Low coolant alarm insists on being on
Thread Starter
n00b
Joined: Jun 2010
Posts: 37
Likes: 0
From: Laurel, MD
Low coolant alarm insists on being on
Why does this happen?
I've got a coolant leak somewhere. I did a pressure test and it dropped about 4 psi over about 30 minutes, though a couple times I bumped it and it looked on the gauge and sounded like it released a bit of air, so the tester itself may be the problem. I haven't tested a different car yet.
I've been for sure losing coolant to somewhere, and I'm pretty sure it's not the ground. I've had to bleed the air out of the system and fill the coolant up a couple times. Before I do that, the low coolant alarm goes off constantly - for several minutes after starting and then intermittently as I'm driving. After I bleed the air and fill it back up, no alarm. I did that two days ago and apparently I've lost enough coolant to have it happen today, as in the video.
Anyway, I'm mainly wondering, why does revving the engine make the alarm go away?
I've got a coolant leak somewhere. I did a pressure test and it dropped about 4 psi over about 30 minutes, though a couple times I bumped it and it looked on the gauge and sounded like it released a bit of air, so the tester itself may be the problem. I haven't tested a different car yet.
I've been for sure losing coolant to somewhere, and I'm pretty sure it's not the ground. I've had to bleed the air out of the system and fill the coolant up a couple times. Before I do that, the low coolant alarm goes off constantly - for several minutes after starting and then intermittently as I'm driving. After I bleed the air and fill it back up, no alarm. I did that two days ago and apparently I've lost enough coolant to have it happen today, as in the video.
Anyway, I'm mainly wondering, why does revving the engine make the alarm go away?
Joined: Sep 2005
Posts: 25,581
Likes: 136
From: Smiths Falls.(near Ottawa!.Mapquest IT!)
You'd better compression test the engine just to be sure where that pressure is going.
You said you have a pressure leak so that doesn't help matters.
I think that the alarm goes off because the Revving causes the coolant to Surge and rush over the sender.It thinks it is OK for coolant level and shuts off the alarm.When you go back to idle the coolant is stable and then the Sender can't see it anymore and sounds the alarm.
This issue could just be a Coolant leak somewhere,or Worst case,a bad coolant seal( rebuild time.
Anyways it should be looked at,if you want to keep the engine going without blowing it up.
You said you have a pressure leak so that doesn't help matters.
I think that the alarm goes off because the Revving causes the coolant to Surge and rush over the sender.It thinks it is OK for coolant level and shuts off the alarm.When you go back to idle the coolant is stable and then the Sender can't see it anymore and sounds the alarm.
This issue could just be a Coolant leak somewhere,or Worst case,a bad coolant seal( rebuild time.
Anyways it should be looked at,if you want to keep the engine going without blowing it up.
Thread Starter
n00b
Joined: Jun 2010
Posts: 37
Likes: 0
From: Laurel, MD
When I filled my coolant back up and eliminated the alarm a couple days before my original post, the overflow reservoir was empty. It's been fine since though.
Also, it's been spitting out smoke for several minutes after startup, in addition to rough starts:
it's somewhat blueish, but doesn't smell much like burning oil to me. Smells like gasoline occasionally. Maybe it's confirmation bias but I imagine it's coolant
Also, it's been spitting out smoke for several minutes after startup, in addition to rough starts:
it's somewhat blueish, but doesn't smell much like burning oil to me. Smells like gasoline occasionally. Maybe it's confirmation bias but I imagine it's coolant
Junior Member
Joined: Oct 2012
Posts: 18
Likes: 0
From: USA
A blocked hose between the radiator and the coolant overflow bottle was causing my coolant light to come on every start-up until the engine warmed up some and caused the coolant to heat and thus expand.
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A coolant seal failure is a common problem....at least in the FDs of which I'm familiar. IMO it's the price for forced induction. Boost is power. More power= more heat= more stress. NA rotarys have the problem, but AFAIK, not nearly as soon as the FDs.
Still, before doing anything, make sure you have a failed seal. Besides the 'Champagne test" these are all the symtoms I can think of... but no single symtom by itself is confirmation. Many symtoms could be from other causes. However the more symtoms/conditions you have in combination, the more likely it is a coolant seal failure.........
*Stumbling idle on cold start-up that clears up quickly. The combustion chamber is fouled with coolant. As soon as it's purged or burned up, your car will run fine until the next cold start.
*Slightly sweet exhaust smell, especially on start-up. See above. Coolant is being burned and it has a distinctive smell.
*"White smoke" (steam) on cold start-up even in warm/hot weather. See above.
