blank off 300tdi vacuum pump

**steane** · 17th December 2015, 02:28 PM

Originally Posted by bee utey

I'm not sure what you mean by a "V8 electric vacuum pump arrangement", the later Rangie Classics use a hydraulic pressure pump for their peculiar Wabco ABS system. The V8 Discos all use conventional brake boosters running off manifold vacuum, and some have Bosch ABS units too.

Really the amount of power a 300TDi vacuum pump took would be trivial, you're better off putting 2psi in all the tyres than stuffing around with an electric vacuum pump! Once a mechanical vacuum pump has achieved full vacuum the diaphragm would be stroking very little compared to full flow.

One of my mates with a 300TDi powered RRC uses his vacuum pump to run an aftermarket cruise control, the other uses his for vacuum trailer brakes. Neither suffers poor economy.

I'm not sure either...

What I should have said is an "electric vacuum pump" and left it at that. I would have sounded smarter than I am.

I wasn't interested from a power point of view, more for when replacing the Wabco becomes necessary. It's holding up alright at the moment.

**slug_burner** · 17th December 2015, 06:18 PM

These appear to be used in a few different cars

Hella Vacuum Pump Electric Street Billet Aluminum 12 V Includes Insulator Mounts | eBay

Not much change out of $200+ for the best prices, some prices are just stupid.

The cam driven ones are fairly simple, diaphragm and a one way valve, much like your old style fuel pump with a glass bulb on the side of your engine.

Not much to putting a mechanical one or electrical one on, either cam or belt drive, some come on the back of alternators on diesels. The electric ones are simple enough, get power onto them, they may have built in control or require external control, a piece of pipe that will not collapse under vacuum and your done.

Noise or fuel consumption are not sufficient drivers for me to change mine. If mine goes and can't be repaired by a simple service kit if they exist I may consider an electric one. So far mine is doing ok.

staplehead01 · 18th December 2015, 07:12 AM

Well sound like i should definitely remove mine because it is not even getting used

Didge · 10th July 2019, 01:47 PM

Hi guys, sorry to resurrect what appears to be a long dead thread but given that 22" or 560mm Hg vacuum equates to approx 75kpa (24 mmHg to Pascal Conversion - Convert 24 mmHg to Pascal (mmHg to Pa) - Pressure Conversion) it appears the vacuum pump should really suck like the proverbial "lady of the night" and if you place your finger on the end of the pump or hose you would have a bit of a job pulling it off again. For reference, I have read that the average vacuum cleaner produces a vacuum of approx 20kpa.
Does that sound right? My pump is sucking with the same force you might expect when sucking a drink through a straw and in my opinion, seems rather feeble. The booster servo is fine, no cracks, etc and was checked with a vacuum cleaner so I expect the pump to be the problem.
Given that the mechanical pump operates all the time, I assume if I went to an electrical one (because the Wabcos seem to be garbage) there would be no need for vacuum relief valves, etc. Any suggestions for types of electrical pumps?
Thanks in advance.
cheers Gerald

**rover-56** · 10th July 2019, 03:52 PM

One thing to keep in mind if considering removal of a 300tdi vac pump is that the air it moves helps to ventilate the crankcase of the engine.
Terry

**roverrescue** · 10th July 2019, 04:26 PM

“Ventilate the crank case”

Only if the booster has cracked! Follow the suction line from pump to booster... it’s a closed circuit and if diaphragm is intact and booster casing intact it pulls down a vacuum and holds it till brake applied.

Although some ventilation is supplied it’s not like a 300 blows up if you drive for a day without touching the brakes!

The PCV does an admirable job of ventilating the crankcase and depositing oil into the turbo and intercooler

What little gas escapes via braking suction would be more than compensated via PCV.

The Wabco pump can be troublesome but it’s not the worst device on a 300!!!!
At least it is easy to get to

To be honest, I would just replace with a new pump. Install with two gaskets, this spaces the plunger back a shade and reduces load on the pump yet still provides plenty of suction

S

Didge · 10th July 2019, 08:20 PM

Thanks gents, I hadn't thought about crankcase ventilation but had read about the extra gasket although I would have thought adding 2 extra gaskets would be more beneficial given they're rather thin.
Oh, what's a PCV? forgive my ignorance

**loanrangie** · 10th July 2019, 08:57 PM

Originally Posted by Didge

Thanks gents, I hadn't thought about crankcase ventilation but had read about the extra gasket although I would have thought adding 2 extra gaskets would be more beneficial given they're rather thin.
Oh, what's a PCV? forgive my ignorance

As above the vac pump does not ventilate the crankcase, the extra gasket is to minimise the stroke of the cam lobe on the pump as its thought to shorten its like span.
PCV= positive crankcase ventilation.

**rover-56** · 11th July 2019, 02:36 PM

Originally Posted by roverrescue

“Ventilate the crank case”

Only if the booster has cracked! Follow the suction line from pump to booster... it’s a closed circuit and if diaphragm is intact and booster casing intact it pulls down a vacuum and holds it till brake applied.

Although some ventilation is supplied it’s not like a 300 blows up if you drive for a day without touching the brakes!

The PCV does an admirable job of ventilating the crankcase and depositing oil into the turbo and intercooler

What little gas escapes via braking suction would be more than compensated via PCV.

The Wabco pump can be troublesome but it’s not the worst device on a 300!!!!
At least it is easy to get to

To be honest, I would just replace with a new pump. Install with two gaskets, this spaces the plunger back a shade and reduces load on the pump yet still provides plenty of suction

S

Yes, I know it's not much, but its worth knowing the blow by fumes are getting diluted a bit.
Terry

**workingonit** · 12th July 2019, 02:30 PM

Originally Posted by loanrangie

As above the vac pump does not ventilate the crankcase

My understanding is that air is pushed back to the crank, in small quantities, but not for the purpose of 'ventilating' the engine.

Read somewhere that engine oil is squirted/flipped/splashed at the back of the pump to lubricate it - I'll have a closer look for a squirter around the cam area next time (although an engine diagram should show or not).

Some of that oil gets into the piston chamber side and mixes with the air that has been 'pulled' from the vacuum assist. The oil polluted air is then returned to the crankcase. Once vacuum has been achieved then very little air goes back to the crank, other than what might leak from the crankcase itself at the back of the pump.

Even if there is no vacuum to pull the cam still has to exert a lot of force to work the spring that is inside the pump unit.

Normally you should not get oil migrating to the vacuum assist unit, unless the poppet valve has failed.

It is the engine oil that lubricates the piston that leaks past the stretched riveted head and crappy welch plugs they put in these units.

You could try a 12 volt Facet unit with a one way valve in the fuel line to stop drainage back to the tank when engine is off. Once the Facet unit has primed the line to the injector you could turn the Facet unit off as the injector has an internaal pump sufficient to continue pulling fuel.

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