Bosh Pump. Intrernal pressure. What is ist?

[TimothyUA]

Today I've heard an interesting info:it appeares, that mechanical Bosh pump can have a WRONG internal pressure which corrupts it's perfomance.
Nonsense? Or truth?

[TimothyUA]

Yes, sir!
It worked!
Taking measurements of the internal pressure gave up the figure of 2 on idle, 6 on max revs.
The pressure control valve was repalced, it showed 4 on idle and 9 on max revs( supposed to be 5 and 10).
Still, results are fantastic.
The van hardly drove 115 km per hour, now-140.

[vanfox]

Can somebody explain what is being discussed here?

[TimothyUA]

Easy)
My van became very sluggish.It wouldn't go above 110 km per hour, mountain was like hell.
You can see a link-that's how you measure the pressure inside the Bosh Pump.
https://www.youtube.com/watch?v=yhC4fsdN12Y

[vanfox]

Just looked at the youtube clip, can't understand how to check and adjust. Is there an English clip with a better explanation?

[TimothyUA]

Ok, you need the device similar to the one, that is being shown-pressure gauge. The one you see is dirt cheap.
You will need a hose of the right size and a 14 key.
With the 14th key undo the the screw-it's on left side of the pump, the biggest screw.Then start the engine-diesel is supposed to come out.
Turn the engine off, fit he the hose with the manometer and start the engine again.
When idle, the number on the manometer is suspposed to be 5, 5,6.
Manually rev the engine, the figure is supposed to rise up to 9-10.
If the pressure control valve is stuck, figures will be much lower-like in my case.Usually you can fix the problem by hammering the vavle slightly.In my situation, i had to repalce the valve.

[Keef]

Is the pressure control valve that you are checking the same thing as the torque tube or is that a different item?

[dieselhead123]

Is the pressure control valve that you are checking the same thing as the torque tube or is that a different item?

See here mate, about 2.10 in;
https://www.youtube.com/watch?v=5yc-zAG3x08

Don't try this at home

TIM

[andypdq]

Right, there is a vane pump at the front end of the IP, this has two functions, it acts as a lift pump ( the Di will run perfectly well without a lift pump, if your lift pump dies you can by pass it) and it pressurises the fuel in the injector pump housing. This has nothing to do with delivering fuel to the injectors, it helps to feed fuel to the main pump head and controls dynamic timing. As pump speed builds the pressure in the case rises relative to pump speed. This pushes on the timing piston which advances the timing. The pressure regulator regulates the pump case pressure so that it is correct at various pump speeds, thus ensuring the rate of timing advance is correct. If internal pressure is too low, then the engine will run retarded, which is what your problem was.

This Bosch publication explains all. http://gnarlodious.com/Vanagon/Bosch_Pu ... _Pumps.pdf

[TimothyUA]

Yes, it was running retarted indeed.
To say the least...Imagine not being able to get up the hill in 3d gear? That was horrible.

[TimothyUA]

Right, there is a vane pump at the front end of the IP, this has two functions, it acts as a lift pump ( the Di will run perfectly well without a lift pump, if your lift pump dies you can by pass it)

can u show me where it is?

[vanfox]

The Bosch pdf is very informative but don't tell you how to check the pressure or where to attach the gauge.

In the youtube vid...... What is the guy doing with the punch and the hammer? Surely this is not the way to set the pressure !!!

Anyone give us a clue? With pics?

After 15-20 years I wonder how many pumps are still running on factory pressure?

[TimothyUA]

"n the youtube vid...... What is the guy doing with the punch and the hammer? Surely this is not the way to set the pressure !!!"
I did not see that part, but yes-the valve gets sort of oxidized and yes, hammering it slightly sometimes produces very good results.

[andypdq]

The Bosch pdf is very informative but don't tell you how to check the pressure or where to attach the gauge.

In the youtube vid...... What is the guy doing with the punch and the hammer? Surely this is not the way to set the pressure !!!

Anyone give us a clue? With pics?

After 15-20 years I wonder how many pumps are still running on factory pressure?

The punch and hammer is exactly how the pressure is set, knock the pin down and you increase the preload on the relief valve spring which raises the pressure. I call it the mechanical "Pump learn" Later on in the video, you will see the timing piston movement being checked, the procedure is, set the internal pump pressure to the correct values for specified RPM, then check the displacement of the timing piston, at specified points, then shim the timing piston springs to give the correct displacement at specified RPM. This is what we do with the MTDI Duratorq pumps, I built a test rig to do it: https://www.youtube.com/watch?v=zaHNZEnOa_o

Probably very few are running at the correct settings. I don't know yet what the correct pressure settings and piston displacement figures are for the Di pump, but will be finding out, when we can wring the information out of Bosch, who like to keep all this stuff a well guarded secret, jobs for the boys, don't you know.

I'm beginning to sound like DBVM.

[andypdq]

Right, there is a vane pump at the front end of the IP, this has two functions, it acts as a lift pump ( the Di will run perfectly well without a lift pump, if your lift pump dies you can by pass it)

can u show me where it is?

The Di has a seperate fuel lift pump which is fitted at the rear of the engine on the left hand side. It supplies fuel to the injector pump and is totally unnecessary. If it fails it acts as an obstruction in the fuel line, by pass it, and it will run fine without it.