Thread: 300tdi: timing for vacuum pump replacement.

Originally Posted by dogman

I am preparing to replace the vacuum pump on my 300tdi d1.

Reading some old posts it seems as if there are a few ways people tackle the
"#1 TDC" thing.

A Good thing because the official injection pump/flywheel method doesn't seem to
work for me at all.

What I think might work is if I do the job with the valve cover off and just
observe the motion of the backmost pair of spring-things that go up and down.

Watching them just now as I crank round I could notice the following:

There is a period when they are still and level with each other - all the
action is elsewhere. Then the backmost one of the pair will start to move down,
then back up, then it stops and the other one starts down, then back up, then
still again. Sound about right?

What I need now is someone to tell me what I am actually seeing here and how it
relates to tdc and succesfully doing the vac pump job. Clear as mud?

At the least can I please be put straight one some terminology:
Spring-things == valves?
Is the backmost pair #1 or #4?
Which of the pair is inlet?

Why do you need to do the timing when only changing the vac pump?

If it is so the cam lobe retracts I wouldn't worry, you can always rock it over by hand a few times until the pump sits in better

Originally Posted by shack

Why do you need to do the timing when only changing the vac pump?

If it is so the cam lobe retracts I wouldn't worry, you can always rock it over by hand a few times until the pump sits in better

"timing" in the subject was probably misleading.

I've just taken the old pump off and I can easily bolt the new one on, connect everything else and possibly it will all work just fine.

Because I'm new to this I read up a fair bit before doing anything, and then I get hung up on the warnings. Haynes and the LR 300tdi overhaul manual both say the engine must be at #1TDC when you bolt on the new pump. I don't know how to recognise #1TDC when I see it.

Looking in where I took the old pump off there are 3 "lobes" or whatever that go round when I turn the crank. Can I use them as any kind of guide?

From what you say It sems like I'm worried about nothing - there is no possible way this job can go wrong. Is that fair?

I'm going to repco in the morning for a gasket scraper. Will I also need some kind of spray or solvent to get it off? Got some isopropyl at home - thought I might try that.

Originally Posted by dogman

....

From what you say It sems like I'm worried about nothing - there is no possible way this job can go wrong. Is that fair?

.....

Yeah scraper is handy if you don't have, but any blade will do, even a paint scraper/putty applicator(steel) will do the job easily. If any hard to get bits still persist, brake cleaner on a rag helps.

As shack said, you don't need to worry about timing for vac pump. But if you can get it on easily, then not to worry, there are two lobes on the cam for it to pump, easiest way to install is to have the motor turned so that the two lobes are vertically aligned, ie. not outward which puts pressure on the pumps piston, and hence harder to install.

FWIW: to get a quick and dirty check of #1 TDC there is a very small divet on the harmonic balancer. If the balancer has a few klms and caked in oil, it'll make it doubly harder to see it, so use some of the brake cleaner on it, around the (rear)outer rim. If cleaned really well, you will more likely feel this small divet/recess, rather than see it.
On the timing cover at about the 11-10(ish) o'clock position is a wee tiny arrow that you will more than likely not see or feel as the timing cover is almost certainly caked with old grease/oil/etc.
The small recess on the HB lines up (roughly speaking) .. with the almost non existent arrow on the timing cover to get you an approximation to #1 TDC(but this may also be 180°C out too).
The crank spins 2x the cam speed. SO real TDC is seen via the small timing hole behind the cover that hides the IP pulley.
If you have AC(more than likely as this is posted in the Disco section), this means the AC adjuster needs to be removed. No AC it'll just be a round triangular cover.

But as said, TDC isn't needed for vac pump removal/refitment.

Front piston/cyl is #1, on the inlet/exhaust side on the passengers side behind the alternator is #1 exhaust port, inlet #1, inlet #2 exhaust #2 ... etc.

if you want to learn more about the Tdi, and video is the easiest way for you to visualise it all more readily, get onto Youtube and search for Brittanica Restorations. 99% of his videos are on Tdi's. There are others that do Tdi's too, but BritRest(Mike) has so much content on there you will certainly find info you are looking for.

