I am building pressure in cooling system in the expansion tank. At idle it looks like its bubbling. I checked for leaks in EGR cooler. EGR cooler is not leaking. Checked for exhasust gas. No Exhaust Gas. Checked compessor air while cap off and no coolant shooting out when air building up. When it cools down pressure build up and expands on all hoses creating excessive pressure. When cool, I remove cap and get air pressure. It is forcing coolant out of the odd hose. When I run the truck, temperature is normal, fan comes on when it should. Compressor seems to be functioning preoperly. Changes both caps on expansion tank. I am stumped.
Volvo D12 pressure in expansion tank. I checked for exhaust Gas, its fine.
Discussion in 'Volvo Forum' started by Richard Trotter, Mar 16, 2016.
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Last edited: Mar 16, 2016
Reason for edit: Posted Egr Delete, wrong wording. I ment I removed exhaust air issue by removing and doing leak test. -
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i had this problem last year, D!2 engine. i tried evrything you have. on my truck it was injector cups. i ran with pressure cap loose until i got to dealer ship.
Last edited: Mar 16, 2016
Reason for edit: typo -
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i did not have exhaust in coolant tank, no fuel either. that is why it took me a long time to figure it out. somewhere in these volvo threads there is a thread where i found a guy who had this same problem and it was his cups. i went to my local dealer in Canada and they did what they called a bubble test? this confirmed it was cups. yours may not be, just saying what myself and others have experienced. it amazed me that this was the problem.
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I appreciate the response. I had my injector cups done a while back, but they dont use good parts anymore, so I gues they could need to be done.
KB3MMX Thanks this. -
most likely you are looking at the air compressor, Best way to find out is drain air tanks get 1/4 hose and put shop air to blue signal hose on compressor head and let truck idle, 90% air compressor head gasket is bad and putting air in the cooling system
Richard Trotter Thanks this. -
I ordered a compressor. I will instrall tomorrow and post the results. A volvo mechanic said it was the compressor. But it was charging the system with air overnight when truck was cooling down. How does air work back from air tanks??
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there is a pressure limiting valve but there is a good chance ive seen it many times before that it goes thru the head specially if the compressor is in the charging cycle without the dryer purging. Ive seen people replace a lot of parts cuz they couldn't figure the air from the tanks can go back, ever since i saw that now i always make sure i drain the tanks before testing it.
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