Fluctuating Idle RPM -Diesel P38

[wammers]

It was placed on 6, where i hv put a dab of correction fluid., visible in the picture. IIRC, 4 and 6 are about 2 links apart, and I doubt the car would even start
when timing set at 4. Anyway, I'm in deep trouble now.

I feel for you mate, but the bottom line is if the two timing marks where the correct distance apart obtaining .95 mm lift would be easy with plenty of movement towards the engine to spare. Looked at an old pump sprocket in garage yesterday, think you will find 4 and 6 are further apart than that. so as you say looking at it you would be lucky to get it to fart on 4 let alone start.

 

[wammers]

Ok further to this. Looking at the photo in post 154 everything looks good. Bright link is in correct position on pump sprocket against number 6 arrow. Pump is in correct position in relation to where it should be with chain links lined up and engine locked at TDC. Unless you changed this i cannot see how it is not possible to gain .95 lift on cam. The only possible explanation i have, is that the woodruff key has fallen out at some stage and the pump has spun in the sprocket.

 

[kapilamuni]

Thanks & appreciate your time & effort. Much relieved now.
No the wood-ruff key never was removed or fallen out. Only thing I did was rotating the pump shaft with an open ended spanner
about 2-3mm to get it aligned to pump sprocket. But I can't remember which direction.
My previous idea to remove the pump & rotate the shaft & install is based on that whenever we rotate the pump when fitted, it will be moving only the outer body

 

[wammers]

Thanks & appreciate your time & effort. Much relieved now.
No the wood-ruff key never was removed or fallen out. Only thing I did was rotating the pump shaft with an open ended spanner
about 2-3mm to get it aligned to pump sprocket. But I can't remember which direction.
My previous idea to remove the pump & rotate the shaft & install is based on that whenever we rotate the pump when fitted, it will be moving only the outer body

The woodruff key should be set vertical on pump which means the next port to be injected is to delivery valve number one. The pump should be moved on it's slots to suit the position of the sprocket with the chains set on the bright links and the engine locked at TDC. With chain bright links on marks and engine locked at TDC key way in sprocket should be at about five minutes past the hour. God knows how you have arrived at what you have. Have you put the injector pipes on incorrectly. See this, woodrufff key is vertical number one is the delivery valve with the yellow mark on it, number 5 the one below it, and number 3 the bottom one. Firing order is 153624 pipes should be fitted in that order in an anticlockwise direction looking from rear of pump.



.

 

[kapilamuni]

I'm sure the pipes are fitted in order given as I removed them after labeling .
Anyway will check them again. I need to remove the intake manifold for that.

 

[wammers]

Have you ever had the pressure head out of the pump?

 

[kapilamuni]

Not completely. When the o-ring changed it was made to push out about 4-5mm, that was two years ago.

 

[wammers]

Not completely. When the o-ring changed it was made to push out about 4-5mm, that was two years ago.

And you have possibly had the modulation problem since then. If that was not done properly with weight maintained on the cam, there is a small spacer that may have dropped out of the inboard part of the piston. That not being there would give you the problems that you have. The cam lift is measured by how much the piston is being pushed out. If that spacer is not in place you will get a false reading. Because the rollers will need to be far more advanced up the cam to give the required piston movement.

 

[Grrrrrr]

And you have possibly had the modulation problem since then. If that was not done properly with weight maintained on the cam, there is a small spacer that may have dropped out of the inboard part of the piston. That not being there would give you the problems that you have. The cam lift is measured by how much the piston is being pushed out. If that spacer is not in place you will get a false reading. Because the rollers will need to be far more advanced up the cam to give the required piston movement.

F*ck me, Wammers. Where did you pull that one out the bag? Sounds like you might be on to something.

 

[Wazzajnr]

I think he has dreams of the internal workings of the pump!

 

[Mark Piercy]

unless! He's done the same by mistake in his past. That usually gives the best experience a mistake like that! Not to criticize wammbles! Oh god almighty, fuel pumps above, blessed be our buses and may the scrapman be tempted not while wammers be still on the forum!

 

[Wazzajnr]

Never learn anything when it all goes well!!!!

