Buzzy turbo diesel :(

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Buzzy turbo diesel :(

Postby Globbits » Sun Jun 16, 2013 11:13 am

Right then, all you clever diesel people, riddle me this one!

Bought a Mk3 Passat TD (AAZ) as a workhorse a few months back. There were a few niggles with him, but the price was right, so he came home with me

Top of the niggles list was that the engine seemed to be vibrating hard and wasn't pulling well. I got the local garage to change the cambelt, making sure the timing was right while they were there. This made no difference and, on further checking, it turned out the turbo had blown!

I swapped on the (known-good) turbo from our Golf TD (also AAZ) and he was a bit better, but still very little turbo response and lots of vibrations. So I played with the timing - no dial gauge, just by feel - and turned the pump back by about 5 degrees

BINGO! We haz turbo! All of a sudden, hills are possible, overtaking is easy, fuel economy is up to 42mpg and life is good. But the engine is still vibrating quite heavily, particularly from 2,500rpm up to 3,200. After that, it smooths out and cruises really nicely?!

I've tried re-tweaking the timing, but I must have found the sweet spot by accident last time. I've also tried winding the fuel screw out slightly, in case someone had been playing before we bought him. But this just reduced his ability to pull at high revs without any reduction in vibration

I've checked the engine mounts and it's not that - the engine is well mounted and stable. But I can't work out why it's so buzzy - it's almost like it's over-fuelling (the exhaust is quite smoky at night, when pulling uphill) but I can't work out what to look for :cry:

Any thoughts?
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Postby SiC » Sun Jun 16, 2013 11:45 am

Flywheel?
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Postby Globbits » Sun Jun 16, 2013 3:25 pm

I'd imagine it's got one, yes :wink:
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Postby SiC » Sun Jun 16, 2013 5:15 pm

Don't AAZ motors have issues with pulley mountings?
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Postby SiC » Sun Jun 16, 2013 5:18 pm

Google crank pulley wobble...
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Postby Muppet » Sun Jun 16, 2013 6:05 pm

If it goes gobble gobble gobble the problem its a Vauxhall :lol:

Are you getting some boost pressure?
Not getting any lights on dash oil pressure?

Is it rough at tick over? if so have you tried cracking the Injector pipes
and see if one makes no difference or less difference.

have you tried checking compression :shock:
if you have another AAZ could you try swapping the injectors and is the Waste gate closing properly.

Don't you just love Diesels :D :D
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Postby GBHgpJON » Sun Jun 16, 2013 7:44 pm

Muppet wrote:
Don't you just love Diesels :D :D

No.....Unless you're a farmer.........or drive a Plumbers van!
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Postby Globbits » Sun Jun 16, 2013 8:52 pm

Sorry SiC, that was unfairly flippant of me :wink:
I'm 99% certain this is "inside" the engine, rather than stuff that's connected to it - certainly the more right-pedal you give, the stronger the vibrations get. I know about the AAZ crank pulley wobble thing and this one's straight and true, so not that (phew!)

Muppet
The idle isn't silky-smooth, but isn't bad for an AAZ. I've tried bleeding the injectors and it made no difference
There's definitely boost from the replacement turbo, but not sure how much. Trying to find a cheap boost gauge on Ebay at the moment and keep getting outbid :cry:
No oil pressure issues. Have run a couple of bottles of injector cleaner and the placebo effect tells me it's smoother, but not by much

I'm pretty sure this is fuelling/timing related, as it doesn't seem to be a particular cylinder running rough. But don't know the AAZ pump well enough to "try stuff"
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Postby regcheeseman » Wed Jun 19, 2013 2:48 pm

dodgy injector.

Had a engine once with mixed up lines - yes, some muppet had managed to make steel lines fit the wrong way - that ran 'rough'
1-3-4-2 if you wondered - looking onto the injector lines at the pump head no1 is at about half one and it runs ati-clockwise from this perspective

timing 180 degrees out - it'll run but not well.

don't poor anymore snake oil in it.
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Postby Muppet » Thu Jun 20, 2013 10:41 am

Since I did the van engine it has run a bit rough on start up but purrs nicely
if i pull the Cold start out a little.

I know the timing is out a tad but not got to tweak it closer yet, Had timed the
crank & head by markers and Put the Pin in the Pump.

It is probably fine adjustment on the timing or the Injectors need servicing
and setting to be balanced.

Did it run well in its donor vehicle or was it unseen?
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Postby Globbits » Thu Jun 20, 2013 11:12 am

The engine's still in the donor vehicle and is staying there :wink: I bought it, knowing the engine wasn't 100%, but thought the problem was just the turbo :cry:

Update
Having apparently found the "sweet spot" on the timing again, I thought I'd go for plan B and reduce the fuel delivery screw slightly (about 1/16th of a turn). I've just driven to Oxford and it's less buzzy and actually even happier/smoother to cruise at 75-80 than it was before?! Can't confirm the effect on fuel-consumption yet, but it may simply be that the previous owner was a twat and went buck-wild on the fuelling screw! :lol:
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It'll be fine
F*&k off it will! (in front of 8-yr old "assistant")
No Carl. Seriously No!
We're gonna need a ton of filler
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Postby regcheeseman » Thu Jun 20, 2013 2:06 pm

but it may simply be that the previous owner was a twat and went buck-wild on the fuelling screw!


NO. It isn't.

I can have a motor laying down thick black lines of soot, it won't run rough or vibey.

Timing or duff injector......you want to borrow my DTI?


Since I did the van engine it has run a bit rough on start up but purrs nicely
if i pull the Cold start out a little.


Touch of advance needed then, when timing a pump up onm pin alone I tend to pre-load the pulley against the locking pin using a 19mm spanner before I nip up the bolts on the pulley slots.
The slop with the locking pin equates to 0.1mm of lift and from the factory means typically your locking pin can fit at anything from 0.85 to 0.95 - I'd rather have an AAZ at 0.95 than 0.85
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Postby Globbits » Thu Jun 20, 2013 8:36 pm

regcheeseman wrote:NO. It isn't.
Timing or duff injector......you want to borrow my DTI?


Would love to buddy. Fancy coming to North Tamerton for a natter, or shall I come to you? Would welcome your input on this one. I can't see it being one duff injector, because it's not lumpy on one cylinder - it's all lumpy :cry:
Krustybarn quotes:
It'll be fine
F*&k off it will! (in front of 8-yr old "assistant")
No Carl. Seriously No!
We're gonna need a ton of filler
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Postby Muppet » Thu Jun 20, 2013 9:30 pm

When I get a moment I will give the timing a small Tweak :mrgreen:

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Postby regcheeseman » Fri Jun 21, 2013 10:49 am

Fancy coming to North Tamerton for a natter,


Dunno why, but I had you down as living somewhere in North Somerset, which was why I've been fairly reluctant to make the drive.

now I know where you are, it's doable. possibly an evening this weekend, a weds or thurs evening or the following weekend?

Did you want me to bring my kit and maybe some spare pumps, to give some pointers on how to strip diesel pumps?
Last edited by regcheeseman on Fri Jun 21, 2013 11:08 am, edited 2 times in total.
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