Flush Power Steering Fluid - Drain Using Engine Idle?

[B.Merr]

Preparing to flush the power steering fluid on my 320d, appears to be several different approaches to draining - one of which is to remove fluid from the PS reservoir until the return entry point is visible, disconnect the return pipe from the pump, place end of return pipe into a collecting vessel for capturing used fluid, then start the engine allowing it to idle for just 20 seconds. In theory all of the old fluid will be forced out of the rack under pressure, in double quick time.

Has anyone attempted this method? Was is successful?

...would be far more efficient than messing around with a turkey baster all afternoon.

[TriggerFish]

Maybe I'm missing something here, but surely that won't get all of the fluid out? Once the fluid level has dropped below the bottom of the pump, it'll be unable to push the rest of the fluid out of the rack/pipe work as there'll be nothing to establish the pressure? If I wasn't in a rush, I think I'd be looking to unbolt the two pipes as they enter the rack, letting all the pipe work drain out under gravity. There would be some left in the rack, I guess, but you'll never get it all out, I don't think.

That said, I don't know how accessible those bolts are from below on the e46.

[TriggerFish]

For clarity (this is an e46 rack in an e30), these pipes, I mean:

[B.Merr]

My thinking is to switch off engine after 20 seconds, add more fluid (to just below the return entry point), restart engine, idle for another 20 seconds....repeat until the fluid expelled from the return hose into the capture vessel appears to be 'fresh'.

To my mind the principle is similar to pressure bleeding brake lines, force ALL of the old fluid out from top to bottom - if that makes sense!?!?

Have 2 litres of fluid at the ready - reckon will that be enough? (Can't find any figures for steering system fluid capacity).

[TriggerFish]

Should be fine if you're adding more fluid. Not sure, bit I'd hope 2l would be OK 

[ian332isport]

I'm not sure the pump will be happy running without fluid. I would just let gravity drain as much as possible and the fill with fresh. Unless the fluid is very old, grey and burnt, you won't gain anything from getting every last drop out.

if you're worried, just drain and re-fill a couple of times. Turning the steering from lock to lock while the pipes are disconnected will also help to push out the old fluid stuck in the system.

Ian.

 

[dontpannic]

I did this method in my Fiesta. Ended up with a wine bottle I had collecting the fluid shooting down the drive and across the road with a 20ft spattering of power steering fluid right across the driveway and pavement.

The far safer method is to jack up the car and put it on axle stands so the front wheels are off the ground, remove the return pipe, put it in a bottle or container and just move the steering lock to lock a few times until the fluid stops coming out of the return pipe. Replace the return pipe, fill to max, turn the steering lock to lock a few more times to bleed the air out, refill to max, and a few more lock to lock to make sure all the air is gone, check it's at max and put the car back on the ground. No need to start the engine then and run the pump with no fluid.

Edited March 1, 2017 by dontpannic

[B.Merr]

Ian - The thought of the PAS pump spinning without fluid concerned me at first, but thinking about it from another angle my understanding is it's driven by the crankshaft via the serpentine belt, so no electric motor to burn out. Correct me if I'm wrong!

Dontpannic - Thanks for the tip, I'll try your method first to be safe. If feeling brave I'll give the tick over method a go after, more out of curiosity that anything else! Fluid has been delivered so just waiting for the weather to play ball.

[ian332isport]

4 hours ago, B.Merr said:

Ian - The thought of the PAS pump spinning without fluid concerned me at first, but thinking about it from another angle my understanding is it's driven by the crankshaft via the serpentine belt, so no electric motor to burn out. Correct me if I'm wrong!

Certainly correct regarding the pump being crank driven. It's more that the pump uses the fluid as lubricant while it spins, so once drained, it's not going to be very happy. I've heard PAS pumps 'rattling their tits off' just from having low fluid level in the system, so running empty won't do it any favours.

Ian.

[B.Merr]

ok, cheers Ian.

...good weather this morning, so got out onto the driveway ready for the dontpannic method of pas maintenance. Jacked the car and propped front end on axle stands, removed the numerous plastic engine covers/shrouds, spied the PAS return pipe and noticed the clip securing it to the pump isn't a regular hose clip, looks like a 'use once' type fitting (see attached pic). Do I need to order this specific hose clip or can I use a regular 'screw tighten' type hose clip when reconnecting the return pipe after the flush?

Bottled it at this point and carried on with an oil change and coolant flush.

Open the PAS reservoir for inspection and was immediately hit with a nasty smell - definitely needs replacing asap.

Couple of other questions to put out there:

1. The pollen filter was sodden - is that ok?

2. Can't see an engine coolant drain plug for this model (M47N) on realoem - is there one? Approx 5 litres of fluid drained from the radiator drain (plastic) plug.

Any advice much appreciated.

[Foe]

I did the syringe method, drain and refill, turn the steering left the right, until I flushed the nasty black fluid through and the red new fluid cam through. It didn't take to long, and seeing under my car I wasn't going to mess about with those clips! 

Anyway let us know how you get on. And sorry I can't help with your last two questions. 

[B.Merr]

...tried the turkey baster method this morning and felt it just wasn't the real deal. Did a youtube search earlier tonight and found this vid, guy unplugs the fuel pump relay in order to control engine cranking with the starter motor, therefore ensuring PS pump doesn't run dry:

https://www.youtube.com/watch?v=TyQ1ZfBZXHU

I'm now on the lookout for a long length of rubber pipe to extend the return pipe

[B.Merr]

...finally got around to a 'complete' power steering fluid flush yesterday, generally following the method in the youtube video linked in the previous post. On one cycle I accidentally ran the pump dry when the engine was cranked continuously for approx 3 seconds . I turned the steering wheel lock to lock in between reservoir top ups (front end on axle stands) and used 2.5 litres of ATF in total. With fluid, replacement hose clamp (16.5mm/9mm) and a roll of kitchen towel, this maintenance cost about a tenner and 1.5 hours effort.

In the picture the transparent pipe used for draining fluid is half inch diameter, this length was snipped from a water level that was knocking around the garage. Temporarily used the new hose clamp to ensure a tight fit into the return pipe. The fluid collection vessel is the 6 litre container from an oil extractor.

Firstly position loads of kitchen towel around the reservoir to soak up inevitable fluid splashes - be especially careful of the alternator which is sited directly below the PS pump on 320d!

Next remove as much fluid as possible from the reservoir, using a turkey baster.

Use long nosed pliers to disengage the factory hose clamp where return pipe meets the pump reservoir. Gently pry the return pipe from the nozzle on the reservoir.

Bung the reservoir return nozzle.

Set up for draining as per photo's, follow the youtube guys instructions - fill/lock to lock/crank, fill/lock to lock/crank,...repeat until satisfied only fresh fluid is being expelled.

Have covered 20 odd miles since flushing and all is well. On inspection the reservoir level is static and no bubbles visible within the fluid when engine is running.