[shankalanks]

All

I can see that there might be some raised eyebrows over final-tightening of the rear crankshaft bolt after loosening the pump pulley lock.

The logic here is that the pump lock is only needed whilst there's a chance that the pump-tension can cause the camshaft pulley to slip on its taper. Over 75nm or so (I made that up) it simply isn't going to slip with the pent up force in the pump.

So if you unlock the pump now and do the final tightening using just the torque-wrench and counter-hold, if there's any slippage here it should be so small as to be managed by the fine tuning of the idler pulley. That's what it's for. And significantly there's no potential to damage the pump now, which is most important.

Perhaps wrongly, I feel there's a hangup with the idler-pulley being set to its reference mark. There is no difference as far as the engine is concerned between 0.55 timing with the pointer 1 cm to the left of the casting ridge, or 0.55 with the pointer 1 cm to the right. All that has happened is the orientation of the four pulleys involved has rotated round a point mid-way between the tension and idler pulleys.

The other suggestion of using the gears/crankshaft and belts may be a little more suspect . . . .

Ciao - (I'll keep updating this post because I can easily find it for my own reference without using the search function.)

 

[bournricha]

Yep ,I think you are right about the rollers and pump position .Takes some getting your head around !160nm is a lot .Holding tool essential .Dont think you should give that sort of torque to the belts though .Think pump must not be locked while torqueing up .The Brickwerks guide suggests rotating and checking with it just nipped up until your are sure you have got it where you want it .Good Luck!

 

[MPH 76]

160 nm and 180 degrees is possible on the ground as I recently done it myself, i used the lock tool and wedged a metal 3/4 bar against the chassis leg and the tool. Now when it came to the 180 degrees i used white paint on the new crank bolt painted at 12 o clock then used my feet to push my 3/4 inch ratchet and 27mm socket till paint mark was facing the 6 oclock position or 180 degrees. Good luck with it

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[shankalanks]

Hi MPH76

The 160nm we're referring to is the rear camshaft pulley when the pump-timing belt is being fitted.

I think the cambelt damper pulley is easier in some ways because of the way you described, plus you could also use hydraulic jacks to finish the extra 1/2 turn. I believe mechanics use the paint-mark method with an air-impact-wrench.

Cheers

 

[MPH 76]

Oh yeah sorry I misunderstood, I use a torque wrench and the counter hold tool, I don't use an air impact gun. But hell yeah these engines need to be done correctly, I brought my T4 with a loose crankshaft pulley and I suspected it was down to a poor quality timing and injection belt replacement. The camshaft was snapped in 4 places, and the crankshaft gear keyway was rounded off.On reading the invoices that came with my van I discovered it had a new timing belt and injection pump belt 1500 miles ago, I also found the injection belt was way too slack. Any engine with an odd number of cylinders relies on balance, my theory is that the injection belt tensioner was fitted incorrectly and this slack in the belt caused resonance that transfered through the camshaft and caused the crankshaft keyway damage. There was tip ex marks on all the pulleys and the rocker cover was in my opinion never removed during the timing belt replacement. Second photo here is off the slack in the injection belt that i found. Also the tensioner as mentioned here in this post was not in the correct position but was tight.

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[shankalanks]

Howdy

OK, short one this time as I need to replace the tensioner on the pump side as the locating tab has bent. I think I may have unscrewed the 13mm bolt a bit too much which allowed the tab to pivot out of the locating slot. Not knowing this had happened meant that tightening the bolt then distorted the tab enough to make it unpredictable. Of course I could blame the VW garage instead. Oh well, just learning-curve stuff - have to be more careful next time I think.

This happened after first start of the engine, when VagCom showed an avg. advance of 0.70 despite me explicitely setting the DTI to 0.55mm lift. I'm not quite sure why the dynamic reading (warmed engine, basic settings etc etc) was significantly different, though I found I could lower it using the rear idler. Anyway, for fun and practice, I decided to redo the pump timing from scratch which is when the tensioner decided to damage itself. Engine took a while to start the first time which I guess was loss of diesel in the fuel lines.

So question is, is the timing discrepancy caused by:
Poor technique (very possibly)
Duff DTI, well I checked my cheapo DTI against a Mitutoyo model and there wasn't enough difference for this job (so no)
Slight movement of the tensioner body in the slot under load, coupled with belt-flex under load (maybe)

So this raises the question about the accuracy of DTI setup without dynamic s/w follow-up. Anyway in contrast to what I said in an earlier post, I now expect to go a**l and once I have the idler and tensioner in their reference positions and stable, then I am likely to do any timing adjustments >5 by slipping the belt on the cam (aiming to get 55-60 as the 'cloud range'). Ultimately I will be comfortable so long as the absolute maximum stays in the low 60s.

