Engine Starter Mystery

[mmranch]

My tractor is 16 years old. It is always stored in my well insulated shop and is even block heatered before starting in the winter. It has always started just fine with normal starting sounds.

About a year ago, it began emitting weird sounds when starting. Basically, it sounded like the starter was having trouble getting nicely engaged with the flywheel to spin it. I suspected my original battery was dying so I nursed everything along with repeated charging of the battery before starting and also plugging in the block heater before starting to make it easier. The bad starter sounds continued but it did start and I continued to get work done.

Each time after the initial start with bad sounds... after the engine was warm, it would always restart perfectly.

Eventually, I bought a new battery but that did not solve the problem. Then I bought a new starter and that did not change anything.

The first start of the day always emits the bad starter engagement sounds... but it does always spin the engine and start. All subsequent starts after the engine has been warmed up start perfectly. Yesterday, I plugged in the block heater for 20 minutes or so before the first start and the sound was slightly improved but not perfect. Clearly, it works fine when the system is warmed up.

Any idea what could be causing this bad initial start? My guess would be that the cold engine has additional resistance to spinning the flywheel and this is causing the starter to have a difficult time doing it's job?

Thanks for any ideas!

 

[LS Tractor Owner]

Just to clarify, after it is warmed up / used for a bit, it no longer makes the sound? It only happens when it's cold?

It does sound like it is a "tight" motor. What oil are you using?

When you had the starter off when replacing, did you notice the condition of the flywheel? Any worn teeth? Is the noise coming from the starter or more from the gear / flywheel engagement?

Did you clean all the connections like the grounds? How are the battery cables? Still original? Did you check amperage draw through the cables?

Lots of variables could cause it. But, if it continues to start and run OK, just use it.

 

[lpakiz]

Can you get to the alternator or crankshaft or someplace/somehow roll the engine a few degrees, to get to a better place on the flywheel ring gear?
8Sometimes you can get a socket or even a wrench on the alternator pully nut, then hold the belt tight and rotate the engine.
Maybe park it half-off a chunk of 4X4? Barn hill?
anyrhing to roll the flywheel a few degrees before the cold start. See if that affects the starter noise....

 

[mmranch]

Thanks for the ideas!

The engine runs standard 10w-30 oil. The bad starter sound only happens when the engine is cold on the first start of the day. All subsequent starts (when the engine is warm) are perfect.

The bad starter sound is coming from the starter not the engine. It sounds like a standard bad starter sound... like the starter gear is tapping against the flywheel ring gear or not engaging properly. This starter bad engagement sound is loud enough that it overshadows the engine turnover sound making it difficult to tell if the engine is spinning. But the moment you release the key and the starter stops spinning, you can hear that the engine is spinning/starting. So the starter is starting the engine just fine... but it sounds bad on the first start.

The flywheel ring gear is fine. I split the tractor a while back to replace the clutch and the ring gear was perfect at that time. Also looked good when installing the new starter.

Not a huge issue but just a mystery.

Thanks again.

 

[mmranch]

I should also mention, the wiring is all original and I haven't tested it but it works fine on all starts after the first cold start of the day so I don't think that's the problem.

Thanks again.

 

[lpakiz]

This is an edit to what's written below. I re-read your initial post and saw that you replaced the starter and it made no difference.
I'll leave this post up to hopefully help someone else in the future, but I suspect this will be of little value to you, the OP.

Does the starter have a "throw-in" solenoid mounted on the top of the starter motor, or is it an inertia type?
If it has a throw in solenoid, I wonder if the solenoid plunger is hanging up, maybe on some stiffer (when cold) oil or grease.
What happens if you, real quickly, just "jog" or "bump" the starter, not letting it even try to engage? After 2-3 jogs, try a normal start and see if it engages correctly. Or pre-warm the solenoid plunger area with a 100 watt light bulb, hairdryer or heat gun. Allow a half hour so the heat soaks into and thruout the metal. Trying to replicate a "hot" start......

If it has an inertia type, (no solenoid on top of the starter) sometimes that type won't "grab" when first powered up. This type has a sprague clutch (like a ratchet) to turn the pinion, and that sprague unit "let's go" after starting so the ring gear can over-run the starter pinion without over speeding the starter motor. These sprague units can slip if gummed up or worn or? Might react differently depending on hot or cold temps. Sometimes these sprague units are called a Bendix.
You could also try the preheat strategy, but you would need to remove the starter, warm up the Bendix, reinstall the starter and then attempt a "hot" start.
Also, are there any signs of damage on the leading edge of the pinion or receiving edge of the flywheel ring gear? There will normally be some minor signs of impingement, but neither one should be beat up too much.

 

[mmranch]

Thanks again for the ideas!

The starter is a solenoid throwout starter (both starters are identical Bosch's).

Yesterday, I plugged in the block heater in for about 30-40 minutes to warm up the engine before starting and when I turned the key... perfect start. So it definitely likes the engine warm. I should also mention that I rebuilt the original starter (teardown, clean, lube) and tried that before I installed a new starter. After the rebuild I got the same bad sound initial start and then the perfect subsequent starts.

I guess she's just getting finicky in her old age!

Thanks again.

 

[BravoXray]

Thanks again for the ideas!

The starter is a solenoid throwout starter (both starters are identical Bosch's).

Yesterday, I plugged in the block heater in for about 30-40 minutes to warm up the engine before starting and when I turned the key... perfect start. So it definitely likes the engine warm. I should also mention that I rebuilt the original starter (teardown, clean, lube) and tried that before I installed a new starter. After the rebuild I got the same bad sound initial start and then the perfect subsequent starts.

I guess she's just getting finicky in her old age!

Thanks again.

Did you check the armature for open/shorted windings with a growler or continuity checker?

 

[nyone]

Yesterday, I plugged in the block heater in for about 30-40 minutes to warm up the engine before starting and when I turned the key... perfect start

Block heater in july? That seams very un needed.
Many times the engine will stop in the same possition and this means flywheel ring gear wear in one spot. For the next few times you start your engine make note of what possition the crank pully is. You can also turn the engine (sometimes with the fan) a few degrees every cold start. This will tell you if it's a starter engagement issue. This is how I diagnosed my kubota b8200 as needing a flywheel ring gear and starter.