Coolant discharge at overflow tank
#1
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2002 Vanden Plas (base). I have read many threads (which are great) but cannot find the answer to my specific problem . After several weeks of only a slight discharge (few drops a day) the overflow tank is now discharging serious amounts of coolant. Cannot drive for more than a proximally 10 miles without overheating and refilling. (Obviously not driving it now) No work has recently been done on car. I have driven for 10 years. Here is what I have checked.
No visible coolant in engine compartment . Flowing from directly beneath overflow tank.
No leaks in any lines coming from expansion tank.
Expansion tank cap Seems in good order.
Removed skid plate and inspected overflow tank (behind fender) can not visually see any cracks.
After shutdown coolant does return to radiator when cooling - no line blockage.
Coolant appears to be coming from overflow tank. Is it possible that engine overheating and dispensing to overflow tank to maximum and forcing coolant out discharge port?
I am at a loss. Any help would be greatly appreciated.
Monty
No visible coolant in engine compartment . Flowing from directly beneath overflow tank.
No leaks in any lines coming from expansion tank.
Expansion tank cap Seems in good order.
Removed skid plate and inspected overflow tank (behind fender) can not visually see any cracks.
After shutdown coolant does return to radiator when cooling - no line blockage.
Coolant appears to be coming from overflow tank. Is it possible that engine overheating and dispensing to overflow tank to maximum and forcing coolant out discharge port?
I am at a loss. Any help would be greatly appreciated.
Monty
#2
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montypeek (08-30-2015)
#3
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montypeek (08-30-2015)
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montypeek (08-31-2015)
#7
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Fundamentally, what is happening is the presence of gas within the cooling system, which raises the pressure until the pressure cap releases.
Where does this gas come from?
There are two common causes :
1) Nucleate boiling (localised in the hottest spots, ie cylinder head), which is happening because the coolant is too hot, and maybe not pressurised.
2) A leak of exhaust gas into the cooling system.
It would be a good idea to eliminate (2), before going further. The best way is with a cooling system exhaust gas test kit, like this :
Combustion Leak Detector at National Tool Warehouse
(1) can be caused by lots of things, a partially blocked radiator, faulty water pump, faulty thermostat. The cooling system relies on being pressurised to not boil. So the slightest leak tends to form a vicious circle : air leaks in, makes it overheat more, and so on. The same goes for nucleate boiling, once you get the slightest bit, it's all downhill from there.
You can get pressure testers to check that the cooling system holds pressure. I tested my Land Rover V8 to just over the release point of the pressure cap, and found 3 different leaks, all from hoses.
So, in summary, while this might be a head gasket problem, it is just as, or more, likely to be a cooling system problem. Don't assume anything, verify.
My TR8 did this chronically. The final fix was a new pressure cap - it wasn't holding pressure.
Where does this gas come from?
There are two common causes :
1) Nucleate boiling (localised in the hottest spots, ie cylinder head), which is happening because the coolant is too hot, and maybe not pressurised.
2) A leak of exhaust gas into the cooling system.
It would be a good idea to eliminate (2), before going further. The best way is with a cooling system exhaust gas test kit, like this :
Combustion Leak Detector at National Tool Warehouse
(1) can be caused by lots of things, a partially blocked radiator, faulty water pump, faulty thermostat. The cooling system relies on being pressurised to not boil. So the slightest leak tends to form a vicious circle : air leaks in, makes it overheat more, and so on. The same goes for nucleate boiling, once you get the slightest bit, it's all downhill from there.
You can get pressure testers to check that the cooling system holds pressure. I tested my Land Rover V8 to just over the release point of the pressure cap, and found 3 different leaks, all from hoses.
So, in summary, while this might be a head gasket problem, it is just as, or more, likely to be a cooling system problem. Don't assume anything, verify.
My TR8 did this chronically. The final fix was a new pressure cap - it wasn't holding pressure.
Last edited by Mark SF; 08-31-2015 at 12:48 PM.
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montypeek (09-01-2015),
rocklandjag (09-06-2015)
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#8
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Thanks - Great Advise from Post -
Quick update!!
Have replace expansion tank cap.
Installed new thermostat.