 

[kds]

unless! He's done the same by mistake in his past. That usually gives the best experience a mistake like that! Not to criticize wammbles! Oh god almighty, fuel pumps above, blessed be our buses and may the scrapman be tempted not while wammers be still on the forum!

Here here.

 

[kapilamuni]

Not possible. I followed the you tube video on changing pump seals on a VW to the dot.
Before touching the pump I went through those video clips so many times & memorized all details. Even now I can do it without referring the video.
They specifically mentioned the spacer & I was extremely careful in releasing the pump head bolts to get to the o-ring.
After that the car started first time and ran fine. Those days too it had the hot start issue but not so noticeable When hot the car started after 7-8 rotations even after 10 minutes of shutting down. Frankly, I did not know about timing modulation or had any gadget to check it, at that time.. After joining this forum only I came to know about timing modulation & it's effects on the hot start issue.
Things started to get worse about a year or so ago and the car would not start even after 1 hour from shut down. The engine kept cranking untill the battery gives up. Before Dec' last year , the time delay required was close to 2 hours after shut down(virtually completely cool down engine). Hence, I opted to change the timing chains which did not solve the issue.

 

[wammers]

unless! He's done the same by mistake in his past. That usually gives the best experience a mistake like that! Not to criticize wammbles! Oh god almighty, fuel pumps above, blessed be our buses and may the scrapman be tempted not while wammers be still on the forum!

Ha Ha very funny.

 

[wammers]

Not possible. I followed the you tube video on changing pump seals on a VW to the dot.
Before touching the pump I went through those video clips so many times & memorized all details. Even now I can do it without referring the video.
They specifically mentioned the spacer & I was extremely careful in releasing the pump head bolts to get to the o-ring.
After that the car started first time and ran fine. Those days too it had the hot start issue but not so noticeable When hot the car started after 7-8 rotations even after 10 minutes of shutting down. Frankly, I did not know about timing modulation or had any gadget to check it, at that time.. After joining this forum only I came to know about timing modulation & it's effects on the hot start issue.
Things started to get worse about a year or so ago and the car would not start even after 1 hour from shut down. The engine kept cranking untill the battery gives up. Before Dec' last year , the time delay required was close to 2 hours after shut down(virtually completely cool down engine). Hence, I opted to change the timing chains which did not solve the issue.

Did you do this when the mid section was off so you could see the pump on full cam, or just guess where it was?

 

[Mark Piercy]

you may have crack your pump open just to verify you haven't made a mistake. Not to doubt, pita to strip it out but it'll confirm either way.

 

[Grrrrrr]

Could anything cause the flywheel timing pips to be out a bit?

 

[kapilamuni]

Did you do this when the mid section was off so you could see the pump on full cam, or just guess where it was?

Yes, mid section was taken out & engine rotated slowly clockwise to get the maximum push towards the head.
The said videos were on a VP37 pump which ,for me(opening an inj pump for the 1st time), had no difference with our EDC pump.
BTW, the small rod that goes into the center of head in the inj pump (with the dial gauge attachment) did not screw in as its thread was different or I did not try strongly to get it screwed in. Though the dial gauge is fixed tightly, could this give reading errors?

Also, I don't think there is another hole closer to the correct hole in the flywheel, unless a substantial deviation from cam lobe positions(the flat V) for TDC.
If nothing works, can I enlarge the pump attachment holes , so that pump can be rotated as required?

 

[wammers]

Could anything cause the flywheel timing pips to be out a bit?

They are dowels set in the flywheel damaging them is most unlikely. That does not explain why if with bottom chain set correctly, with it's bright links on crank and pump sprocket timing marks with engine locked at TDC it is not possible for him to turn pump towards engine to get .95 mm on dial gauge. With all set and fitted correctly with new unstretched chains it should be possible to exceed that by a considerable margin without getting anywhere near the extent of the adjustment slot. If he has crank locked properly and yet can only get .71 mm on dial gauge at end of adjustment slot something is wrong somewhere. That is why the piston thrust spacer was mentioned as the next obvious possibility. The more i think about it the more it fits his scenario. When the seal is changed the pump MUST be on full cam and the slot for the seal just visible or it can fall out.