Khrrck
Professional Amateur
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- Mar 11, 2015
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- Beaverton, OR
Sure, it's possible, but I don't remember seeing posts about it so I think it's rare at best. How's the trans fluid look? "Acting up" how?
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240 Coolant keeps overflowing out of tank?
- Thread starter EivlEvo
- Start date
Sure, it's possible, but I don't remember seeing posts about it so I think it's rare at best. How's the trans fluid look? "Acting up" how?
coalminer
New member
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- Mar 14, 2013
- Location
- North Georgia Mountains
Cooling System Operation...a long, long post....sorry
The cooling system pressure (on most cars) will be at or below 15 psi.
Pressurizing the coolant will RAISE it's boiling point.
The fact that it has had a recent head gasket replacement and is now pushing coolant out the reservoir is enough information for me to suspect that you have a small leak in the head gasket, or a small crack in the head.
You likely have a leak and are losing compression from a engine cylinder or exhaust port and into the coolant system.
If you can rig a pressure gage on the cooling system to check what the actual pressures are in the (hot) cooling system, I suspect that your problem and the reason for it will become obvious.
In normal operation of cooling systems with a expansion reservoir.
The system is pressurized because because the natural physical reaction to the coolant being heated is that it will expand.
This expansion cannot be stopped, it's physically impossible, so it must be dealt with or things will break.
This causes the need for additional space in the cooling system for expansion of the liquid.
By holding the coolant under low (cap) pressure, the coolant is allowed it to expand against the small amount of air in the reservoir.
This pushes coolant into the reservoir and causes pressure to rise on the system.
Under normal circumstances, the pressure will not rise high enough to overcome the set pressure limit of the coolant cap, and the coolant is retained in the coolant bottle.
As the engine and coolant cools, the coolant will contract and pull the coolant back into the engine.
This is caused by the vacuum created by contraction of liquid coolant in a small closed cooling system.
This is why pressure caps have a small one way vent that acts as a vacuum break.
This prevents the cooling system from pulling too much vacuum on the cooling system as the coolant cools and retracts it's expansion.
This vacuum can damage components of the cooling system.
If everything is working as designed, the process repeats itself over and over without losing any coolant to the environment.
Older cars that didn't have a expansion reservoir, relied on the air space above the coolant in the top of the radiator (radiator not quite full) to absorb the expansion of the liquid.
That's why the radiator wasn't ever completely full of coolant in these old systems.
As the liquid expanded, the pressure in the system it would occupy the air above the coolant in the top of the radiator.
This would cause a pressure rise in the enclosed system.
If the expansion was too great (too much coolant in system) the pressure increase to the point where the pressure cap would open and and allow just enough liquid to escape to lower the pressure to pressure cap setting, and the liquid loss would stop.
If you took a empty system and completely filled it with coolant, put the pressure cap on and started the engine, it wouldn't be long until you noticed coolant dripping out the overflow on the pressure cap.
This is caused by liquid expansion requiring more space, and making it's own space.
Eventually the pressures would stabilize against the cap setting, and there would be no more loss of coolant.
In Abnormal Operation of a Closed Cooling System with a expansion reservoir.............
Operation that is affected by a problem such as uncontrolled temperature and pressures in the system caused by leaks between the combustion chamber in the engine into the cooling system, and vise versa.
If there is a pressure leak out of the engine cylinder and into the cooling system it severely affects the operation of the system.
This could be through a leak in the head gasket or a leak through a crack in the head or engine block.
If that happens, the pressure in the cooling system cannot be controlled because the combustion chamber pressures are far above the ability of the cooling system to contain the pressure.
This pressure rise happens could begin as soon as you start the engine, or it could take a while as the engine block and head expands allows the leak ( or crack) to open.
At this point, pressure will rise in the cooling system that is far above the ability of the system to contain, and coolant will be forced through the pressure cap and out in the driveway.
As the coolant is leaked out, the temperature on the system will increase to the point to where steam is generated, and pressure climbs quickly.
The leak gets worse, and eventually all of the coolant will be blown out of the engine.
This is where severe engine damage can occur.
I suspect that the reason there is no pressure on your system when you remove the cap is either the system is completely empty, or that the pressure is leaking back into and through the combustion chamber when you turn the engine off.
Have you seen any indication of oil in the cooling system, or water in the engine oil?
Any water (or steam) coming out of the tail pipe when the engine if running?
Have you tried removing the pressure cap before you start the engine (engine cool) to see if any bubbles are being formed in the coolant as the engine warms??
If so, these are the air bubbles that are over-pressurizing your system.
I know that this is a long post, but maybe it will give some people a insight to how their coolant system works, and also give them a place to start trouble shooting.
Hope this helps someone.
The cooling system pressure (on most cars) will be at or below 15 psi.
Pressurizing the coolant will RAISE it's boiling point.
The fact that it has had a recent head gasket replacement and is now pushing coolant out the reservoir is enough information for me to suspect that you have a small leak in the head gasket, or a small crack in the head.
You likely have a leak and are losing compression from a engine cylinder or exhaust port and into the coolant system.
If you can rig a pressure gage on the cooling system to check what the actual pressures are in the (hot) cooling system, I suspect that your problem and the reason for it will become obvious.
In normal operation of cooling systems with a expansion reservoir.
The system is pressurized because because the natural physical reaction to the coolant being heated is that it will expand.
This expansion cannot be stopped, it's physically impossible, so it must be dealt with or things will break.
This causes the need for additional space in the cooling system for expansion of the liquid.
By holding the coolant under low (cap) pressure, the coolant is allowed it to expand against the small amount of air in the reservoir.
This pushes coolant into the reservoir and causes pressure to rise on the system.
Under normal circumstances, the pressure will not rise high enough to overcome the set pressure limit of the coolant cap, and the coolant is retained in the coolant bottle.
As the engine and coolant cools, the coolant will contract and pull the coolant back into the engine.
This is caused by the vacuum created by contraction of liquid coolant in a small closed cooling system.
This is why pressure caps have a small one way vent that acts as a vacuum break.
This prevents the cooling system from pulling too much vacuum on the cooling system as the coolant cools and retracts it's expansion.
This vacuum can damage components of the cooling system.
If everything is working as designed, the process repeats itself over and over without losing any coolant to the environment.
Older cars that didn't have a expansion reservoir, relied on the air space above the coolant in the top of the radiator (radiator not quite full) to absorb the expansion of the liquid.
That's why the radiator wasn't ever completely full of coolant in these old systems.
As the liquid expanded, the pressure in the system it would occupy the air above the coolant in the top of the radiator.
This would cause a pressure rise in the enclosed system.
If the expansion was too great (too much coolant in system) the pressure increase to the point where the pressure cap would open and and allow just enough liquid to escape to lower the pressure to pressure cap setting, and the liquid loss would stop.
If you took a empty system and completely filled it with coolant, put the pressure cap on and started the engine, it wouldn't be long until you noticed coolant dripping out the overflow on the pressure cap.
This is caused by liquid expansion requiring more space, and making it's own space.
Eventually the pressures would stabilize against the cap setting, and there would be no more loss of coolant.
In Abnormal Operation of a Closed Cooling System with a expansion reservoir.............
Operation that is affected by a problem such as uncontrolled temperature and pressures in the system caused by leaks between the combustion chamber in the engine into the cooling system, and vise versa.
If there is a pressure leak out of the engine cylinder and into the cooling system it severely affects the operation of the system.
This could be through a leak in the head gasket or a leak through a crack in the head or engine block.
If that happens, the pressure in the cooling system cannot be controlled because the combustion chamber pressures are far above the ability of the cooling system to contain the pressure.
This pressure rise happens could begin as soon as you start the engine, or it could take a while as the engine block and head expands allows the leak ( or crack) to open.
At this point, pressure will rise in the cooling system that is far above the ability of the system to contain, and coolant will be forced through the pressure cap and out in the driveway.
As the coolant is leaked out, the temperature on the system will increase to the point to where steam is generated, and pressure climbs quickly.
The leak gets worse, and eventually all of the coolant will be blown out of the engine.
This is where severe engine damage can occur.
