Wrecked coolant reservoir
03-11-16, 06:39 AM
#1
Full Member
Thread Starter
Wrecked coolant reservoir
Great, yesterday I blew my coolant reservoir. Last time the coolant temperature was at 105°C (221°F) the fans didn't came on and I wondered if thats normal and wanted to check if the fans work but forgot it. I read in the forums, that the temperature for the fans to come on is 105°C (221°F) so I was not to alarmed.
Yesterday the car was idling for a short period of time and I was doing something in the engine bay so I couldn't watch the coolant temp gauge. After driving it into my garage it startet smoking out from under the hood, only a little bit at first. When I opened the hood it was smoking from the right headlight more heavily (driverside RHD) and when I saw it drippling down I immediatly turned the engine off. The coolant temp gauge showed 114°C (237°F).
When the engine was shut down I heard a very loud gurgling from the front (it came from the reservoir) and a rhythmic fizzling sound from the thermostat cap. The coolant was obviously heavily boiling (about 50/50 mix). The fans where not running when I shut down the engine.
Since the whole area was full of smoke while the water was still escaping from the reservoir I couldn't see exactly where it was coming from, but I think its somewhere near the position where the filler neck attaches. Is this a typical spot for this problem?
I have 2 concerns now:
- Engine: Do you guys think that the engine could have taken serious damage from that? It was running at 114°C (237°F) 2-3 minutes at most, presumably shorter. I'm planning on doing a rebuild shortly, I think its the cars way to tell me to do it RIGHT NOW.
- New reservoir: I assume it doesn't make sense to repair it with jb weld or something, but of course I firstly have to take it out and have a closer look at the damage. I also assume the price for a new one would make me cry. Would it be advisable to buy a used one?
Last but not least, obviously my fans don't work. Where would you start searching the error? Is there a possibility to test the fans without the coolant temperature beeing at 221°F? With my Ford Probe, which has the exact same dignosis box (Mazda KL- engine), its possible to wire bridge 2 pins, when the ignition is turned on the fans than start spinning, regardless of any other requirements.
Edit: Or is there some kind of pressure valve on the top of the reservoir? Like I said, it wasn't clearly visible, but I think this is the spot where the water came from:
http://i217.photobucket.com/albums/c...owtankedit.png
Edit 2: When I connect ground and TFA in the diagnosis box like stated here:
https://www.rx7club.com/3rd-generati...orking-913565/
and turn on the ignition, both fans are working.
Yesterday the car was idling for a short period of time and I was doing something in the engine bay so I couldn't watch the coolant temp gauge. After driving it into my garage it startet smoking out from under the hood, only a little bit at first. When I opened the hood it was smoking from the right headlight more heavily (driverside RHD) and when I saw it drippling down I immediatly turned the engine off. The coolant temp gauge showed 114°C (237°F).
When the engine was shut down I heard a very loud gurgling from the front (it came from the reservoir) and a rhythmic fizzling sound from the thermostat cap. The coolant was obviously heavily boiling (about 50/50 mix). The fans where not running when I shut down the engine.
Since the whole area was full of smoke while the water was still escaping from the reservoir I couldn't see exactly where it was coming from, but I think its somewhere near the position where the filler neck attaches. Is this a typical spot for this problem?
I have 2 concerns now:
- Engine: Do you guys think that the engine could have taken serious damage from that? It was running at 114°C (237°F) 2-3 minutes at most, presumably shorter. I'm planning on doing a rebuild shortly, I think its the cars way to tell me to do it RIGHT NOW.
- New reservoir: I assume it doesn't make sense to repair it with jb weld or something, but of course I firstly have to take it out and have a closer look at the damage. I also assume the price for a new one would make me cry. Would it be advisable to buy a used one?
Last but not least, obviously my fans don't work. Where would you start searching the error? Is there a possibility to test the fans without the coolant temperature beeing at 221°F? With my Ford Probe, which has the exact same dignosis box (Mazda KL- engine), its possible to wire bridge 2 pins, when the ignition is turned on the fans than start spinning, regardless of any other requirements.
Edit: Or is there some kind of pressure valve on the top of the reservoir? Like I said, it wasn't clearly visible, but I think this is the spot where the water came from:
http://i217.photobucket.com/albums/c...owtankedit.png
Edit 2: When I connect ground and TFA in the diagnosis box like stated here:
https://www.rx7club.com/3rd-generati...orking-913565/
and turn on the ignition, both fans are working.
Last edited by Namxi; 03-11-16 at 09:30 AM.
