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Sun May 31, 2009 12:24 pm

Hi all. Question. I recently installed a alternator on my 1600 DP buggy.
Well last night while driving and had some squealing, I stopped to adjust the tension on the belt , I grabbed the alt case, to lean on and burnt the hell out of my finger tips! I have done this before on my generator and never been burnt before. I have asked a friend and he said that alternators typically are hot to touch on any vehicle. I havent touched one after running on any vehicle before last night so I have no reference. Is this true? BTW, the pulley is not rubbing nor is the fan. This may be common knowledge to yall but im new at this do it yourself repairs and upgrades so any info is appreciated :D

Sun May 31, 2009 12:33 pm

Alternators get warm but they shouldnt get hot enough to burn you

Sun May 31, 2009 12:44 pm

The stock VW fanshroud system blows air through the alternator and generator. Not a lot, but a small amount, enough to cool it.

Operating normally, the alternator will be warm, but shouldn't be "hot". My alternator gets "hot" because I don't run a fanshroud with it. I also seem to cook them often because of it as well. If yours is getting "hot", I would be cautious, possibly be ready to replace it soon.

Sun May 31, 2009 12:45 pm

Well uh oh. It was hot for sure. I loosened up the belt this morning and that is when I was looking for grooves or gouging into either the pulley or alt case. There was no grinding noises when the belt was off. Should I place a shim between the inner half and alt case also just incase or is that going to chew up the case as well?

Sun May 31, 2009 11:23 pm

I would not put in a shim if it doesn't appear to be rubbing. I would actually smell the alternator to see if it is burning or shorting internally. I would think internal problems with it if it hot enough to burn you.

Mon Jun 01, 2009 5:28 am

thought i read here somewhere if the belt angle is off too much or too tight it can cause things to heat up...I know my genny got very hot to the touch but I just replaced the lower (wobbly) and belt but havent road tested yet.

Mon Jun 01, 2009 5:32 am

Thanks you sir for the advice. I was wondering if by me not changing the backing plate to a alt version could that cause the problem of being too hot? After work today I am going to run it for a few minutes without the battery connections to see what happens to the heat level afterwards. Then with it connected and start sniffing around. I would like to wish that it was a breaking in deal with a new alt, no name alt BTW. But it hasnt run longer than 5-10 minutes total since installed, maybe im being paranoid?

Thanks guys for the help! :D

Tue Jun 02, 2009 5:08 pm

Well I have checked the amps, its charging. I checked the volts while running. I am at 14V. I still need to check for AC, I tried but my meter must not be functioning correctly cause it showed no change. None. But its still running pretty darn warm to hot. Someone mentioned to me that the backing plate, or the one that rest inside the shroud , part of the mounting plate sandwich, should be positioned a particular way to help in cooling. I have it installed now. I swapped it so quick that I didnt notice the orientation. Can anyone tell me is this is so, that there is a particular way the backing plate should be mounted? Any pics of what am I looking for?

Tue Jun 02, 2009 5:35 pm

Correct orientation of original tin is with the internal vent pointing down, and the alternator in the correct clocked position.

Tue Jun 02, 2009 5:59 pm

what do you mean by check for AC?

Tue Jun 02, 2009 6:27 pm

Thanks Joe for that. Im not sure what the clock position should be, I know it looks similar to others but I honestly dont know how it lines up behind the scenes. Dang. Actually, double dang. I gotta try and figure out how to find that vent and rotate the backing plate.

AC.... apparently, if there is any AC or something like up to 40V in the line, that is a sign of a blown diode. I have DC though, so that has to be a good sign :-) Thanks for that info on the plate. I wish I would of paid more attention to the position before bolting it all up again. It is a little cramped n there and I got big fat hands :lol:

Mon Jul 27, 2009 7:28 am

I noticed the same thing just recently. On a recent trip to the desert, my engine was running a bit warm(230-240 oil), so when I stopped for a break I popped the decklid open. After a while, everything in the engine compartment was cooled off......except the alternator. There was almost no heat to the touch on the dipstick, the case, or anything else other than the Alternator.

That is why I searched for a thread about this. I wouldn't say the Alternator was burning the skin hot, but it was Hot in comparison to everything around it. Is this normal?

It seems to charge normal, work correctly, but I wonder how much of this extra heat it's generating is contributing to above normal temps with the decklid down.

Mon Jul 27, 2009 7:53 am

Augiedoggy wrote: what do you mean by check for AC?

Alternation Current.........

Alternator produce AC just like wall sockets.... BUT Alternators use a diode stack to change AC into DC and regulate it at approximately 14 volts output....

Dale

Mon Jul 27, 2009 10:17 pm

I'm wondering if all the windings in the Alt. just act as a heat sink and pick up heat from the engine compartment? Possibly a reason why the Alt. is still warm after everything else has cooled off.....