*A coolant over-flow tank that is over-flowing. This will usually result in a puddle under the car near the right front...the area of the over-flow tank. When coolant gets hot it expands and that's what the overflow tank is for. But with a failed seal the nature vacuum that forms and pulls that coolant back out as the engine cools down is lost. That leaves that coolant stranded in the tank and eventually it overflows.
*Coolant loss that isn't explained by a puddle on your garage floor. It's being consumed by the engine and going out the exhaust.
*Spiking temps that seemingly recover on their own almost as quickly. Air pockets in the cooling system allow steam to form. That will cause temp spiking. This is different than a rising temp just after a period of hard boost. It can happen as your steadily cruising down the highway.
*Boiling sounds after shut down even shortly after properly "burping" the system. See above.
*Failed coolant system pressure test.
*Failed test of coolant for hydrocarbons.
*Unusually clean plugs, or wet plugs if you pull them right away after starting the car. (Sometimes you can even smell the coolant)
*One or more episodes of serious overheating in the car's history regardless of miles. (from what I've read, 115 C./240 F. seems to be the critical number for OEM seals to begin to degrade)
*An otherwise well maintained and cared-for FD approaching 100K miles or so.
As for a bandaid, some have used one of the many "Stop-Leak" coolant additives to give them a bit more time but use at your own risk. While it's not anything that will leave you on the side of the road, a failed coolant seal can lead to errosion/rust/pitting of the coolant seal grooves in the irons. That can cause a junk iron and make the inevitiable rebuild more expensive.
Still, before doing anything, make sure you have a failed seal. Besides the 'Champagne test" these are all the symtoms I can think of... but no single symtom by itself is confirmation. Many symtoms could be from other causes. However the more symtoms/conditions you have in combination, the more likely it is a coolant seal failure.........
*Stumbling idle on cold start-up that clears up quickly. The combustion chamber is fouled with coolant. As soon as it's purged or burned up, your car will run fine until the next cold start.
*Slightly sweet exhaust smell, especially on start-up. See above. Coolant is being burned and it has a distinctive smell.
*"White smoke" (steam) on cold start-up even in warm/hot weather. See above.
*A coolant over-flow tank that is over-flowing. This will usually result in a puddle under the car near the right front...the area of the over-flow tank. When coolant gets hot it expands and that's what the overflow tank is for. But with a failed seal the nature vacuum that forms and pulls that coolant back out as the engine cools down is lost. That leaves that coolant stranded in the tank and eventually it overflows.
*Coolant loss that isn't explained by a puddle on your garage floor. It's being consumed by the engine and going out the exhaust.
*Spiking temps that seemingly recover on their own almost as quickly. Air pockets in the cooling system allow steam to form. That will cause temp spiking. This is different than a rising temp just after a period of hard boost. It can happen as your steadily cruising down the highway.
*Boiling sounds after shut down even shortly after properly "burping" the system. See above.
*Failed coolant system pressure test.
*Failed test of coolant for hydrocarbons.
*Unusually clean plugs, or wet plugs if you pull them right away after starting the car. (Sometimes you can even smell the coolant)
*One or more episodes of serious overheating in the car's history regardless of miles. (from what I've read, 115 C./240 F. seems to be the critical number for OEM seals to begin to degrade)
*An otherwise well maintained and cared-for FD approaching 100K miles or so.
As for a bandaid, some have used one of the many "Stop-Leak" coolant additives to give them a bit more time but use at your own risk. While it's not anything that will leave you on the side of the road, a failed coolant seal can lead to errosion/rust/pitting of the coolant seal grooves in the irons. That can cause a junk iron and make the inevitiable rebuild more expensive.
Thread Starter
n00b
Joined: Jun 2010
Posts: 37
Likes: 0
From: Laurel, MD
*Stumbling idle on cold start-up that clears up quickly. The combustion chamber is fouled with coolant. As soon as it's purged or burned up, your car will run fine until the next cold start.
Check
*Slightly sweet exhaust smell, especially on start-up. See above. Coolant is being burned and it has a distinctive smell.
Check
*"White smoke" (steam) on cold start-up even in warm/hot weather. See above.
Check
*A coolant over-flow tank that is over-flowing. This will usually result in a puddle under the car near the right front...the area of the over-flow tank. When coolant gets hot it expands and that's what the overflow tank is for. But with a failed seal the nature vacuum that forms and pulls that coolant back out as the engine cools down is lost. That leaves that coolant stranded in the tank and eventually it overflows.
*Coolant loss that isn't explained by a puddle on your garage floor. It's being consumed by the engine and going out the exhaust.
