Canadianc5ns

Question re alternator heating up. Just how hot does your alternator get? Mine gets so hot can't touch. Recently had an intermittent problem with gauges showing alternator wasn't charging however had it bench tested and ok. I realize bracket for alternator is attached to the block so must get some heat transfer. Does anyone with another C5 2000 want to start your car and check the heat? Thanks guys and gals.

Bill Curlee

You can check the charging voltage by measuring the battery terminal and measuring the BATT terminal on the back of the alternator to chassis ground.

You need to go to a shop to have the charge current tested . If the output is normal, I wouldn't much worry about it.

Can you use a inferred thermometer and get the exact temp?

Bill

martysauto

If you have a stock thermostat and fan settings, everything under the hood is going to get hot to the touch!

lionelhutz

The insulation used in the alternator is probably safe for over 125*C operation. It's not running hot when just because you can't hold your hand on it.

Canadianc5ns

Thank you all for your input. I have measured the voltage at the battery and it runs between 13.5 to 14.2 with car running which I understand is normal. I shall see if I can get the temp of the alternator housing.

dadaroo

If you do decide you have an issue with alternator, DO NOT turn in your core until you have a good functioning replacement. The C5 ones are unique and have an interface with the PCM.

Many people have had replacement issues and ended up rebuilding their originals.

dankhts

alternators get pretty hot, the more juice they need to produce then the hotter they get.... too hot to put your hand on one after it's been running a while....

Canadianc5ns

Again thanks for the input. A couple of questions.

1. Took the car into dealer. They did a charge system check. Told me the battery cracking power failed, 400 instead of 800. Sold me a new battery. It's still not right. I had changed the voltage regulator on the alternator but got low readings on gauge in car, 12.5 to 13.1. So we decided to put back the original voltage regulator.

2. I measure the voltage at the battery with car idling and it is 13.9v then I measure the large red wire at the alternator to ground and I get 15.01 v. Is that too high?

It seems the output from the alternator is at least 1 volt more than at the battery and yet they are directly connected thru the starter. Any comments are appreciated.

Richard

lionelhutz

Clean the connections at the solenoid.

Canadianc5ns

I did a voltage drop test between the alternator B+ and the + side of the battery. Voltage drop of 1.4 volts with heavy load, lights, radio, heat, and revs at 2000. I've read that should only be .2 or .3 at most. So the only connection between those 2 points is indeed the connection at the solenoid. I shall have the dealer put it up on a hoist and check it out.

R

lionelhutz

If you're paying to get it checked, also clean the connection on the back of the alternator and check fusible link on the end of the alternator wire at the solenoid and check the battery cable out too to ensure that the wires look OK.

My car started to show voltage drops like that and it was the solenoid connections. Now I have 14.2-14.3V at the battery all the time.

Canadianc5ns

Had the car on the hoist at the dealer and the connection on the solenoid was indeed loose. Cleaned it and after tightening, all is well. 14.2 volts, voltage drop is now .3 volts. Hopefully that's a wrap.

One question however. Does the red wire from the alternator go to the solenoid and from there to the battery? That's what I understood however in the schematic there is a dotted line after the fusible link to the starter. Tech told me the wire from the alternator goes directly to the battery. Can't be so.

lionelhutz

The solenoid is the junction point. The tech is wrong.

martysauto

Probably the same tech that sold him the battery. He never checked voltage at the alternator or did the voltage drop test. It's pretty bad when the customer has to tell them how to fix their car.

Bill Curlee

The DOTTED LINES indicate the weird color wire that comes off the end of the fuse/ If you look at the connection on the solenoid, its NOT a red wire. See picture The dotted line is that different color wire coming off the fuse link





You CAN run a wire directly fron the alternator to the battery but it needs to be fused and you would also need to run a feed back wire to the battery.