MG ZT / Rover 75 - VIS Valve Motor: How to?

[Keith Alexander]

Right this is swiped from the Xpower forum
original Author Sheddist so all credit to him as it a damn good howto
lets grow this into a Vis Valve and Manifold Howto

Sheddist Said

"Thanks to Aldon, who donated a dead actuator to the cause. Here is what this is all about:
[IMG][/IMG]

These are a bit of a pain to get apart and is about the longest part of the process.
First, ease back the clips
[IMG][/IMG]
Then using a thin, wide blade,
[IMG][/IMG]
gradually prise the cover away from the housing. It will not come off at this stage
[IMG][/IMG]
Cut a suitable piece of wood or metal to fit right inside the electrical connector
[IMG][/IMG]
Then push the connector blades and cover apart. This requires a fair bit of force and don't worry if a blade bends or pulls out of the circuit board. When the cover is off the motor internals with the worm gear removed look like this
[IMG][/IMG]
One or both of the two black limit switches is likely to be loose. This is due to poor location resulting in broken soldered joints. The next stage is to remove the circuit board. First, prise out the worm. Take care not to loose the washer off the end of the worm shaft. Use a wide flat blade to spread the load and unclip the worm, bringing the motor and PCB with it.
[IMG][/IMG]
At this stage the switch terminals can just be resoldered and the actuator put back together, only to fail again. You can improve matters by screwing the swtiches down. You will need a 1,8mm drill, 8BA tap and 8BA by 1/4 inch screws. Or use 2mm if you prefer metric! These can all be obtained from http://www.mainlytrains.co.uk/acatalog/index.html
Just do a search for 8BA and then for the drill.
Drill out the switch pegs with the 1,8 drill
[IMG][/IMG]
Tap the holes
[IMG][/IMG]
and fit the screws. TAKE CARE TO ENSURE THE SCREWS DO NOT SHORT OUT 2 PCB TRACKS. FILE A FLAT ON THE SCREW HEAD TO AVOID THIS.
[IMG][/IMG]
Once the screws are fitted, resolder the switch terminals.
Remove the old sealing bead from the case joint and apply new sealer. I use blue Hylomar
[IMG][/IMG]
Reassemble the parts, taking care to clip the motor and worm in together, not forgetting the washer.
Fit the worm wheel so that neither switch is operated- both white switch plungers are not pushed in by the cam, then fit the cover.
I have a test box to test these things - another "how to" coming for this.
Before refitting, plug the actuator into the wiring harness and turn on the ignition- dont try to start the car. This will reset the actuator. Align the actuator output to the manifold slider, and secure with the 4 screws. Start up and check for air leaks, the screws need to be tight and you may have to add a bit more sealer around the actuator joints.
Take a test drive"

[Keith Alexander]

Inside a KV6 inlet manifold, this is one Mucky piece of plastic

Pictures courtesy of lates who said :-

"Afternoon gents,
In my quest to unwind and get ready for me holidays I came across an old gopping inlet manifold I just had to get to bits.

I do not recommend anyone taking theirs to bits "just to look" as it involved a bit of bashing and there are no servicable parts inside.So curiosity got the better of me. I do not think this car had a good service history or higher quality oils judging from the amount of gunked up goo inside.


Anyway here goes, 56k apologies.....
























Thats ya lot folks, outcome is if your manifold rattles throw it away.

edit see here for descriptions and original sizes.....
http://s30.photobucket.com/albums/c3...es600/?start=0
"

[Keith Alexander]

These are place holders for further additions to the Howto to keep the useful info all at the top of the thread assuming there will be anything for me to add :-)

[JohnA]

Stereo - Keith, I have tried to be nosy and take a unit apart before now to look at the motors and switches, how much does it take to separate the cover and housing? That was the point where I called it a day.

Also, recently, took manifold off and sprayed through with carb cleaner which is a dirty experience - try not to let the small flap valve from side of manifold fall out whilst this is going on.

Immediately after, I thought I had created a VIS valve problem as on start up things were a bit clattery, but a 70 mile drive appeared to cure it and no noises since, so I guess a bit of oil does no harm.

