Strange voltage drops and swings.

[Don Holg]

Background: I’ve been having weird starter issues. The starter was grinding when cold out so I put a new one in, still grinding. Had battery load tested and readout said OK.

New thing: If I check the voltage at the battery posts I get 12.4 volts. However, if I check the voltage at the starter solenoid post or even just on the battery cable near the battery post, I get a wide range of voltage readings. It will swing from 3 volts to 9 volts in the space for a few second, then swing back to around 3.

Any idea on where to look for where the volts are going?

Topic

[college man]

check out this link on voltage drop testing.

http://www.ericthecarguy.com/faq/solving-automotive-electrical-problems

[Tom]

You could have a loose or bad connection. I would examine the battery terminals, and battery cables / ends very carefully. Clean, tighten, replace as necessary, and re-check voltages.

[Don Holg]

I tried that test and was only showing 0.25 amps of draw. I assumed that wouldn’t be enough to cause a problem.

[Kevin Criswell]

.25 Amps? A starter should be drawing between 100 and 150 Amps, not a quarter of an amp.

Try these tests.
http://easyautodiagnostics.com/bad_starter_test/starter_oncar_tests_1.php

[EricTheCarGuy]

When you say ‘grinding when cold’ I’m wondering if this is a GM product. It may have nothing to do with a voltage drop if that’s the case. Some GM starters need to be shimmed to work properly. Here’s a video.

[Don Holg]

It’s a 2003 PT cruiser non-turbo. The old starter wasn’t shimmed so I didn’t shim the replacement.

Some more research has led to me think its more of a whirring that a grinding. The teeth are sticking to the flywheel and that’s causing the starter to keep spinning post-crank. But it doesn’t sound like anything breaking. I recorded the sound, I’ll try and post it tomorrow. Thanks.

[EricTheCarGuy]

It might be the installation, or the starter itself might be defective. You might want to remove and inspect the contact pattern on the drive gear.

[Don Holg]

New theory.

It’s not the starter at all. It’s the power steering pump. I had the pressure hose to the rack replaced during the summer and my mechanic put some stop leak in to keep me from having to replace the rack, which had a small leak. But the stop leak stuff often gets thicker when it’s cold and it’s really cold here. -25 celcius right now. I’m in Canada. So the pump is freaking out and being noisy because the fluid is way thicker than it should be til the car heats up.

I knew it had to be something to do with freezing because the colder it got the worse the noise was and the less time it could sit before making the noise again.

Too cold to work in my unheated garage, I’m taking the car to my mechanic next week for some suspension stuff and I’ll get him to look at it.

Eric: If you read this… here’s a video you could do. How to turn an unheated garage into a place you could actually work in the winter.

Thanks.

[EricTheCarGuy]

My garages, both old and new, are not heated. I just dress warm and use space heaters.

Thanks for the update. Let us know if your theory changes.

[Author]

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