03-11-16, 09:31 AM
#2
When you say you blew your coolant reservoir, do you mean it overflowed? Unfortunately, that's one of the tell-tale signs of a blown coolant seal. Others are gas in you coolant (i.e. the champagne bubble test) and white exhaust smoke.
Don't recall the exact temp the fans cut on, but it's well before 221 (think it's around 195ish).
Don't recall the exact temp the fans cut on, but it's well before 221 (think it's around 195ish).
03-11-16, 11:28 AM
#4
Full Member
Thread Starter
I tested it today the hard way: filled the coolant up, started the car and let it idle up to 100°C coolant temp, than shut it down. Nothing leaked, so I assume its really just a valve for exessive pressure.
This leaves me with the fan problem.
According the https://www.rx7club.com/3rd-generati...thread-571088/ this are the temps:
7. Optimum Temps
65C (150F): too cold. According to service manual, EGR valve is non-operational below 150F, "to improve drivability when cold."
82C (180F): getting warm. Thermostat begins to open, circulating coolant through the radiator. Some coolant is still bypassing the radiator.
95C (203F): fully warm. Thermostat is fully open, not bypassing the radiator at all.
100C (212F): boiling point of pure water at atmospheric pressure.
105C (221F): getting hot. Stock ECU will activate fans to cool the car down. Fan speed will be low, or medium (if A/C is already on).
108C (226F): hot. Stock 93-95 coolant thermoswitch activates, changing fan speeds from low>> medium (or med>>high if A/C is already on) (switching to an FC thermoswitch will change this temp to 203F)
115C (240F): getting dangerous. OEM temp gauge begins to rise.
117C (243F): dangerous. boiling point of pure water with 13psi pressure cap.
121C (250F): too hot. OEM temp gauge will point to white line. Boiling point of pure water with 16psi pressure cap.
124C (256F): way too hot. Boiling point of pure water with 19psi pressure cap. Boiling point of 50/50 coolant mix with 13psi pressure cap.
127C (260F): way too hot. OEM temp gauge will point to red line.
So the fans should come on at 105C (221F), but they didn't. As I mentioned above when I ground the ATF pin in the diagnosis box they come on. Maybe the Thermoswitch is defective? I have no error codes though.
This leaves me with the fan problem.
According the https://www.rx7club.com/3rd-generati...thread-571088/ this are the temps:
7. Optimum Temps
65C (150F): too cold. According to service manual, EGR valve is non-operational below 150F, "to improve drivability when cold."
82C (180F): getting warm. Thermostat begins to open, circulating coolant through the radiator. Some coolant is still bypassing the radiator.
95C (203F): fully warm. Thermostat is fully open, not bypassing the radiator at all.
100C (212F): boiling point of pure water at atmospheric pressure.
105C (221F): getting hot. Stock ECU will activate fans to cool the car down. Fan speed will be low, or medium (if A/C is already on).
108C (226F): hot. Stock 93-95 coolant thermoswitch activates, changing fan speeds from low>> medium (or med>>high if A/C is already on) (switching to an FC thermoswitch will change this temp to 203F)
115C (240F): getting dangerous. OEM temp gauge begins to rise.
117C (243F): dangerous. boiling point of pure water with 13psi pressure cap.
121C (250F): too hot. OEM temp gauge will point to white line. Boiling point of pure water with 16psi pressure cap.
124C (256F): way too hot. Boiling point of pure water with 19psi pressure cap. Boiling point of 50/50 coolant mix with 13psi pressure cap.
127C (260F): way too hot. OEM temp gauge will point to red line.
So the fans should come on at 105C (221F), but they didn't. As I mentioned above when I ground the ATF pin in the diagnosis box they come on. Maybe the Thermoswitch is defective? I have no error codes though.
03-14-16, 03:49 PM
#6
I have not had the fun of having this problem, but it could be several things, the fans, the relays, the sensors, wiring, or any combination. I would start with the fans first (cause they are easy), then the relays (which is my hunch to be the problem). Last would be the sensor, which usually don't fail, but could be the wiring from the sensor
Quick search found...
https://www.rx7club.com/3rd-generati...ntrols-876767/
https://www.rx7club.com/new-member-r...-issue-990212/
I am sure there is more out there
Last edited by TomU; 03-14-16 at 03:51 PM.
03-14-16, 04:23 PM
#7
Rotary Enthusiast
All the reservoir does is provide somewhere for the extra coolant to go once it heats up and expands. It is not a pressure valve.
