Hills and temperature
 

I might just be nuts, but it seems like my water temp always reads higher when I'm on an incline than on a decline....not necessarily under a climb, even when sitting still.

I was cruising on the interstate in 100F temps the other day at 70mph, my fans were on and my temp was around 195F. All was fine until I hit a slight incline on the interstate...temps started creeping up to 215F so I turned the heat on...dear god my skin roasted but temps dropped back to 200F. As soon as the slight incline was over, temps dropped immediately back to 195f.

Car NEVER used to do this with fans on when I had it all stock. It would sit at 185F all day long. My only mods are SMIC/Large Aluminum Duct for I/C, Aluminum intake pipes, Airpump delete, DP, Koyo radiator. Could all the aluminum cause heatsoaking?

Same thing happens on hill when I am sitting, like at a light on a hill with fans on...my temp will climb from 185F and start climbing until I face downward.

Does this sound like a slipping waterpump/poor circulation...maybe on an incline, gravity is pushing the water to the back of the radiator/motor and pump can't keep up? I do have the stock wp pulley w/ airpump removed. If I try to turn it, I can with my hand, but the belt still gets enough grip to rotate. I have a larger pulley ready to put on.

come on guys

Possible. But I personally have never heard of this before. Is it possible that going up hill your simply loading the engine and/or loosing some head-wind you had on level ground? And 215 F. is not unheard of with a triple digit ambient temps and high engine load.
Running your car with the stock WP pulley and no airpump isn't a good idea, but unless there's evidence of severe slippage...worn/shiny belt face and noise, it's probably not soley responsible either. In my experience, slippage is usually during cold start, quick acceleration and high rpm. Since you mentioned you recently added those mods from stock, other things that might have influenced the change.....
*Your coolant to water ratios were changed?
*Some air was left in the system?
*Did you fill the gaps around your radiator with foam?
*Your belly-pan isn't completely secure?
*Making sure your relays are working properly, the connectors are secure and fans are coming on as they should?

On a side note you could also consider....
*Install of an FC (IIRC 89 to 91) thermoswitch to lower threshold temp for fans to come on
*Adding the airpump idler pulley to keep full belt contact (Garfinkle and Chadwick both sell them here as authorized vendors)
*Redline Water Wetter

Let me sell you an Idler that goes where the air pump was that may help .Look in the vender section under Garfinkles motor works ,also look at Dan Chadwicks sight for an other design,different from mine .Both work fine just different . Is your water level full for sure .

water level is full, no air in the system. Never have the buzzer go off. Neck is always full when I pop the cap off cold.

*No slipping on start up or squealing.

*I have a larger WP pulley I'm about to install.

*I have a fan switch wired to one of the relays that was on the car form the previous owner. I'm guessing it keep the fans on medium or low...not sure which one. If I flip the A/C switch with the car off but ignition on, fans speed up.

*Undercover is cracked towards the back in places, but the front half from the oil pan foward is pretty sealed up. I do have foam around the radiator gaps.

*I have the AST relocated to the side of the engine bay...its bolted where my battery used to be...battery is relocated.

*I have Large SMIC with Aluminum Ducting. I'm thinking either this is causing heatsoak, or my fans just aren't running fast enough with my fan switch to cool down the car. I"m too afraid to run it up to 225 to let the stock fan sensor kick in.

*If I turn the heat on, temps always drop DRAMATICALLY (which is why this is puzzling).

*Also, I CANNOT, CANNOT, run the a/c in this heat...even on the interstate, at 70mph, the car will creep really fast in temps.

*I also have dual oil cooler....my temp sensor is the Defi D-gauge and I believe the sensor is tapped at the water pump.

*When I first purchased car, before the I/C/Duct/Airpump removal, the car never creeped above 185 with fan switch on.

*I've checked the thermostat, replaced it twice. I've changed the coolant probably 4 times in the past 3 years. 80% water/20% Coolant


Please help me figure this out....I just want to know whats causing the creeping temps before I purchase anything...whether it be the aluminum intercooler duct blocking airflow from the fans, fans running too slow, or undercover being cracked. In the winter car stays pegged at 180F

I've never heard of "aluminum ducting" for a SMIC, how much are you taking away from the airflow to the radiator? At any rate, "heat soak" shouldn't be an issue when your moving.
Consider that FC thermoswitch, it will lower threshold for the fans to come on from something like 108 C to 95 C. (226 F. to 203 F.) and is simple replacement...no modifications.

you've never heard of it, because it was custom fabbed. Problem is I'm worried it retains to much heat and maybe thats the issue? I guess Ill try taking it out to see if temps drop. It doesn't block to much flow in the bumper tho.


http://img191.imageshack.us/img191/6601/duct.jpg

Sounds like you have some air in the system, a bad thermostat and/or coolant that is no longer working properly.

i'd also like to see some pics of your setup.

