On a recent trip to visit my brother in another state, my 2004 Tahoe with 216K decided to stop starting. Battery is new, Tahoe made the standard single click noise when trying to start. I purchased a starter from local parts store, put starter on with no real issues. However, now with the new starter Tahoe seems sluggish to start. It starts but seems like starter isn’t quite strong enough to start Tahoe. This is my wife’s daily driver so obviously she’s worried so I figured I’d ask the question. Why would a new starter act sluggish like this. It always starts but it’s noticeable even to me. Thanks in advance.
Slow cranking could be low battery, corroded battery connections or you just got a bad starter.
A voltmeter will likely tell you which. The battery should be over 12.3 volts just sitting there not running. Once started you should see 13.5 to 15 or so volts coming from the alternator. Check the voltage at the starter, engine off and see how close it is to the battery voltage… hint: it should be the same! Check the battery ground, too. The resistance should be pretty close to zero ohms. If all that checks out, its probably the starter.
I can think of a few reasons:
- (almost) bad starter, especially if rebuild and not new
- poor terminal contacts, loose or corroded
- battery on its last leg
The problem might be with the positive side mount battery cable.
These cables are known to have corrosion leech where the two wires coming out of the cable create a poor connection.
This can cause a major voltage drop to the starter, causing it to turn slower.
I had the a similar issue in a similar car, looked into shims etc. pulled the motor because I thought it was bad,and said to myself, self you should video this, so I put the starter motor back in, making sure to push the motor towards the top of the engine as far as possible.
Not sure what happened the first time but reinstall and starter motor sounds great and has been trouble free for 3 years since. Could be a bad starter motor, but mine was slow and sounded bad, and now all is good, hope this helps.
Ask your shop to measure the voltage at the starter during cranking, both terminals, terminal to starter case. They should both be 10.5 volts or above. If they are, you got a problem with the replacement starter. If either is less than 10.5 volts, the shop should work backwards towards the battery to find out why.
Starter motor problems, if that’s what it causing it, could be: (1) the starter solenoid contacts are pitted or corroded or misaligned or the rebuilder installed the wrong parts; (2) the commutator surface is corroded, it is out of round, or the brushes are failing. There’s usually a way to test for (1) with the starter motor installed, but most shops would just replace it if it failed the voltage test above.
There’s a less likely problem with this symptom, something major wrong with the engine. That would usually show up as poor engine performance, weird noises, poor idling when the engine is running. If you don’t notice any of that it probably isn’t an engine problem. There’s an off chance however the starter motor is binding up tho, due to a faulty cock-eyed install, so ask the shop to double check for that if nothing else above turns up.