Powersteering reservoir overflowing while idling?

Shani Technician Ontario Posted   Latest  
Unsolved
Chassis
2016 GMC Savana 3500 6.0L (G L96 Gas) 6-spd (6L90)
Powersteering Reservoir Overflowing

Good day everyone,

A customer approached me with a question that I myself have never experienced before and could not think as to why this would happen. I would like to point out that this happened when the weather was around 25 degrees Celsius. As the customer was having lunch break in their vehicle, idling, with the air conditioning on, he noticed a puddle under his vehicle. After looking under the hood it was clear that the power steering reservoir was overflowing out of the cap. This has happened twice to the customer. Customer has never topped up any of the fluids. Unable to find anything abnormal visually and confirming fluid levels were good I simply washed off the mess and haven't heard anything about it since. I'm just wondering if anyone has experienced this before?

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Jared Diagnostician
Maryland
Jared Default
 

Is there a screen at the bottom of the reservoir? Ive had other cars with similar issues where the screen at base of reservoir gets clogged with mucky fluid.

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Shani Technician
Ontario
Shani Default
 

I'm not sure if there is, I will take another look closer when I see the vehicle again. Thank you.

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Chris Diagnostician
Pennsylvania
Chris Default
 

Shani, Is there any sign of heat damage to the reservoir or other components? Perhaps a possible restriction in the system from debris passing through (this could cause intermittent sticking of the pressure relief valve causing excess return flow or excess restriction which would cause heat build-up, fluid expansion, and finally overflow)? Is the power steering pump making any noises, is…

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Shani Technician
Ontario
Shani Default
 

Hi Chris, It didn't appear to have any signs of excessive heat, no abnormal noises or odd feedback from the steering system itself. Of course when I looked at the vehicle the problem was not present. I will keep in mind that there very well may be a restriction that could be an intermittent issue. Thank you.

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Mark Engineer
Colorado
Mark Default
 

Shani Wonder if the P/S fluid is "worn out". The fluid has additives to reduce/eliminate foam. When the additives are depleted foam will occur and not dissipate. Also, if the owner is meticulous about keeping the underhood/engine area clean, many products have silicone in them (the spray products that make the plastic glossy looking. They result in a good appearance, but bad for O2 sensors…

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Shani Technician
Ontario
Shani Default
 

Hi Mark, No this vehicle does not receive any special attention regarding engine detailing and such. Just the required maintenance to keep it on the road. I may suggest a fluid exchange the next time I see the customer, thank you for your reply.

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James Owner/Technician
Saskatchewan
James Default
 

I've not seen it on GM stuff, but there may be a bit of an air leak somewhere on the suction side of the pump aerating things, V6 Hondas of a certain age have an oring on the inlet fitting of the pump that can cause some ickiness.

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Shani Technician
Ontario
Shani Default
 

Now that you mention it I have seen this before on a Ford Focus. Although it wasn't intermittent by any chance.

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Victor Owner/Technician
Florida
Victor Default
 

I saw happen just today​.​The power steering system seemed to be somehow drawing air into system​.​There seem to be excessive belt slippage caused by a faulty tensioner. " MURPHY" never seem to go on vacations.

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Shani Technician
Ontario
Shani Default
 

Good point don't skip the basics, thank you Victor I will take a good look at the belt and tensioner. The belt was in good shape visually but that was as far as my inspection went.

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Victor Owner/Technician
Florida
Victor Default
 

It is my belief that the belt slippage is causing fluid overheat and eventual boil over.

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Jason Technician
New York
Jason Default
 

I've seen a reservoir o-ring start to suck air, cavitating the fluid, causing a leak out of the cap.

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