Misting Bilstein Dampers on Mk3.75

[captainhaddock]

Searching for info on my damper issue, I found this  4 year old post from Roadster Robbie.

@Roadster Robbie

I wouldn’t worry about a light misting of oil on a shock absorber body. I’d only worry if it started dripping oil off the bottom and leaving a puddle. Mazda allow a light misting of oil by design, some do it some don’t.

 

Can I ask over what period of time is a light misting of oil on both my rear Bilstein dampers on my Mk3.75 Sport Graphite acceptable? They were noted as having a misting at the two year service 12 months ago and again this week at the three year service and noted as a warning on the MOT certificate (the car is out of warranty on 1st August). Is a continual misting for over 12 months likely to be an issue and is it possible to tell over what period of time it might become an issue? It seems that Mazda don’t consider the length of time this issue has been there when deciding if they should be replaced or not.

 thanks in advance for any replies.

[ChrisRs]

I had Bilsteins on my last car…They were gas filled…I think they all are

Do you know which number they are?

Mine were a B12 kit

[captainhaddock]

@ChrisRs

I had Bilsteins on my last car…They were gas filled…I think they all are

Do you know which number they are?

Mine were a B12 kit

Hi Chris,

Thanks for posting, I haven’t a clue which Bilsteins I have fitted, they were a standard fit to the 2.0 litre Sport Graphite and listed as “Bilstein Suspension” in the brochures.

[Roadster_Robbie]

I’ve stripped a MKI Bilstien damper and it has a gas chamber at the bottom of the damper body with the gas pressure acting on an oil filled chamber at the top that the damper valve moves through. My understanding is that the gas works to extend the damper. As the damper rod retracts into the damper it displaces the oil which compresses the gas. I would assume that all the Bilstien dampers that Mazda use operate on the same principle.

[captainhaddock]

@Roadster Robbie

I’ve stripped a MKI Bilstien damper and it has a gas chamber at the bottom of the damper body with the gas pressure acting on an oil filled chamber at the top that the damper valve moves through. My understanding is that the gas works to extend the damper. As the damper rod retracts into the damper it displaces the oil which compresses the gas. I would assume that all the Bilstien dampers that Mazda use operate on the same principle.

Any thoughts on my original question Robbie?

“Is a continual misting for over 12 months likely to be an issue and is it possible to tell over what period of time it might become an issue?”

Thanks

[Roadster_Robbie]

Have you cleaned the misting off? Does it return? I’d say that if it stays as a misting I wouldn’t worry about it too much.

From my understanding after stripping the MKI damper, is that if the oil leaks out, the sealing plate between the oil and gas chambers is forced upwards by the gas pressure. In the end, I think the plate contacts the bottom of the damper piston rod and that is what’s happening when people describe old Bilstiens as being crashy. I’ve seen a nut shaped dent in the plate before that was the same size as tthe nut on the bottom of the piston rod that holds the valve block on. The leaking Bilstien would allow the piston rod to be fully compressed into the damper body compared to a non leaky one, it seemed to bottom out… Against the plate?

The Bilstien I stripped left a puddle of oil on my garage floor one night so I knew that had had it. I can’t say how long a misting Bilstien will last, but I’m of the opinion that a little oil spreads a long way so as long as it is only misting then it’s probably only loosing a very small amount.

Just my opinion.