3200- loss of brake servo vacuum at high revs

[beau]

it has become apparent that if i apply brakes after i have done full throttle (and taken it over 4000 revs) my brake pedal goes hard (looses its vacuum) for about 1 second, then back to normal, normal or not normal? its not a usual thing to notice, the only way to really find out is to go full throttle in 1st gear to 6000 revs then try to emergency stop, doesnt really work, normal driving its fine, only when really going for it then suddenly braking which is not something anyone would do often, if at all.

 

[hodroyd]

Hi Beau,
Not heard of the one before, strange. Have you checked the vacuum pipe to see if it has any splits, or bulges..? Feel at it and see if it's squashy, if it is the pipe might be collapsing inside and bits falling off are blocking the system up under heavy use.
Cheers
R

 

[allandwf]

As above, sounds like a collapsing hose to me. had it before on an MG of all things. Might also be a sticky non return valve if there are any of those in the Maserati system.

 

[MUC3200GT]

The 3200GT has been supplied without and lateron with Kaiser Valve (Vacuum boosting) in order to improve breaking power , with the open Air filters there would be no possibility to supply the Kayser valve with additional vacuum, I would assume that one has rely on the vac from the intake manifold which is turbo pressurized at high revs..could this contribute to the issue ?



Also the diagramm show the one way valve at 2, The Kayser valve is 6

 

[hodroyd]

If one of the pipes has gone soft, the high vacuum could be sucking the pipe flat, check the pipes.

 

[Danny]

Like MUC3200 suggests, I would 1st check the Kayser valve. I have seen a couple of cars with identical symptoms as yours where the Kayser valve was faulty. Good luck

 

[hodroyd]

Let's hope that's the problem, if so a simple fix..!!

 

[deano]

Good afternoon,I experianced a very similar situation with my 3200,when i would come off the throttle from a mid to large throttle opening to immediately onto the brake pedal,to find the pedal was rock hard,and no matter how hard i pushed there was none to very little retardation,if i was to come off the pedal and back onto the brakes all seemed fine,i went down the route of new vacume lines,kayser valve,even to the extent of a new servo/master cylinder,which did not cure the symptoms,This turned out to be the phonic rings on the back axle,though this did not throw up any dash lights,they are a cheap and easy replacement in comparisson to a servo.hope this might help you in the right direction

 

[hodroyd]

That's an interesting angle Deano, never thought of that, excellent and worth a shot..!!

 

[beau]

deano, that is exactly what is happening to me, so maybe it is linked to the fact the ABS is not working

 

[hodroyd]

Hi Beau,
Have you checked that the ABS Warning Light actually works when you switch on, it has been known for previous owners to remove these so as to not show a problem.
Cheers
R

 

[deano]

i found it was more speed related as apposed to rpm,i was only lead to the phonic rings when i ggot agearbox error light come on,and come to the conclusion there was a miss match in speeds being seen by the management system,have a look to see if the teeth are corroded,there about £40 a side from memory

 

[deano]

Dont be misslead by no ABS warning light,mine did not come on and i expected it should have being safety critical,a symptom like this today would throw a light on