Thread: 300tdi vacuum pump fix

I dredged up this thread since my vacuum pump is leaking oil. My question is: Are gaskets necessary (for both the vacuum pump end plate and vac pump to engine) or could I just use RTV silicone?

Originally Posted by wally

I dredged up this thread since my vacuum pump is leaking oil. My question is: Are gaskets necessary (for both the vacuum pump end plate and vac pump to engine) or could I just use RTV silicone?

I guess you could use BlueMax or equivalent, but it's quite simple to make the gaskets - go to Repco and buy a sheet of the thinnest gasket paper, impress the surface to be mated onto the paper and carefully cut it out, bolt holes can be cut with a wad punch. Use with a gasket goo or the above sealant on both sides (always seems to work for me, anyway).

Originally Posted by wally

I dredged up this thread since my vacuum pump is leaking oil. My question is: Are gaskets necessary (for both the vacuum pump end plate and vac pump to engine) or could I just use RTV silicone?

I'm on the third vacuum pump, none have leaked oil, but have failed internally and stopped producing vacuum.

When I bought the last one I was told to put a thicker (actually 2) gasket as they have been known to internally hammer themselves to death.

So I would say definitely a gasket at the pump/block junction.


Martyn

For what it's worth, I repaired one years ago that the one way valves had disintegrated in.I discovered that the valves off a CAV fuel pump from a 2 1/4 litre Landy engine were virtually identical and made for a successful repair.
Wagoo.

Originally Posted by Bushie

I'm on the third vacuum pump, none have leaked oil, but have failed internally and stopped producing vacuum.

When I bought the last one I was told to put a thicker (actually 2) gasket as they have been known to internally hammer themselves to death.

So I would say definitely a gasket at the pump/block junction.


Martyn

That actually makes alot of sense Bushie, im gunna replace mine, my fix has lasted 4-5years now and my brake performance is declining. I have some heavier duty gasket paper in my tool box i might cut my own when i fit the new one and see how that goes.

Matt

Hi All

Is there something that can be used to replace the diaphram ?
I have never pulled one of these pumps down so I can only surmise this what is inside.

I replaced my first pump and popped the old one in the wheely bin ------- I didn't know I could fix it. Gloom!

Cheers Arthur

Originally Posted by wrinklearthur

Hi All

Is there something that can be used to replace the diaphram ?
I have never pulled one of these pumps down so I can only surmise this what is inside.

I replaced my first pump and popped the old one in the wheely bin ------- I didn't know I could fix it. Gloom!

Cheers Arthur

There is no diaphram.

The pump works off a piston and valves.

Piston is driven by an internal engine cam lobe that pushes a plunger rod that in turn pushes the piston rod. The piston Rod has a heavy duty return spring to force it back to down position (or rod out position). The piston is alloy about 10cm diameter and has a rubber gasket around the rim to make the seal. In the head are 2 one way valves made of plastic.

What fails is the plastic valves. they then get chewed up by the piston and the bit of plastic and springs then get jamed in and around the piston rim sealing gasket. When it is bad the piston spring will break and the piston will seize up (usulally in the up or in position) and you will hear what is really bad tappet like noise above 1500rpm - it is just the plunger rod getting slapped back and forth as it is now not under spring tension.

How do I know I have 3 faulty units in 4 months.

Basically if you are leaking oil from the pump you can replace the riverts with M5 bolts and nyloc nuts.

If your have no brake assist, Check the lines and the brake booster for cracks causing a vacuum leak but if the you have a dead pump I think you are are better off just replacing the pump. My cost $410.

If you need to replace the booster, go genuine.

This was an after market booster, I couldn't get any decent pedal feel, you can see why.

[ame="http://www.youtube.com/watch?v=wU3CyjTFiZ4"]YouTube - ‪booster1.avi‬‏[/ame]

Every mm at the master cylinder I'd say translates to probably 5 or 6mm at the pedal.

Martyn