So just got my new exhaust installed over winter and plated the FD today. Bone stock other than an exhaust and intake, nothing crazy special. Drove fine all day, then tonight (not even pushing it) it just died. I noticed the stock heat gage was at the high, so I shut it down. I pushed it with a buddy to my garage (2 blocks away) and currently have it parked. I do not think the coolant is low, checked it and seemed fine. When you try to start it, it struggles but if you give it gas sometimes rolls over. At first I thought dead battery, but it won't even support an idle. Will try starting it again tomorrow morning. Don't have a compression checker, but will be reading up and hopefully performing one. These symptoms seems like a blown engine I think?

Temp gage at high, and pour/stalling idle along with a slow start. Is this symptoms of a blown engine? No smoke or coolant smell what so ever. Any help?

 

How long was the temp gauge high for?

 

The light never came on, but I do glance at my dash often and check gauges I would say a couple of minutes tops, but am liking to think even less.

 

Alright update. The car starts fine, idles fine and still drives quite nice. Problem is after not too long (10min or so) the temp gauge goes way up. When I stop the car you hear a "thumping" from the engine bay. Anyone? advice?

 

Pop the hood and look around for the source of the noise. Most likely your AST cap blowing steam into your overflow tank.

a. Bad cap
b. Bad thermostat
c. Bad coolant seal
d. any combination of a,b,c

 

Add
e. clogged radiator or
f. bad (slipping impeller, etc.) water-pump.

And his temperature goes up BEFORE anything else happens, so it doesn't sound to me like a coolant seal or cap problem.

 

Yeah, currently trying to check my thermostat and radiator. The car can idle fine for 30 minutes, but under driving conditions (even slow ~30 mph) it will heat quite quickly,maybe 5 minutes before I shut it off. I go an feel the radiator and it is very "luke warm" it did not "heat up my hand" or hurt it at all. Maybe slightly above the temperature outside. Any tips on checking thermo and radiators condition? Thanks guys! Slowly starting to think less and less of a coolant seal, but not ruling it out yet!

 

Another thought - collapsing radiator to WP inlet hose, but that is pretty unlikely, since when hot there is pressure in the system that would keep it open.

Your symptoms indicate to me a very low coolant flow rate - OK at idle, but not able to handle the heat output from even gentle driving. My 1st guess is the thermostat is barely opening. The best way to diagnose that is to pull the thermostat and test it no the stove in hot water with a thermometer alongside. The thermostat should begin to open around 180F and be fully open by around 210F, IIRC.

The next suspect would be the radiator, but even a very clogged radiator ought to be able to handle gentle driving, and you said it can't.

Dave

 

Put a new thermostat in , no need to screw around testing it on the stove, it is a $10 part. Make sure you get a new o-ring with it.

 

You are, of course, correct. However, my goal was to isolate the problem to the thermostat before driving to test whether the car would overheat again. I always like to know if I've found the real cause of the problem. I guess it's my engineer's approach (overly complex).

Dave

 

Will grab a new thermostat from a store tonight or tomorrow we will see when I have time. Hopefully this fixes the problem would be great! So I need a new thermo, gasket and o-ring? Thanks guys! Very much appreciated

 

Alright started to take apart the engine-bay to get to the Thermostat. Not wanting to remove too much, what is required to remove in order to get to the thermostat? Will I need any other seals/gaskets other than the thermostat. Thanks guys, help is much appreciated.

 

Alright, got the thermostat out, one (hopefully) minor problem. One of the bolts (easiest one to get to, out in the open) came about about half way then snapped. There is about 1/4" sticking out, but getting vice grips on it is a challenge, the material seems to be rather soft. I have never used a screw extractor and often hear people breaking them off and then being royally screwed. What would be the top ways to get this bugger out? I also notice that the hole is right through, meaning perhaps could take the screw out the other side. The housing appears to be cast (is drilling/tapping an option here? Advice guys, anyone?

 

The bolt is steel and the flange is aluminum, so I would try penetrating oil and heat to expand the aluminum, so the bolt will be easier to extract.

Dave

 

Figured it out, about 2 hours with cobalt drill bits! Next problem, apparently they don't sell the thermostat in my city! Someone ordered one in for me, but arrived and was NOT the right size. Going to call Mazda and see what they can do, unless one of you guys that have access to them easily could ship one with gasket down to Canada. Online stores are giving me a quote of roughly 35 bucks shipped, can anyone beat that? If not, no biggy. A simple thermo job has turned into a nightmare and it may not even fix my overheating!

 

Call Ray Crow at Malloy Mazda. He is the best/cheapest source for OEM parts. His number is all over the forum but for easiness here ya go: 1-888-533-3400