Recently my 87 wouldn't start and was dead. I tried jump starting to no avail. I took the battery in for an exchange and noticed the voltage was reading 31.2 to 13.4. I then decided to exchange the alternator as well since I had receipts for both. It was fine for the 1st day then after that it wouldn't start the following day. The vette had to be jumpstarted and I took the car back to the auto store in which they tested it. It showed the battery was good but low on charge. Under no load it tested at 13.70 and under load tested at 13.69. Overall it tested out as no problems. The alternator was hot to touch as well. I then went back inside and asked to exchange for another alternator in case it was defective and none was in stock at least until tmw. I went back to my car and it wouldn't start until I tried to jump start it with my truck. It didn't work at that time and I had the guy come back out to do another testing. Before he tested it I was able to start it ok. So what could be the problem? I have a new alternator coming tmw and I plan to get the battery either charged or replaced again at the same time. I used to have a trickel charger when I was renting a house with a garage, but right now I live in an apt and have no place to do so. The guy also mentioned the starter but I disagreed. Any thoughts?

 

You're saying the engine won't turn over, correct? Turn the ignition key to start and the starter probably just clicks? The battery is new and jumping it doesn't help?

If I have all that right, I'd be looking at the starter and battery cables for a problem.

 

The car wont turn over at all unless I have the jumper cables attached to it. Even with that.. it doesn't even try to crank in the beginning stages. After a few minutes it will start to turn over till it is successful. Doesn't sound like a starter to me?

 

Your second description sounds more like a dead battery.

 

Keep in mind that a fully charged 12 volt batt will read approx 14.0 volts. So with that said, when car was running did you have the opportunity to check the charging rate? Next question, when you jumped the car to crank did you have the negative jumper cable connected to your batt or the car chassis? Reason for asking this is possibly you have a ground problem with the car's neg cable. If you suspect the "new" batt might be bad, insist to have the parts store swap it for a new one. Just be sure it's got a full charge. Can't rule out the starter completely, but these are a few things to look at first. I noticed your in Lawrenceville. There is a good automotive electrical shop on Hurrican Shoals road that has been in business for many years. I'm sure they could do a load test on the starter. Good luck

Joel

 

31.2 volts? That is impossible!!!!!!!!!!!!!!!!!!!! And so is 13.7 volts (engine off). The maximum sustainable voltage in a lead acid battery is 13.2 volts.
Measure the battery terminal voltage with the ign switch held in the crank position. It should not be below 9.0 volts or you have a discharged battery, poor battery cable connections, or a battery at the end of its life (no matter how old the battery is). You can tell the state of charge of a car battery by measuring its no load voltage at the battery terminals, 12.0 volts and below, discharged. 12.9 volts and above (to 13.2 v) fully charged and linear in between.
I would remove the battery cables (neg first) and clean the cable lugs, battery posts, bolts, and replace the cables (neg last). Then measure the battery voltage under no load and determine its state of charge. If discharged, charge up overnight with a battery charger. Measure the battery voltage while attempting a crank and if below 9.0 volts, replace the battery.
Alternators are normally hot, but if you cannot keep your fingers on it, then you might have a battery with a shorted cell and the alternator puts out maximum current trying to charge up the battery. This will make the alternator very hot, too hot to touch. Alternator cold, engine running, the battery voltage will be 14.7 volts, and alternator at normal operating temperature, the battery voltage will be 13.7 volts, this is normal. Voltages are measured at the battery posts. Your dash voltmeter will read about 0.3 volts lower than the battery post voltage.

 

I will look into this... I also forgot to mention that the new alternator I put on makes a whining/whistling sound. Sounds as if the bearings are shot? I didn't like the sound of it and I'm picking up a new one today.

 

Thanks... I might stop by there sometime soon.

 

None of these auto parts houses have new alternators for your car anymore. I have an 86 and run into the same problem. I am on my third alternator this summer. The last one lasted about two months. I just came apart inside, broken pieces everywhere.

Good luck with those rebuilt alternators.

 

Not true...AutoZone carries NEW, bought one for my 87.

 

Anyhow I just had the alternator replaced again since the bearings were making a high pitch whistling sound that didn't sound good. Once that was in, the car started up and ran fine for a while. The battery voltage would read 14.0 . Then it would go all over the place from 12.1 to 13.2-13.4 I then let her sit for a day and came back out this morning and the car is dead. No power or anything. So I come back inside the apt with the battery and hooked it to the trickle charger to see if it needed to be charged. It then showed fully charged. I don't get it. Do I have some other kind of bigger electrical problems going on? I didn't start having problems until after the bad rain we got a few weeks ago from the storm and found an inch of water on the drivers side floor. The car is now covered outside and hasn't gotten wet since then. I also had a power seat issue in which I posted in another link.. .http://forums.corvetteforum.com/show...258&highlight=

The power seats are working intermittently from time ot time now. I guess I need to check the ground on this thing under the drivers seat to see if its pulling volts from my battery? DOesn't make sense though since it shows its fully charged.

