vacuum leak (CVT)

Post by **ebdl** » 30 Apr 2006 06:24 pm

In the ongoing quest to make my 340 driveable...

I'm searching for vacuum leaks. I think this (above) is known as the 4-way valve for the CVT system. At either end of the big rubber domes I can feel air being sucked in and make the noise louder by placing my finger over the holes where the wires go in. I suppose my questions are i) is this normal?, and ii) what should I do about it?

Today I also noticed, after turning the engine off, that as the car was cooling down there was an intermittent "wheesh" of air being released from somewhere. I couldn't really identify the source of the sound, so if anyone recognises this and can tell me the likely culprit that would be very helpful.

Thanks, Ed

Post by **wjp01908** » 01 May 2006 05:13 pm

I don`t think this is right - I`m not sure of the internal workings of the valve, never having had a dodgy one, but I suspect things have gone awry if air is being sucked in at the dome ends. AFAIAA there are two solenoid operated valves and I have heard that the rubber seals can perish - I suppose this could lead to suction in the wrong place.

Solution? Possibly the seals can be replaced though I would not know where to get them (if indeed this is the problem) maybe a new or SH 4 way valve.

I`ve got another one in the shed - I might just go and have a look inside and report back.

Will

Website · Post by **antiekeradio** » 01 May 2006 05:22 pm

leaking through the housing indicates torn off valve rubbers or wrong assembly. (most parts fit in 3 different orientations

)

replace by known good. 85 euro @volvo dealer.

Post by **wjp01908** » 01 May 2006 05:34 pm

Ok just had a look and it seems the only way it can leak out the ends is if the seals are gone. Maybe also a crack may do this.

I don`t know how brave you are but I`d open it up and have a look - make a load of drawings / photos so you know how it all goes together and be careful when you open it - the 3 screws at the end go all the way through and it all comes apart in your hand if you are not careful.
Best take it off the car and do it on the bench so you don`t lose bits.

You may get lucky and find a seal just has a bit of crud preventing it sealing.

Incidentally anyone know if the boots serve any useful purpose - my car doesn`t have them.

Will

Post by **foggyjames** » 01 May 2006 06:55 pm

No useful information from me, just a 'thanks'. The CVT is the one model that we haven't had much coverage on, so I'm very glad to see some more technical posts on this subject. Thanks guys

cheers

James

Post by **ebdl** » 01 May 2006 11:11 pm

As long as there are people to provide answers, I foresee a lot more CVT-related topics cropping up in the near future.

Thanks for the answers so far. I'll get a replacement from Volvo and then take apart the existing one to see what's going on. It makes me sad to see the car out of my window and not be able to use it

Post by **petefarrell360** » 13 May 2006 12:32 am

The early vacuum stystem for the CVT like yours Ed is shown in the Autodata book in some places, I can't remember if there was much detail or not. Then I also don't know what the differences between early and later types are, so be careful when getting a replacement.

I too hope to be part of the CVT advice section, if I ever find time to work on it! It's good to learn more about the CVT.

Pete

Website · Post by **antiekeradio** » 13 May 2006 09:55 am

Then I also don't know what the differences between early and later types are,

1978-1991: none... all CVT parts interchangeable.

Post by **ebdl** » 13 May 2006 01:16 pm

I've got the replacment part (about £65 from Volvo) and hopefully fitting it next week sometime. I'll let you know how it goes.

Post by **petefarrell360** » 13 May 2006 11:30 pm

Ahhh right, point taken mate! All I knew is that they looked slightly different, which may have meant different connections or some working difference, but that's useful info that the parts are interchangeable all throughout the 340 CVT's.

It only looks like the black end caps are missing, and different lengths of pipe tbh!

Glad you've got the part, let us know how things go.

Pete

Post by **foggyjames** » 14 May 2006 11:17 pm

Looks like the T piece is out of shot on Ed's picture...otherwise the same, minus end-caps. Had me going for a minute!

cheers

James