Basically here's what happens - when coolant heats up it expands.
When its hot/ expanded it can no longer fit in the system so the excess goes to the overflow tank. (when the system will allow it to go to the reservoir is dependent on the psi rating of your pressure cap)
When the engine cools down & the coolant contracts - the excess coolant that was pushed into the overflow tank is pulled back into the system.
Coolant can overflow from the overflow tank due to several reasons.
A. leak in line from overflow tank to ast/filler neck (this will allow coolant to get pushed out into the reservoir but will not allow it to return to the system when it cools, leading to overflow tank overflowing.
B. too much coolant in the overflow tank/system as a whole. Coolant will get pushed out of system into an already full overflow tank causing it to overflow.
C. bad coolant seals. pressure from combustion pushes coolant out of the system.
Basically here's what happens - when coolant heats up it expands.
When its hot/ expanded it can no longer fit in the system so the excess goes to the overflow tank. (when the system will allow it to go to the reservoir is dependent on the psi rating of your pressure cap)
When the engine cools down & the coolant contracts - the excess coolant that was pushed into the overflow tank is pulled back into the system.
Coolant can overflow from the overflow tank due to several reasons.
A. leak in line from overflow tank to ast/filler neck (this will allow coolant to get pushed out into the reservoir but will not allow it to return to the system when it cools, leading to overflow tank overflowing.
B. too much coolant in the overflow tank/system as a whole. Coolant will get pushed out of system into an already full overflow tank causing it to overflow.
C. bad coolant seals. pressure from combustion pushes coolant out of the system.
Last edited by 96fd3s; 03-14-16 at 04:25 PM.
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03-14-16, 04:35 PM
#8
Full Member
Thread Starter
[QUOTE=TomU;12039096]Nothing leaked. Was that on the outside or on the inside?
What do you mean by inside/ outside? I watched the spot where the water came from when the water temperature was 237°F, and this time (with 212°F) there was no water coming from this spot, and no water was dripping on the floor.
This brings me to the next point, if there was a bad coolant seal, wouldn't the pressure go into the cooling system all the time, so also pressurizing the system at 212°F and lower?
Concerning the fans, as I wrote they run when I bridge ATF and ground, so I assume the fans are ok and one relay at least. I will have a look at the sources though.
What do you mean by inside/ outside? I watched the spot where the water came from when the water temperature was 237°F, and this time (with 212°F) there was no water coming from this spot, and no water was dripping on the floor.
This brings me to the next point, if there was a bad coolant seal, wouldn't the pressure go into the cooling system all the time, so also pressurizing the system at 212°F and lower?
Concerning the fans, as I wrote they run when I bridge ATF and ground, so I assume the fans are ok and one relay at least. I will have a look at the sources though.
03-14-16, 05:00 PM
#9
You overheated your engine, so the coolant expanded and overfilled your overflow tank. This is what happens when you overheat the coolant. All normal. Unlikely you did damage to your engine.
Fix the fans, and all will likely be well. I would start by making sure the fan relays are all plugged in and working properly.
Fix the fans, and all will likely be well. I would start by making sure the fan relays are all plugged in and working properly.
03-16-16, 12:27 AM
#12
If it just boiled and pushed coolant into the plastic overflow tank, you may be okay. If it has no further symptoms after this event, it should be fine.
However, if it begins "using" coolant at any increased rate and it is not leaking externally, then it may be drinking its own coolant through a failed water jacket O ring that may have failed or melted in the higher heat.
Vice versa, if it begins to over pressurize the cooling system constantly and the radiator hoses are going rock hard, there's a chance its blowing compression outwards through a failed/melted water jacket O ring, into the coolant.
You'll know fairly soon if there was any lasting damage. They tend to show signs quite abruptly and then constantly.
However, if it begins "using" coolant at any increased rate and it is not leaking externally, then it may be drinking its own coolant through a failed water jacket O ring that may have failed or melted in the higher heat.
Vice versa, if it begins to over pressurize the cooling system constantly and the radiator hoses are going rock hard, there's a chance its blowing compression outwards through a failed/melted water jacket O ring, into the coolant.
You'll know fairly soon if there was any lasting damage. They tend to show signs quite abruptly and then constantly.
03-16-16, 12:32 AM
#13
And I'm getting a vibe you might think the coolant reservoir is sealed- its not actually a sealed bottle as in some cars.
Its quite possible for the coolant to boil into the reservoir and then gurgle up and overflow out of the top of it as its not able to seal pressure (was never designed to be a pressurized bottle. its just a piece of plastic bottle with a semi firm fitting cap) so seeing coolant and steam coming out of it does not mean its somehow busted or got a hole.
