Oil Pump Replacement

Generac, Guardian, Honeywell, Siemens, Centurion, Watchdog, Bryant, & Carrier Air Cooled Home Standby generator troubleshooting and repair questions
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Eric4bfp
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Tue Nov 26, 2019 11:11 am

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I received low oil pressure shut down. I brought a pressure gauge from work and the unit had 0 psi. The tech who installed it came out and found white plastic in the oil.

Unit is over 7 years old but less than 350 hours. We have a lumber business and are not afraid of rebuilds. From looking around the forum it looks like we will need the oil pump and o ring. Also new o ring/gasket for sump cover.

The distributor said while we have it apart we may want to put new brushes in generator. Thoughts??

In case the picture doesn't post.
Model 0059242
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Chris
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Tue Nov 26, 2019 6:19 pm

This is one of those things where I think I'd want to get it apart and assess the damage before ordering parts. I can get you anything you need for it, but no sense making 3 orders if there is something missed or a piece flew off and did more damage than expected. The plastic you're seeing is almost certainly the plastic drive gear from the pump assembly.

As far as the brushes go, they're fairly cheap and might not be a horrible idea. I would also (and more importantly) clean up the slip rings and make sure the brush pack is aligned properly to the slip rings. I sell a brush pack kit with alignment washers and instructions if needed.
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MacL
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Tue Nov 26, 2019 7:19 pm

My thoughts are get a new engine.

You probably have a blocked oil gallery, perhaps from a spun crankshaft bushing.

The white plastic is the teeth off of the plastic oil pump gear. Once inside, you will find a freely spinning pump with no teeth on the gear.

So I put a new pump in it, tested for pump output to make sure it engaged properly and finished putting it together.

But once I started it, it was bad. Smoke, funny noises, slowing down as if binding. Heated up too much and too fast. If I had let it run it wouldn't have run ten minutes. Maybe it would have destroyed the new pump, maybe finished off the engine.

I suspect the pump discharge was blocked by a spun bearing, making the pump tremendously hard to turn, which in turn wears the teeth away in minutes.

If the pump were to seize on the other hand, the plastic gear would break free from the metal shaft and the teeth would remain intact. I've seen that as another type of pump failure.

Lesson learned is that the oil pump failure was a symptom of another problem.

But to look at the flywheel end bearing requires removing the flywheel, cylinder heads and one piston.

You can look up the hole wear the filter screws on with a flashlight, and you should not see any "brass" at the far end. If you don't see round silver, you see brass or partial brass the pto bearing is spun.

To view the other bearing's alignment would require a total engine teardown (crankshaft removal).


It's very tricky to get the engine sump cover back on as well unless you pull the engine and lay it on its front. You'll have to release all the rocker arms and wrap a string around the camshaft to get it in its hole.


All I know is once started I immediately knew it was not right. Sounded like it had a 100 amp load on it. If my customer buys a new engine from us I'll tear down and let you know the root cause of the pump failure. But if you tear yours down let me know what your root cause is, in case I'm not able to get her old engine to autopsy.
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Eric4bfp
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Wed Nov 27, 2019 9:19 am

Thanks for the input. Makes total sense that the oil pump failure could be a symptom. I am very displeased with Generac.

It seems Generac is great at marketing but less than stellar at building durable engines.

I am considering replacing the unit with a Briggs or Cummins.
Eric4bfp
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Sat Nov 30, 2019 12:20 pm

We have everything apart. The oil pump gear is chewed up. Bearing alignment looks fine. We are going to replace the oil cooler along with the oil pump. The oil cooler is between the pump and filter so we are concerned that it could be clogged with plastic.
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MacL
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Chris
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Sat Nov 30, 2019 3:37 pm

If you need parts, let me know and I can put together a custom shopping cart for you on the store :cool:
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Eric4bfp
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Mon Dec 02, 2019 7:41 pm

Chris,

Is it better to email you a list or give you a call. I cant find a parts list in my literature.
Chris
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Mon Dec 02, 2019 9:15 pm

E-mail is probably easiest. PM me your e-mail address and I will send you over an email with all my info and a parts diagram for the engine. :cool:
Generac tech for over 12 years. I'm here to help!
"The only source of knowledge is experience" -Albert Einstein
Looking for Generac parts? Gentek Power offers the full line of Generac replacement parts! Shop Gentek Power Generac Parts
A list of my favorite Generator & Electrical Tools! https://www.amazon.com/shop/gentek_power
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