I suspect that the reason there is no pressure on your system when you remove the cap is either the system is completely empty, or that the pressure is leaking back into and through the combustion chamber when you turn the engine off.
Have you seen any indication of oil in the cooling system, or water in the engine oil?
Any water (or steam) coming out of the tail pipe when the engine if running?
Have you tried removing the pressure cap before you start the engine (engine cool) to see if any bubbles are being formed in the coolant as the engine warms??
If so, these are the air bubbles that are over-pressurizing your system.
I know that this is a long post, but maybe it will give some people a insight to how their coolant system works, and also give them a place to start trouble shooting.
Hope this helps someone.
Most informative (I meant it raises the boiling point)
Saying this... the car has probably had close to 8000 miles put on it since the HG was replaced. The head was milled and pressure checked for cracks. I'm not ruling it out... but I'm not going to jump there either.
As I've mentioned in a few posts. Today I swapped caps, and I get the pressure relief sound when I open the cap now. There is plenty of coolant in the system. Too much maybe even, which is maybe what caused it to overflow. The oil looks crystal clean. I'm definitely going to check it again this weekend though.
Either way... something odd is happening.
Saying this... the car has probably had close to 8000 miles put on it since the HG was replaced. The head was milled and pressure checked for cracks. I'm not ruling it out... but I'm not going to jump there either.
As I've mentioned in a few posts. Today I swapped caps, and I get the pressure relief sound when I open the cap now. There is plenty of coolant in the system. Too much maybe even, which is maybe what caused it to overflow. The oil looks crystal clean. I'm definitely going to check it again this weekend though.
Either way... something odd is happening.
cwdodson88
Well-known member
- Joined
- Oct 27, 2011
- Location
- The Dalles, Oregon
air bubbles, no coolant pressure.... sounds like the problem to me.
There are no air bubbles, and there IS coolant pressure.
thismachine13
New member
- Joined
- Sep 22, 2015
- Location
- Kansas City
^^^^The OP may have resolved his issue by replacing the coolant overflow cap.....at least the indications would lead one to believe that is the case. At this point its a matter of acquiring continued positive data to confirm his resolution.
Here's hoping you got it fixed man!
Here's hoping you got it fixed man!
^^^^The OP may have resolved his issue by replacing the coolant overflow cap.....at least the indications would lead one to believe that is the case. At this point its a matter of acquiring continued positive data to confirm his resolution.
Here's hoping you got it fixed man!
Yeah... as mentioned. I'm seeing a result, AND an indication that there may have been a problem. I'll do the full diagnostic this weekend to confirm the findings.
It all sucks. Was just about to drive up east coast to NY (next week) and this happens. PLUS... pretty sure my AW is on the way out (someone asked how it was acting up... it seems to be slipping a bit... I checked fluids on that and it was definitely low. Did the "add fluid dance" and it seemed alright but slipped again this AM. Hence why I was asking about coolant and ATF blending)
Luckily my T5 is ready to go... BUT, not sure I want to drive 1500 miles round trip on an "untested" T5.
Owsley
Active member
- Joined
- Dec 3, 2008
- Location
- San Francisco
On my 1992 745T I was experiencing similar issues. It turned out that while the e-fan was coming on, it wasn't reliably coming on. Some of the newer Volvos have the e-fan fan relay wired to the ECU temp sensor, others use a temp sensor on the radiator. Regardless, pay attention to when your fan does and does not turn on. When temp sensors fail, they usually fail intermittently instead of a sudden, complete failure.
James10952001
New member
- Joined
- Feb 17, 2007
- Location
- Woodinville, WA
Luckily my T5 is ready to go... BUT, not sure I want to drive 1500 miles round trip on an "untested" T5.
What better test? Haven't you seen Captain Ron? "If anything's gonna happen...it'll happen out there!"
What better test? Haven't you seen Captain Ron? "If anything's gonna happen...it'll happen out there!"
Hahaha... captain ron is a classic! I actually might just put the damn thing in. My trans jack is at the other end of the journey... was hoping to bring it back with me. That way... less bench pressing. But hell, maybe it's a sign from God.
