Club 80-90 Forums

So the alternator failed 1 week before we were due to go away. The new alternator has been fitted but a new belt was needed fine.

However while trying to tighten the belt up my mech friend noted the the alternator was burning hot.....

After a spell of high price replacement parts I am very close to giving up and buying a tent.

Oh I go away on Wednesday hurrah. A borrowed tent it may well be.

sorry for anguished rant

New alternator or second hand?
Very hot implies bearings are shot but it will get very hot in this weather after a run
opened my car bonnet after an hours run home tonight and it was like an oven
so need to get a temperature reading really ?
Is it charging ok?

Im guessing diesel from your posts but get your van in your sig would help?

what was wrong with the old alt? Still got it?

It is a new alternator rather than second hand.

The old one's bearings went after an adventure in France resulted in a new belt which was too short (but did get me home) being fitted.

The van is a 1.7 diesel.

It is getting hot very quickly, it should be noted that the battery is flat due to the previous alternator not doing the job.

I am running a split charge system could a fault in this be responsible?

Regards

Simon

As additional detail by hot I mean burning hot and due to the brief run time hotter than the engine block

Disconnect the alternator from the battery and run the engine.
If it stays cool you have a dead short or a dead battery

Alternators get hot when they are working that's why they have their own fan to keep them cool. The harder they are working the and the slower they are turning the hotter they get. Without us knowing what you where doing before you checked it it could just be normal or a fault with it.

kevtherev wrote:Disconnect the alternator from the battery and run the engine.

Good idea, but would it even start with a dead short or dead batt

itchyfeet wrote:

kevtherev wrote:Disconnect the alternator from the battery and run the engine.

Good idea, but would it even start with a dead short or dead batt

The battery is also new this year (I seem to be throwing good money after bad)

After running the van for a bit the batt does seem to hold enough residual charge to restart the engine.

When charging from the alternator I was getting approx 13V

If this info is of any use

bigherb wrote:Alternators get hot when they are working that's why they have their own fan to keep them cool. The harder they are working the and the slower they are turning the hotter they get. Without us knowing what you where doing before you checked it it could just be normal or a fault with it.

I was simply testing to see if the belt was tight enough so stationary with some enthusiastic revving.

Kevs idea is the right one, disconnect it electrically and it will prove if its mechanical or electrical heat being generated
need to insulate connections

Si_P wrote: It is getting hot very quickly, it should be noted that the battery is flat due to the previous alternator not doing the job.

Simon

Then that is most likely why.


And never run an alternator with the battery disconnected the diodes don't like it.

bigherb wrote:

Si_P wrote: It is getting hot very quickly, it should be noted that the battery is flat due to the previous alternator not doing the job.

Simon

Then that is most likely why.


And never run an alternator with the battery disconnected the diodes don't like it.

I appreciate it would get hot during big charge moments but burning hot? Is that really normal!!

Yes alternators can run over 70 deg

bigherb wrote:Yes alternators can run over 70 deg

As bizarre as this may sound that information has restored a little hope in me.

After a long line of 'issues' I thought this would be another nail biter.

I'll run some more checks (with a more car savvy mate) with any luck we will get the all clear.

Thank you all for your help so far.