Fame at last….

Regarding the V pump, the repair kit for a Mk5 and Mk6 V pump is the same and are available via Force 4 by clicking here.

As for your pressured water system, you will need to do a little investigation as there are a number of possible causes, the main one being losing pressure due to leaks as John has already stated but could also include blocked filters, kinked pipes and blocked breathers.

I guess you have already looked in the bilges to check for leaks although I would recommend you have a particularly good look in and around the calorifier and pressure relief valve when the pump is running.

Providing you can’t see any leaks, the next thing I would suggest looking at would be the filter located on the inlet side of the pump; with the pump turned off you can unscrew the cover and take it apart to clean the gauze, if there isn’t a stopcock fitted to the outlet from the tank you may wish to drain down the water tank before doing this. It is also not unknown for these filters to become damaged and let the pump draw air into the system, have a really good look at the filter and replace the seal or any parts that are damaged, a temporary fix can sometimes be effected by wrapping some self amalgamating tape around the filter body. It is possible that the pump is actually working hard trying to draw water into the system rather than making up pressure loss caused by a leak further into the system.

I would also look for any secondary water filters fitted in the system and remove or bypass them. While these filters work well, they do need regular replacement or they can produce the same effect as a restricted accumulator and the pump can run quietly for quite a time as it attempts to balance the pressure differential.

Then I would retry the system, hopefully your problem is cured. If this is the case I wouldn’t bother to replace the inline secondary filters until the spring as they are only really good for about a season and they can grow some horrible bacterial when left drained down over the winter.

If however the problem still exists then I would fill the tank, turn on the pump and then open each tap one at a time, checking the list below before turning the tap off and moving onto the next one.

Do you have good flow from each of the taps when you turn them on individually?

Does the flow drop off substantially as the tap is left to run?

Does the tap start to splutter?

Does the pump sound louder with the tap open and start to get quieter the moment the tap is shut?

Carrying out these simple tests will help identify any issue with the pipe work which maybe causing restriction

One last idea, many years ago I was completely stumped by a problem on a canal barge, after many hours of searching and head scratching I finally found a cloth inside the water tank covering the outlet, it was acting like a wick letting some water through over time but not enough when under heavy demand which caused some really bizarre symptoms. When I showed the cloth to the owners they recognised it as the one they used to put in the filler neck next to the hose pipe when filling the tank to stop the hose pipe jumping out, one day when filling the tank the cloth went missing, they thought it must have gone overboard and never gave it another thought.

Perhaps taking the cover off the tank and having a look inside with a torch maybe a good idea, you just never know what you might find!

I would be interested in hear about your progress,