Won't be able to do anything for three weeks or so now but not a problem. Also pleased that I finally managed to find the obscure 'service position for the long-nose version', NOT the short-nose version which has about 100 YouTube videos.

Just to add a useful picture, I found that an o-ring at the base of the DTI adaptor made it more secure on the pump, and also allowed it to be rotated so I could get the Allen key in the grub-screw.

Ciao

 

[MPH 76]

Most people say forget the dti use vcds, they also mostly say don't set it to 0.55 lift set it to 0.70 unless it's a brand new engine, some people even say advance it as much as possible till it smokes and then retard it a bit. So when i done mine I set mine with the dti to bang on 0.55, with the thought it must be the best base setting. I found it started immediately and there was no smoke and no diesel rattle. So I stayed with that and never bothered with the vcds. I think the vcds reading is a compensated reading.

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[shankalanks]

Think that's going off topic and deserves a discussion of its own (which probably already exists on this forum).

Alternatively I'm sure there are many opinions about DTI vs VagCom vs VAG1552 on the RossTech forum, but I have to admit I am not brave enough to diss VCDS.

All I can say for sure is the generation of a 'cloud' of timing marks suggests timing is not an exact science and 0.55mm lift does not directly translate into a precise injection point. The ECU is one of a number of variables, including injector/sensor condition for example, that impact on engine running. The DTI preset is as much about allowing the engine to start, so that you can subsequently tweek the system until you are happy, and any compromises you make are your choice. I, for example, will choose a cloud between 55-60 because I live in Spain and want to keep engine temperatures lower.

à chacun son goût , as they say.

 

[bournricha]

Very good discussion and excellent pictures .Thanks .

 

[MPH 76]

Off topic lol , ok back on topic how much did you pay the official VW garage to misfit your belts?

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[Or_GazM]

Guys, VCDS takes it's reading from the ECU.
The ECU "tries" to compensate for any mis-adjustment of the "mechanical" timing.
"Basic" readings shuts the ECU down, showing what the actual pump is doing without the help of the ECU.
A very "knowledgeable" Polish guy messed with mine for ages....setting the timing "by ear" using a rattle gun to loosen the bolt on the timing pulley.
After about 3 hours, he got it "close".
Then I showed him the results from VCDS, and told him about adjusting the idler/tensioner pulleys.....he'd never heard about that!
There's a guy in UK, Simon Baxter, who actually got a 3 page write up in a motor magazine about changing timing belts/setting them up....I don't think he owns a DTI.....or at least I never saw one whilst he was doing my van!
He had "the tools".....but I DO remember him complaining that since they'd "upgraded" to a tablet PC (with genuine RossTech lead), that it was more difficult than with his old laptop!
About 2 hours to do all belts/pulleys/etc....and after the work, went for a drive to warm the engine up....VCDS showed 0.55-0.57.....I was happy with that!

 

[shankalanks]

Hi Or_GazM

Thanks for chipping in there, appreciated.

My defense of the DTI is because the belt has been removed on the pump timing side, so I can't simply lock the pump and retain the advance that it has been using up to this point. The DTI allows me to find a 'starting' position (literally and metaphorically). After that I'll use VCDS to give me the timing that I want. If I was changing the belts on a van that had been running well, then I'd lock the pump, mark anything that moves in Tippex and hope I don't put the belts on one tooth out. As we've seen, that last still happens.

ElsaWin describes the DTI followed by VAG1552 method, and who am I to argue with them as this is ideal for the situation I am currently in, and it is clear that VW expects that some dynamic final setting of the timing is carried out.

Clearly if your van is chugging away quite happily and you get there with only the DTI or Dynamic method, and you are happy - then it's your van so do what you want. I'll use both because it's best in my situation. I don't have any ego to bruise over this - I'm just going the best way to do what I thought I'd paid for.

My comments in the previous post about variables were there to illustrate that VCDS/VAG1552 etc are not there to confirm the DTI got the timing right, but are there because the DTI setting is NOT expected to get the timing right.

I think I need to walk away from this discussion.

 

[shankalanks]

P.S.
Almost forgot.
Thanks to everyone for contributing. It's been very useful as I've gone from not even considering doing this kind of job to (almost but not quite) looking forward to doing it in 4 years time.
Useful picture time for the inexperienced like me:

The thin white Tippex marks are the ones I painted using masking-tape after aligning the crankshaft and camshaft to exactly TDC.
I found that these marks are the single most useful alignment marks for all subsequent work on the timing side, as looking at the flywheel for TDC is unnecessarily painful and also impossible when underneath the vehicle.
Good luck to anyone else who tackles this for the first time.
Ciao