lately, i've noticed that my temperature needle tends to rise quicker and during just normal driving without much boost. the car still seems to run fine and boost fine, but if i push it hard, the temps go way up real quick. i have an exhaust, downpipe, intake, and stock intercooler (no pfc) and alum radiator. i've had this car for about a year now, and the engine had about 40K miles on it (50K now) and never noticed the temps rising this quickly before. is this a sign that it's getting close to rebuild time? or could it be a coolant issue? i've noticed my coolant light comes on occasionally even after i top it off, but then turns off after the car warms up. any help would be great. thanks.

 

once your coolant system is full & burped properly you shouldn't need to top it up. if you keep topping it up, maybe it's time to think about coolant seal failure? i'm no guru but if you need to top it up, it has to be going somewhere.

 

check for leaks? I think my coolant seals are going out on mine. my fd started to have the hard starting problem with white smoke coming out. it's now getting worse but not overheating(i have the fans on to keep it cool). everytime I drive and shut off the engine I have to release the pressure from the pressure cap so it won't flood the engine.

 

Spaceman_spiff,

I'm guessing that you have a WP (slipping?), thermostat (not opening completely or aftermarket type w/o bypass block-off), or radiator (partially plugged) problem. Not enough coolant is flowing to keep the temperature where it belongs with higher power output.

Both times I've had your symptoms (on old beaters, not on the FD), it was a plugged radiator. A new radiator fixed the problem both times completely, despite other people saying that it was a thermostat or WP problem.

 

radiator eh? okay, i'll take a look into that and hopefully that should be it. so this isn't a sign that my engine is about to die on me?

 

Nah, you're not losing coolant, so it's just a cooling capacity problem like I mentioned.

Dave

 

if it's a clogged issue, will a coolant flush take care of it?

 

Maybe. Depends on how badly it's plugged. On the old beaters I mentioned above, flushing didn't fix the problem. Sometimes a radiator can be plugged so badly that it can't be properly cleaned by flushing.

Also, a really thorough flush has the possibility of creating leaks (heater core, etc.) where none existed before.

What radiator do you have? If it is still the original radiator, now would be a good time to replace it and avoid end-tank seal failure. I replaced mine with a new OE rad 2 years ago just for preventive maintenance. The original one was working fine. I still have it, and I'd sell it to you cheap, but since it's so old, I would recommend getting a new one to be safe.

 

When the car is warmed up, carefully feel the radiator to see if the entire core is getting hot. Changing the thermostat is easy and cheap insurance. I like the Mazda oem units. Are the fans coming on properly?

 

it has an aluminum radiator that was installed by rotary performance in texas i believe. the car has had that radiator in it for at least a year when i bought it used, and never had an issue with seeing the temperature rise up so quickly until recent weeks. could a radiator run well for almost a year without issue and suddenly get clogged up over the course of a few weeks so quickly?

the fans still kick in when i shut the car down after running hot, so i assume they are operating fine. i will feel the radiator tonight after i fire her up. the other issue, like you mentioned, could be a faulty thermostat. but you said the mazda oem units are your favorite, i thought the temperature gauges in these cars were notorious for being inaccurate. do you have a recommended aftermarket temp gauge?

 

1. On my old Pinto, it worked fine all winter, but as soon as the weather got warm it wouldn't cool. So the answer is maybe, if the system was filled with tap water when the radiator was replaced, and not flushed since.

2. Faulty thermostat (not opening completely) is more likely, given the relative newness of the rad. The mazda oem thermostat is the best. The oem temp gauge is center-loaded - that is, it doesn't move off center unless the coolant is REALLY cold or hot. By then it may be too late. I linearized my oem temperature gauge to see what the coolant temperature is actually doing. There is a link to doing that in the stickies, IIRC.

Dave

 

thanks for the reply. i've just been topping off with anti-freeze 50/50 premix that i picked up from the gas station (green stuff) whenever the coolant light comes on. your bit about the temp needle worries me cuz i have seen that needle shoot waaay up in recent weeks when i run full boost for just a few seconds (it comes right back down when i take it easy for a minute afterwards). if it went up as high as it did (i would say half way between the middle and top, so 3/4), then that must mean it got REALLY hot REALLY quick.

 

Hi IS losing coolant. He says he just tops it up whenever the coolant light comes on! It is either leaking somewhere or seals are going bad.
--Jeff

 

Well, he didn't say that earlier - you could be right.

Dave

 

Actually, he did say that earlier - I missed it somehow...

I did make an assumption (actually stated it in a post) that he was not losing coolant, and he didn't correct my mistake.

So he is probably getting combustion gasses in the cooling system and that is probably causing the overheating.

To Spaceman, sorry that I missed that point. So the thing to do now is to pressure test the system and see if you get water leaking somewhere external, or into the combustion chambers.

Dave

 

how/where can i get this done? should i take it specifically to a rotary shop, or will any mechanic do?

 

It sounds like your have a coolant leak, I had this problem before, check the main upper and lower radiator hoses as when they get old it gets brittle and leaks towards the ends. Usually it drips out on idle and burns up before seeing any drips on the ground. If you haven't upgraded your radiator I would recommend you to do so to a Koyo or Fluidyne.

Unless your white smoke smells sweet like burning coolant you should be fine. You may want to check up on your starter, plugs and coils before you start to get paranoid.