Its quite possible for the coolant to boil into the reservoir and then gurgle up and overflow out of the top of it as its not able to seal pressure (was never designed to be a pressurized bottle. its just a piece of plastic bottle with a semi firm fitting cap) so seeing coolant and steam coming out of it does not mean its somehow busted or got a hole.
03-16-16, 01:20 AM
#14
Full Member
Thread Starter
Thanks for all the replies, they are much appreciated!
Yesterday I checked all 4 relays, they all work like they should. Than I turned on the iginition and activated the A/C, the fans started working. Than I grounded the TFA pin in the diagnosis box, turned on the iginition, fans started at the same level es before with the A/C. On turning on the A/C again, the level was going up, I assume from low to medium.
My conclusion is that it is most likely that the thermo switch is not working, right? Since I'm pulling the engine for a rebuild soon and wanted to switch to the FC thermo switch anyhow, thats no big deal, though.
Edit: Does a faulty thermo switch throw an error code? I don't have any namely.
Edit 2: I forgot that I switched ECUs inbetween the failure search. When I first tried to ground the ATF, the normal ECU was installed, a Blitz Access Computer (Stock ECU with fancy stickers and presumably a changed ROM). Later I switched to the stock ECU for checking error codes again (They both give no error codes btw). The test with A/C on and TFA grounded was done with the stock ECU.
Yesterday I checked all 4 relays, they all work like they should. Than I turned on the iginition and activated the A/C, the fans started working. Than I grounded the TFA pin in the diagnosis box, turned on the iginition, fans started at the same level es before with the A/C. On turning on the A/C again, the level was going up, I assume from low to medium.
My conclusion is that it is most likely that the thermo switch is not working, right? Since I'm pulling the engine for a rebuild soon and wanted to switch to the FC thermo switch anyhow, thats no big deal, though.
Edit: Does a faulty thermo switch throw an error code? I don't have any namely.
Edit 2: I forgot that I switched ECUs inbetween the failure search. When I first tried to ground the ATF, the normal ECU was installed, a Blitz Access Computer (Stock ECU with fancy stickers and presumably a changed ROM). Later I switched to the stock ECU for checking error codes again (They both give no error codes btw). The test with A/C on and TFA grounded was done with the stock ECU.
Last edited by Namxi; 03-16-16 at 06:51 AM.
03-17-16, 08:43 PM
#15
To test your thermoswitch, connect it to an ohmmeter and suspend it in a small pot of motor oil with a thermometer.
Heat the oil slowly on a hot plate and note the temperature that the contacts close. (0 ohm reading).
It should close within a few degrees of the design temperature. If not, replace it.
Heat the oil slowly on a hot plate and note the temperature that the contacts close. (0 ohm reading).
It should close within a few degrees of the design temperature. If not, replace it.
03-18-16, 04:26 AM
#16
Full Member
Thread Starter
I did a little more research and if it was the thermo switch, the fans would start at 105°C (ECU triggered), but would not go to the next level at 108°, right?
So, since they do not come on at all, either the ECU (I only tested it with a aftermarket one, Blitz Access Computer) doesn't trigger at 105°C AND the thermo switch is defective or the thermo switch and the water temperature sensor for the ECU are defective, but that should throw an error code, doesn't it? Has the ECU its "own" sensor or does it use the one for the instrument cluster? Because the water temperature gauge in there is working.
I would test it with the stock ECU also, but bringing the car up to these temperatures every time makes me somehow uncomfortable.
I think I will just make the fans switchable from the cabin until I install my recently bought electrical water pump (Pierburg CWA400) and the tinyCWA Controller I'm planning to purchase. The latter can be programmed to controll the fans depending on water temperatures.
So, since they do not come on at all, either the ECU (I only tested it with a aftermarket one, Blitz Access Computer) doesn't trigger at 105°C AND the thermo switch is defective or the thermo switch and the water temperature sensor for the ECU are defective, but that should throw an error code, doesn't it? Has the ECU its "own" sensor or does it use the one for the instrument cluster? Because the water temperature gauge in there is working.
I would test it with the stock ECU also, but bringing the car up to these temperatures every time makes me somehow uncomfortable.
I think I will just make the fans switchable from the cabin until I install my recently bought electrical water pump (Pierburg CWA400) and the tinyCWA Controller I'm planning to purchase. The latter can be programmed to controll the fans depending on water temperatures.
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