Hello,
I do have this issue with my VW Golf 2010 2.5 manual where i get check engine light with error P0301.
The error means that there is misfires. At the same time i noticed my coolant is slowly disappearing.
My theory was that coolant leaks to the combustion chamber that causes misfires.
I went to dealer and ask them to find where coolant leaks.
They could not find any coolant in oil after removing the cap from the engine.(showed me video with clean oil)
They could not find anything after basic pressure test so they recommended to do:
Compression Test: vehicle has misfire faults for cylinder 1 due to history of vehicle rec to perform compression test to verify no compression is lost
(450$ just for that, was able to get it down to 350$)
with below result:
AFTER DOING TEST HAD MINOR COMPRESSION LOST, ADVICED TO REMOVED VALVER COVER AND INSPECTED CAM ROCKERS SPRINGS AND CAMS NO ISSUES FOUND
Next, they recommended to do more services which i rejected as it was not making sense and were just basic tuneup things.
I agreed to one as i was worried that engine internals might be already compromised:
Maintenance Kit (BG): REC TO PERFORM TO HELP WITH CARBON BUILD UP ON CAM ADJUSTER PORT AFTER WILL NEED TO PERFORM SERVICE VEHICLE IS DUE EITHER WAY. BG SERVICE IS RECOMENDED TO CLEAN OUT ALL PORTS IN BLOCK AND HEAD. REC TO START OF BY DOING THIS SERVICE TO AVOID HEAD REPLACMENT. BUT DOING THE SERVICE DOES NOT ELEMINATE THE POSSIBILITY THAT THE HEAD NEEDS TO BE REPLACED.
They also wanted to change oil but i just did that 2 months before that but something told me just to do so maybe something comes up related to coolant leak.
They found that oil was yellow and they said oil cooler is leaking coolant to oil.
https://yourimageshare.com/ib/tO4xsVuASe
So now they want to replace oil cooler with housing which make sense as oil is yellow.
"
Recommended service
$3,016.74
Oil Filter Housing Gasket: found coolant in oil when draining oil. need to replace oil cooler with oil filter housing.
The oil filter housing is the casing that holds the engine's oil filter. The housing uses a gasket to ensure a proper seal.
"
I am surprised that they did not check the oil by dripping a little in the first place to eliminate oil cooler leak.
Now my question is, how the oil cooler replacement (3000$) will fix the error P0301.
How mixed oil with coolant can lead to misfires? Are those related?
I am not an expert so if i think incorrecly please tell me.
I want to make sure if this is really the cause of misfires.
Something tells me that after they replace the oil cooler i will still have misfires due to some tiny leak. (maybe the head gasket)
Then i will end up with another expensive repair.
Any comments would be really welcomed.
Bart
""
I do have this issue with my VW Golf 2010 2.5 manual where i get check engine light with error P0301.
The error means that there is misfires. At the same time i noticed my coolant is slowly disappearing.
My theory was that coolant leaks to the combustion chamber that causes misfires.
I went to dealer and ask them to find where coolant leaks.
They could not find any coolant in oil after removing the cap from the engine.(showed me video with clean oil)
They could not find anything after basic pressure test so they recommended to do:
Compression Test: vehicle has misfire faults for cylinder 1 due to history of vehicle rec to perform compression test to verify no compression is lost
(450$ just for that, was able to get it down to 350$)
with below result:
AFTER DOING TEST HAD MINOR COMPRESSION LOST, ADVICED TO REMOVED VALVER COVER AND INSPECTED CAM ROCKERS SPRINGS AND CAMS NO ISSUES FOUND
Next, they recommended to do more services which i rejected as it was not making sense and were just basic tuneup things.
I agreed to one as i was worried that engine internals might be already compromised:
Maintenance Kit (BG): REC TO PERFORM TO HELP WITH CARBON BUILD UP ON CAM ADJUSTER PORT AFTER WILL NEED TO PERFORM SERVICE VEHICLE IS DUE EITHER WAY. BG SERVICE IS RECOMENDED TO CLEAN OUT ALL PORTS IN BLOCK AND HEAD. REC TO START OF BY DOING THIS SERVICE TO AVOID HEAD REPLACMENT. BUT DOING THE SERVICE DOES NOT ELEMINATE THE POSSIBILITY THAT THE HEAD NEEDS TO BE REPLACED.
They also wanted to change oil but i just did that 2 months before that but something told me just to do so maybe something comes up related to coolant leak.
They found that oil was yellow and they said oil cooler is leaking coolant to oil.
https://yourimageshare.com/ib/tO4xsVuASe
So now they want to replace oil cooler with housing which make sense as oil is yellow.
"
Recommended service
$3,016.74
Oil Filter Housing Gasket: found coolant in oil when draining oil. need to replace oil cooler with oil filter housing.
The oil filter housing is the casing that holds the engine's oil filter. The housing uses a gasket to ensure a proper seal.
"
I am surprised that they did not check the oil by dripping a little in the first place to eliminate oil cooler leak.
Now my question is, how the oil cooler replacement (3000$) will fix the error P0301.
How mixed oil with coolant can lead to misfires? Are those related?
I am not an expert so if i think incorrecly please tell me.
I want to make sure if this is really the cause of misfires.
Something tells me that after they replace the oil cooler i will still have misfires due to some tiny leak. (maybe the head gasket)
Then i will end up with another expensive repair.
Any comments would be really welcomed.
Bart
""