Hills and temperature - Page 2

ZachFD · 08-01-2009, 01:13 AM

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?

ZachFD · 08-01-2009, 01:50 PM

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.

Doc-1 · 08-01-2009, 08:19 PM

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.

rx4ur7 · 08-11-2009, 01:27 PM

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.

rx4ur7 · 08-11-2009, 02:46 PM

"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.

ZachFD · 08-13-2009, 11:57 AM

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.

rx4ur7 · 08-13-2009, 02:38 PM

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.

08-11-2009, 01:27 PM	#19
rx4ur7 Rotary since 1972 Join Date: Nov 2008 Location: Tucson Posts: 231 Rep Power: 17	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. Last edited by rx4ur7; 08-11-2009 at 02:29 PM.

08-13-2009, 11:57 AM	#21
ZachFD Rotary Fan in Training Join Date: Jul 2008 Posts: 40 Rep Power: 0	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. Last edited by ZachFD; 08-13-2009 at 12:03 PM.

08-01-2009, 01:13 AM	#16
ZachFD Rotary Fan in Training Join Date: Jul 2008 Posts: 40 Rep Power: 0	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?

08-01-2009, 01:50 PM	#17
ZachFD Rotary Fan in Training Join Date: Jul 2008 Posts: 40 Rep Power: 0	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.

08-01-2009, 08:19 PM	#18
Doc-1 Rotary Fanatic Join Date: Feb 2008 Location: Madison Alabama Posts: 115 Rep Power: 18	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.

08-11-2009, 02:46 PM	#20
rx4ur7 Rotary since 1972 Join Date: Nov 2008 Location: Tucson Posts: 231 Rep Power: 17	"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.

08-13-2009, 02:38 PM	#22
rx4ur7 Rotary since 1972 Join Date: Nov 2008 Location: Tucson Posts: 231 Rep Power: 17	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.