White Smoke/Coolant Leak
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Joined: Nov 2002
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From: Austin, TX
White Smoke/Coolant Leak
I have a 1993 RX-7 with 36,000 miles. Is it normal to have white smoke blowing out of the exhaust at start up? It goes away after a couple minutes then the car runs perfectly. There is also coolant leaking from the front bottom of the car. Is this my seals? If not, what else could this problem be? A faulty radiator hose? Thanks.
don't race, don't need to
Joined: Oct 2002
Posts: 1,292
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From: Tri-Cities, WA
HA! Another one strikes...
White smoke at startup: IFF it smells sweet, is very thick, doesn't look like steam, more like, well, powdery... this is blown internal seal leaking coolant into the combustion chamber. Check your spark plugs to confirm. If they are wet, begin looking on the brighter side of engine rebuild.
IFF it smells more like exhaust, is more like steam,doesn't really start coming out until roughly 30 seconds or so after startup, this is condensation being boiled off the pre-cat and then main cat as they warm up in this dense cool air of autumn. Normal, look to the coolant leak next.
Leaking from the front bottom: WHERE, exactly? Under the passenger side headlight? Overflow tank is overflowing. Could be a crack, but vastly more likely you have a sealing problem in the cooling system that is making it impossible for the coolant to be drawn back into the system on cooldown. This really only starts happening when you keep adding coolant to a low coolant light coming on. It should be noted that a blown seal can have gasses go INTO the coolant system, rather than the coolant going into the combustion chamber. These gasses displace the coolant, and it overflows from the overflow tank. Common symptom is a low coolant beep that goes away after a bit, coolant constanlty coming out the overflow, bubbles in the coolant seen in the filler neck right after startup that stink like car exhause and/or are analyzed with a smog sniffer to contain unburned hydrocarbons. Rebuild time.
Coming from the belly pan? If from the middle louvres of the pan, this is most likely coming off the radiator. If from the back of the pan, look to a heater hose, radiator hose or the turbo cooling hoses.
Note that 1) the stock air separation tank (AST) is a liability in this car. REPLACE IT NOW with an aftermarket one. There is a nice one most likely going to be produced by spooledupRX7. Look for a thread entitled "best AST?" Look to Pettitor the other manufacture listed in that thread if he won't make em.
2) the stock radiator is prone to failure. It has PLASTIC end caps that are crimped onto the core, and these can fail after many heat cycles. You have low mileage for a 93, but the plastic degrades all by itself. A good replacement if you want drop right in is Fluidyne, and there are many sources for it. Replace it AFTER the AST IFF it is not the source of your current leak (pull that belly pan and look). I only put it this way cause that AST gotta go!
3) the coolant carrying hoses in this car are numerous (14!), and all begin to rot over time, from the inside out. A good indicator of failing hoses is the upper radiator hose, the big one you see as you look down the filler neck. If it bulges AT ALL around that stock clamp, REPLACE THE HOSES. It is real cheap insurance against a replaced motor, especially with your low miles.
4) make sure you have new caps. Make sure the cap on the filler neck is a plain cap, without the spring and lower gasket. The cap on the AST should have the spring. Both should be 13lbs 0.9bar.
Hope any of this helps...
White smoke at startup: IFF it smells sweet, is very thick, doesn't look like steam, more like, well, powdery... this is blown internal seal leaking coolant into the combustion chamber. Check your spark plugs to confirm. If they are wet, begin looking on the brighter side of engine rebuild.
IFF it smells more like exhaust, is more like steam,doesn't really start coming out until roughly 30 seconds or so after startup, this is condensation being boiled off the pre-cat and then main cat as they warm up in this dense cool air of autumn. Normal, look to the coolant leak next.
Leaking from the front bottom: WHERE, exactly? Under the passenger side headlight? Overflow tank is overflowing. Could be a crack, but vastly more likely you have a sealing problem in the cooling system that is making it impossible for the coolant to be drawn back into the system on cooldown. This really only starts happening when you keep adding coolant to a low coolant light coming on. It should be noted that a blown seal can have gasses go INTO the coolant system, rather than the coolant going into the combustion chamber. These gasses displace the coolant, and it overflows from the overflow tank. Common symptom is a low coolant beep that goes away after a bit, coolant constanlty coming out the overflow, bubbles in the coolant seen in the filler neck right after startup that stink like car exhause and/or are analyzed with a smog sniffer to contain unburned hydrocarbons. Rebuild time.
Coming from the belly pan? If from the middle louvres of the pan, this is most likely coming off the radiator. If from the back of the pan, look to a heater hose, radiator hose or the turbo cooling hoses.
Note that 1) the stock air separation tank (AST) is a liability in this car. REPLACE IT NOW with an aftermarket one. There is a nice one most likely going to be produced by spooledupRX7. Look for a thread entitled "best AST?" Look to Pettitor the other manufacture listed in that thread if he won't make em.
2) the stock radiator is prone to failure. It has PLASTIC end caps that are crimped onto the core, and these can fail after many heat cycles. You have low mileage for a 93, but the plastic degrades all by itself. A good replacement if you want drop right in is Fluidyne, and there are many sources for it. Replace it AFTER the AST IFF it is not the source of your current leak (pull that belly pan and look). I only put it this way cause that AST gotta go!
3) the coolant carrying hoses in this car are numerous (14!), and all begin to rot over time, from the inside out. A good indicator of failing hoses is the upper radiator hose, the big one you see as you look down the filler neck. If it bulges AT ALL around that stock clamp, REPLACE THE HOSES. It is real cheap insurance against a replaced motor, especially with your low miles.
4) make sure you have new caps. Make sure the cap on the filler neck is a plain cap, without the spring and lower gasket. The cap on the AST should have the spring. Both should be 13lbs 0.9bar.
Hope any of this helps...
Re: White Smoke/Coolant Leak
Originally posted by Rx7isthebest
I have a 1993 RX-7 with 36,000 miles. Is it normal to have white smoke blowing out of the exhaust at start up? It goes away after a couple minutes then the car runs perfectly. There is also coolant leaking from the front bottom of the car. Is this my seals? If not, what else could this problem be? A faulty radiator hose? Thanks.
I have a 1993 RX-7 with 36,000 miles. Is it normal to have white smoke blowing out of the exhaust at start up? It goes away after a couple minutes then the car runs perfectly. There is also coolant leaking from the front bottom of the car. Is this my seals? If not, what else could this problem be? A faulty radiator hose? Thanks.
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Joined: Feb 2001
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From: Huntington Beach, CA, USA
Also don't confuse an external leak with an internal leak. If you have coolant dripping onto the ground then you have an external leak that needs to be fixed like spurvo said. However this is unrelated to any kind of internal leak (except if its coming out the overflow, but then that isn't really a leak 
), they are totally seperate things. You may very well have both an internal and external leak at the same time, this is possible although your symptoms sound like only an external leak.
), they are totally seperate things. You may very well have both an internal and external leak at the same time, this is possible although your symptoms sound like only an external leak.
Last edited by Nathan Kwok; Nov 13, 2002 at 06:30 PM.
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