Expert: Ernest (Ernie) Kenward - 7/18/2007

Question
QUESTION: i picked up an 86 audi 4ks yesterday that is a project that i would like to have
as a daily driver. there are a few things i've run into recently that have got me
a little frustrated. here is the sequence of events. thanks for the help in
advance. browsing this site in the past has been a huge help.

the guy selling the car put in a new battery. car started right up.
i test drove the car. i noticed the gas gauge was at 0. i put in a gallon so i
could drive it some more.
i turned off the car when we got back.
i bought the car. started right back up and drove it back to where i live about
5 miles away.
i decided to top off the tank since it is mine now.
when i got to the gas station, the car was overheating.
i let it cool down and put in some antifreeze.
it started right up and the temperature gauge stayed in the middle and then
slowly moved to the cooler end.
drove about 9 or 10 miles.
i was at a stoplight. when the light turned green, i started pulling out and the
car started stuttering and jerking like i was out of gas.
i looked at the gas gauge and it was at 0.
so i assumed there was a fuel leak.
i left it on the side of the road and went back today to put gas in it and drive
it back to my place.
it wouldn't start.
i noticed the clamps weren't tight on the battery terminals.
a friend came and jumped it and it started.
i drove it the last mile to my house.
i noticed that when i started it up, the gas gauge went to half a tank after i
had only just put in 1 gallon, thinking there was a fuel leak.
it slowly went from half a tank to empty in just a mile.
as i was backing in behind my apartment, it stuttered again and cut off.
this may have to do with the fact that the last time i drove a stick shift was
close to 8 years ago. i still do fine! backing up an incline was a bit of a
challenge.
it wouldn't start back up.
i got it in place and started messing with some of the electrical problems at
hand.
as i turned the key into the start position, the gas gauge went up to half a
tank.
the voltmeter in the car has been sitting around 8.

am i dealing with a bad thermostat and alternator? i have no clue about the
fuel gauge.

ANSWER: Sorry for the delay in getting back to you; I would like to help with this project - and certainly encourage you with it - but my time is a bit tight.  The car certainly does seem to offer some maintenance challenges, but they appear to be fairly typical ones that come about as a result of a lack of preventative maintenance by the previous owner.  Dealing with them in turn will probably give you the driver you want, and also give you that sense of ownership that comes of solving its problems!

I am going to stick to a few brief points tonight.  Deal with them first, and feel free to get back to me as you progress through them.

First, clean up/tighten up/replace as required the battery cables and/or clamps.  Loose clamps and - worse - corroded clamps make for the high resistance that causes excessive voltage drop on starting, causing in turn that labouring turning over that most people interpret as indicative of a bad battery.  Use corrosion-preventative terminal grease when you reassemble the battery connections.  (Your 8V reading could indicate a REALLY loose clamp!)

Check out the starter relay (contactor, actually) and the connections at the starting motor itself while you are at it.

In regard to the cooling system, there would be no time like the present to do a good general cooling system tuneup.  Provided you don't need a new radiator or - much worse - a new head gasket or anything like that, you likely will be investing only in a thermostat, flush solution, antifreeze, and rust inhibitor / water pump lubricant.  If any of the hoses are soft, replace them.  If the water pump bearing is noisy, you might want to trade in your core for a new - or quality rebuilt - unit; these are not pricey, even for my Mercedes diesel.

Your fuel gauge may have only a loose electrical connection powering it, or the 5V gauge voltage regulator could be intermittent, or a new tank sender unit might be needed.  The fine wire used in the rheostat used in most senders tends to wear out in time, from the float wiper passing oven it incessantly as the gas sloshes in the tank.

Make sure you don't have a tank or fuel line leak!  Leaks sometimes occur at the point where in-line filters are installed, often under the car.

How is the clutch?

Over the past couple of months, I have given some quite detailed answers on some of the points above.  Several deal with bad connection issues, and one recent one dealt with a regimen for doing the cooling system service.

Too, see about getting a shop manual, even one of the very general ones by Haynes.

Go to it, and let me know how it works out.

Cheers ... EGK

---------- FOLLOW-UP ----------

QUESTION: fist of all, thanks for all of the advice! i did replace the alternator before i got a response, which has fixed my charging/starting issue. it also fixed the fuel gauge. i'm going to replace the thermostat this afternoon and hope that it fixes my cooling problem. the car isn't leaking any fluids that i can notice.

the clutch is a little goofy going into first and second. when i press down on the clutch and shift into gear it shifts in nicely, but as i let up off of the clutch it tends to stick in a spot for just a second and then let up and go into gear.

thanks again for all of your help and your quick response. hopefully i'll have this fun little ride road ready soon!

-cory

Answer
Alternators themselves usually are pretty reliable, but they can suffer from reduced output if one or more diodes fail.  Grounding rotors can also cause some bizarre antics, ie: charge output is normal on start up and for light load, but becomes very unstable once the unit heats up.  When the rotor windings expand enough that they begin to short to ground, the regulator short-circuit protection starts cycling, and the alternator begins to output spiky raspy DC, with high transient peaks.  Nasty.

Replace that stat, but why not buy a can of rad flush and clean out the system while you are at.  Put in new antifreeze and a can of water-pump lube /rust inhibit and, if the hoses are okay, the system will be good for the next couple of years.

Time to throw out the throw-out bearing?  Maybe.

Good to hear it is all coming together!

Cheers ... EGK