JoeWinkie

Ok here's the deal. I have an 87 nonturbo and my temp gauge normally reads 1/2 or a little under in cool or cold air (mainly at night, but on cool days too). But in warm air, or worse, on a hot summer day, the needle will loiter around 3/4 or 7/8, scaring the crap out of me I've had a coolant flush, and I've made sure the drive belts are tightened properly (as per the Mazda manual; I have no A/C drive belt). Not too many months ago I had a new thermostat put in. I've got a brand new Mazda filler cap and 13 psi radiator cap on there too. My next idea is to jack the front of my car up when the engine's cold and manually check for and straighten any bent fins on the radiator with a flathead screwdriver. If that doesn't work, I'll have to deal with draining my coolant, getting at my thermostat, removing it, and testing it in a pot of water on my stove to verify its opening and full open temperatures (maybe my mechanic gave me a crap thermostat). If that checks out, I may have to deal with getting some Water Wetter of that Evens stuff out in (supposed to cool better than 50/50 water/ethylene glycol antifreeze?) Is it possible that I just have a crap temp guage? My car is 15 years old and I don't know if my temp guage is the source of all my frustrations. Is it easy to replace? Are they expensive? What is the likelyhood that it's bad? Any help at all would be appreciated. Thanks.

bob13bt

iTrader: (9)

You need a new radiator, 99% sure. And a new Mazda thermostat. Yes the Evans coolant has had great reviews from members of this board, and Water Wetter is the ****. But if youve already flushed the radiator and have a good thermostat and tight belts (A/C is irrelevant) and your STILL running hot, its the radiator. They clog up like the drain in my sink.

And good god, dont bother trying to straighten out bent radiator fins. That would be like washing your car with a toothbrush. It still wont cool better.

Icemark

Make sure the engine undercover and upper front cover are in place as well. Without them, the cooling ability drops 25%.

And make sure you are using a Mazda thermostat. Most of the aftermarket ones like the Stant are poor subsitutes

JoeWinkie

What are the differences between Mazda thermostats and aftermarket ones? If they both physically open to allow coolant flow, and they open at the same specific temperature, shouldn't an aftermarket one work just as well? Or do the aftermarket ones just not open as much or at as low a temperature?

What's this engine undercover thing that Icemark mentioned? I know there's some kind of shielding under my engine, but I don't see anything around the underpart of my radiator. Do you have a picture you could show me?

If the radiator's clogged, wouldn't that completely impede the flow of coolant and make my engine just altogether overheat? Or are there multiples paths for the water to flow through the radiator?

If I end up needing a new radiator, can anyone make any recommendations?

Thanks for the input guys

The Ace

Usually the aftermarket thermostats claim to open at lower temperatures, in order to "maximize cooling effect". But if you take a closer look at the theory behind this, if the thermostat opens at a lower temperature, then it stays open for longer periods than the stock one, which means that the coolant circulates faster, which in turn means that the coolant does NOT stay in the engine long enough to absorb the heat thus reducing the cooling effect. Stick with the stock thermostat...

As for the underpan, this has a two-fold use: protect the engine and the various lines/hoses in the lower area, and deflect incoming air towards the radiator. If this is missing, then the cooling effect from the incoming air is reduced drastically (dont know about the "25%" remark, but something anyway).

The radiator does not have a one-way route inside. Its actually multiple small passages with fins between them (to expell the heat from the coolant). If one or more of the passages are clogged, that means that a) cooling area is reduced -> cooling effect is reduced, and b) coolant flow is obstructed to some degree. If and when it gets to the point where not enough coolant can move through the radiator, then your engine will overheat.

Damn, thats some nice info. I better give this 5 stars

Scott 89t2

your gauge should be at 1/4 . you are way too hot!

BlackRx7

my gauge is at 1/4 or less and I have no splash gaurd, plus possibly crush my thrust-washer and bearing

Ryde _Or_Die

Just go all out and get the fluidyne Its only $417

http://www.absoluteradiator.com/cgi-...0a2+1017359372

bob13bt

iTrader: (9)

"Only $417" Ha!

Get a Griffin from Summit racing for $190. All aluminum, and Im sure it cools just as well as a Fluidyne. Yes it will take some custom work to fit it, but the savings should be worth it, eh? You need one with the stock hose inlet and outlet locations. Shouldnt be too hard to mount. Hell, its not a 20B swap.

Or if you plan on staying under 200-250 hp then get a new stock radiator. Bolt it right in and go.

Icemark

the undercover BTW fits from the lower part of the front bumper to back around the front suspension cross member. Mazda P/N FB01-56-111C

jimmyv13

I am hunting a "running hot" issue as well. I have the undercarriage plastic piece in place, stock fan with shroud, but it runs warm while driving. The temp will come down some when I stop for a while( ten minutes or more), but it climbs right back up to 3/4-7/8 on the stock gauge when I get on the highway. I have a dual alt pulley, but here's my concern.....my front belt of the two on the alt/water pump is getting chewed up. That would suggest that the pulleys aren't lined up right, but the back belt is fine. I am working out a lot of bugs from a J-Spec install, and this problem has just come up. The coolant has been flushed with running water many times. This last time, I left the thermostat out to see if that had any ill effects, but it still ran hot. I have a new Mazda thermostat waiting for me at the dealer, so I am putting a thermostat back in. Anybody else pay $18 for a new thermostat from the dealer?

vaughnc

I'm talking to mazcare in Atlanta about this right now.

Planning to get an aftermarket temp. gague first and go from there:

jimmyv13

I'm hoping my gauge is off, too. Last night coming home on the highway, mine was running about three needles width higher at 60 MPH. Heater on defrost full blast, too.

Rpeck

Wow the oil pressure looks really low to me in that picture. These engines are Oil cooled also.. that could be part of the problem. My 87 at that RPM is above 60 PSI closer to 80.

Icemark

Your oil pressure is about 15 ft/lbs low.

You need to check you ecentric oil bypass valve and pressure. You may be only lubeing half your motor!!!!