Overheating daily
 

So on the days that I take the miata out I start to overheat if I don't keep moving. I'm talking even sitting at a red light for a little too long the needle starts to climb.

I was assuming it was an issue with the larger IC, but now that I think about it I've had this IC for awhile now and this is a newer issue. Last night when I got home I could hear the overflow tank burbling and the upper hose was insanely hot.

Shall I just remove the thermostat?

Are the fans working?

Yeah the fans are coming on like normal.

To help things I suppose I should include the following:

Ron Davis radiator with updated silicone hoses (1 piece bottom)
Recently replaced the thermostat to try and fix the overheating
Recently flushed
No leaks

I even put the OEM coolant overflow tank back in to try and fix the overheating.

I have heard of the shaft on a water pump breaking before. While that is highly improbable, with your list of stuff done already, it may be something to check out.

Is the overheating the same as what is was before you swapped out the thermostat? Did it even get a little better?

Do you have a coolant reroute? Is the heatercore still installed? If it's only overheating when you're stopped and the fans are working, I would think it'd have to be an issue with water flow.

Burp your coolant again. Lift the front of the car as high as you can in the air and let it just run. I usually let the fans turn on and off 3 times to make sure I have all the air out of the system.

how high is the gauge climbing?
12?
1?
i ask because on occasion, right before my thermostat opens, my gauge sometimes climbs to 12 or 1 and then immediately goes back down to 11 once the thermostat opens.

if sitting/idling for a couple of minutes, the gauge sometimes reaches 12 and then goes down to 11 quickly after moving the car.

thermostat was also just recently replaced in my scenario, but the gasket wasn't scraped 100% so there is a tiny (literally miniscule) "leak" that happens sometimes...not all the time, just sometimes.

my loss of coolant is negligible so i don't think that's my "issue"

again, how high does your gauge climb?

Make sure your T-STAT bypass hose passage is open. What you are describing is a symptom of blockage in that hose. I've had it before.

Good info on Miata cooling system here:

http://www.miata.net/garage/cooling_system.html

Its hard to say, but if anything it was slightly better before I swapped the t-stat.

No reroute and heater core is still there.

Yes, I'm thinking the water is not moving through the system. Due to blockage, malfunction, or otherwise.

I burped this guy like 10 times AT LEAST. Maybe I'm doing it wrong, but I'll give it another go when I get to the shop this afternoon.

Gauge used to sit at 11-12 since the day I've owned the car. Now the needle is climbing at a fast rate (when not moving) all the way pegged to H if I'd let it. Already tried seeing what would happen if I let it go all the way. I hope its not causing any permanent damage (head gasket) by driving it like this. By this I mean not letting it climb past 1 while driving, but turning it off and letting it sit afterwards is a different story I suppose.

"Check your radiator cap
Your cooling system is a closed system, designed to build up pressure as the temperature rises. The higher pressure raises the boiling point of the coolant mixture. (Remember college physics?) When the temperature/pressure rises to the proper level, the valve in the radiator cap (yep, they have a valve - ever wonder what that spring is for?) causes the cap to open and the coolant to flow out to the overflow reservoir. As the coolant flows out, the pressure drops and the valve in the cap closes. As the engine cools, the valve opens in the other direction and the pressure drop in the radiator sucks the coolant back into the system, re-establishing equilibrium. Similar in operation to a thermostat, the cap can freeze up causing pressure problems in your cooling system, leading to an increased possibility of overheating. One symptom of a bad cap would be hearing a sound like a coffee percolator when you shut down. They are cheap enough that you should just plan on replacing yours every year or so. NAPA sells a "Stant" cap (part #703-1406) with a higher pressure rating than stock for about $8.95."

Hmmmm. I guess I'll pick up a new cap today and see if that helps anything.

He'd always be overheating if that were the issue.

What's your ducting like? With my new ducting I can feel the air being sucked into the mouth. Undertray?

thanks. i replaced one of the little water hoses that goes to the tstat housing. there's one more on there. i'll replace the other one as well.

wait, you let it get all the way to H, just to see if it would?
the head gasket on the miata is somewhat decent in my experience (already blown one and pegged H on the new car), but i wonder if you did actually damage it.

Make sure you Q-tip or blow out the passages as well. A lot of times, there is gunk built up and only replacing a hose doesn't get you there.

No undertray, no ducting.

Its on the list but this was never an issue before.

I swear the car used to be my DD and I never had issues with overheating. This is the same setup I've had all along, with exception to add ons like the newer manifold/dp, newer IC setup, etc etc.

Sitting in traffic at idle the hot air vapor is visibly coming our of the vents in the hood. I see no reason why I'm overheating unless its blocked or something.

I should also mention that I did replace the water pump back when I did the tb in like '04-'05, so its not the original.

When it very first overheated it was when I was away from the car. I was talking to a client and when I was walking back to the car it was smoking and pegged on H. I had no choice in the matter, but I know damn well it'll go there if I let it. lol

Joe, I'd say your problem is either low water flow or low air flow. Not sure which. Note that our fans do get weaker as they age. Turn your heater on full blast . . . any difference? If not, then it might be time for a timing belt and water pump. You can check your crank nose while you're in there (assuming a 1.6). Rosenthal has a package deal on a water pump and timing belt that is hard to beat. That's what I'm planning to do when the time comes.

Fans are also newer. I bought a set of slim fans (I forget the rating on them) and have the wired together to go on at the same time. At one point I was having a problem with the fans so I triple checked my MS settings and went over the wires only to find a loose connection.

Like I said before, TB and water pump are both newer. When I first bought the car (2004) the very first thing I did was all around oil change, timing belt, water pump and the SNC (woodruff key, bolt, gear, loctite) fix. Before the turbo parts went on I gave this car a one over more than a few times. lol

works great to help burp coolant.

a. Thermostat

b. blown head gasket

c. radiator cap

d. clogged radiator

e. Although rare, retorque head bolts

f. warped cylinder head

g. radiator fan going bad, although it turns on, could be not pushing enough air

h. timing too low

i. stuck open fuel injector/injectors, may need to be cleaned, calibrated, check for excessive carbon deposits on the electrode.

j. defective, or wrong settings on the fuel pressure regulator. I had one go bad and it was sending 70 psi of fuel, the car overheated immediately. Luckily there was a junkyard nearby, those U pick U pull.

k. With the engine turned off, can you spin the compressor shaft easily? Is there any resistance? Any possibility the turbo is not spinning as efficiently resulting in a clogged exhaust system.


Dont boost the engine until you resolve the overheating issue. Check your sparkplugs for coolant smell, and whitish layer on the electrode. Could you do a compression test and post results?

When did it start overheating? Did it happen after racing the engine a lot?

Did you jack with teh tune and leave it at 10* static?