Plenum Check - The Reason Why **ALL OWNERS PLEASE NOTE**

[alanaslan]

Well at least you agree that water is a good insulator i.e. H20 tds 0.000 will not conduct electricity and that is a fact.
As the tds increases so does the conductivity. That I'd also a fact.
Have you ever put a camera in the near side plenum. I have and strangely enough very little water goes down there probably why you don't get false alarms from sensors.
Also why if it is as wet s you seem to think it is would anybody put a filter unit in it for the cars internal air supply system. More to the point a main ECU for the car in a wet environment. I think not.
I am always amused by those of us who do not let facts cloud their perspective.
In a Rover 75 near side plenum there is very little water egress like I say mount a micro cam take a years footage and work out how little water we are talking about.
Neenah again the offside plenum houses the brake and clutch master cylinders. I am sure Rover mounted them in a wet area.
May I suggest you look at the car design then print your retraction. On the plenum being a wet area. Yes they have drains no they are not wet areas that is why the drains block .
Put a paper filter in a wet area I ask you?
Yes there is paper in OE cabin filters. Kind of blows your wet theory out the water. Go on mount a micro cam. Then comment.


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[alanaslan]

Originally Posted by alanaslan

Well at least you agree that water is a good insulator i.e. H20 tds 0.000 will not conduct electricity and that is a fact.
As the tds increases so does the conductivity. That I'd also a fact.
Have you ever put a camera in the near side plenum. I have and strangely enough very little water goes down there probably why you don't get false alarms from sensors.
Also why if it is as wet s you seem to think it is would anybody put a filter unit in it for the cars internal air supply system. More to the point a main ECU for the car in a wet environment. I think not.
I am always amused by those of us who do not let facts cloud their perspective.
In a Rover 75 near side plenum there is very little water egress like I say mount a micro cam take a years footage and work out how little water we are talking about.
Neenah again the offside plenum houses the brake and clutch master cylinders. I am sure Rover mounted them in a wet area.
May I suggest you look at the car design then print your retraction. On the plenum being a wet area. Yes they have drains no they are not wet areas that is why the drains block .
Put a paper filter in a wet area I ask you?
Yes there is paper in OE cabin filters. Kind of blows your wet theory out the water. Go on mount a micro cam. Then comment.


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Thinking about these things takes me back to the 60s when the last volume British car manufacture who survived after Rover made a small saloon and estate to compete with the Austin and Morris Mini.
Back then Reliant were intent on trying to break into the market the mini had created. They launched their answer the Rebel. This little car was powered by their 700cc engine that they had used in their three wheeler. The engineering methods used were to keep things as simple as possible, and true to form used many parts available from others parts bins.
The hydraulic clutch and brake cylinders were mounted on the back of the chassis outrigger below the pedals. The operation was simple the pedal was welded to a arm with a pivot hole in it half way down, meaning that when you pushed the pedal down and away from you the bottom of the arm moved towards the rear of the vehicle. The bottom of the arm was connected to a Land Rover mk1 master cylinder which produced the hydraulic pressure to operate the system. Sadly no thought was given to the fact that the underside of the car got wet in the rain making all nuts and bolts very difficult to work on the next spring. Worse than that in snow the offside wheel threw slush up into the front of the outrigger the master cylinders were mounted on this resulted in a large block of ice forming around the operating rods of the pistons, resulting in no brakes or clutch. The solution was to put rubber hood over the piston rods and make a fibreglass shield preventing the snow from reaching such a critical part.
Then we had the steering. Remember the only little cars Reliant had built up to then had only three wheels.
Rather than going down the rack and pinion route they used a steering box with a double crank so the steering wheel drove a crank through a track rod end. Whilst one of the bottom cranks went to the off side via an pivot arm then another rod connecting to the wheel the other arm at the bottom arm on the box connected to a second box mounted on the near side of the car again through a bottom arm through a pivot arm then out to the wheel.
By my count that was eleven adjustable track rod ends. Very simple but a nightmare to set up the steering geometry. Also with each end of the track rods being opposite threads it was near to impossible.
These parts were all parts that were mounted in wet areas with water being thrown at them by the front road wheels sadly les than ten thousand of these little cars were made. The public were just not ready for a company who built three wheelers for bikers to be making motor cars.
The estate had a single rear door hinging on the offside, opening up to a massive space with the seats folded down..
I have included this article as an insight into the wet problems that have existed for others and there solutions. Great British engineering at its best or worst.


