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-   -   Can't find the problem. What would you do? Replace VR? (http://forums.pelicanparts.com/porsche-911-technical-forum/796824-cant-find-problem-what-would-you-do-replace-vr.html)

tirwin 02-25-2014 06:26 AM
Quote:
Originally Posted by T77911S (Post 7930049)
i dont know if i am being to critical of your description, but it does not sound like a "spike". your problem makes me think of a bad solder joint. maybe something internal to the VR or a soldered wire or diode (dont know if one diode would do this) that may be dropping the voltage perhaps due to vibration. thats why i would swap out the entire alt/VR. (my VR has a broken brush.).
I just don't see how a voltage drop would cause the parking brake light to randomly come on. That seems like a spike to me. Maybe I'm missing something though. Either way if it is something like a bad diode or solder in the VR I would've expected (hoped?) that it would show up on a bench test but it did not.

Quote:
Originally Posted by T77911S (Post 7930049)
testing resistance with a meter does not really give you a definitive result. the meter does not provide enough current to really test the connection. i have seen this problem on pelican several times:
someone has a light that does not light. they check it with a MM and all is good. they tare the car apart trying to find the answer. turns out to be a connection that is good enough for the meter to show as good but not good enough to pass the current required to light the light bulb.
(this is why i use a test light for electrical work).
That's exactly what I'm thinking. Maybe it's just worth the cost of a new ground strap. It's a braided wire. Lots of surface area for corrosion. Electricity will follow the path of least resistance and if there is a lower resistance path available...

tirwin 02-25-2014 06:37 AM
Quote:
Originally Posted by timmy2 (Post 7929700)
Hi Tim,
You can order parts and replace with possibly good results. Or, you can test and make sure you find the problem. (I'm naturally cheap at heart and starting to sound like Tony...):)

To test your engine ground strap for resistance just connect the DVM to the end it is attached to on the Alternator and the other probe to the case of the engine near where it is bolted on. You should scratch the probe into the metal a little to get past any gunk and oxidation of the engine case. Should be very low reading basically the same as when the 2 probes are touched together, maybe 1 ohm at most.

To clean the 14 pin female connector sockets, a bit of vinegar on a Q-tip should remove any oxidation. Rinse clean with water. Try spreading the male contact pins with a razor blade. They have an X pattern that can be slightly (gently) spread out. Apply a little no-ox to the posts and the connection should be good for a while.

Then check the blue excitation wire to eliminate it as a problem.
I'm right there with you! I'd rather save that scratch for the suspension refresh or new A/C! Spending money on an alternator/VR is not my idea of fun.

The reason I started this post was I could just buy a new VR but if the problems come back (after I go through the wiring of course) then I've got a new VR that I can't use because the only thing left is to replace the alternator. I'm hoping to get back to it tonight. Will keep you posted on the progress.

Think I'm going to take this as a chance to go through and do some other work. I replaced the rear fuse panel and cleaned up all those connections already. I bought one of Fred Cook's front fuse panels but haven't installed it yet. Think I'll do that too. There should be no chance of poor grounds when I'm done!

porwolf 02-25-2014 01:25 PM
As mentioned before on my Landcruiser that has a standard dashboard voltage meter I found that very useful to monitor my battery charging situation constantly. When my charging was weak I could see the battery voltage drop substantially below the normal 13.8V. Sometimes with headlights on It dropped to almost 12V. After the car heated up sometimes the voltage was back to 13.8V sometimes not. It always happened here in the "winter season" in Southern California, never in the summer. Some times I had to recharge the battery with a charger. I am not absolutely sure that another reason was not a slipping belt. I changed that and tightened it. So far not a problem anymore. So, I don't know whether it was the VR or a slipping drive belt, or both. Anyway the fix was cheap. Hope it holds up. Now I want install a voltage meter in my '79SC" together with a CIS pressure meter on the center console. I like to see what is going on all the time.

tirwin 03-09-2014 09:13 PM
Time for an update. I sent off the fan and housing to Mark Motshagen to powder coat it while I had it out of the car. I'm taking the opportunity to do some other work during the downtime. I started taking a closer look at the alternator. No obvious issues with any diodes or the windings. However, I did find a place on the positive side where the wiring looks like it is flaking (possible charring?) and there is definitely some corrosion.

Here is a couple of pics. Sorry if the quality is not good. It is hard to take a pic of this area. Is this a potential concern? If so what should I do about it? Seems odd because the alternator itself doesn't seem that old.

Appreciate the help...

http://forums.pelicanparts.com/uploa...1394428338.jpg

http://forums.pelicanparts.com/uploa...1394428357.jpg

tirwin 03-10-2014 04:12 PM
Last night I posted the above update and I got a smart-alecky response from what I suspect was a spammer. Looks like that response got deleted by a mod so I'm not sure if people saw my update and follow-up question. If anyone has an opinion on whether the above would cause a problem I would appreciate it so I can figure out the next step.

rusnak 03-10-2014 04:29 PM
I don't know if a visual check of the alternator is the way to go. Can you take it in to an alternator shop and have it tested under load? We call that smart alecky spammer "Loren". So you can now address him by name.

