DAF 33 over-revving problem

[howard]

Hi Folks!

One of my 33s has a problem in that it doesn't seem to want to be "changing gear" the way it should.

Basically it just seems to rev far too much compared with the others I have. Easing off at 20 or 30 mph for example doesn't seem to make an awful lot of difference.

I have replaced all the vacuum pipes and blowing down both pipes to the vario shows the diaphragms are seemingly intact.

I have also changed the vacuum switch and also the valve behind the carb where the pipes connect with known workers yet I still have a problem.

The adjustment of the linkage behind the carb compares with the other cars I have.

The hill descent button is functioning as it should - does anyone have any ideas of what I can try now?

Many thanks!



Howard

[pauldaf44]

Apr 8, 2014 20:16:12 GMT howard said:

Hi Folks!

One of my 33s has a problem in that it doesn't seem to want to be "changing gear" the way it should.

Basically it just seems to rev far too much compared with the others I have. Easing off at 20 or 30 mph for example doesn't seem to make an awful lot of difference.

I have replaced all the vacuum pipes and blowing down both pipes to the vario shows the diaphragms are seemingly intact.

I have also changed the vacuum switch and also the valve behind the carb where the pipes connect with known workers yet I still have a problem.

The adjustment of the linkage behind the carb compares with the other cars I have.

The hill descent button is functioning as it should - does anyone have any ideas of what I can try now?

Many thanks!



Howard

Try disconecting the vacuum line from the rear of the manifold and plug it, then take her for a spin to rule out problems with the vacuum system. Also are the vacuum pipes in the right order, if there wrong then it will hold it in a lower ratio rather than assisting change up

[Nick]

reversed pipes I reckon

[howard]

They're definitely right Have checked with pictures on the 'net, the manuals, and indeed compared with the other cars! It really isn't that simple - honest! Haven't plugged the hose at the back of the manifold yet. It's a weird one though, that's for sure!

[macplaxton]

Have you tensioned the belts?

[howard]

That's not a bad idea - I might have been thrown by thinking it was simply a vacuum issue. That'll be the next thing to check! Cheers, Rich!

[macplaxton]

First place to start Howard, as slack belts will put the gearing low. Don't go for a mad gap (2-3mm) though, the Service Bulletins give it all this "improved materials" talk and so revised that to the 1.5-2.00mm and no more than 0.5 difference side to side.