2002 Audi A6 3.0L Hard Start Issue & Coolant Leak HELP!
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AudiWorld Newcomer
Joined: Apr 2018
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2002 Audi A6 3.0L Hard Start Issue & Coolant Leak HELP!
My car starts easily in the morning when it is cold. The issue is after I drive the car and park it for 5 minutes or more, it will be a hard start. It will takes about 5 seconds of cranking before the car turns over and starts. After the car starts, if I turn it off, and start it again, it will crank over and start immediately. I tried all the following with no avail. Any ideas or advice?
It seems that now I also have a coolant leak issue. The car gets hots and starts to overheat. The reservoir boils over and drips onto the metal and make steam. I had this issue about 2 years ago and I replaced the reservoir and coolant cap and it seemed to fix it.
• Replaced fuel filter
• Replaced fuel pressure regulator
• Replaced crankshaft engine speed sensor
• Replaced coolant temperature sensor
• Cleaned MAF sensor
• Replaced PVC valve
• Mechanic tested fuel pressure and says it is OK
• Coolant reservoir does leak drip out of bottom after driving awhile
• Occasional check engine codes P0421 (Warm Up Catalyst Efficiency Below Threshold (Bank 1) and P0431(Warm Up Catalyst Efficiency Below Threshold (Bank 2)) but passed smog emission test recently
It seems that now I also have a coolant leak issue. The car gets hots and starts to overheat. The reservoir boils over and drips onto the metal and make steam. I had this issue about 2 years ago and I replaced the reservoir and coolant cap and it seemed to fix it.
• Replaced fuel filter
• Replaced fuel pressure regulator
• Replaced crankshaft engine speed sensor
• Replaced coolant temperature sensor
• Cleaned MAF sensor
• Replaced PVC valve
• Mechanic tested fuel pressure and says it is OK
• Coolant reservoir does leak drip out of bottom after driving awhile
• Occasional check engine codes P0421 (Warm Up Catalyst Efficiency Below Threshold (Bank 1) and P0431(Warm Up Catalyst Efficiency Below Threshold (Bank 2)) but passed smog emission test recently
AudiWorld Super User
Joined: Jul 2013
Posts: 2,665
Likes: 213
From: In the Cloud
For your hard start problem, it's probably the residual pressure not meeting specs.. Maybe a leaking injector...
Bentley A6 Service Manual - Fuel pressure specs
2.7L and all V8 idling, gauge connected inline bet. fuel rail and fuel suply line.
-Fuel pressure regulator vacuum line connected = 3.5 bar (51 psi)
-Fuel pressure regulator vacuum line disconnected = 4.0 bar (58 psi)
Residual pressure, leave gauge connected, shut off engine, wait 10 mins
With engine cold: approx. 2.2 bar
With engine hot: approx. 3.0 bar
-----------------------------------------------------------------
Once you have solved that problem, I would guess that coolant loss is a completely different problem. Pressure test the coolant system using the proper tool. Replace the cap as a likely culprit.
Bentley A6 Service Manual - Fuel pressure specs
2.7L and all V8 idling, gauge connected inline bet. fuel rail and fuel suply line.
-Fuel pressure regulator vacuum line connected = 3.5 bar (51 psi)
-Fuel pressure regulator vacuum line disconnected = 4.0 bar (58 psi)
Residual pressure, leave gauge connected, shut off engine, wait 10 mins
With engine cold: approx. 2.2 bar
With engine hot: approx. 3.0 bar
-----------------------------------------------------------------
Once you have solved that problem, I would guess that coolant loss is a completely different problem. Pressure test the coolant system using the proper tool. Replace the cap as a likely culprit.
Last edited by georgeb944; Apr 3, 2018 at 04:07 AM.
AudiWorld Senior Member
Joined: Jan 2015
Posts: 1,186
Likes: 43
From: Sierra Vista, AZ
My car starts easily in the morning when it is cold. The issue is after I drive the car and park it for 5 minutes or more, it will be a hard start. It will takes about 5 seconds of cranking before the car turns over and starts. After the car starts, if I turn it off, and start it again, it will crank over and start immediately. I tried all the following with no avail. Any ideas or advice?
It seems that now I also have a coolant leak issue. The car gets hots and starts to overheat. The reservoir boils over and drips onto the metal and make steam. I had this issue about 2 years ago and I replaced the reservoir and coolant cap and it seemed to fix it.
• Replaced fuel filter
• Replaced fuel pressure regulator
• Replaced crankshaft engine speed sensor
• Replaced coolant temperature sensor
• Cleaned MAF sensor
• Replaced PVC valve
• Mechanic tested fuel pressure and says it is OK
• Coolant reservoir does leak drip out of bottom after driving awhile
• Occasional check engine codes P0421 (Warm Up Catalyst Efficiency Below Threshold (Bank 1) and P0431(Warm Up Catalyst Efficiency Below Threshold (Bank 2)) but passed smog emission test recently
It seems that now I also have a coolant leak issue. The car gets hots and starts to overheat. The reservoir boils over and drips onto the metal and make steam. I had this issue about 2 years ago and I replaced the reservoir and coolant cap and it seemed to fix it.
• Replaced fuel filter
• Replaced fuel pressure regulator
• Replaced crankshaft engine speed sensor
• Replaced coolant temperature sensor
• Cleaned MAF sensor
• Replaced PVC valve
• Mechanic tested fuel pressure and says it is OK
• Coolant reservoir does leak drip out of bottom after driving awhile
• Occasional check engine codes P0421 (Warm Up Catalyst Efficiency Below Threshold (Bank 1) and P0431(Warm Up Catalyst Efficiency Below Threshold (Bank 2)) but passed smog emission test recently
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