose. If it's very hot, (ie boiling water in the hose) as opposed to warm to hot, then the thermostat is working because the coolant is flowing through the radiator. If it's not too hot then your thermostat isn't opening properly.

This is where you'll need to go to feel the hose.

kris · Postby **kris** » Fri Oct 14, 2011 4:32 pm

You guys are all champions!

I followed the instructions, my coolant levels were near perfect, but a short gentle drive today back from work and my temp gauge was normal for awhile before going through the roof! I was able to nurse the car to the mechanic (i was in that area just in case) and literally pulled up at the right time.

Popping the hood, the coolant was fiercely bubbling, some had escaped through the cap and made a mess while the whole engine looked generally very angry.... after cooling down, then running some diagnostics with the mechanic (like checking for leaks and pressure loss), it was clear that the thermostat had died. I was even able to inspect the hoses as charlie mentioned, and the temperatures of the particular hoses was clearly out of whack.

So I'm not just topless for the weekend but carless, while I wait for the part to arrive and be installed on Monday. Just shy of 60000km and the thermostat dying is a bit concerning- should i be worried? Charlie, did your original last twice as long?

monte5 · Postby **monte5** » Sun Oct 16, 2011 8:58 pm

Interesting mine died at around 70k's (running cold) and then about 2 weeks later CB's died. Possible weak point?

Postby **Okibi** » Sun Oct 16, 2011 9:47 pm

Glad it's getting sorted Kris, fingered crossed your careful attention to the temp gauge means is hasn't cooked the engine.

Charlie Brown · Postby **Charlie Brown** » Mon Oct 17, 2011 10:04 am

kris wrote: Just shy of 60000km and the thermostat dying is a bit concerning- should i be worried? Charlie, did your original last twice as long?

monte5 wrote:Interesting mine died at around 70k's (running cold) and then about 2 weeks later CB's died. Possible weak point?

There doesn't seem to be any relationship to the number of kilometres travelled. They just seems to decide to go when they want too.

I'd say my next major part change will be the clutch. It's done 127,000 klm of daily driving with just a few :roll:

track days thrown in. It still feels fine but my NA's died at around those Klms.
One notable NC racer was surprised way back at 80,000 klms that I was still using the original clutch.
Just shows you that if you match the revs on gear changes wear is reduced.

kris · Postby **kris** » Tue Oct 18, 2011 9:16 pm

All seems well, new thermostat installed. Temp gauge back to being still as a rock.

BTW, I think if you are not a 'switched on driver' you would infact miss the quite subtle temp gauge changes- there was no warning lights or beeping!

Engine is just as brilliant- no harm done