Engine: D52447: Vacuum Assisted Engine Mounts & Vacuum System Test

[BestGear]

Originally Posted by Shadeyman

I purchased 4mm to use between the vacuum pump and where it T's and separates. One side feeds the engine mounts/pads the other side feeds the turbo actuator, I did both of those in 3mm. I suppose I could have done it all in 3mm or even in 4mm but I wanted to keep the size quite small so it reduced the amount of air the vacuum pump had to remove from the system to maintain a good vacuum. Seems to have worked as the car responds to the throttle better now, especially from a stand still.

Many thanks

[xc90nut]

the photo that is shown whats that thing called as I may need a new one

[Shadeyman]

Originally Posted by xc90nut

the photo that is shown whats that thing called as I may need a new one

The valve in my photo is the vacuum control valve for the engine mounts.
Here's one forsale, £25.
http://www.ebay.co.uk/itm/VOLVO-XC90...-/300806790987

[Shadeyman]

I've finally finish fitting all new vacuum pipes and with a little more investigation I'm sure the O-ring seal where the feed to the braking system fit onto the pump was leaking to so I've replaced that as well. The car feels so much better now, no hesitation at all unless I instantly go from hard braking to full throttle and then its hardly noticeable.

I'm pleased to say the rear vacuum assisted engine mount isn't leaking and doesn't need replacing. I may purchase one in the coming months and replace it anyway before its next Volvo service in January.

In conclusion, if your having boost problems resulting in hesitation and ENGINE SERVICE REQUIRED, check the pump is producing a good vacuum then change all the small bore pipe. Cost me £15 to replace every inch of it, the resulting increase in performance is amazing. No hesitation, much better throttle control and judging by todays trip to Bridgenorth I'm getting slightly better MPG too.

[Shadeyman]

Originally Posted by Shadeyman

I may purchase one in the coming months and replace it anyway before its next Volvo service in January.

I finally found a vacuum pump at a good price, brought it today, hopefully it will be here by the end of the week and I can strip it down and find out exactly how they work and if they can be reconditioned, similar to how a diesel pump is done, by replacing seals etc..

[Shadeyman]

Here's a few pics of the pump taken from the eBay listing.
Took me a while to find the exact same pump as the one on my 2004 XC90. Struggled to find the correct part numbers. This ones off a 2004 V70 and looks identical.

[Ducklakeview]

Hmm..

Interestingly, whilst having a snoop under the bonnet today, seeing even more new items I noticed that the exact same valve on mine has be bypassed, by joining the two pipes together with 30mm of copper brake pipe...

Now due to it's history, and the fact that not only does no expense seem to have been spared, AND the fact it has a complete set of shiny new engine mounts, I suspect this little "bodge" has been performed by the dealer who took it in in PX, and from whom I purchased it...

So, I reconnected the pipes, and car ran like a dog, no boost.. (according to "Torque" on my phone) Reconnected the pipes together, and sweet as a nut again, so I presume said valve is in fact, duff, possibly cracked etc, I will borrow a friends' vac tester tomorrow to check...

[Shadeyman]

Originally Posted by Ducklakeview

I noticed that the exact same valve on mine has be bypassed, by joining the two pipes together with 30mm of copper brake pipe...

Valve ?

[Ducklakeview]

Originally Posted by Shadeyman

Valve ?

Yes, Item No 5 in your pic:

[Shadeyman]

Originally Posted by Ducklakeview

Yes, Item No 5 in your pic:

Thats the engine mount/pad control solenoid, it cuts the supply of vacuum to the mounts/pads(item 4) when the engine revs are above 1250rpm making them stiffer.