Also my car is non-efan, so motor fan is running based on engine RPM. Also have the Nissens 3 row and tropical fan clutch so cool as a cucumber. You know... aside from my coolant apparently evacuating itself
VB242
I.M. Weasel
- Joined
- Sep 21, 2011
- Location
- Driving the No Malarkey Bus
I've been through that head gasket denial process a few times but I'd give good odds you have a bad one
Again... testing this weekend. When I was siphoning some coolant out last night, it was black as could be. Oil level seemed low to me (but not THAT low). Which sucks because I'm concerned about WHY it failed (if it failed). Oil still looks crystal clear, but yeah... we'll see what the leakdown test reports.
My transmission was bone dry on ATF again after only a day (~30 miles) and there was no apparent leak. I'm still wondering if there's any way for the ATF to mix with the coolant via a cracked trans cooler (the style within the radiator end tank)?
VB242
I.M. Weasel
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- Sep 21, 2011
- Location
- Driving the No Malarkey Bus
I'm pretty sure that can happen, you might not have a blown head gasket
freevolvos
Active member
- Joined
- Jan 5, 2011
- Location
- hillpoint
it can happen but you will know it with the nasty strawberry gobs of oil in the trans
KeizerBrickGuy
Sh*t pot stirrer
- Joined
- Jun 7, 2016
- Location
- Keizer, OR
There could very well be a split in the radiator end tank trans cooler. But if you're saying the some of the coolant is "black as can be", it could still be a HG from combustion gasses getting into the cooling system. Acustrip has some test strips for testing of oil and transmission fluid that checks for glycol within it. http://www.acustrip.com/cgi-bin/proddesc.cgi?s=ACU711254
Well... I've got a mystery on my hands it seems.
The coolant is sitting nicely on top of whatever the blackish stuff is. They're not chocolate milky like when they mix, and it's not strawberry like with ATF. I had been fairly certain INITIALLY (a month or so ago) when I noticed the discoloration that it was simply rustiness.
Not sure it matters, but when the engine runs or revs with coolant cap on or off I'm not getting any bubbles in the overflow tank.
If in fact there is a leak in the ATF cooler in the radiator, I might be able to see coolant running out of it if I were to open those lines up yes?
The coolant is sitting nicely on top of whatever the blackish stuff is. They're not chocolate milky like when they mix, and it's not strawberry like with ATF. I had been fairly certain INITIALLY (a month or so ago) when I noticed the discoloration that it was simply rustiness.
Not sure it matters, but when the engine runs or revs with coolant cap on or off I'm not getting any bubbles in the overflow tank.
If in fact there is a leak in the ATF cooler in the radiator, I might be able to see coolant running out of it if I were to open those lines up yes?
Tonight I only had time to check for hydrocarbons in the coolant via chemical block tester. Ran the car up to temperature with no issues. Pulled a vacuum and the dye stayed blue the whole time. No change at all to yellow.
So it seems I have no hydrocarbons present in the coolant which is a preliminary plus.
So it seems I have no hydrocarbons present in the coolant which is a preliminary plus.
coalminer
New member
- Joined
- Mar 14, 2013
- Location
- North Georgia Mountains
After that book I posted the other day, I'll try to be brief.
After reading further in your posts, the mention of (chronically) low transmission fluid and black residue in the coolant reservoir rings a bell to me.
I had the some of the same symptoms on my 94 Model 940 B230F a couple of years ago.
The cause of this problem in my case was a leak in the transmission oil heat exchanger tube which is located inside the radiator
The transmission pumps fluid to, through and back from the radiator continuously whenever the engine is running.
The first thing that I noticed was a black scum on the inside of the coolant reservoir.
Luckily, I never found any trace of coolant in the transmission oil, and the black scum was being formed by transmission fluid that was leaking into the coolant.
Apparently, the crack in my heat exchanger or the nature of the pressures differentials involved between the inside fluid pressure of the tube verses the coolant pressure outside the tube were never "just right" to allow any coolant to leak back into the transmission fluid.
It was always the transmission fluid leaking into the coolant.
Strange, but that's the way it happened.
