Crunching when trying to get gear on CVT

[morgan105]

HI all,

Anyone got any ideas of what the problem may be? Car runs fine but once it has a drive it gets difficult to change gears, crunching noise. I have checked the microswitch and seems to be working fine, new clutch put in and spaced correctly, warning light works but buzzer is intermitent when pressing down button, no holes in any vacuum hoses and are secure, declutching servo gap is correct, emissions and revs are right down but still get the crunching.

Just wondered if it has anything to do with the buzzer being intermitent? Maybe a dry joint in solder on the gear change or possibly somewhere else, but where are other possibilities of dry solder joints in the circuit for gear change?

How does the vacuum regulator valve work, white one located at bottom of engine bay. I have vacuum to it and very little coming out so should keep the declutching servo off on low revs.

This started before the clutch was changed so looking for any other ideas on what to look for.

[trabitom99]

Do you mean this?


Mine wasn't working when I bought the car, and the only way to change gears without crunching, with the engine cold, was to push the choke back in every time I wanted to change gear. But if the gears are still crunching at very low revs, it's unlikely to be the declutching servo.

Having said that, are your revs really low? If the idle speed is set just a little bit too high, AND the declutching servo is broken, then you can get gear crunch even with a warm engine.

Tom

[morgan105]

That is the thing i'm talking about.

Wifes just said it will do it when cold if choke is half way out so now sounds like it could be this. How do you know if it's broken, how do you test this? Just wondering if it may be a earth fault?

[trabitom99]

If it's not working, and the choke is half way out, the gears will definitely crunch. I don't know how to test it TBH, other than wiring up a replacement (like I did in the pic) to see if it really is that part at fault. You can't really open them without breaking the casing.

Tom

[macplaxton]

It'll crunch at anything above warm idle if the declutch system isn't working. Then you have to adopt the old-school DAF approach to shifting the stick.

As Tom said, check that the thing is actually declutching.

With the selector in Drive, depress accelerator and note at what point the car moves forward. Then, do the same in Drive, but this time with the button on top of the lever pressed down. If it works, it shouldn't move forwards until the revs are around 2000rpm or thereabouts. If it still moves forward at just over idle, there's something wrong with the declutch, which can be electrical or vacuum. If wiring is okay and the thing is clicking then perhaps get a vacuum gauge* of the pipe end on that thing in the photo on the servo side and see if it's actually sucking when it should.

* or finger or cheek or back of hand, etc.

[trabitom99]

IIRC, if you don't get the "clicking" sound, there is a microswitch in the gear selector which can be at fault. Hard to source these days, can be remedied by swapping the whole gear selector mechanism over.

Cheers

Tom

[macplaxton]

The microswitch shouldn't be a problem to get hold of. Like microswitches on DAF carburettors, they're off-the-shelf switches. Not Volvo specific, so if you know what to get, it can be got so to speak.

I recon the solenoid in that clutch vacuum unit should be fairly reliable (like the main vacuum valve), but the rubbery bits inside may be causing the issue. I've never had one apart, so I'm working in the dark a bit here. (Only had a main vacuum valve in pieces.)

[morgan105]

Only hear a click on the valve when ignition is switched on not when button is pressed. Seems a bit intermittent in working as will click sometimes. I know power gets to the switch so will check tomorrow and run a seperate earth to see what happens. Possible bad connection somewhere on the gear stick as the buzzer is also intermittent. Will also check the small diodes on the gear stick.

If I don't find anything in the wiring or switch are the valves easy to source?

[trabitom99]

Every 300 vario had them, and AFAIK all Volvo 66's as well, so it shouldn't be that hard. My first port of call would be Dafhobby.

Cheers

Tom