 

Have you checked for a current drain? Disconnect the negative battery cable and place a volt-ohm meter in line between the cable and the battery terminal. Use the mA setting on the VOM and see what the readout says. Post that here.

It's possible that a relay for the seat motor is sticking open allowing the battry to lose voltage. The harness connector for the driver's seat motor sits flat on the carpeting and it's possible there is a short from the water. The motor sits up an inch or so off the carpet but it's also possible that it may have gotten wet inside.

One qucik test you can do is to remove the seat base cushion and disconnect the motor at the harness connector (make sure the seat is where you want it!). Charge the battery if necessary and see if the car start in the morning.

Also if your battery is discharging to where nothing works, you may need to have the battery charged using a professional-type charger that will output 20-40 amps. This will give you a full charge where a trickle charger can take over 24 hours to bring the battery up to close to a full charge.

I would also suggest that you take the car to a reputable auto repair facility to have the battery and alternator tested as a system. A shop will have testing equipment that will load test the battery and also test alternator output when the motor is running. Doing that will save you trips to a parts store swapping out pieces.

Don't know what kind of battery you are buying, but if you do need another battery, go with a quality battery not something you get from chain parts stores. Look at an AC Delco Professional Grade (sold at auto repair shops, they are different from the ones you see at retail stores), Interstate, or even a Sears DieHard Gold for your application (Group 75).

I would avoid an Optima battery at this point until you solve the discharge problems. Batteries like the Optima require a special re-charge process and a trickle charger will do more harm than good.

 

My 86 Vette was doing exactly the same thing a few years ago. Turned out to be a bad starter. I replaced the starter and it has been just fine every since.

FYI -

 

starter....that was my exact thought.

 

What would a starter have to do with no power at all in the car?

 

Anyhow.. I left the trickle charger hooked up to the battery most of the afternoon and when I thought it was fully charged due to the light.. it later went to charging mode. I didn't want to wait till tmw for it to charge so I took it to the auto store and they charged it fully. It tested good. I then came home and removed the circuit breaker for the power seats and unplugged the one wire coming from under the rug under the seat. The car cranked up on 1st time with no hesitation. It showed 14-14.2 volts on the dash then later went down to 13.7 mostly at idle. When I put the AC on at idle it dropped to 13.2 to 13.5. I took it for a spin and it stayed mostly at 13.7 with the AC off. I'm going to wait till morning to see if it starts up and has power. I'm hoping it does. Will post back tmw.

 

She fired right up this morning! Idles good and voltage reads 13.7. Now what would it take to fix my power seat that seems to be shorting out the circuit breaker on and off? Do I just leave it unplugged for a while and let it dry out or does something else need to be done?

 

If the motor itself is wet, that can cause short-circuiting and may have even killed the relay. It's easy enough to leave the harness unplugged, but it's also easy to remove the seat and dry everything out.

With the seat base out, you will find 4 bolts that hold the plastic seat base to the metal frame. Remove the bolts and the base and seat back can be removed from the car. Then remove the plastic caps from the front of the seat frame horns (you need to pull out the plastic pop rivet) and then remove the 4 nuts that hold the seat frame to the floor.

Place a lamp like a drop cord or similar with a 100w bulb over the motor and let it sit there for a day. That should be enough heat to evaporate any moisture inside the motor. Re-install the seat and see what happens.

If it turns out that the motor has internally shorted from the water, you may have to find a replacement seat base. I don't think the motor is easily rebuildable and they could be hard to find as a replacement.

After looking at my 87 FSM Electrical Diagnosis manual, it looks like there is no relay for the seat motors. Power for the seats comes from the fuse block to the switch assemblies in the console and down to the seat motors. There are actually 3 motors in a single assembly and they operate based on which console switch is used.

I would let everything dry out and re-install the seat frame and connect the harness. Then use a VOM to measure any current drain at the battery to see if there is an excessive drain somewhere. With the VOM connected as I described earlier, remove the Power Accessory circuit breaker from the fuse panel. It will be on the right at the bottom (next to the cruise sontrol fuse. If the resistance value in Ohms drops off when you remove the breaker, then there is a problem in the harness for the power seat. I would still suspect the motor itself or the harness connector. It's possible that moisture in the car may have affected the power seat switches but I would try checking with a VOM and drying out the motor first.

 

 

Well guys.. I haven't gotten the chance to do anything yet to the car. However I did let the vette sit for a few days without driving. However today the car has no power again. I'm back to where I started. Something else must be causing this then. I'm hoping to get my hands on a Volt meter this weekend. Then I will post the reading after I get the damn battery charged again. Just my luck.