2.25 petrol vacuum system

I've noticed there is a lot of talk on here about the diesel vacuum set up but not much, if anything, on the petrol.

Does anyone know the set up on the petrol? I have no vacuum to the servo and I suspect that is the cause of my brake warning light as well. I've seen talk of fitting an electric pump which may be the result but if I can repair what is there first rather than adding electrics.

Many thanks!

You don't really need anything on the petrol other than a pipe from the servo to the manifold. When you take your foot off the throttle in a petrol it cuts off air and fuel to the inlet manifold and the engine is still sucking so it creates a vacuum. On a diesel there is no need to cut the air, just the fuel and so there is no vacuum for the servo. On series machines there is an extra throttle just to create a vacuum for the brakes which is the bit everyone talks about.

If you brake warning light is on you need to find out why. This is not that simple as there are differing sets of sensors depending on the age of vehicle. You should be able to work out what you have from the wiring diagrams, you then need to work from the furthest sensor in disconnecting each until you find the one causing the fault light. The warning sensors are all wired with one wire in, one wire out to the next sensor round in a loop to a test switch which lights a light when you press it.

Loss of vacuum assist will cause the brake pedal to feel heavy/hard. A simple test is to get in the motor with the engine off, pump the brake pedal a couple of times then press hold down firmly, but not hard. Without removing your foot from the pedal start the engine, you should then feel the pedal move down on its own as the vacuum assist starts to work. If that's not working check the pipes and unions to the manifold, if they're ok your servo might be knackered.

A bad vacuum leak on a petrol will usually also show up as the engine idling badly/erratically though that can end up being masked by richening the idle mixture.

Thank you so much for that, I didn't think it would be too complicated.

I'll check out the vacuum on it tonight and see what the score is, again many thanks!

Lack of vacuum can be a dodgy non return valve on the servo. Find out why the warning light is on though.

Warning light is low brake fluid.

The warning light is definitely not from low brake fluid.

There are three occasions where the warning light will come on, loss of vacuum, imbalance between front and rear braking system due to leaks or pushing the switch itself to test the bulb. Or number 4 and a plus point of it being a landy, if one of the switches is buggered. :grin:

What year is your landy?

1983

That's why there are extra functions then.