Your temps of around 215 F. really don't seem out of line for a 100 degree day IMO. Would I keep an eye on it? Absolutely. You always should anyway, but especially on a hot summer day. And I'd try to stay out of boost as much as practical too. But as mentioned above, the stock thermosensor doesn't even trip fans until 108 C. (226 F.).
BTW, while turning the heat on will help a little, it's probably the electrical draw of the heater fan turning on the radiator fans that was doing the most good. Just think, with the FC thermoswitch, you wouldn't have to do that anymore. :)

You must have missed that i have a fan switch wired to the relay system. Fans are ON when I want them to be on....car creeps to 215 with fans ON. Maybe they just aren't running as fast with my switch as they would with a thermoswitch.

I don't think there is air in the system because I remove the cap after the car sits for a while and theres no release of pressure or gap of air.

I did forget you mentioned that switch. Is it possible it's bypassing the high speed fan relays and your just stuck on a lower speed?
In my experience typically (but not always) if there is air in the system, you'll hear that boiling sound after shut down. And while the car is running you see spiking of temps...not so much a steady rise as you've described.
I also don't see how heatsoaking of the aluminum IC ducting could have anything to do with it.

But I can't think of anything else to suggest. Sorry.

hmm, after shutdown I do hear a bubbling sound that comes in groups.....ill shut the car off and after a minute or two ill hear brsh,bhrsp,bhrsp.........brsh,bhrsh, I thought it was water returning into the system from the overfill due to heat expansion/cooling

My buzzer never goes off, and my level is always full at the fill neck, so i figured theres no air in the system...however, is the AST supposed to be at a high point above the filler neck, because mine isn't

You still have air in the cooling system.

Heat soak is an issue when you shut down. As long as air is flowing you are getting some cooling effect. Polished aluminum will not exchange heat as well as non polished. Steel and iron are going rise more and hold the most heat on a soak.

Lack of good air flow through the engine compartment will also cause temps to rise. But that would show in all conditions and get worse the faster you go.

A blocked or partially blocked exhaust will cause temps water and oil (when extreme) to climb on a incline. Leaking housing seal will also cause it. A FC3S just came in that got hot going up Mount Lemmon. Temps went up on the way up but were fine on the way down. When I checked it it is now pushing water.

From your discription of the gurgling I would do a bubble check, just to rule it out a seal issue.

Easy enough to do the bubble check for seals,
Start it up cold with the fill cap off.
It will push a little coolant out as it expands but once it comes to temp it will stabilize.
Let it get to full warm up.

If a seal is going - These guys will start with very fine bubbles, so small they can look more like dust. And there may only be one or two in 10 or 15 ses.
The next stage is there are enough that they form a foam.
Next bigger bubbles, becoming large enough that when they break you see combustion gas.
Last stage, blows water out as soon as you start it.
In the very early stages there will be no signs until it reaches full operating temps.

General Rule of thumb, You can be allowed 3 overheats (close to the mark) before $$$$.

well the temps always drop when I'm moving...it just heatsoaks really bad at idle with fans on...the fans just dont seem to keep the temps down.

The gurgling occurs when the car is shut off....it sounds like water returning into the overflow tank slowly from the vaccuum.

As far as the fill neck, I get very very very very tiny bubbles in the neck. They don't occur at cold start...they occur as the water level starts to rise as the car is warming up. Very little bubbles that do look like dust but its not a steady stream and they don't look like they would cause pressurizing. They do not speed up as the engine is revved I don't think....

---It really seems to me like these bubbles are just from the movement of the water pump.

Should I just do a hydrocarbon test? Wouldn't this tell me if those bubbles are exhaust gases? BTW I never have overflow issues or loose coolant from the fill neck.

My 2 cents. You have air in your system. Would explain it.

well, I'm going to block test it tommorrow with a hydrocarbon coolant test kit from autozone.

Does the AST need to be located higher than the fill neck? I relocated my AST to the side of the engine bay where the battery used to be and its much lower than the fill neck. Maybe this is causing air to not seperate?

I'll also pull the TB coolant line and run the car....isn't this the sure-fire way to bleed the system?

Block tested it at express oil. I watched the guy do it...he took a cylinder filled with blue liquid and placed it ontop of my filler neck. The tiny bubble came up into the blue fluid, but the fluid did not turn colors. He let the cylinder sit ontop of the filler neck for about 2 minutes and nothing happend.

So, theres air coming in somewhere. I'm going to try replacing my AST pressure cap and bleed the engine through the throttle body hose.

No that will not get the air out. You will need to burp the system. This is a common problem with these cars. There is a lot of threads about this.

