Slow crank issue - FIXED

[FW_Z71Burb]

Howdy and Happy 2026!
A few days ago the Burb started not turning over as quickly and beautifully as had been. It will click and “whir” one or twice and then turn over

Here’s what we know

Ever Start 1 year Battery with date code 3/25
No CEL
New fuel pump
O’reilly tested the following and all checked out
- battery
- starter (unknown age)
- electrical / charging system

It’s pretty much the same whether hot or cold. I turn all accessory / HVAC when starting.

Unknown age of ignition coil / spark plugs

The only thing I can think of is I got a spare key cut and maybe it’s messing with the ignition cylinder? But it’s the same with either key and there’s no other symptoms related to a failing ignition cylinder

Is there anything else I can diagnose in the meantime?

I’ll get a cold start video posted tomorrow

 

[ORVietVet]

Key cut has nothing to do with it. If it turns, no problems there. You said, "click and "whir" one or twice and then turn over". You are saying, clicks and then you turn key off, correct? Then next time, it whirs and you turn off again, right? then after those attempts you turn the key and the engine cranks and starts. correct? Not once, during all that, did you say it cranks slow, which is a whole other symptom. How did O'Reilly check the starter? On the vehicle or you carried in and was tested off the vehicle? Testing a starter is a whole other process on vehicle and off. What was the starter draw and voltage drop?

Your list of symptoms point to the unknown age starter but the list of checks/tests/symptoms are scattered.

 

[FW_Z71Burb]

Thanks OR
it never just “clicks”, it goes into starting normally but it will whir like it’s struggling and you don’t hear cranking, then it will sometimes crank then turn over or sometimes go straight to turning over

The test kit they used was on the vehicle. Checked battery engine off, checked starter during ignition through the battery terminals same connection.

 

[FW_Z71Burb]

Could my rear main seal oil leak cause some electrical issues at the starter? Looks like it’s in the same general area. Will need to crawl around and check that out tomorrow too

 

[99Sierra2500]

Grab like your main wires to your starter, and see if they are getting hot.

 

[ORVietVet]

Could my rear main seal oil leak cause some electrical issues at the starter? Looks like it’s in the same general area. Will need to crawl around and check that out tomorrow too

If leak is bad enough, the oil can get on the flex plate and spin the oil out to the starter nose and effect the starter drive gear operation. It would need to be a pretty bad oil leak though.

 

[stutaeng]

Could my rear main seal oil leak cause some electrical issues at the starter? Looks like it’s in the same general area. Will need to crawl around and check that out tomorrow too

Negative on that one...

On the previous generation of GM trucks, there's something commonly called "the big three"...I'm embarrassed to say this (in spite of being a member if the GMT4OO forum for YEARS), but that DOES NOT affect our GMT800 trucks AFAIK...

You most likely have a weak battery. Swap a kown good one and report back... confirm your alternator IS charging...

 

[FW_Z71Burb]

Negative on that one...

On the previous generation of GM trucks, there's something commonly called "the big three"...I'm embarrassed to say this (in spite of being a member if the GMT4OO forum for YEARS), but that DOES NOT affect our GMT800 trucks AFAIK...

You most likely have a weak battery. Swap a kown good one and report back...

My gut is saying the battery too.. it’s a cheapo and this only really started when cold weather entered north Texas

I wanna replace it with a better one anyways now that the wife is driving it

Keep y’all posted

 

[ORVietVet]

Thanks OR
it never just “clicks”, it goes into starting normally but it will whir like it’s struggling and you don’t hear cranking, then it will sometimes crank then turn over or sometimes go straight to turning over

The test kit they used was on the vehicle. Checked battery engine off, checked starter during ignition through the battery terminals same connection.

When you turn the key and just clicks, that is a voltage supply problem to the starter because of voltage drop, connection problems or low voltage feed or even a solenoid problem. Whirring is the starter drive gear just spinning but not engaging the flex plate. Cranking is the actual spinning of the engine before starting. Either normal or slow speed or too slow speed. Your descriptions are off. Again, sounds like a starter problem. 100% for sure, no.

 

[stutaeng]

My brother just told me his "summer bought new" 01 Sierra left hi wife stranded...battery light came one, truck died .


He swapped the battery and truck fired right up. He then bought a new battery, but suspected alternator, which was actually bad. New replacement and off he went...well, his wife anyways...

 

[FW_Z71Burb]

When you turn the key and just clicks, that is a voltage supply problem to the starter because of voltage drop, connection problems or low voltage feed or even a solenoid problem. Whirring is the starter drive gear just spinning but not engaging the flex plate. Cranking is the actual spinning of the engine before starting. Either normal or slow speed or too slow speed. Your descriptions are off. Again, sounds like a starter problem. 100% for sure, no.

Yea my descriptions aren’t great.. I’ll snag a YouTube video tomorrow so you can see exactly what I mean by whir

 

[FW_Z71Burb]

Sorry for the seat belt ding but you can hear it in this. I’m about to stick a new battery in it

 

[FW_Z71Burb]

Warm start vid

 

[FW_Z71Burb]

Wrong size battery in the truck… guy just threw what he had in there before he sold it to me. Hopefully that does it

I always thought it looked a little wimpy for this rig

 

[ORVietVet]

Wrong size battery in the truck… guy just threw what he had in there before he sold it to me. Hopefully that does it

I always thought it looked a little wimpy for this rig

New one should be a 78 series battery.

 

[FW_Z71Burb]

New one should be a 78 series battery.

Affirmative!

 

[AuroraGirl]

Affirmative!

Youn could have gotten a 78/34 dual posts battery and converted to top posts. I got one and left the spacer tray on it so I can use it for better jump starts, but I have not converted

 

[FW_Z71Burb]

Youn could have gotten a 78/34 dual posts battery and converted to top posts. I got one and left the spacer tray on it so I can use it for better jump starts, but I have not converted

Yea I saw that in a vid, decided to not use that battery this time

 

[FW_Z71Burb]

Okay definitely wasn’t the battery.. problem persists and was worse after an hour drive

What other items can i diagnose today?

EDIT:
Drove another 45 minutes, shut it down, fired right up perfectly. So strange

Here's pics of the starter

 

[ORVietVet]

Having the wrong series battery should have been addressed anyway. That is a lot of oil leakage there. How do you know it is from the RMS? That oil could be from back of intake, back of valve covers or oil pressure sender.
Looks like the starter heat shield is there. That is a plus.