29mpg and a flashing oil light.

[914turboford]

We have only driven our NA caddy 116 miles. I wanted to see about this legendary fuel economy so I filled it up at that point. 4.1 gallons, or about 29mpg US. I thought these things were supposed to get 40+. Is that a myth or is there something wrong with this truck? It seems to run really nice. Slower than a slug but sounds great, idles great and has reasonable acceleration around town. I've never seen any smoke coming out of the tailpipe under any conditions. Will cruise at 65mph on level ground, slows to 45 in third on some of the grades near my Sierra Nevada home. All of this driving was done at elevations between 2000-4000 ft with lots of hills. I have an AWD Honda with 108 rated hp that gets 31mpg in 2WD mode and 26mpg in 4WD mode, so I'm not too impressed with this VDub if all it can do is 29 under these conditions. Secondly, the oil light has flashed on a couple of times. Last night going down the freeway it flashed on twice and a buzzing sound emitted from the dash area(I guess it has an audible warning). I stopped to check the oil level and it was at the top of the safe area. It flashed on without the buzzer one other time on the freeway. This morning it came on once while at idle then went away when I revved it slightly. I guess I should test it with a gage. It is not making any knocking sounds. Are the oil pumps prone to go out on these? Or is it more likely the rods/mains. The engine and truck look nice and clean and it has 149K miles.

[fuslit]

How much maintenance have you done on the truck? I suspect that if the fuel filter is plugged it could cause the issue, maybe  a new Fuel filter might take care of your sluggishness/mpg issue?

bentley says that (just snagged the info about excessive fuel use from my mk1 diesel trouble shooting section)

excessive fuel consumption could be caused by.
a. dirty air filter
b. fuel leaks
c.return pipe blocked
d. idle speed to fast or max rpm too high
e. faulty injectors
f. injection timing incorrect
g. engine mechanical faults as described earlier in heading
h. faulty injector pump

The buzzer is common (at least the mk1's that I've had anyway) Caused from the a loose wire, bad sensor, or bad relay. I don't remember off the top of my head which one to check but if you don't have one a Bentley manual will help you trace down these problems.

Sorry I'm not more help on this.

-todd

[Vincent Waldon]

The buzzer is common (at least the mk1's that I've had anyway) Caused from the a loose wire, bad sensor, or bad relay.

Or the most common reason of all: actual low oil pressure, usually caused by worn bearings.

It might be a good idea to get an oil pressure gauge on the filter flange to make sure you really just have a sensor or wiring issue.

A worn engine could also help explain less than typical fuel economy.

[89VWdieselGolf]

wow thats bad, i used to get that in my 2.0L gasser before i turbo'd it
now its 18MPG :cry:

[914turboford]

I put a gage in the oil pressure housing. At ice cold idle this morning I had 80psi at idle. Later, after the engine was as warm as I could get it on this 40 degree day, the lowest I saw  was 30psi at idle and revving the engine brought it up to 60. I did not route the gage into the cab so did not check while driving. I bought a new oil pressure switch so I'll put that in and assume the oil pressure issue is resolved.

Sounds like you agree about my fuel economy that it sucks. How much should the elevation affect the mileage? What should I be getting? Are these trucks really supposed to get 40+?

[914turboford]

Yes, you should get higher than 40 MPG.  I live at 7,000 ft of elevation and routinely got 45+ in an '86 jetta, sometimes 50+.  

Andrew

Where do you live? I am jealous of your elevation.

[vanagonturbo]

Check the pump timing. Should be around .85mm

[burn_your_money]

Check the pump timing. Should be around .85mm

I prefer mine set at 1.00

It could be faulty injectors.

You should check the oil pressure at the side of the head as well and make sure it is in spec.