Fri Jul 31, 2009 4:48 am

mattt wrote: I noticed the same thing just recently. On a recent trip to the desert, my engine was running a bit warm(230-240 oil), so when I stopped for a break I popped the decklid open. After a while, everything in the engine compartment was cooled off......except the alternator. There was almost no heat to the touch on the dipstick, the case, or anything else other than the Alternator.

That is why I searched for a thread about this. I wouldn't say the Alternator was burning the skin hot, but it was Hot in comparison to everything around it. Is this normal?

It seems to charge normal, work correctly, but I wonder how much of this extra heat it's generating is contributing to above normal temps with the decklid down.
Just had the exact same scenario,the Alternator appeared to be charging fine when checked at the battery terminals,ie 14v,but it would get hotter than the engine.So I took it down to my local auto elec guy who tested it under load and guess what, it very quickly heated up on his bench rig so no heat soak from the engine.Diagnosis was a stuffed diode,cheaper to replace the whole alternator than to repair.It was a shit looking chrome one anyway 8)

Fri Jul 31, 2009 9:10 am

ozkombi234 wrote: mattt wrote: I noticed the same thing just recently. On a recent trip to the desert, my engine was running a bit warm(230-240 oil), so when I stopped for a break I popped the decklid open. After a while, everything in the engine compartment was cooled off......except the alternator. There was almost no heat to the touch on the dipstick, the case, or anything else other than the Alternator.

That is why I searched for a thread about this. I wouldn't say the Alternator was burning the skin hot, but it was Hot in comparison to everything around it. Is this normal?

It seems to charge normal, work correctly, but I wonder how much of this extra heat it's generating is contributing to above normal temps with the decklid down.
Just had the exact same scenario,the Alternator appeared to be charging fine when checked at the battery terminals,ie 14v,but it would get hotter than the engine.So I took it down to my local auto elec guy who tested it under load and guess what, it very quickly heated up on his bench rig so no heat soak from the engine.Diagnosis was a stuffed diode,cheaper to replace the whole alternator than to repair.It was a shit looking chrome one anyway 8)

Thanks...I should have mine checked for that as well. It is charging just fine according to the voltmeter on the dash. I wonder if I can find a shop locally that can diagnose a bad diode, but good alternator. Most of the typical auto parts stores here just do a basic check for charging or not charging.

Thu Oct 15, 2009 10:38 pm

Old Thread resurrection......anyone know of a shop in Socal that can check a VW Alternator for a bad diode?

I'm fresh out of ideas and haven't found anyone that can check a VW Alternator. The damn thing is still very hot to the touch after running.

It's hot enough that I think it is pre-heating the engine compartment air that is going into the fan, and cooling(or not) the engine oil and engine.

For reference, this a DTM shroud'd 2056 Type 4 engine which uses a T1 fan and Alt. on a custom stand with the shroud. Only other thing I'm thinking could be at play is that the DTM shroud may not have the correct vanes to send the cooling air thru the Alt. I have the backing plate with the inlet facing down as it would be on a T-1 shroud'd engine.

One other issue that is mostly taken care of is pulley alignment. When the engine was first put together the Alt. pulley was very much inside of the crank pulley. I believe this is caused by the original OPP Alt. stand. To correct this mis-alignment I installed a shim behind the Alt. pulley which moved the pulley out more or less in line with the crank pulley. I've read about a supposed pulley out there with more offset for this type of T-4 setup, but have never located said piece.

If the pulley alignment is just a small tad off, would it still cause overheating of the Alternator?

Thu Oct 22, 2009 10:52 am

Well, I had the Alternator checked at Autozone. They wheeled their test cart out to the car and hooked up to the battery. The Alternator tested good according to the test cart....however, I noticed during the test procedure that the voltage would occasionally drop into the 10-11V range for a second or 2. I'm guessing that was a load test of sorts, but it still surprised me to see the voltage drop into the 10's. Problem????

At the conclusion of the test, the cart flashed on it's screen "Diode pack is good."

It's still hot to the touch after running for more than 5 minutes. Could a very slight belt mis-alignment cause the Alternator to heat up enough to burn your hand?

Thu May 27, 2010 3:45 pm

Eaallred wrote: The stock VW fanshroud system blows air through the alternator and generator. Not a lot, but a small amount, enough to cool it. Reviving this old thread...

My alternator runs pretty hot too - hotter than the surrounding case. I've got a Raby TIV with a DTM shroud and there doesn't seem to be any special catch to blow air through the alternator. The alternator that Jake put on in '06 just failed and I'm thinking the heat may have contributed to it.

Has anyone tried one of these pulleys?

http://www2.cip1.com/ProductDetails.asp?ProductCode=C24-040-903-109

It looks like it would draw air through the alternator and maybe keep it cooler. Cheaper than a new alt.

Tue Jul 06, 2010 5:27 pm

Has anyone solved the hot alternator issue? Mine's still hot and still workin....