Again though, heat soak is only when a motor is shut down. Over heating while running is another issue. http://cjbfire.com/Heatsoak.pdf

Ok, well there really isn't any way for ambient air to get sucked into the cooling system without having coolant leaking somewhere. I have seen a few that there was no outside indication of a leak because it was so small and the coolant was spraying onto the turbos. I am sure you pressure tested the system hot.
If the temps are climbing sitting at idle you may not be getting good circulation. Non-rotary thermostats are common or removal of thermostat.
One other thing I have found on idle overheats is RTV in the system, or Bars leak. See my forum on gaskets and sealants.
Both can restrict coolant flow in the rotary.
Water pump could be a culprit, but I have never seen a Mazda water pump have that kind of failure. I suspect anything that isn't Mazda or I haven't tested on the race cars.
If there is enough air in the system it could hang up in the water pump causing flow issues. You could possible have a lot of air hanging in pump chamber or excess RTV blocking something.

A quality cap is a must. The only other thing I can think of right now might be a hole in the line to the overflow tank.

The way I fill these puppies is
1-set the heater to hot
2-get the nose in the air as high as I can
3-Pull the TB hose
4-fill until fluid comes out the TB hose
4a-on stubborn ones I pour the fluid into the TB hose
5-install TB hose
6-burp by squeezing lower rad hose
7-start car run to temp, let it cool down
8-top off ast if it needs it, usually it doesn’t, occasionally it does.
9-repeat 7 and 8 if needed. There has been a couple that I had to do 7,8 three times.

Another real quick and dirty - Once filled you can put a pressure gauge on the ast, put the 14psi on it. Wait a few minutes remove the gauge, if there is air in the system it will usually migrate to the ast.

I am afraid though from my experience from R100 to RX8 the fine dust bubbles are the first signs of housing seals. To me you are describing all the classic symptoms. Everyone that come into the shop with those symptoms the seals failed within a year. Water pump churning would usually be larger clear bubbles and with the cap off any air in the water pump chamber is expelled quickly. The tiny bubbles will not get larger when revved, until the leak gets worse. Many times they will not over pressurize the system until they get larger. When I have tested these in the early signs I haven't picked up any HC or CO until they got worse.
I tell my clients to buy some time is to drive it easy, relieve the pressure on the system after shut down, and squirrel pennies away. Out here in the desert we may be able to get it to next year before having to do the build.
Not being able to see the car and not knowing it's complete history I am only able to give you my experience. Hopefully in your case I am wrong. Listen I don't like being the bearer I don't want to do a motor unless I really have to or the client wants it. One of the reasons I spent so much time and testing on keeping these things cool.
How many miles on this motor? Original? Water pump or thermo replaced? PM or better yet email me at the shop if you want.

"The gurgling occurs when the car is shut off....it sounds like water returning into the overflow tank slowly from the vaccuum."

Is this correct, the water is going into the overflow when shut down? If so that means you are overheating and heat soaking badly. That is not vacuum but pressure. You could try a higher pressure cap, but I really don't recommend that for normal street cars.
Don't know if you got the new cap yet and the results.

Everyone, one thing to check on your radiator caps, the bottom piece of rubber, if it is wider in diameter than the metal support it will not allow the engine to suck the coolant back into the motor as the coolant contracts as it cools causing. This is where the vacuum comes in. Pressure from the expanding heated coolant is what pushes the coolant into the overflow.
The radiator cap is a two way valve.

well, at night, the car is rock solid with its temps. I drove it last night, temps were 85F, I did some WOT runs and ran a steep mountain....temps stayed right at 185F with fans on...occassionally fluctuated up to 195F.

Its only in hot weather/a/c on, that the car creeps up in temps...the other day in 105F, I turned on the A/c and watched the needle creep to 220F before I shut it down.

The gurgling sound is like a sloshing noise coming from the turbo area....maybe its water returning to the system from the overfill.


As far as the filler neck, there are a few dust bubbles at idle, and tons when I rev the engine up...at 4.5k rpms, the water level drops down deep into the neck and when I release the throttle is comes back up to the top with tons of champagn bubbles. We performed this with the hydrocarbon tester on the neck and it never changed colors.

The only spot I know of that could potentially cause any problem would be the radiator plug is cross threaded in, but its a very mild cross thread and its fit flush against its rubber gasket.



The motor is a mazda reman with around 50k miles on it. I replaced the thermostat not to long ago and replaced the 13psi ast cap the other day. I had this temp creep problem last summer and the summer before. In the winter there is NO flucuation in temp.

Zach,
Do you have to add water to it first thing in the morning? The lowering and rise of water is correct for normal operation. It's the bubbles I am concerned with. Early stage bubbling only showed overheat issues during the summers out here. Temps where fine under 90. Keep checking it before the first start. You are checking and filling at the non pressure cap on the motor I am sure. Keep checking bubbles, watch for any change in size. 50K is a good run for a MANA motor. They only had to do 12. At one time they were notorious for being 13 month motors. If you got one that had all new housings you got the gonga deal.
One other test to try, remove engine water cap, pull leading plugs and pressurize the rotor chambers with compressed air watch for any change in water level. This is the original Mazda check procedure.
Water wetter? How much antifreeze? Out here we can run straight water with waterwetter.