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[HarryM1BYT]

Originally Posted by alanaslan

Well at least you agree that water is a good insulator i.e. H20 tds 0.000 will not conduct electricity and that is a fact.

No, that is neither what I said nor what I would agree with. Water comes in firmly as a conductor - ABSOLUTELY NOT AN INSULATOR. Rain water picks up all sorts of pollution on its way down making it quite conductive, especially rain water which has washed up off a road - is even more conductive due to the included dirt. In winter that water will be laden with salt. All of this progresses down your plenum.

Have you ever put a camera in the near side plenum. I have and strangely enough very little water goes down there probably why you don't get false alarms from sensors.

Why would I need to put a camera down, I stripped and cleaned the area a few years ago. All of the water which hits the windscreen, drains down via the plenums. Only the drains, prevent it collecting that water and the plenum flooding. My filter was wrecked by water and despite it never having to my knowledge flooded. The ECU has a plastic molded cover over it, which acts as an umbrella to protect it from the water ingress as the water flows down. It is open at the bottom and it is open to breath, so it cannot help if the plenum floods - Hence all of the advice to check the drains are clear often and the suggestion to add some means of preventing leaves and other debris getting in.

Also why if it is as wet s you seem to think it is would anybody put a filter unit in it for the cars internal air supply system. More to the point a main ECU for the car in a wet environment. I think not.

See above.. Certain members on this forum make some reasonable income from rescuing drowned ECU's.

I am always amused by those of us who do not let facts cloud their perspective.
In a Rover 75 near side plenum there is very little water egress like I say mount a micro cam take a years footage and work out how little water we are talking about.

I'm sure you meant ingress?

No need, play a hose on the windscreen and watch just how much water flows out of the drains. They deal with a considerable amount of water. Were there not a lot of water, there would be no concerns about it draining.

Neenah again the offside plenum houses the brake and clutch master cylinders. I am sure Rover mounted them in a wet area.

They did, as do many manufacturers. It is also usual to have the wiper motor and linkages too in the plenum.

May I suggest you look at the car design then print your retraction. On the plenum being a wet area. Yes they have drains no they are not wet areas that is why the drains block .
Put a paper filter in a wet area I ask you?
Yes there is paper in OE cabin filters. Kind of blows your wet theory out the water. Go on mount a micro cam. Then comment.


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Nothing to retract at all. If it is not a wet area, it would not be prone to flood, if it doesn't flood (it obviously does) why are you so concerned about detecting that flood?

You are attempting to suggest it is both a wet and at the same time a dry area, which rather obviously is a nonsense.

We all know the best fix for the plenums, is to prevent leaves and debris getting in there to block the drains, plus occasionally checking the drains are clear. To prevent leaves and debris getting in, you can purchase the plastic filters Jules designed or do as I did - simply fit some mesh.

[alanaslan]

Originally Posted by HarryM1BYT

Nothing to retract at all. If it is not a wet area, it would not be prone to flood, if it doesn't flood (it obviously does) why are you so concerned about detecting that flood?

You are attempting to suggest it is both a wet and at the same time a dry area, which rather obviously is a nonsense.

We all know the best fix for the plenums, is to prevent leaves and debris getting in there to block the drains, plus occasionally checking the drains are clear. To prevent leaves and debris getting in, you can purchase the plastic filters Jules designed or do as I did - simply fit some mesh.

