C5 II runnig hot (overheating) when towing

[GiveMeABreak]

They were originally separated pre C5 days, but as electronics advanced and with safety considerations they separated them to provide separate circuits for the brakes and a separate power supply / pump for the steering depending on model so if the main pump / system failed it would not affect the safety / handling of the vehicle.

On my CX, I had an LHM leak on the way back from work and green blood spewed out all over the road - needless to say, steering rapidly diminished and I had to stop where I was as I could not turn the wheel. Had to improvise a hose clamp and then use all the spare LHM to at least get me home! Not a good experience and always at the back of your mind... If this had happened on a motorway, it could of turned out differently.

[white exec]

. . . they separated them to provide separate circuits for the brakes and a separate power supply / pump for the steering depending on model so if the main pump / system failed it would not affect the safety / handling of the vehicle.

Or maybe a preparatory step towards those models which would get steel springing, but with power steering.

[Paul-R]

As the X7 is based on the underpinnings of the 407 you could look at it as being the other way. The power steering pump is always there and only if the car is wet suspended does a second pump have to be fitted.

[xantia_v6]

With a shared pump or an engine-driven pump, it is difficult to implement controlled variable assistance steering.

[GiveMeABreak]

Yes but going back to what EDC5 mentioned, some of the X7 C5s did have mechanical pumps for the steering, it all depended on the model. The most common models had the electro hydraulic steering pump though. Which ever way you look at it though it was to decentralise the key systems.

Wherher they fitted the mechanical pumps on the higher powered C5s because of the extra power the engine had we won’t know, But the petrol ones and the 2 L diesels had the electro hydraulic power steering pumps IIRC.

Good point Mike I must look at the mechanical version operating notes to see how they implement that on the X7 in terms of variable assistance. I do miss the CX system though, that’s for sure.

[EDC5]

Interestingly, the power steering system is described as 'unvariable power steering' for my car on servicebox even though I have the electro-hydraulic pump. Is this a mistake? I'm pretty sure that the main advantage of the electro-hydraulic pump is that the output power can be varied to finely match the demand as detected by steering angle sensor, vehicle speed etc.

[GiveMeABreak]

Yes that’s correct it’s just the term they apply to the mechanical variants Elis. Ours operates as a function of vehicle speed, angle and rate of turn to provide the assistance on the Electro pumps.

[EDC5]

That's great, thanks for clarifying

[xantia_v6]

Interestingly, the power steering system is described as 'unvariable power steering' for my car on servicebox even though I have the electro-hydraulic pump.

I think the terminology gets confused between variable ratio steering and variable assistance steering. I think that for historical reasons, servicebox might be using the terminology for ratio, not assistance.

I am not aware of any PSA vehicle that has variable ratio steering (not even the Citroen DIRAVI), but maybe there was.

[Mandrake]

On my CX, I had an LHM leak on the way back from work and green blood spewed out all over the road - needless to say, steering rapidly diminished and I had to stop where I was as I could not turn the wheel. Had to improvise a hose clamp and then use all the spare LHM to at least get me home! Not a good experience and always at the back of your mind... If this had happened on a motorway, it could of turned out differently.

Err, if you had a hydraulic leak in a conventional power steering system with dedicated pump (steering only, no brakes/suspension) you're still going to lose power steering and find it difficult to steer, so I don't understand your point ?

How does separating the steering from the suspension and brakes help reliability and ability to steer in the event the power steering circuit is compromised ?

For that matter how is an electric power steering system with a blown fuse or failed 12v system any safer ? The battery lead could snap off the battery while you're driving or a fuse blow and you'd instantly have no power steering assistance ?

[Paul-R]

I suppose it comes down to - if you have separate circuits then one of them going down won't take something else with it.

[GiveMeABreak]

Exactly, having steering, brakes and suspension separated reduces the risk of 3 critical systems from failing at the same time because of the failure of one component - pretty obvious to me.

In my case although it was 20 years + ago, one of the hoses came off and rapid loss of LHM led to suspension lowering, then steering difficulty, so although the STOP warning light came on, I had to quickly find somewhere I could pull over (Welsh coastal road with narrow roads and few places to stop).

I had another problem with the XM on another occasion and managed to pull into somebody's drive - to use the phone (no mobiles then), but I do remember leaving a big green puddle on their drive - belated apologies if that was your your drive you are reading this.

[white exec]

Our BX dumped most of its fluid on the ground one day, just as my wife pulled off the A3 at Eashing, a mile from home. Got a phone call, and arrived shortly afterwards to find the car sitting very squat. Engine ran ok, but no power steering.
The unassisted steering was so heavy, I had to take the towed car and wrestle the wheel - really, really heavy work. Can't remember much about the braking; maybe it was a handbrake job.
Left a massive green puddle on the Esso forecourt...
The spiral pipe between engine and underside had given way.

[GiveMeABreak]

Err, if you had a hydraulic leak in a conventional power steering system with dedicated pump (steering only, no brakes/suspension) you're still going to lose power steering and find it difficult to steer, so I don't understand your point ?

Yes, but that would be one system failure, not the loss of 3 which was my point considering I was talking about the CX

How does separating the steering from the suspension and brakes help reliability and ability to steer in the event the power steering circuit is compromised ?

I can't see that I said that anywhere Simon.

For that matter how is an electric power steering system with a blown fuse or failed 12v system any safer ? The battery lead could snap off the battery while you're driving or a fuse blow and you'd instantly have no power steering assistance ?

In the case of my electro hydraulic pump on the X7, if the electronics fail, the warning is illuminated and the backup mode is engaged. My pump will continue operating without the engine running - more than can be said for my CX.

More recently, my alternator belt snapped on the X7 and everything ran on battery power allowing me to get home - some 20 miles - including suspension and steering. The beauty of the BHI and this setup is that once up and running the suspension pump really doesn't do a lot except make minor adjustments - so even without the electric motor driving the suspension pump, you won't have rapid loss of suspension, whereas with a purely mechanical pump the loss is more sudden with a pump failure once accumulated pressure is lost.

I'm not saying it's a perfect system, but more reliable in my opinion, even if I liked the feel of the CX steering better.

[Romzi]

I inspected old thermostat with bypass valve.
It looks like it was there to make fine regulation of engine temperature. But obviously too complicated or too defective. Or both.
Mine was stuck open, thus returning a part of hot coolant directly back to the engine.
I took a caravan to test drive, so far so good.