If The coolant had leak back into the transmission fluid (as I suspect may be happening to your car), the transmission would have been seriously damaged....
If I were you, and BEFORE I change the (now defective) transmission, I would check for a leak in the heat exchanger tube in the radiator.
Disconnect both of the transmission lines to the radiator, plug one of the ports, and use air to pressurize (<20psi) the exchanger tube.
I use a air hose nozzle with a rubber tip, and a hand control.
Push some low pressure air into the tube and hold it for few seconds.
If you don't have any leaks on your air test connections, or inside on the exchanger tube, the air pressure should hold on the gage, and not waver.
If there is a internal leak in the exchanger tube, the pressure will drop steadily down to zero.
If that happens, you need a new radiator before you install and damage the new transmission.
Another way to check the exchanger is to remove the radiator, lay it flat with the connections pointed up fill the radiator (not the exchanger tube) completely full of water, and using your finger to seal one fluid connection, apply low pressure air to the other connection.
If air bubbles come out of the radiator hose connection(s), the tube is leaking and is defective.
I'm not recommending this to you, but I thoroughly washed the inside of the engine cooling system and hoses before I installed the new radiator.
I drained the (black, slimey) coolant out of the engine and system, disconnected the bottom hose from the radiator and removed the thermostat and housing.
Using a water hose, I flushed the engine with water. I pushed the water into the thermostat opening and let it drain out the lower radiator hose.
After I did this about 5 times, I installed the thermostat housing (less thermostat), reattached the bottom radiator hose, poured about a cup full of "Simple Green" (original general purpose) into the engine via the thermostat housing, and reattached the upper hose.
I filled the coolant reservoir and engine with water (adding a small amount of "Simple Green" here too) and started the engine and let it run (about 5 minutes) and get warm, adding water to the coolant reservoir as required to keep it full.
I then removed the lower hose from the radiator and dumped the coolant and "Funk" into a 5 gallon bucket.
I repeated this process a few times until I had the coolant coming out a clear green color.
I then flushed with clear water a couple more times, removed the reservoir and cleaned it thoroughly inside.
After installing the new radiator, I put the cooling system back together (reservoir, thermostat, hoses, etc.) and filled the cooling with a 50% mixture of anti-freeze and water.
This had been about five years ago, and I haven't had any problems with this cooling system since then.
Sorry for another long post.
I hope this helps
After reading further in your posts, the mention of (chronically) low transmission fluid and black residue in the coolant reservoir rings a bell to me.
I had the some of the same symptoms on my 94 Model 940 B230F a couple of years ago.
The cause of this problem in my case was a leak in the transmission oil heat exchanger tube which is located inside the radiator
The transmission pumps fluid to, through and back from the radiator continuously whenever the engine is running.
The first thing that I noticed was a black scum on the inside of the coolant reservoir.
Luckily, I never found any trace of coolant in the transmission oil, and the black scum was being formed by transmission fluid that was leaking into the coolant.
Apparently, the crack in my heat exchanger or the nature of the pressures differentials involved between the inside fluid pressure of the tube verses the coolant pressure outside the tube were never "just right" to allow any coolant to leak back into the transmission fluid.
It was always the transmission fluid leaking into the coolant.
Strange, but that's the way it happened.
If The coolant had leak back into the transmission fluid (as I suspect may be happening to your car), the transmission would have been seriously damaged....
If I were you, and BEFORE I change the (now defective) transmission, I would check for a leak in the heat exchanger tube in the radiator.
Disconnect both of the transmission lines to the radiator, plug one of the ports, and use air to pressurize (<20psi) the exchanger tube.
I use a air hose nozzle with a rubber tip, and a hand control.
Push some low pressure air into the tube and hold it for few seconds.
If you don't have any leaks on your air test connections, or inside on the exchanger tube, the air pressure should hold on the gage, and not waver.
If there is a internal leak in the exchanger tube, the pressure will drop steadily down to zero.
If that happens, you need a new radiator before you install and damage the new transmission.
Another way to check the exchanger is to remove the radiator, lay it flat with the connections pointed up fill the radiator (not the exchanger tube) completely full of water, and using your finger to seal one fluid connection, apply low pressure air to the other connection.
