MatraSport Forum

Each model => Murena => Topic started by: klumzer on June 26, 2011, 04:56:51 pm



Title: vacuum actuator of the headlights
Post by: klumzer on June 26, 2011, 04:56:51 pm
Is it possible to disassemble and revive the vacuum actuator? Has anyone tried it yet?


Title: Re: vacuum actuator of the headlights
Post by: Matra_Hans on June 26, 2011, 05:15:58 pm
As long as the actuator is working there should be no reason to open it.
However I have heard of someone who has opened the actuator in order to repair a leak in the membrane.

Hans


Title: Re: vacuum actuator of the headlights
Post by: klumzer on June 26, 2011, 05:45:19 pm
It works only one direction so it needs some repair...
The seal around the piston got stuck on it and moved in.


Title: Re: vacuum actuator of the headlights
Post by: Jon Weywadt on July 04, 2011, 07:44:10 am
It works only one direction so it needs some repair...
The seal around the piston got stuck on it and moved in.
If the vacuum actuator works in one direction there is nothing wrong with the actuator itself. The actuator has two hose connections that go up to the vacuum valve. If one hose is cracked there will be no vacuum to that side, thus no force from the actuator. Therefore check the hoses and if still a problem look at the valve. The valve switches the vacuum from one side of the actuator to the other.


Title: Re: vacuum actuator of the headlights
Post by: suffolkpete on July 04, 2011, 07:42:31 pm
Surely if the seal has got stuck and moved in then there will be no vacuum on that side and that is the reason why it only works one way.  The fact that it works one way shows that the membrane is ok, but you may have to dismantle the unit anyway to replace the seal in its correct position.


Title: Re: vacuum actuator of the headlights
Post by: klumzer on July 04, 2011, 10:01:59 pm
Thanks.
Yesterday we managed to disassemble the actuator but I did not have time to post the photos. It is quite easy if you find the proper tool to bend out the clamps on the housing (shown on photos).
The housing is fully galvanised so the inner side is in very good condition and the membrane is also perfect.
There is a busing behind the seal to give direction to the piston and that was the sticky part. After removing it a reamer (10mm) refreshed the hole and the piston was polished again.
Now the housing is waiting for having a new zinc bath (the outer surface have some rust) and I have to buy a new seal.
I will post some photos about the assembly in the future.


Title: Re: vacuum actuator of the headlights
Post by: Jon Weywadt on July 05, 2011, 11:04:51 am
Thanks.
Yesterday we managed to disassemble the actuator but I did not have time to post the photos. It is quite easy if you find the proper tool to bend out the clamps on the housing (shown on photos).
The housing is fully galvanised so the inner side is in very good condition and the membrane is also perfect.
There is a busing behind the seal to give direction to the piston and that was the sticky part. After removing it a reamer (10mm) refreshed the hole and the piston was polished again.
Now the housing is waiting for having a new zinc bath (the outer surface have some rust) and I have to buy a new seal.
I will post some photos about the assembly in the future.

I am curious. Was there rust on the shaft that prevented it from moving in and out? You wrote ealier that it worked in one direction, so I presume it was not stuck. As you found there was nothing wrong with the membrane.
Usually a bit of WD40 or such will be sufficient to make it move freely. Most problems are with cracked hoses to one or both sides of the actuator, or the vacuum valve.
The vacuum valve can me taken apart and, if you do, it is better to drill completely through the screw holes and install long 4mm bolts with nuts on the other side, rather than the original tapped kind. The tapped kind has a tendency to crack the nylon on the valve.
That had happened on my valve and i had a constant hissing from it, because it was not tight.


Title: Re: vacuum actuator of the headlights
Post by: klumzer on July 05, 2011, 05:47:45 pm
'The vacuum valve can me taken apart and, if you do, it is better to drill completely through the screw holes and install long 4mm bolts with nuts on the other side, rather than the original tapped kind. The tapped kind has a tendency to crack the nylon on the valve.
That had happened on my valve and i had a constant hissing from it, because it was not tight.'




Yes, I found some cracks on the valve housing so I have been doing it. But I made an aluminium plate as a common washer with five holes (one bigger in the center). I also found some cracks on the attachment of the valve so I have to repair it on similar way.

Probably I did not write the problem exactly. We tried to make the actuator move by blowing the hoses. It worked only in one direction and it could not move to the other side because the seal was not in its place. So it was not hermetic.
I did not find rust on the shaft but it had to be corrosion or something like that. Probably it got stuck because of the salty air and humidity in Holland and it was not used a long time ago. The bushing and the shaft are made of different metals. We had to use a hammer to make the shaft to move.


Title: Re: vacuum actuator of the headlights
Post by: Jon Weywadt on July 06, 2011, 08:11:15 am
---
 But I made an aluminium plate as a common washer with five holes (one bigger in the center). I also found some cracks on the attachment of the valve so I have to repair it on similar way.
---

I replaced the thin aluminum plate that is mounted on the valve and prevents the piston from falling out. I used a 2mm thick piece of aluminium and it worked great, except the valve stopped switching the vacuum to one side. This turned out to be due to the thicker plate preventing the piston from moving all the way in. If I recall correctly, I ended up filing 1 mm off the nylon of the valve on the side of the plate. This made the valve work correctly again.