Last time I looked under a naked Rover 75 near side floor there were three discharge outlets behind the front wheel (car in question was a launch 75 saloon with all the toys ) one was the front near side sunroof drain one was the plenum drain and the other carried the water from the windscreen and scuttle panel.
I will check my estate next week when I have the front end off my car. The wife's saloon has two outlets but it does not have a sunroof.
My reason for mounting the micro cam was to monitor how much water was carried into the plenum to see how effective the seals around the two covers fitted to prevent water egress from the gutters around the bonnet and the sealing strip at the front of the plenums it has to be said they all work very well with only small amounts of water passing into the plenum.
As to water I did state H2O with a tds of 0.000 i.e. Distilled water,
Which does not conduct electricity. By the fact that it is non conductive it falls into the category of an insulator every bit as good as upvc under these conditions no free electrons to be excited by a current being applied.
It was a throwaway comment. Swimming pool water is a fantastic conductor lots of free electrons with a tds around 400 for a calcium pool and getting near to 1000 on a sodium pool, lots of free electrons. In its polluted state it works well as a conductor hence why a water level alarm works well in the plenum. I used egress as it leaving the preferred route to get into the plenum. Ingress would be it following the preferred route. Another advantage of the micro cam is that it allows you to see in the offending area without disturbing the rubber seals and the windscreen surround clips also the flexing of the two plastic covers of the plenum. When you change the cabin filter you have access to clean down everything and blow through the drain hose at the same time. Less number of times you go in the better condition the parts remain in. As I said the plenum alarm has never given me a false activation in eighteen years. The dozen or so Rovers have never had false activations. And I know that many companies have sold refined kits operating on the same system and I have never seen any complaints about these kits on any of the different rover club sites.
But as we always say it is horses for courses.
It is very important to keep all drains clear they can be blocked from above and below. If you have a sun roof please make sure their drains are kept clear. Because when the block or become disconnected. They have a habit of flooding the inside of the car wet carpets and underlay takes ages to dry out the car.
I have witnessed a main dealer put a compressed air blow gun in to the top of the drain and blast air down the hose, a fantastic way to blow the hoses of their spigots. Have looked through the service instruction discs, and can find no mention of clearing drains by this method.

[alanaslan]

Originally Posted by HarryM1BYT

Nothing to retract at all. If it is not a wet area, it would not be prone to flood, if it doesn't flood (it obviously does) why are you so concerned about detecting that flood?

You are attempting to suggest it is both a wet and at the same time a dry area, which rather obviously is a nonsense.

We all know the best fix for the plenums, is to prevent leaves and debris getting in there to block the drains, plus occasionally checking the drains are clear. To prevent leaves and debris getting in, you can purchase the plastic filters Jules designed or do as I did - simply fit some mesh.

My own plenums have a 2 micron stainless mesh as well as the two plastic covers to keep out muck. Another interesting point quality stainless steel does not conduct electricity either. Silicone steel not carbon steel. A big problem now is there is much junk stainless out there the best affordable stainless to use is 316 or 312 grade. Sadly the days of getting composition certificates when you buy steel these days very rare bring back the 70s when you knew what you were buying and were given paperwork to back up your purchase.
I still have part of a roll of find stainless mesh if any body needs any just let me know happy to send it out to you the roll is about a foot wide just let me know what length you would like. Happy to send out. I found some old stamps in the attic sheets of low denomination both pre and post 1971 so you won't be charged for postage. When I say some it is several thousand stamps from 1/2 pence to £1.50.
Also 1d to 3/- 6d .
Can't use the pre 71 ones but can use the post 71 ones even have some railway postage stamps. Ah the things we used to collect.
Some day they will be worth money but I am using them as postage.


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[Arctic]

Hi Alan.
Remove the wing plenum tubes and cut the flap off, reinstate and you will find the water will flow more freely and will not block up.

The two plenum tubes in the bulk area, on under the ECU and the other under the brake servo can also be cut off but only from under the car, I did this way back in 2010/11 I also do it if I have to get under any members car for any reason, once this as been done the plenums should never flood or even get enough water in them to wet the pollen filter ever.

[tony062622]

Originally Posted by Arctic

Hi Alan.
Remove the wing plenum tubes and cut the flap off, reinstate and you will find the water will flow more freely and will not block up.

The two plenum tubes in the bulk area, on under the ECU and the other under the brake servo can also be cut off but only from under the car, I did this way back in 2010/11 I also do it if I have to get under any members car for any reason, once this as been done the plenums should never flood or even get enough water in them to wet the pollen filter ever.

I noticed mine have the flaps on underneath. I have fitted the guard and "rod" and inspect them regularly especially as it was flooded when got car and water had got into the ECU but Mbrian sorted that for me.But next time I,m under will cut the flaps off.

[Jules]

There's no flaps on plenum tubes!!

Do not confuse these with the AC evaporator drains which have a flap type cover at the ends and are level with bottom of car.

The plenum drains are hidden above the steering rack.

I'm sure Arctic will a have a library picture to illustrate 😉

[Arctic]

I stand corrected not flaps as such named, but they taper down into the two sides are touching each other a good pair of sharp scissors or snipping pliers will help you cut off about 15mm, thus doing away with the touching ends, stopping debris from collecting in the end of the tube blocking the water from getting away a quick as it should.

Photo's duplicated from above post these are before they were cut

[T-Cut]

Later models have full bore drains without the flattened/fanned ends.

TC