D5 (D5244T to 2005) Coolant system problem

[Alexei]

Dear Colleagues,
Sorry for my not so good English, because I am from Russia. I am an owner of the XC90 D5, 2004 year. Just know I have a problem with engine of my car.
The problem is the following: The level of coolant to the max. mark, starting engine and go. After a period of time at dashboard display appears the message: "Coolant is low, stop safely and refill." Time of occurrence is always different. Message can be ignited in an half of hour or can be one hour travel.
When I see this message, I am stopping the car, opening the hood and see that the level of coolant is below the minimum mark. I am opening the cap of the expansion tank and the level of coolant is returning to the maximum mark. It is not necessary to add coolant to the system. I am closing the cap, hood and going to the next occurrence of the inscription.
I bought a new expansion tank cap - did not help. Everything remained as before.
The temperature of coolant is clearly at 90 ° C, no leaks. For last month I do not add the coolant at all.
Burning smell from the expansion tank or an emulsion in motor oil on the dipstick is not observed.
Help me to understand what's the catch?
Thank you in advance.

[outnumbered]

is the tank split or cracked also have a look at the level sensor that is underneath it may have come adrift .
mike

[Backhill1]

My guess you have an air lock that the system is just struggling to get rid of. Someone has filled the sytem and not vented properly. You may be lucky if you run it next time the level drops with the cap off for some time and it may purge the air out. You will know you have been successfull if the level stays low and you manage to get to p it up job done. either that and drain and re-fill when the system is cold and loosen some hoses at the top of the engine etc to make sure you get all the air out and hoopefully it will take a little more coolant than you take out. Check the capacity and make sure it takes at least what is recommended. Fix ASAP as it could reduce flow and cause problems on a long journey.

[Alexei]

Originally Posted by outnumbered

is the tank split or cracked also have a look at the level sensor that is underneath it may have come adrift .
mike

Thank you Mike.
I checked the expansion tank - everything o'k. When the level of the coolant is becoming low the pipes from engine to radiator and from engine to preliminary heater becomes very hard. Them not possible to squeeze. But when I am opening the cap of the expansion tank all mentioned pipes again becomes soft.

Originally Posted by Backhill1

My guess you have an air lock that the system is just struggling to get rid of. Someone has filled the sytem and not vented properly. You may be lucky if you run it next time the level drops with the cap off for some time and it may purge the air out. You will know you have been successfull if the level stays low and you manage to get to p it up job done. either that and drain and re-fill when the system is cold and loosen some hoses at the top of the engine etc to make sure you get all the air out and hoopefully it will take a little more coolant than you take out. Check the capacity and make sure it takes at least what is recommended. Fix ASAP as it could reduce flow and cause problems on a long journey.

Thank you Backhill1.
I am thinking about it, but there is not a airlock. I checked it. I think there is something more serious, but could not define what?

[Alexei]

[QUOTE=Backhill1;1023306]

[Backhill1]

Remember not to dismiss the basics, the fact it is lowering and rising with flow pretty much points to an Air lock and as you have a matrix in the interior etc this is very likley. Also you are not loosing coolant, oil clean and not overheating. I have had engines before needing only 1/4 ltr of vent and additional coolant to fix problems like this. A good run with the cap off and a rag in to stop splashes etc sometimes does the trick (remember to keep the heater on max).These are hard engine without a history of coolant problems.

[Alexei]

Originally Posted by Backhill1

Remember not to dismiss the basics, the fact it is lowering and rising with flow pretty much points to an Air lock and as you have a matrix in the interior etc this is very likley. Also you are not loosing coolant, oil clean and not overheating. I have had engines before needing only 1/4 ltr of vent and additional coolant to fix problems like this. A good run with the cap off and a rag in to stop splashes etc sometimes does the trick (remember to keep the heater on max).These are hard engine without a history of coolant problems.

Thank you,
Yesterday I was in BMW service (they have a special device with chemical liquid) for checking the presence of exhaust gas in cooling system. The device shown that the exhaust gases are presented in cooling system of my engine. The specialist said that in this case is necessary to check the gasket between cylinder block and head of cylinder block. He said there is a high probability of microcrack in this gasket. So, tomorrow I will go to the Volvo service for checking the problem.

[Backhill1]

I dont like to argue with technology but as a specialist for a well known Diesel Engine company we for warranty or any other purposes would not trust this equipment unless the system is flushed / cleaned and fresh water / coolant added as there could be a minimal amout of Co2 causing the dye to change (these kits make garages a lot of money). If the system is not pressurising (normally a pressure gauge should be added to the filler cap at the same time as the fluid to measure the maximum pressure) i would have my doubts as you are not using water. Unfortuantly if the system is pressurising and changing colour im afraid the diagnosis is probably correct. When you have the head off ensure it is pressure tested (hot) and skimmed proffessionally. If these works are not completed correctly this will become a regular job and you will become very friendly with the garage;do it right the first time. These are good heavy engines and if the repair is done proffessionally you should have no further problems. Good Luck.

[Alexei]

Originally Posted by Backhill1

I dont like to argue with technology but as a specialist for a well known Diesel Engine company we for warranty or any other purposes would not trust this equipment unless the system is flushed / cleaned and fresh water / coolant added as there could be a minimal amout of Co2 causing the dye to change (these kits make garages a lot of money). If the system is not pressurising (normally a pressure gauge should be added to the filler cap at the same time as the fluid to measure the maximum pressure) i would have my doubts as you are not using water. Unfortuantly if the system is pressurising and changing colour im afraid the diagnosis is probably correct. When you have the head off ensure it is pressure tested (hot) and skimmed proffessionally. If these works are not completed correctly this will become a regular job and you will become very friendly with the garage;do it right the first time. These are good heavy engines and if the repair is done proffessionally you should have no further problems. Good Luck.

Thank you. I hope the specialist of Volvo service will be good and done this work proffessionally.

[Alexei]

Backhill1
The problem was in gasket between cylinder block and head of cylinder block. It was an overheating near second cylinder. See attached photo: