Servo Vacuum Pump

[steve.cafc]

Many thanx for the replies on my previous post about steering pumps, That problem now resolved.
My wife now tells me that the brakes have been feeling funny last few weeks, Not doing the school run I wouldn't have noticed the brakes.
When the car is stop/starting on the footbrake down a hill in heavy traffic, on the forth or fifth depression on the footbrake the pedal will go solid and you loose servo assistance, you have to then give the accelorator a tap then brakes work again.
I have tested the servo by starting the car with foot on pedal, and the pedal does sink down slowly. I've replaced the hose between the Servo and the vacuum pump and the brakes are no differant.
Would everyone agree that my vacuum pump is likelyto be at fault or is there anything else I should look at ?
Cheapest pump I've found so far is on German/Swedish/French for £110 .
Any help greatly appreciated.
Steve C

[Peter.N.]

If its belt driven, could be the belt slipping, check the tension.

[AndersDK]

There is a non return valve closing off to keep the vacuum inside the actuator. This may leak ...

[Kowalski]

If its belt driven, could be the belt slipping, check the tension.

The later 1.9 TD has the vacuum pump on the end of the camshaft, so there is no belt involved apart from the cambelt, and if that were slipping, funny brakes would be the least of your problems.

I'd be willing to bet that the hose that goes from the EGR electrovalve to the EGR valve has hardened and cracked and come off the EGR valve. This would mean that when the EGR electrovalve operates (like at part throttle and idle) your vacuum is vented to atmosphere, rather than just a little bit of it being used to operate the EGR valve. Does this all sound plausable?

On the Xantia, that little hose is fairly hard to get at because its down the back of the engine. On a Synergie its going to be difficult, can you see the inlet manifold under the bonnet and get a hand over the top of it / in behind it?

How to prove my theory... difficult. Is there more than one hose coming off the vacuum pump i.e. one going to a T piece and a pair of electrovalves? If so, disconnect the plugs from the two electrovalves and see if that makes the problem disappear. If it does, the EGR operating hose I mentioned above is most probably the culprit, if not I'll have to have a bit more of a think about the problem!

[steve.cafc]

Hello Kawalski,
My Vacuum pump has a large pipe ( 10mm bore ) going to the brake servo and a smaller 4mm bore pipe going to the cold start device ( cable thing ).
What would the EGR thing look like and what would it be connected to ?, I can't refer to a Haynes manual as they don't make one for Synergie, So I have to rely on a peter russek handbook which is a bit vague !

[Kowalski]

Hello Kawalski,
My Vacuum pump has a large pipe ( 10mm bore ) going to the brake servo and a smaller 4mm bore pipe going to the cold start device ( cable thing ).
What would the EGR thing look like and what would it be connected to ?, I can't refer to a Haynes manual as they don't make one for Synergie, So I have to rely on a peter russek handbook which is a bit vague !

Can you see where the smaller hose goes to?

On my Xantia (with the same engine), I have a single small bore hose off the vacuum pump and it goes to a 'T' piece which connects to a pair of electrovalves, one does the EGR the other does the cold idle. If you find the electrovalves, coming off them you should find a pair of hoses, one goes to the EGR valve (this is the one I'd expect to have come adrift) the other goes to the vacuum device (cable thing) that operates the cold start cable. On the Xantia, I've had this EGR vacuum hose come off twice, first time the end had hardened and split so I cut the hard bit off the hose, turned it around (end to end) and put it back on, second time around it came off because I'd not put it on properly the first time.

[steve.cafc]

Hello Kawalski,
You wont believe this but someone's done a botch job with my rubber tubing !
The smaller tube that's supposed to go into a T-Piece actually goes straight to the cold start device !
I can see the two green electrovalves minus the T-Piece and tubing, I'll get some tubing from work tomorrow.
Is there anyway I can test the electrovalves, in case they've been disconnected for a reason ?
Many Thanx

[Kowalski]

Hello Kawalski,
You wont believe this but someone's done a botch job with my rubber tubing !
The smaller tube that's supposed to go into a T-Piece actually goes straight to the cold start device !
I can see the two green electrovalves minus the T-Piece and tubing, I'll get some tubing from work tomorrow.
Is there anyway I can test the electrovalves, in case they've been disconnected for a reason ?
Many Thanx

I know on my Xantia, I can hear the valves operate, its a slight clicking noise I hear. I'm not sure whether the noise is mechanical from the valves themselves or the popping noise you get when you release the vacuum to atmosphere. The valves do fail its fairly common, the coils on them go open circuit and they stop working, you can check their resistance with a multi-meter, if its open circuit they're broken.