Check
*Spiking temps that seemingly recover on their own almost as quickly. Air pockets in the cooling system allow steam to form. That will cause temp spiking. This is different than a rising temp just after a period of hard boost. It can happen as your steadily cruising down the highway.
Check
*Boiling sounds after shut down even shortly after properly "burping" the system. See above.
Maybe?
*Failed coolant system pressure test.
Check
*Failed test of coolant for hydrocarbons.
*Unusually clean plugs, or wet plugs if you pull them right away after starting the car. (Sometimes you can even smell the coolant)
*One or more episodes of serious overheating in the car's history regardless of miles. (from what I've read, 115 C./240 F. seems to be the critical number for OEM seals to begin to degrade)
I forgot to put the radiator cap back on once before driving. That was a real d'oh moment. It was the first time I'd encountered the spiking temps. That time it was my water pump that was leaking, though. I pulled over immediately the first time the temp spiked, let it cool a bit and added the rest of the coolant I had. Kept driving, temp spiked again. Pulled over and found the radiator cap sitting on the battery. So I'm guessing that time was probably a real overheat.
*An otherwise well maintained and cared-for FD approaching 100K miles or so.
S5 FC @ 168k
crap... I can't afford a rebuild :/
Check
*Slightly sweet exhaust smell, especially on start-up. See above. Coolant is being burned and it has a distinctive smell.
Check
*"White smoke" (steam) on cold start-up even in warm/hot weather. See above.
Check
*A coolant over-flow tank that is over-flowing. This will usually result in a puddle under the car near the right front...the area of the over-flow tank. When coolant gets hot it expands and that's what the overflow tank is for. But with a failed seal the nature vacuum that forms and pulls that coolant back out as the engine cools down is lost. That leaves that coolant stranded in the tank and eventually it overflows.
*Coolant loss that isn't explained by a puddle on your garage floor. It's being consumed by the engine and going out the exhaust.
Check
*Spiking temps that seemingly recover on their own almost as quickly. Air pockets in the cooling system allow steam to form. That will cause temp spiking. This is different than a rising temp just after a period of hard boost. It can happen as your steadily cruising down the highway.
Check
*Boiling sounds after shut down even shortly after properly "burping" the system. See above.
Maybe?
*Failed coolant system pressure test.
Check
*Failed test of coolant for hydrocarbons.
*Unusually clean plugs, or wet plugs if you pull them right away after starting the car. (Sometimes you can even smell the coolant)
*One or more episodes of serious overheating in the car's history regardless of miles. (from what I've read, 115 C./240 F. seems to be the critical number for OEM seals to begin to degrade)
I forgot to put the radiator cap back on once before driving. That was a real d'oh moment. It was the first time I'd encountered the spiking temps. That time it was my water pump that was leaking, though. I pulled over immediately the first time the temp spiked, let it cool a bit and added the rest of the coolant I had. Kept driving, temp spiked again. Pulled over and found the radiator cap sitting on the battery. So I'm guessing that time was probably a real overheat.
*An otherwise well maintained and cared-for FD approaching 100K miles or so.
S5 FC @ 168k
crap... I can't afford a rebuild :/
Junior Member
Joined: Oct 2012
Posts: 19
Likes: 0
From: Pennsylvania
help please
im having similar problems with mine.
1991 rx7 2nd gen n/a
has 184,500 miles on it.
coolant system has been completely replaced. New hoses New water pump New thermostat and a (new to the car) used rad from another rx7.
my coolant is back channeling into the tank and then leaking from that.
Upper rad hose is cold and pressurized and Lower hose is Hot.
i disconnected the upper rad hose from the rad and ran a garden hose into the rad and ran the car to try to flush out whatever was inside of the ports. water came out in surges not like a steady stream. didn't matter so much if the car was wide open or idling. temp doesn't spike coolant alarm comes on never let her get to H if it came up between half and hot i shut down the car. no white smoke coming from the back. starts right up every time.
1991 rx7 2nd gen n/a
has 184,500 miles on it.
coolant system has been completely replaced. New hoses New water pump New thermostat and a (new to the car) used rad from another rx7.
my coolant is back channeling into the tank and then leaking from that.
Upper rad hose is cold and pressurized and Lower hose is Hot.
i disconnected the upper rad hose from the rad and ran a garden hose into the rad and ran the car to try to flush out whatever was inside of the ports. water came out in surges not like a steady stream. didn't matter so much if the car was wide open or idling. temp doesn't spike coolant alarm comes on never let her get to H if it came up between half and hot i shut down the car. no white smoke coming from the back. starts right up every time.
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