Alternator Temperature?

[Matthew Jeschke]

This is kind of off the wall. My alternator performs perfectly, however, it's old and I'm always concerned about it...

I JUST finished upgrading to Yella Terra shaft roller rockers. I fired the engine up and was listening to the lifters with a mechanic's stethoscope when I touched the alternator. It burnt me! I don't think I had the engine running more than 5 minutes. I got out my laser thermometer gun and it told me the alternator was 140F.

Is that normal? It makes no noises and voltages are all right in spec.

 

[Doubeleive]

140 doesn't seem all that hot to me, if I remember I will check mine tomorrow
if my memory is correct I think I checked under the hood temperatures in various places before after I had been driving and I think it was over or around 200deg but i could be mistaken, if coolant temp is around there then engine components are going to be that or more.

 

[OR VietVet]

Agree with @Doubeleive, and think 140 degrees is ok. Where on the alternator did you check? At the middle front where the internal fan is or at the center back where that bearing is?

 

[exp500]

Aim at the Diode heat sinks, That's where the work gets done.

 

[Matthew Jeschke]

I checked on the case... The aluminum front half by above the pulley. Good to know they get hot like that. Was just shocked, I'm over thinking things. I'm simply amazed, some of these parts are still original on my truck at 255,000 miles. GM did a AWESOME job of sourcing quality parts to build these. Wish I could say same of interior.

On topic of engine bay temps. I've been kind of kicking around idea of headers. Kind of wonder how they affect (1) valve temperatures at head and (2) engine bay temperatures.

 

[SnowDrifter]

Yeah 140 is fine. Operating range for an alternator exceeds the operating range for the human body
Back in my audio days, we'd get alternators so hot you could sizzle water on them. Had fans set up to blow cool air over them

The windings are generally rated >150c and diodes >180c

 

[Matthew Jeschke]

Wow, it all makes since now Crazy stuff!

 

[Doubeleive]

alternator after a little drive 194, that was about the hottest thing aside from the exhaust manifolds 300

 

[Matthew Jeschke]

@Doubeleive wow thanks for taking those pictures! I really appreciate it.