If the vacuum hose connects direct to the cold start device and has no leaks in it, what I said about it being a fault with the EGR hose can't really apply since it isn't connected. If this hose is connected all of the time your engine will idle at the slightly higher cold idle speed. On my car, one electrovalve / plug is blue (idle speed) the other from memory is green and does the EGR.

As interesting as this little wild goose chase has been, I don't think it can be whats causing you to lose your vacuum assistance to your brakes since the hoses aren't connected to any valves. The electrovalves operate in a seemingly random way when you press the accelarator, the fact that you said tapping the throttle made the servo came back made me think that it was these valves.

I'm not really sure how to test the master cylinder (since I haven't got one on my Xantias), but if you pull the vacuum hose off the pump and stick your finger over the pump outlet, you should feel good suction, if there is good suction the problem is not with the vacuum pump.

[steve.cafc]

Hello Kawalski,
Thanx for all of your help in my problem, If you hadn't had mentioned about the EGR valve, I wouldn't have even known that mine was dis-connected !
As there's no Haynes book for my car , I purchased a Haynes Brake book, and in there it says that a vacuum pump should be producing a minimum of 15 inches HG, I borrowed a gauge from work and mine is sucking out 8 to 10 inches HG.
So either my pump is knackered or I'm looseing vacuum through the master cylinder, I don't seem to be looseing any fluid ?
I think my servo is fine as the pedal does slowly depress when you start the engine.
Then when I've finally sorted out my brakes, I can then sort out the EGR electrovalve ! , Will I be doing any engine damage with the EGR electrovalve dis-connected ?
Again Many Thanx.

[fastandfurryous]

Will I be doing any engine damage with the EGR electrovalve dis-connected ?

No. You'll be doing it a favour. EGR is the spawn of satan. It causes huge amounts of clogging in the intake manifold, and ruins engines. Leave it disconnected.

[Kowalski]

The 1.9 TD engine was originally designed without EGR, its a later feature just like the catalyst to reduce emissions. The thing it has in common with your catalyst is that it increases fuel consumption, sacrificing one type of emissions (CO2) for another (NOx). The emissions that the catalyst and EGR reduce on your diesel (gaseous hydrocarbons and NOx respectively) aren't even tested for in the MOT.

As FastandFurryous says, it does help clog the inlet manifold. Your inlet manifold tends to be oilly and your exhaust tends to have soot in it, the EGR valve lets soot in the exhaust into the inlet manifold and the two mix and make a nice sludge.

[fastandfurryous]

The bit that annoys me about EGR valves is that they are apparently an "emissions reduction" system.

Well.... it is likely that having EGR will speed up the demise of the engine (the soot/oil sludge in a high mileage XUD inlet manifold, and on it's intake valves has to be seen to be believed) and in many cases will mean that the car is scrapped sooner than it might be.

Hence new cars will have to be manufactured to replace them. the TINY improvement in emissions is completely wasted in comparison to the manufacturing emissions in making a new car.

Remove the EGR, keep the older car on the road, and be environmentally friendly!

[Kowalski]

This is offtopic but kindof related to what you're saying about the environmental aspects of maintaining an older car.

The local "environmentalists" have taken to vandalising the 4x4s found parked on the streets in one of the more upmarket areas of Newcastle. Outside where I work yesterday was a Porsche Cayenne and every panel on the car had been scratched. It even had words scratched into the paintwork all in the name of the environment. What the idiots that scratched that car probably don't realise is that respraying it isn't going to do the environment much good now is it?

I do see 4x4s that don't get driven off road or used to tow something heavy as pointless (or close to pointless, an estate or MPV would be as practical), its purely a fashion statement. I would concede that 4x4s are not good for the environment, this Cayenne being at the worst end of the scale but this struck me as nothing more than envy driven vandalism in the name of the environment and wasn't doing the environment much good overall.

In the states they set fire to them, I wonder what the emissions from a burning 4x4 are like for the environment, compared to what comes out of its exhaust.

[fastandfurryous]

In the states they set fire to them, I wonder what the emissions from a burning 4x4 are like for the environment, compared to what comes out of its exhaust.

Couldn't agree more.

Plus, the insurance company will pay out for another new car to be manufactured.... which uses more energy than the car would use over it's lifetime....

It's not environmental at all. It's vandalism.