It works as a servo, but I think it's also broken. If I ram the brake pedal at idle the engine note changes and the afr leans. Correct me if I'm wrong... Normally there is vacuum both sides of the diaphram. Press brakes lets air in the atmosphere side via the breather but it's not supposed to pull air continuously right through the servo into the manifold? I should know this.
I had something similar there is a test some where ste u can do on ratwell I think but mine was missing the 1 way valve Sent from my iPhone using Tapatalk
I believe that’s how they work. Vac on both sides until the valve lets in air on one side. It’s atmospheric pressure that does the pushing. I’d change it anyway.
Either the valve inside between the two halves is leaking (gets my vote) or the diaphram is split. Either way I'm glad I didn't send the servo back. This bloke is good, clear, fast, no words wasted. I like his snap ring pliars. Is he on coke?
There is a double valve thing going on. One part closes the path between the halves while the other lets atmospheric pressure into the pedal side.
Why didn’t I use an old pair of underpants to catch brake fluid ? A gem. Like the way all the fasteners ping off in all directions.
There wasn't a wasted second! No messing with vague descriptions of how it works - 'ere, I'll chop it up and show you. All that time I wasted looking at diagrams!
I think servos are like compensator valves. You can look at diagrams, but you’re still none the wiser as to how it works...
None of the ones I looked at explained how they work, nor did the descriptions on the linked pages. Too much glossing over the crucial valve. In effect I've got a split o-ring in there.
Today I drove to Halfords for brake fluid and a new drip tray - someone, probably me, ran over the last one. Servo is working fine, no leakage.
....so I've ordered some 15w40 oil. I'd been going down from 20w50 to 15w40 to 10w40 just because. 10w40 is too thin when it's cold, it takes too long to build pressure.
20W50 mixed 50:50 with petrol is typical.. And taking time to build pressure sounds like a tiny air leak allowing the oil to run back. I see pressure rising immediately on cranking, which goes up to about 60 psi as the engine fires up..26mm pump..
The way you test them is to switch off the engine you should then have three to five applications of the pedal still with servo assistance before the pedal goes hard, obviously do this when stationary.
Yes, that was working after replacing the jammed non-return valve but it was drawing air right through the servo too. Now after some exercise it's stopped leaking through. I don't think I'll be returning the servo I bought though or the next day, sod's law, it will play up again!
If you’re using a standard oil filter try one with an anti-drain back valve such as a Mann W920/14; it might help with initial oil pressure build up especially when you have an external cooler. 15w40 should be fine but I'm using 15w50 until the ambient temperature drops.
All groovy with the 15w40. The 40 bit is fine, the 10 bit is too thin for mine certainly in the summer.
