2.9 VR6, sounds like a tractor and knocking?

[mikehiow 0]

Evening all, after a 10 minute spirited drive this evening, I noticed something strange, the engine/exhaust note went very deep (and "gurgley", almost tractor like) and the engine felt very sluggish. I crawled the extra mile home - and opened up the bonnet, there appears to be a slight knocking noise and the oil is down to about 4mm showing on the dip stick (it wasn't this low when I bought it a few days back) - edit: an after thought, that was immediately after stopping, a lot of oil would have still been around the engine - this may not be a cause for concern?

Now, it sounds a bit to me like not all cylinders are firing, but I've no experience of a V/VR engine - so not entirely sure - if it isn't firing on all 6, would this perhaps cause extra stress somewhere resulting in the knocking noise I'm hearing? Could it purely be a lack of oil, and a top up/change may fix?

My first thought was perhaps the big ends, but I'm not sure that'd give the "tractor" sound, would it? Plus, the knocking sounds very precise, and not rattley like I'd imagine big ends would?

Oil was reading at around 103c, water at around 90.

Any help/advice would be much appreciated!

added:

I've just been out to the car again to investigate.

The knocking, as far as I can tell certainly isn't top end, and sounds more like it's from the gearbox area.

Oil level has returned back to where it was previously (just a bit over minimum).

However, I tried unplugging each lead from the distributor/coilpack on the side of the engine.

The middle from both top and bottom rows makes no difference, where the rest, when unplugged cause the engine to almost stall (I plugged them back in before allowing this to happen). I didn't pull the leads off the plugs to test for spark, as I saw no easy way of getting them back in properly, is there a "method" to this?

The two middle leads from the coil appear to correspond with the top left, and bottom-middle cylinders (if standing at the front of the car).

It's probably worth mentioning that this is a Corrado.

[thegoth 5]

hiya and welcome.

There is a tool available from German Swedish and French for pulling the plug end of the leads. The part number was posted recently, I guess in this forum somewhere.

Could be the middle section of the coil has gone, so that when you remove any of the others it struggles as it's then only running on 3.

When you were playing with the coil end of the leads did you see and arcing? Have a look for cracks in the coil pack in the light.

The timing chain is the gearbox end of the lump. How many miles on the engine?

[thegoth 5]

here's the lead tool number.

Part number for lead removal tool from GSF is 98721B about £22 ish

if you are lucky there may be a plastic one still on the bonnet prop.

[craggsy 91]

yes...someone found it of some use!!!!!

[mikehiow 0]

Thanks, the engine has 129K on it - the timing chain thing is quite worrying - it's been mentioned on the corrado forum that I should be checking the top tensioner, I'll have to dig through the receipts/service history tomorrow. Although, I'm almost certain that the knocking wasn't there previous to tonight's problems.

What hadn't occurred to me already, was that this knocking, could infact be arching somewhere (perhaps internally to the coil pack?)

Are each of the 3 coils replaceable individually, or is it a whole new coil pack?

No arching visible when pulling the apparently two affected leads out, there were on all other four however - but I understand with wasted spark, if one isn't working the other won't either - so it's between coil pack, two plugs and two leads. The previous owner has informed me that the plugs and leads were done not so long ago (last year somewhen and probably <1000 miles)

If you were referring to arching else where, I didn't notice anything.

[UnitedMotorsport 55]

The center 2 leads on the coi pack shoud correspond to the center 2 cylinders, these being 3 and 4.

[mikehiow 0]

It was dark, I may have that bit wrong.

Although, it was working fine before, so I'm not sure that'll be it

[leespeza 0]

sounds like timing chains, chains might of come loose like mine did and all the timing went out new set of chains and tenisor shud do the trick take the cover off the timing chain and see if it loose

[boundsw 0]

best way to check for a spark, is to remove each lead from each plug in turn. undo the spark plug, and then plug the spark plug back into the lead (out of the engine)

Get someone to crank the engine while you hold the plug tip against the engine, (use pliars-dont hold it) you shoudl see a spark

this is a pretty basic methos, but it works. do this for each spark plug to teat

if they are ok, and your looking at chains, then check the top tensioner as a guide to how bad they are.

But at that sort of millage it might be owth doing the chains as a fail safe anyways (i have dont mine, and made no end of differance to the sound of the engine

If your timing is loose/ jumped, then new chains time !

[Timah89 1]

Sounds as though new coil unit should be first item to replace. Mine went down on Cyl5 and it sounded awful! New part £120 from GSF and runs sweeter than ever1

Good luck

[mikehiow 0]

If the chain has slipped, is it likely to be just one tooth, what about valves? Is the VR6 an "interference" engine?

[mikehiow 0]

I did a bit more investigation this evening, I tried grounding each "faulty" lead with a screwdriver, and got nothing but the most miniscule spark when rubbed against a grounding point.

Down to VW tomorrow for a new coilpack