Best way to clean the Plenum drains

[john91919]

Hi,

Just found out where some of the Plenum drains are.

Where are they all and what is the best way to clean them please?

Cheers
John

[daveb57]

Originally Posted by john91919

Hi,

Just found out where some of the Plenum drains are.

Where are they all and what is the best way to clean them please?

Cheers
John

Hi John,

There you go mate, explains all.

http://giantrhino.co.uk/mgr/Unblocki...20channels.pdf

Have few more bits to add to this little task. Bit busy at the moment, will post in about 15 mins mate.

Regards,

Dave.

[pab]

John,have a look at this,plenty of information on the Plenums and other subjects that could be of interest.

[john91919]

Many thanks for the info.

I assume you do the same the other side ?

Cheers
John

[daveb57]

Hi John,

Sorry about that, was in the middle of a call when i saw your post.

Yes, as i said, there a couple of more bits i will add to the above.

When MG Rover manufactured the car, they left an open void on the offside wing area near the brake reservoir. This allows not only water to drain down int the chamber but also any other debris as well, leaves, twigs etc etc. This in turn blocks the drain hole which will allow the chamber to fill with water.

Three things can occur if this happens.

1. Soggy Pollen Filter.

2. Drowned ECU. An expensive fix!!

3. Water will overflow into the cabin and soak the carpets.

A solution to this has been found by Jules, a respected person on the forum. Take a look at the link below.

http://www.the75andztclub.co.uk/foru...ad.php?t=68151

Best £12 you will spend on your car when you take into account the points mentioned above!!!

Should you loose or have any of the scuttle panel clips missing, here is a link to Rimmer Brothers, suppliers of all parts MG Rover!! Item 7 on the grid is what you need.

http://www.rimmerbros.co.uk/Item--i-GRID001775

When all the above is done, some folk do the spy hole mod. Once this is done, you do not need to remove all the above to check the chamber is dry, just the rubber bung that you have fitted.

http://www.the75andztclub.co.uk/foru...ad.php?t=64542

Last but not least, whilst the bonnet is up, you might as well to the bonnet cable splitter box mod as well.

http://www.the75andztclub.co.uk/foru...e+modification

Another thread here with some more pics of how to get into the Plenum area.

http://forums.mg-rover.org/showthrea...=1#post4134512

Post #3 is the one you want.

All the jobs above are not as bad as they look, trust me!!

Hope the above is of help to you,

Regards,

Dave.

[T-Cut]

Originally Posted by daveb57

When MG Rover manufactured the car, they left an open void on the offside wing area near the brake reservoir.

The plenum performs a specific job in the ventilation system. Here's a thesis I wrote when I was younger.

The plenum is a chamber that collects fresh air to feed the interior vents/aircon system. It's located between the firewall at the rear of the engine and the wall which forms the front of the cab section. Air is supplied via the scuttle grills, which run across the body below the windscreen. It acts as a fresh air reservoir and pressure buffer. The air here is isolated from that in the engine bay.

Much of the rain and wash water draining from the windscreen also goes into the plenum, so this must be drained off. To do that, the plenum floor has two rubber drain tubes. One is accessible on the near/passenger side, but the second one is positioned under the brake servo and for all practical purposes is not accessible from under the bonnet. These tubes pass through a second panel below the plenum floor, from where they drain onto the ground. From under the car, these tubes can be seen as short, rubber nozzles with a flattened end. The flattened ends are supposed to minimise the ingress of road debris. In practice, they tend to harbor debris which enters them from the plenum. For this reason, they must be cleared on a regular basis.

It's important that the plenum remains dry because it houses the ECU. This is mounted a few inches above the floor on the firewall face. Also vulnerable to flood water is the pollen filter, which is mounted over a large hatch on the nearside of the rear wall. If the lower edge of the filter gets wet, it soon starts to smell and this gets into the cab with the incoming air. If the water gets too deep, it will overflow the pollen filter hatch and enter the interior passenger side, where the carpets will become soddened.

On Mark 1 models, there are two further rubber tubes which drain the upper plenum area. These are located on the upper front wings, near the bonnet hinges. On Mark 2 models, the driver's side drain is plugged off. This is because the drain is actually too high for water to enter and is therefore redundant. The upper drain tubes are similar to the others and have a flattened nozzle, which directs water onto the back of the wheel arch liner. From here, it runs onto the ground. An MGR service bulletin suggests that the flat nozzel should be trimmed to a 45° angle to improve drainage. Whether this is worth doing is a matter of opinion. Regular clearing of the tubes with a cane, etc. is the better strategy.

The official service schedule advises that the lower drains should be cleared every 15,000 miles/annually. In reality, this is not often enough. As a minimum, they should be rodded through on a monthly basis. If the car is parked under trees or during particularly wet weather, rodding should be even more frequent. Failure to keep the plenum dry may cause flooding of the front passenger footwell as water enters the cab via the pollen filter hatch. A wet pollen filter will soon cause a bad smell from the air vents inside the car.
Flooding may also allow the ECU to become wet/submerged, leading to serious issues with the electronic systems.

Accessing the drains and rodding them through is well documented elsewhere. In practice, it's sufficient to clear the only accessible tube on the nearside of the plenum floor. This can be made much more convenient by making a rodding hole in the water shield which lies under the grill panel. The hole should be filled with removable grommet. Then, only the grill and grommet have to be removed to clear the drain. This modification is also described in detail elsewhere. To clear the driver's side floor drain requires you to raise the car on ramps so you can prod out any debris using a thin wire. This is not really necessary if the nearside drain gets regular attention.

The plastic cross-head scrivets used to attach the water shield / plenum chamber are discontinued as OEM parts. However, Halfords sell the identical item HFX363 - Trim Panel Rivet at £2.30 per pack of 10

Windscreen scuttle panel Black Clip Part Number EYC101470PMA

Rimmer Parts Diagram: http://www.rimmerbros.co.uk/Item--i-GRID004308

This post has my quick find marker: #plen#

[daveb57]

T-Cut,

Excellent reading my friend. You live and learn every day!!

Gained something valuable from 'tother side a couple of days back also.

There is a wealth of information on these sites that can be accessed from asking about your own, and like i have done here, replying to other folks problems as well.

Dave.

[john91919]

Hi,

Many thanks all for the info and details.

Both drains have now been cleaned and cleared with very few problems (getting the ecm back into its slot took a while).

I have just bought the cover for the drivers side.

I checked the bonnet release block which was back to front and turned that around while I was under the bonnet.

Thanks again.
John

[daveb57]

Originally Posted by john91919

Hi,

Many thanks all for the info and details.

Both drains have now been cleaned and cleared with very few problems (getting the ecm back into its slot took a while).

I have just bought the cover for the drivers side.

I checked the bonnet release block which was back to front and turned that around while I was under the bonnet.

Thanks again.
John

Glad to have been of some help John.

That is what these forums are here for, helping each other out.

Personally, in the 7 years i have owned my ZT, i have saved £££'s in garage bills, even tackling jobs that i thought would have been beyond my capabilities!!

The search bar is always a good place to start, but if that fails, there is always somebody willing to point you in the right direction

Regards,

Dave.

[Germanlemon]

I found a good way to clean muck and leaves out of the plenum chamber is to tape some garden hose to a wet and dry vacuum cleaner hose. You can push it as far as the brake servo. I found it particularly useful 'cos I couldn't get the pollen filter out so space was very limited.