If the alternator checks out, then you may have a bad ignition switch. The radio acting weird, windows, car won't shut off, etc etc are all symptoms of that too.

tirwin 03-10-2014 04:35 PM
Nah. It wasn't Loren. It was garbled list of letters guy.

I have already taken it to a shop but they didn't find anything. It was recommended that I do a visual inspection. That was the only thing I turned up.

schulr 03-25-2015 02:49 PM
Tim, what was the outcome of your alternator problems? I'm having issues with mine again with an intermittent voltage change, charging to no charging. I have a post going on this.

Bob

tirwin 03-25-2015 03:52 PM
Quote:
Originally Posted by schulr (Post 8547211)
Tim, what was the outcome of your alternator problems? I'm having issues with mine again with an intermittent voltage change, charging to no charging. I have a post going on this.

Bob
Hey, Bob!

Long time, no see!

Short version: took my old alternator to local repair shop. They said it bench tested fine. All symptoms pointed to a failing VR or alternator diodes though. Problem was, if I bought just the VR and the problem was still the alternator then I have to buy a new alternator (that comes with a new VR) or find another shop that can rebuild the alternator PLUS I would have to R&R the alternator AGAIN.

So I ended up buying a new Valeo. There is a guy that sells them on Amazon for a reasonable price. Installed the new one and the problem went away.

schulr 03-26-2015 05:23 AM
Tim, can u send me the link for the Amazon guy? I have not been able to locate a new one incl with our host. They say they r back ordered with no time est. I ended up with a rebuilt Bosch which was supposed to incl rewinding and all the other stuff so in theory it should be good as new....but I'm having issues. Is your ride back together yet? Porsche gathering this Sunday at that warehouse.

tirwin 03-26-2015 06:03 AM
Ok I went back in my Amazon order history and it says "sold by Amazon LLC" -- not sure that helps.

The part number is W0133-1597770-VAL

I'm not sure you can use the same Valeo in your '87 though.

Engine is still sitting on my garage floor BUT I am now making steady progress. Getting closer every day!

T77911S 03-26-2015 08:43 AM
i see the new alt fixed it???

those solder joints look ok. you want to look for small cracks or lines in the joints.
i am going to contradict myself here. yes, hot spots are a sign of resistance and a lot of current making it hot, but with the alt, i dont think this is any problem because they all pretty much do that. they can also burn like that do to a lot of current period, then add in the heat already being generated.

i would really lean towards a diode as your problem. as it get hot is stops working like it should.

a lot of the ILS guys here at work have to trouble shoot with freeze spray or a heat gun.

grizzfan 03-26-2015 09:13 AM
I don't know where this thread has been! Glad you found happiness!! Very interesting.

I have had similar problems for forever and finally pulled my alternator, housing and fan. At everyone's urging I had the alternator rebuilt. Found these guys (Pelicans) in Zanesville, OH - Sagle Auto Electric - who replaced diodes, rectifier, bearing and brushes for peanuts! Very happy. Beautiful work. But can't put everything back as the housing and fan are with Motshagen in California for ceramic coating.

I will have to replace my VR as it's a Bosch and the Alternator is a Marshal-SEV. Remember this engine decal:

http://forums.pelicanparts.com/uploa...1427389935.jpg

Tom

tirwin 03-26-2015 09:41 AM
Bob resurrected my old thread and I'm glad he did. I hate it when people never follow up with their solution and I was guilty myself!

I think the takeaways are:

(1) intermittent failures are sometimes hard to find

(2) finding competent testers/rebuilders may be an issue

tirwin 03-26-2015 09:49 AM
Bob, you asked about the engine... Here's how it looks as of last night.

http://forums.pelicanparts.com/uploa...1427392179.jpg

schulr 03-26-2015 10:12 AM
That looks fantastic Tim, will even look better installed. My issue is going to the shop today, jack Lewis. I'll let u know the outcome but it's pointing to the Alt/VR again. At least I have a warrenty for the replacement. Battery checked out fine which is too bad. Would have been less costly.

grizzfan 03-26-2015 11:52 AM
Tim,

There ought to be a law about having an engine that looks that beautiful. Motshegen warned me about making the fan/alternator housing look too blingey, particularly if the rest of the compartment looks like a chicken coop!

Tom

tirwin 03-26-2015 12:10 PM
Like someone walking blindfolded into a field of land mines, I somehow manage to find ALL the slippery slopes. :)

schulr 04-03-2015 03:48 PM
Tim, fixed mine now by replacing the rebuilt Bosch that was causing the trouble with a new velao which is OEM. My mechanic found a new one from one of his contacts as our host and everyone else I checked with had them on back order. All is in order now.

tirwin 04-03-2015 03:59 PM
Quote:
Tim, fixed mine now by replacing the rebuilt Bosch that was causing the trouble with a new velao which is OEM. My mechanic found a new one from one of his contacts as our host and everyone else I checked with had them on back order. All is in order now.
Glad to hear you got it resolved!


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