[Keith Alexander]

I have had the lid off the front motor but not the back one they are a wee bit tight but the feeler gauge method above looks ok

The rear butterfly valve can go in any way round so I took mine out to clean it. I can't see that one ever causing a problem itself it will just be the back motor unit

The front valves are a different story what a silly idea sealing it all up that sort of thing we were taught to reject during the first months of my engineering apprenticeship. as it makes it impossible to 100% indentify if all six are ok or not

As for the front motor I took apart it looked ok but that was before I found the above howto so I did not however check the soldering to the switches though, I will next time I am in the mood as the above mod is a good one, most components over a certain weight subject to heat and vibration should not be secured only by solder as it will fail over time

I would like to disect a failed inlet manifold one day when I get the chance and post the photos here same as I am doing for the rad fan motors

Hence the two place holders above

Anyone got an old one lying around? If not next person to get one changed don't leave it at the garage please lets put it to good use on here.

[lates]

Just for you Keith.....

http://forums.mg-rover.org/showthread.php?t=139432

Let me know if you want it posting up.

[Keith Alexander]

Thanks I will send you my address as I am terminally curious about all things that fail prematurely

btw look up I have pinched your post for posterity or until something more sticky comes along :-)

Assuming nothing is broken is that manifold actually worn out or could one be revived in a cleaning bath?

[lates]

The difference between pics 8 and 9 show where the spindle goes through the throat and one of them is completely oval. I think it is only fit for the wheelie bin. I will send it so you can see how it all works.All of the bits are there but not pretty as brute force is required to get it into bits.You could put it all back together with plenty of hot glue and sealant I guess ?

[JohnA]

Having said that Lates, those spindles, do they go into collars that might be replaceable?

[lates]

No replaceable parts inside John.

[Keith Alexander]

I agree although I haven't got the one Lates is sending for a close up yet but they do look terminal.

I wonder, are the butterflys and their pivot points plastic or metal?

It will be interesting to see how the valves are actually fitted I wonder if out of desperation they could be rebushed using PTFE or something

[1955diesel]

The butterfly valves and spindles are all plastic and are injection moulded in place! (New technology at the time) They are made from a different plastic to the manifold which stops the parts sticking together when being made.

[sheddist]

Beg to differ!
I recon these can be fixed.
My plan is to fabricate new butterfly valves and slider out of brass. Just need the dead manifold to play with! May just need to ream out the holes to take the spindles.

With respect to the state of the disected unit, then looks like the oil catch tank is a method to reduce this.

[Keith Alexander]

Hiya

I wondered when you would turn up

Every thing is fixable but materials need to be thought about, brass and plastic might expand differently when warm leading to all sorts of grief have you thought about PTFE especially for the bushes?

[1955diesel]

Originally Posted by sheddist

Beg to differ!
I recon these can be fixed.

I didn't say they could not be fixed, just how they were made.

Anything can be fixed with enough ingenuity, although it may not be time or cost effective depending upon who is doing the fixing.

[sheddist]

Thought you could hide on the 75/ZT section?

No offence 1955 diesel

Agreed about the expansion issues. These can be allowed for when considering clearances. PTFE will be fine for bushes, provided the bushes cannot fall out! The existing system may have expansion issues. The plenum is glass filled PA or PBT. The slider and butterflys look unfilled and will expand more rapidly. This could lead to the hot weather problems suggested by Parsec

My main concern is the ability to get the cover off and refitted/replaced and maintain a seal. If a plenum does darken my door, first job will be to make a mould over the cover to stand a chance of producing a replacement. Will also, given the chance, try splitting the weld using a hot blade. The walls look thick enough to refit a cover with a row of proper screws.

[lates]

Originally Posted by sheddist

Just need the dead manifold to play with!

Dont hold your breath just yet, a mate of mine who works for himself had one last week when I seen him. If it still there I will see what I can do to send it up to you.

[sheddist]

Thanks Mate!

[Keith Alexander]

Well after my tour around the Midlands yesterday looking at various tourers during a hi speed blat home I gained the impression something was not right!

definate feeling of power fluctuations through the gears

I put testbook on it this afternoon and sure enough Vis valve fault looged in ECU so off it came and as expected one micro switch with a dirty great big dry joint

Both switches are firmly fixed and resoldered to the board now so that won't happen again

[funnydummy]

Hi i have a MG ZT 190 a few things are going on but cant find the answers except for this forum thread i may be wrong though.
1) around 2000 rpm and then again at around 3500rpm i get a rasping sound, it sounds roughly like a loose heat sheild vibrating.
2)power seems pretty poo until around 3000 but only sometimes
2)and this is where i am gonna sound really thick i can only find the front spark plugs where are the other three im guessing below the manifold (black) does this have to come off? and is there a how to do.

Hopefully somebody can help and sorry if im a pain.

Thanks

Ian