2001 GTi mpem replaced, but new questions about rectifier/stator

[MacAddict]

Hey guys... Had some issues with my GTi, which turned out to be a smoked mPEM. In troubleshooting that, all grounds and positive leads were checked and refined with nonconductive grease. Also replaced the post.

But... now that I got it running again, I decided to test the Rectifier, wondering if that was maybe the culprit for frying the MPEM. Well, as it turns out, the rectifier is only returning 12.6-12.9 volts, which that in of itself points to there being a problem. But the thing I noticed was that the voltage drops out at random... Doesn't spike, but rather drops out... goes as low as 1.5 volts, just for a split second... then right back to 12.6-12.9v... (yes - my connection to the voltage tester is solid) Has anyone seen/heard of this, and could the lack of voltage have caused the old mpem to blow up? (I know with like car speakers, you will blow them faster by under-powering them versus over-powering them, and thought the same principle might apply)

I guess my 2nd question is that through the research I've done on rectifiers, is that the stator can be the culprit for the rectifier going bad. But should I first start with a new rectifier, ($40) and see if there's still voltage drops, then pursue the stator? or the other way around? Pulling the stator sounds like a real project, as you have to pull the flywheel, etc. and I don't know if a new rectifier might solve things temporarily, but then burn up in a year (and potentially burning me new MPEM) because of a bad stator. Just don't want to have to revisit this again in a year....

Thanks for your help! Here's all that I have done to it so far to get this thing rolling:

• Rebuilt carburetor with new gaskets/seals/orings
• Tested and verified POP off
• Replaced fuel lines
• Replaced motor mounts
• Cleaned fuel system top to bottom
• Total top end rebuild, due to previous owner f@$&ing things up by putting pistons In backwards, and rings snapping off on exhaust port, then jamming against head. (Cylinders bored and honed, head ground and repolished, ports chamfered) Went up .5mm oversize
• Clipped cable and re-did copper fittings @ end of positive and negative cables with ncg and shrink tube

 

[Bills86e]

If you remove the Magnito cover you will need to replace the cover gasket, and grease the screws or anti-seize. It takes three 4" long x 8mm by 1.25 thread pitch metric bolts screwed into flywheel only 1/4" (or you'll be into the coils behind it) to pull the flywheel useing an automotive three slotted harmonic balancer puller. Correct Torque is what melds the two parts from slipping. All Bolts torque are specified in your Shop Manual. Very Important to consult that. A woodruff keyway is for locating the flywheel to the crankshaft position only. Correct Torque is what melds the two parts from slipping. All Bolts torque are specified in your Shop Manual. Very Important to consult that. Once you get in there look for any discolorization on the coils and remove any cat-hair whisker metal particle bits. They can create electrical havok to the rectifier & mpem. If your looking to test the magneto and regulator/rectifier..........all you need to do is have a cheap, digital multi tester.

Bills86e

 

[MacAddict]

Thanks Bill... was hoping that I wasn't going to need to go that route... at least not until after finishing the season in 2 weeks in the Keys with my two skis. Then I can take a couple months over winter and check this stuff out right, and pull flywheels from both, etc.

I've got a halfway decent multitester that can test amps up to 10 amps, as I read that you can test the amperage, which should be about 7 amps. But I was trying to figure out how to hook it up to read the amps flowing through. Can't possibly disconnect the negative cable and use this little multitester as bridge to battery. I suppose I could go get a full on load tester over at harbor freight that would handle being a bridge, but was wondering if there were other tests I could run to tell me if it was the stator or the rectifier, or both. (other than voltage @ battery) Like I said in my post... from what I read, the stator can cause the rectifier to crap out.

Thanks for your detailed post though. When I go the route of pulling the flywheel, I will definitely pay close attention to torque and bolt length. :thumbsup:

 

[Minnetonka4me]

A good puller is key.... unfortunately I dont have much to add than that. Your test seems to indicate that the charging coil isnt working.

One thing though that I didnt read...you have to Rev your motor up to 4-5000 RPM to see the voltage go up.

I have a few used stators in stock for $75.