If air bubbles come out of the radiator hose connection(s), the tube is leaking and is defective.
I'm not recommending this to you, but I thoroughly washed the inside of the engine cooling system and hoses before I installed the new radiator.
I drained the (black, slimey) coolant out of the engine and system, disconnected the bottom hose from the radiator and removed the thermostat and housing.
Using a water hose, I flushed the engine with water. I pushed the water into the thermostat opening and let it drain out the lower radiator hose.
After I did this about 5 times, I installed the thermostat housing (less thermostat), reattached the bottom radiator hose, poured about a cup full of "Simple Green" (original general purpose) into the engine via the thermostat housing, and reattached the upper hose.
I filled the coolant reservoir and engine with water (adding a small amount of "Simple Green" here too) and started the engine and let it run (about 5 minutes) and get warm, adding water to the coolant reservoir as required to keep it full.
I then removed the lower hose from the radiator and dumped the coolant and "Funk" into a 5 gallon bucket.
I repeated this process a few times until I had the coolant coming out a clear green color.
I then flushed with clear water a couple more times, removed the reservoir and cleaned it thoroughly inside.
After installing the new radiator, I put the cooling system back together (reservoir, thermostat, hoses, etc.) and filled the cooling with a 50% mixture of anti-freeze and water.
This had been about five years ago, and I haven't had any problems with this cooling system since then.
Sorry for another long post.
I hope this helps
This is what I'm thinking is my issue tbh. I'm not worried about the integrity of the transmission OR the trans cooler as I'm going with the Ford T5 (it's ready to go... it's just you know... 128 outside). BUT! I need to know how I can cap that system off (after I test and ensure that's the problem obviously) so that coolant doesn't leak out of those two holes when I have no auto box hooked to them.
Alrighty squad. I ran the gamut today.
As mentioned somewhere in one of my threads I ran the chemical test for hydrocarbon vapors in my coolant tank (blue juice and squeezy bulb). Clean.
Compression test was between 180 and 190 dry on all 4 cylinders.
Leakdown test was right around 10% for each cylinder which was kind of surprising to me tbh.
I sent the boroscope into the cylinders for good measure and everything looked as normal as normal can be.
Sparkplugs were all pretty identical, and showed nothing off.
I pulled the schrader valve out of my compression tester and ALSO just pumped air into cylinders. NO bubbling in coolant at all.
So... then I pulled the top line off of the trans cooler that is inside the end tank of my nissens 3 row radiator... and set my compressor to discharge about 30psi. LOTS of gurgling. Couldn't locate the gurgling but if I put my hand over the overflow tank and squeezed air, I could feel it pushing my hand off of the tank.
Correct me if I'm wrong crewtons, but this seems to indicate I have a bad transmission cooler that has now leaked trans fluid into my cooling system yes?
Since I'm going T5, can I just cap these lines when I yank the AW7X out of there? Or should I seriously consider a radiator replacement?
As mentioned somewhere in one of my threads I ran the chemical test for hydrocarbon vapors in my coolant tank (blue juice and squeezy bulb). Clean.
Compression test was between 180 and 190 dry on all 4 cylinders.
Leakdown test was right around 10% for each cylinder which was kind of surprising to me tbh.
I sent the boroscope into the cylinders for good measure and everything looked as normal as normal can be.
Sparkplugs were all pretty identical, and showed nothing off.
I pulled the schrader valve out of my compression tester and ALSO just pumped air into cylinders. NO bubbling in coolant at all.
So... then I pulled the top line off of the trans cooler that is inside the end tank of my nissens 3 row radiator... and set my compressor to discharge about 30psi. LOTS of gurgling. Couldn't locate the gurgling but if I put my hand over the overflow tank and squeezed air, I could feel it pushing my hand off of the tank.
Correct me if I'm wrong crewtons, but this seems to indicate I have a bad transmission cooler that has now leaked trans fluid into my cooling system yes?
Since I'm going T5, can I just cap these lines when I yank the AW7X out of there? Or should I seriously consider a radiator replacement?