'96 A6 oil pressure sending unit
11-25-2007, 07:27 AM
#1
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'96 A6 oil pressure sending unit
Are there any known issues with the oil pressure sending unit for this model? Could there be any major problem with the vehicle if the light comes on or does it just need to be replaced?
What's you experience and suggestions for diagnosing issues?
What's you experience and suggestions for diagnosing issues?
11-25-2007, 10:05 AM
#2
Easy to test for oil pressure
You can make a nice little mechanical test gauge:
1) 24" grease gun "whip" hose
2) Coupler that is 1/8" pipe thread female at both ends
3) $15 pressure gauge that reads 0-140psi(or whatever it comes)
4) 1/8" pipe thread cap to put over the other end of the whip hose so it doesn't leak oil into your tool box during storage.
Thread this all together and you have an oil pressure gauge. Remove the oil pressure sender that's located next to the a/c compressor (at about 10 o'clock of if you're facing the compressor. HAND TIGHTEN your new pressure gauge into the engine and fire it up. See what your pressure is.
If you've got good oil pressure (and I'm sure you do) Make sure the wire for the oil pressure sender hasn't rubbed through and grounded against the engine block. It travels up the front of the block, behind the timing belt cover on the driver's side and up into the valley. Plenty of places for it to get in contact with metal and that will turn the light on.
It's very common for the pressure swithes to fail and start leaking, they're cheap, so not a big deal to replace.
1) 24" grease gun "whip" hose
2) Coupler that is 1/8" pipe thread female at both ends
3) $15 pressure gauge that reads 0-140psi(or whatever it comes)
4) 1/8" pipe thread cap to put over the other end of the whip hose so it doesn't leak oil into your tool box during storage.
Thread this all together and you have an oil pressure gauge. Remove the oil pressure sender that's located next to the a/c compressor (at about 10 o'clock of if you're facing the compressor. HAND TIGHTEN your new pressure gauge into the engine and fire it up. See what your pressure is.
If you've got good oil pressure (and I'm sure you do) Make sure the wire for the oil pressure sender hasn't rubbed through and grounded against the engine block. It travels up the front of the block, behind the timing belt cover on the driver's side and up into the valley. Plenty of places for it to get in contact with metal and that will turn the light on.
It's very common for the pressure swithes to fail and start leaking, they're cheap, so not a big deal to replace.
11-25-2007, 03:05 PM
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Re: Easy to test for oil pressure
So, with your experience it is not likely that the oil pump is bad as this would be an expensive fix. This car has 126k on it now so it may be due for a timing belt change as I have no way of knowing for sure when it was last changed. However, the belts do look newer and in good shape.
11-25-2007, 07:31 PM
#4
Um, have you actually done that on your Audi?
The pressure switches have metric threads. Not to say it's a bad idea, but it'll probably take more than a trip to the local hardware store to make.
11-25-2007, 07:47 PM
#5
I built this tool years ago and works in metric and SAE threads because it's 1/8" pipe
As I said, you simply hand tighten it. It doesn't take any thing more than that. It won't leak, and you can drive the car around with it installed in order to do things like hot oil pressure tests, etc.
Haven't used it our Avant because I haven't needed to, but I made it when I was working at the dealer and have used it countless times over the years.
Haven't used it our Avant because I haven't needed to, but I made it when I was working at the dealer and have used it countless times over the years.
11-25-2007, 07:55 PM
#6
It is so rare to have a German car with a bad oil pump. Don't think I've ever seen one.
In my opinion, it's sort of a German engineering tradition that their oil pumps and oil systems are bulletproof, and usually their oil pressures are way high compared to other manufacturer's engines. VW Rabbit Diesels used to blow oil filters completely off if you didn't install a German filter!
There's no way you've got an oil pressure problem. You either have an oil pressure sender wire that's grounding out on the engine block somewhere along the path I mentioned, or the sender itself is bad. The sender is the one with a white plastic center, and it may have a black rubber boot covering it. There is also an oil temp sensor down there, but it's next to the crank pulley at about 2 o'clock and has a black plastic center.
You'll spend about $25 building that oil pressure tool and then you'll know exactly what's what.
One word of caution. I've seen Fram and other cheap oil filters fail internally and cause a loss of oil pressure. If you don't have a Mann, Mahle, Knecht, or Bosch oil filter on there, go get one and put it one (and then top up the oil).
There's no way you've got an oil pressure problem. You either have an oil pressure sender wire that's grounding out on the engine block somewhere along the path I mentioned, or the sender itself is bad. The sender is the one with a white plastic center, and it may have a black rubber boot covering it. There is also an oil temp sensor down there, but it's next to the crank pulley at about 2 o'clock and has a black plastic center.
You'll spend about $25 building that oil pressure tool and then you'll know exactly what's what.
One word of caution. I've seen Fram and other cheap oil filters fail internally and cause a loss of oil pressure. If you don't have a Mann, Mahle, Knecht, or Bosch oil filter on there, go get one and put it one (and then top up the oil).
11-25-2007, 08:22 PM
#7
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Eh, some 12V folks on the 80/90 forum have had to replace oil pumps...
...I've never had to nor has anyone that I've known personally with a 12V ever had to.
If I had to guess the cars that have needed them suffered some sort of oil starvation at some point in their lives.
If I had to guess the cars that have needed them suffered some sort of oil starvation at some point in their lives.
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11-25-2007, 10:28 PM
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What should the oil pressure be?
Also the temperature guage was not moving when I drove his vehicle.
Thermostat? Or, possibly related to the oil pressure sending unit/oil pump issue?
Thermostat? Or, possibly related to the oil pressure sending unit/oil pump issue?
11-26-2007, 07:29 AM
#10
Take one thing at a time...
Oil pressure will be 60-90psi cold at speed and probably 60+ hot at speed. Idle oil pressure might be 50 something cold and maybe in the 30's hot.
These engine coolant thermostats can fail in the open position and then it can take forever for the engine coolant temp gauge to read. A new t-stat can be installed without removing the timing belt.
I think you're going to have to take this one step at a time.
1) Confirm oil pressure
2) Solve the oil pressure reading problem
3) Confirm coolant temp
4) Solve the coolant temp read problem
These engine coolant thermostats can fail in the open position and then it can take forever for the engine coolant temp gauge to read. A new t-stat can be installed without removing the timing belt.
I think you're going to have to take this one step at a time.
1) Confirm oil pressure
2) Solve the oil pressure reading problem
3) Confirm coolant temp
4) Solve the coolant temp read problem
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