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[Big_Roger]

Hi Debs,
Be carefull not to enlarge the hole or you will have an equivalent of a nasty air leak into the plenum. Try it by hand first with maybe smaller drill in a pin chuck.

I had a job to clear the crud from the small "tube" in the black plastic assembly on top of the plenum. If you look at the projection that fits into the plenum there are two small holes, maybe about 2mm dia. This is where the small breather tube exits to. Make sure both are clear.

Unless you have access to compressed air, I used a tyre pump, it fits neat over where the hose goes on.

Roger

[MutantCav]

Arrrgh!!! Had the plenum off to see if the caged o ring needed replacing...figured I wouldnt need the car till the replacement arrived Wednesday...needed the car this weekend, started it up forgetting there was no plenum attached, very rough couple of chugs and it died...so got the plenum all attached up again, started no problem all be it rough as before...

Now the brakes seem to be locked up...barely working like there is no power assistance to them, presumably an air leak or something but I cant see how it suddenly happened as surely the plenum area would not affect this??

[Debs.]

It`s a result!.....the idle is significantly smoother since I renewed the breather bridge o-rings and cleared out the breather-bridge and breather-box/hoses, and as a bonus; the slight oil-weep from the N/S valve cover appears to have stopped.  
 
I was surprised how much 'crud' had aggregated in these assemblies and how difficult the crystalline deposits were to remove.....regular oil changes and checks on the breather system are on my regular to-do list from now-on.

[Debs.]

Arrrgh!!! Had the plenum off to see if the caged o ring needed replacing...figured I wouldnt need the car till the replacement arrived Wednesday...needed the car this weekend, started it up forgetting there was no plenum attached, very rough couple of chugs and it died...so got the plenum all attached up again, started no problem all be it rough as before...

Now the brakes seem to be locked up...barely working like there is no power assistance to them, presumably an air leak or something but I cant see how it suddenly happened as surely the plenum area would not affect this??

...surely that`s got to be 'something' to do with the manifold to servo vacuum pipe, it`s non-return valve or tee-piece Chris....I wonder has something split on that vacuum circuit (perhaps out of sight)?

[MutantCav]

Are they the 4 pipes going into the breather box? one thing I did notice was the one of the smaller pipes was only half way on...didnt think much of it...till now! lol

[Debs.]

Are they the 4 pipes going into the breather box? one thing I did notice was the one of the smaller pipes was only half way on...didnt think much of it...till now! lol

No, they are different pipes!....The brake-servo pipe attaches to an 90 degree elbow on the N/S face/edge of the aluminium manifold....from there the vacuum-pipe passes across the top of the engine; just beneath the scuttle, passing via a tee-piece and a non-return valve before reaching the brake-servo....a BIG leak in the plenum/manifold or in that vacuum-servo pipe would leave you with insufficient vacuum for any power assisted brakes.

[MutantCav]

Aluminium manifold??? The thing below the plenum with the fuel rails/injectors attached to it?? So maybe I have knocked a pipe off when messing about with the plenum perhaps...the brake servo is the ABS/TC unit bit/area??

[Debs.]

So maybe I have knocked a pipe off when messing about with the plenum perhaps...the brake servo is the ABS/TC unit bit/area??

The brake vacuum-servo is that large(ish) drum-shaped object sandwiched between the bulkhead and the brake-fluid reservior/brake master-cylinder.....The brake-pedal piston (effectively) passes through it.  

[Debs.]

Aluminium manifold??? The thing below the plenum with the fuel rails/injectors attached to it?? So maybe I have knocked a pipe off when messing about with the plenum perhaps...the brake servo is the ABS/TC unit bit/area??

Sorry Chris....`meant to call it Aluminium plemum.  

[MutantCav]

Ok got the pipe you mean, nothing obvious there...but while I was checking it out found one of the really thin long little pipes off, so reconnected that and started the car to check...no joy with the brakes, but reminded me that (I doubt coincidentally) when you press the brake pedal in park (and only in park) there is now a clunk noise (like something is loose and moving from under the auto gear lever!! Could this be the park brake come loose or something like that and stopping the brake servo working???

[ians]

Ok got the pipe you mean, nothing obvious there...but while I was checking it out found one of the really thin long little pipes off, so reconnected that and started the car to check...no joy with the brakes, but reminded me that (I doubt coincidentally) when you press the brake pedal in park (and only in park) there is now a clunk noise (like something is loose and moving from under the auto gear lever!! Could this be the park brake come loose or something like that and stopping the brake servo working???

That noise (I think) is the interlock which means that you have to have foot on brake to move out of Park.  or is it louder than that?

[MutantCav]

~Its a definite clunk and it wasnt there before when the brakes worked ok...

[Marks DTM Calib]

Can you get the car to me next week Chris for a little look?

[MutantCav]

Yeah Mark, pretty sure I can but probably could do with sorting the brakes before I do...they do work but barely atm...any particular day better for you?

[MutantCav]

Well I got the parts from Vaux today...putting them on after lunch...think I may know whats causing the air leak now...when I looked there were 5 o rings which looked to me having not seen them before like they were just worn down...and the 6th one was more like a rubber washer fully filling the slot...so I'm now thinking having seen the new ones are like the 5 worn down looking ones...the 6th one is completely wrong and is causing the air leak...we will see!!