Originally Posted by AK83

if you want to learn more about the Tdi, and video is the easiest way for you to visualise it all more readily, get onto Youtube and search for Brittanica Restorations. 99% of his videos are on Tdi's. There are others that do Tdi's too, but BritRest(Mike) has so much content on there you will certainly find info you are looking for.

x100. Mike knows his stuff, and he's a really good teacher.


Britannica Restorations Ltd - YouTube

cylinders and valves are numbered front to rear and its a 4 stroke diesel

1-4
1-8
pots 1+4 and 2+3 are on the same phase of the crank (they go up and down together)
the valves rock on the rule of 5, if 2 valves on 1 cylinder are moving at the same time then that cylinder is rocking. the other cylinder of the pair is ready to do a power stroke so both valves are now closed. 2+3=5 so pot 3 is ready to adjust

the 4 strokes are, induction (suck in fresh air) compression (squeeze the air till its hot) Power( fuel injected, catches fire makes heat and pressure and pushes the piston down) and exhaust (blow the burnt gasses out

so for 2 cylinders (2+3)
if 2 has its valves rocking then 3 is at injection and is about to do its power stroke this means 2 is about to do intake
so
2 power, 3 intake
2 exhaust, 3 compression
2 intake, 3 power
2 compression, 3 exhaust

The valves follow the rule of 9 if 1 is open then 8 is closed and can be adjusted

But you're doing the vac pump. soooo...

screw that noise, unbolt it while you push it in with one hand, if it didn't push out put the new one on, if it did, look at the cam double lobe and turn the engine 180 degrees.

use 2 gaskets and hylomar #3 to seal it.

Originally Posted by Blknight.aus

...use 2 gaskets

Thanks Dave.

Not an expert on cams and followers. I've assumed the follower should always touch the cam and have smooth progression around the lobe geometry - there should be no 'thumping' reconnects. Any chance two gaskets could change this or there is still margin for full contact? Or my assumption the follower and lobe should always be in contact is incorrect.

Often seen the two gasket recommendation but hesitant to try it after the 'shove a coin behind the belt tensioner to stop squeal' debacle I let myself in for once. Or where I was the victim trying to undo the harmonic balancer bolt on a newly acquired vehicle where a previous owner had taken the online advice to 'locktite the bolt' rather than torque it correctly, and the key way was munted regardless.

Cheers.

Originally Posted by workingonit

Thanks Dave.

Not an expert on cams and followers. I've assumed the follower should always touch the cam and have smooth progression around the lobe geometry - there should be no 'thumping' reconnects. Any chance two gaskets could change this or there is still margin for full contact? Or my assumption the follower and lobe should always be in contact is incorrect.

Often seen the two gasket recommendation but hesitant to try it after the 'shove a coin behind the belt tensioner to stop squeal' debacle I let myself in for once. Or where I was the victim trying to undo the harmonic balancer bolt on a newly acquired vehicle where a previous owner had taken the online advice to 'locktite the bolt' rather than torque it correctly, and the key way was munted regardless.

Cheers.

its a simple rotating flat follower, not a roller. Pretty much at this point trying to use similarities of a system that is direct operated at about 17pound of spring force (might be KG I'd have to dig out the spec to confirm) as compared to a system thats operating at a mechanical disadvantage (small lever moving long lever) against much tougher springs is (putting it bluntly) over thinking it.

that said

primarily it reduces the pressure on the spring, and brit part ones from exploding "entertainingly" when the laws of physics provides an adequate demonstration about the incompressibility of metal vs the compressability of gasses due to build tolerances that are about as accurate as a Melbourne weather forecast

just hylomar or sika 2 gaskets together, slap it together and then when its dry send it.