No boost 2.0 D and repair

[IainG]

Hi
Parked up yesterday with no issues, came to drive away and there was no turbo boost at all.
Realised it was a "Turbo" issue as opposed to an intercooler or charge air pipe split as there was no black smoke, just no power.
It was not in limp mode either.
I discounted the Turbo itself as it was working perfectly before I parked.

I had a spare new solenoid so decided as it was a five minute job I would just change the TCV solenoid. No change.

I checked all the vacuum pipes best I could and all looked fine.

I then changed the other 2 solenoids one at a time, with only minor improvement when I changed the lower of the 2 sitting under the alternator.

Still about 70% power missing.

I read the codes and there were loads, cleared them and retested.
Various communication ones related to turbo control circuit so my heart sank.

However I have a vacuum test gauge so decided on a bit more logic.
"T" 'd it in to the vacuum line near the vacuum pump
Zero or as near.
Blanked off the pipework going down to the 3 solenoids, that control
Turbo,
Intercooler bypass valve,
Anti shudder valve,
The latter 2 are on the "Y" air intake "Throttle body"

Went up to 20" vacuum. In the end I just removed all the vacuum pipes and refitted new pipes that came with the new solenoid valve ( Volvo 30757740)

The pipes replaced all the pipework for the TCV and also the top solenoid below the alternator.
Still had no vacuum.
The lower of the 2 solenoids below the alternator still had the original hoses as they didn't come with the solenoid.
Had 2 spare lengths of hose and fitted to lower valve. 20" of vacuum now
Checked the hose removed and found a small split on the underside of the elbow.

Whilst all in bits I checked the 2 valves on the throttle body just by running the engine and using a vacuum hose direct to each actuator and watched them move. I cleaned and tested the temp sensor(12K ohms) and removed loads of carbon from inside the throttle body.
Test drive and all is back to normal

I was a bit daunted with all the vacuum hoses going everywhere but now realise it is so simple

Basically the vacuum from the vacuum pump goes via a hose with a non return valve, to the end connection on each solenoid but also there are 2 connections by the oil filter on the engine. I believe these 2 pipes basically attach to a sealed plastic empty box. This I believe acts purely as a vacuum store or accumulator. The inner pipe fitting on each solenoid goes to its associated actuator. Such a complicated looking system but actually very simple.
The new valve comes with a set of hoses and one of them (the main vacuum feed pipe) has a non return valve fitted. The car didn't have one fitted so I fitted the new valve as I assume it is a modification.

The Solenoid fitted by the battery and vacuum pump is the TCV and controls the turbo boost

There are 2 solenoids on a plate under the alternator.
Top one does the Anti shudder flap
The underside one does the Intercooler bypass flap (used during regeneration to help raise the charge air temperature I believe)
All the solenoids are the same and interchangeable.
They can be tested with 12 volts and you hear an audible click
All the various related fault codes have reset and gone
Hope this is if use to everyone, if you notice any mistakes or have any questions let me know.

When I bought the solenoid a few years ago I was told the solenoid on its own was £50 but if I bought it with all the hoses (30757740) it was £29 !!!! The number is described as "Hose" but does actually come with a solenoid as well.!!
so I bought one with all the hoses.

[Sidonas]

Here's a visual representation of the entire system:

https://i.imgur.com/apNRBEJ.jpg

Euro3 (single throttle body) engines don't have the "C" valve and all of its connections, other than that it's the same.

[IainG]

Hi

Excellent, wish I had seen that before!!!
However matches mine exactly

Thanks

Iain

[Tannaton]

It's great when members take the time to do write ups like this - it will save someone hours and hours one day. Thank you.

I had this on a S40 once, I just swapped over the solenoids and jammed open the anti-shudder valve and I suspect the car is still being driven around like that today....

[IainG]

Hi

Just to put everything in one place.

Stealing this picture from Sidonas (in case the picture link breaks) and putting it on the forum


Euro3 (single throttle body) engines don't have the "C" valve and all of its connections, other than that it's the same.


Iain