Eliminated any coolant loss while driving (YEA) however I am still getting discharged on cooldown after stopping. This is Random - it occurs sometimes but not consistent . In all cases engine is at normal operating temp prior to shutdown.
Additional advice would be greatLy appreciated.
Also - in the process I managed to crack one of the expansion tank flex hoses. ( One going from tank to top of thermostat housing ) I had to cut the flex line and run high temp hose from there to thermostat housing port. ( short term fix to say the least)
I cannot seem to find the Pre formed flex line online. Does anyone know where this can be purchased?
Thank you in advance for your good advice!
Quick update!!
Have replace expansion tank cap.
Installed new thermostat.
Eliminated any coolant loss while driving (YEA) however I am still getting discharged on cooldown after stopping. This is Random - it occurs sometimes but not consistent . In all cases engine is at normal operating temp prior to shutdown.
Additional advice would be greatLy appreciated.
Also - in the process I managed to crack one of the expansion tank flex hoses. ( One going from tank to top of thermostat housing ) I had to cut the flex line and run high temp hose from there to thermostat housing port. ( short term fix to say the least)
I cannot seem to find the Pre formed flex line online. Does anyone know where this can be purchased?
Thank you in advance for your good advice!
#9
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I think that line you are looking for, if I am understanding your description, is bleed hose part number MNC4582AC.
Here is a link to one possible place to buy it:
http://www.terrysjag.com/product/MNC4582AC.html
Here is a link to one possible place to buy it:
http://www.terrysjag.com/product/MNC4582AC.html
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montypeek (09-04-2015)
#10
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Thanks - Great Advise from Post -
Quick update!!
Have replace expansion tank cap.
Installed new thermostat.
Eliminated any coolant loss while driving (YEA) however I am still getting discharged on cooldown after stopping. This is Random - it occurs sometimes but not consistent . In all cases engine is at normal operating temp prior to shutdown.
Additional advice would be greatLy appreciated.
Also - in the process I managed to crack one of the expansion tank flex hoses. ( One going from tank to top of thermostat housing ) I had to cut the flex line and run high temp hose from there to thermostat housing port. ( short term fix to say the least)
I cannot seem to find the Pre formed flex line online. Does anyone know where this can be purchased?
Thank you in advance for your good advice!
Quick update!!
Have replace expansion tank cap.
Installed new thermostat.
Eliminated any coolant loss while driving (YEA) however I am still getting discharged on cooldown after stopping. This is Random - it occurs sometimes but not consistent . In all cases engine is at normal operating temp prior to shutdown.
Additional advice would be greatLy appreciated.
Also - in the process I managed to crack one of the expansion tank flex hoses. ( One going from tank to top of thermostat housing ) I had to cut the flex line and run high temp hose from there to thermostat housing port. ( short term fix to say the least)
I cannot seem to find the Pre formed flex line online. Does anyone know where this can be purchased?
Thank you in advance for your good advice!
#11
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thank you very much for the link. Purchased the expansion tank hose and I am preparing to install. One additional question-is there a trick to disconnecting the expansion tank flexible hose. It appears the clip simply needs to be depressed while applying pressure to pull hose free? I am just trying to avoid damage to the expansion tank port. THANKS AGAIN!
#12
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The attached picture is of a simple plastic Jaguar tool that was supposedly included with our cars when new. I've never seen one in person.
Many use needle nose pliers to engage each side and then open the pliers to release the connector. I have done that, and it works.
My preferred method is to use snap ring pliers that open out (external, I think they are called).
Many use needle nose pliers to engage each side and then open the pliers to release the connector. I have done that, and it works.
My preferred method is to use snap ring pliers that open out (external, I think they are called).
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montypeek (09-05-2015)
#13
#14
#15
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Harvest14 I have 2 of those and surprisingly they were found located on the vehicle. When I did tensioners on my XJ-8 I found the tool in one of the fittings below the throttle body. Out of curiosity I went over the lines on my XK-8 and it to was found on a fitting under the throttle body. I think a lot of them were used and removed by mechanics and tossed in a tool box.
They are a handy little gadget and they do work. Interestingly with 2 of my friends XJ-8's I couldn't find theirs.
They are a handy little gadget and they do work. Interestingly with 2 of my friends XJ-8's I couldn't find theirs.
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harvest14 (09-27-2015)
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