VR6 engine failure diagnoses

[kerrly 0]

Hello all.

 

Well today has had it's ups and downs. On the plus side I relocated my G60 to a new heated/lit/powered secure unit ready to make the final push to get it on the road.

 

However on the way home in my VR6 I was doing around 20mph when it felt like I lost all power, I took my foot off the accelerator and the revs hovered at 1000rpm then dropped and I switched the engine off - IT DIDNT STOP ON IT'S OWN -

 

The starter motors spins and it sounds like the timing has gone but DOESN'T sound like there is metal on metal contact and it's not knocking or banging more whining.... I have tried doing a compression test on cylinder number 2 ( front left - easiest spark plug to get to) and there is NO COMPRESSION.

 

 

I ended up getting the AA to recover me (which it's worth mentioning, they had a mechanic with me in 10minutes - TEN minutes - AMAZING!!)

 

Tomorrow I am going to strip the inlet manifold/rocker cover off and have a look at the upper timing tensioner/cams and also whip the spark plugs out.

 

What do you think I am likely to find????

 

At the moment I'm undecided, my possible scenarios are:

 

1)if there is a obvious cam chain tension failure - whip the head off and if the pistons look ok, buy a second hand head, new timing chains/tensioner and get the clutch done. IF damage to the pistons to , then it's a case of find a cheap 2.8 or strip the car.

 

2) if there is no obvious damage to the tension & spark plugs all look ok - Crank position sensor??? but doesn't explain the funny sound when turning it over (compared to a traditional non starter from lack of fuel/air type scenario) I can swap the one off my brother's car to do a test. - Are they fragile??? Is it worth buying new just in case?

 

3) inspect the cams/tensioners, no sign of damage - book it into the garage for VAG COM , if that shows no electrical faults - crank sensor/cam sensor

 

Are there any other tests I can do, I have a Bentley manual, plenty of tools but sadly no VAG COM and only a basic multermeter to work with.

 

I appreciate you taking the time.

Dave

[iceviolet 0]

Your initial symptoms were what I got when my coilpack failed. Lost all power sounded like a bag of spanners.

That wouldn't explain no compression?? That is an odd one.

[kerrly 0]

funnily enough I put a new coilpack on a couple of months ago, even paid a bit extra for a Beru one with 2year guarantee.

 

The engine was running absolutely fine prior to today... at the time of death - coolant temp was 80, oil 88, 25miles at 29.8mpg , previously idling at 600rpm smoooth as.

 

According to the service history it had a brand new engine fitted at VW in 2004 which would now be on around 90k

[mr.ots 10]

No compression sounds like possible timing chain failure.

[iceviolet 0]

Yes most likely the timing. Can you see the cams turning when you are turning the engine over? Through oil filler cap.

If so then the chains hasn't snapped, it may have slipped a tooth or stretched?

I would check the timing is correct by putting cylinder 1 to tdc, remove rocker civer and check the slots in the camshafts are in-line above the surface of the head.

Then take it from there.

[kerrly 0]

The weather has been dreadful but I managed to get the cam and tensioner covers off....result... not good. It's tensioner failure

 

 

note damage to the area around the top bolt and a 3inch section

 

Managed to recover this part.

 

 

 

too dark and crap now to continue, at this stage I have 4 more manifold bolts to undo and the headbolts and the head is off. At that point I can decide how far I need to go. 2nd hand head/clutch/tensioners or 2.8 VR, or VW heaven.

[Roger Blassberg 0]

Where's the bottom chain?

 

RB

[dr_mat 0]

.. yeah and I thought the top end had a dual chain setup on the VR6 .. ?

[iceviolet 0]

It looks like the later chain set up normally found in the 24v engines with the single chain and solid polymer tensioner instead of the steel and riveted plastic that the 12v engines have.

The bottom chain has gone so unfortunately it's best to get the engine out and assess the damage.

[dr_mat 0]

.. that's what I thought.

Anyway, your big problem is the bottom chain, not the top tensioner!

[Roger Blassberg 0]

The bottom chain has clearly broken so it is a gearbox/clutch/flywheel/bottom timing cover removal scenario. Pray that the chain sprocket on the crankshaft hasn't been damaged, because it is not removable or repairable and you would need a replacement crankshaft.

 

As above comments, you clearly have a replacement simplex top chain arrangement, maybe an AAA 2.8 engine rather than the original 2.9 ABV. You'll need to check the head for bent valves particularly as you have no compression on at least one cylinder. It's an unusual failure to break a chain, unless the bottom tensioner failed completely and the chain was repeatedly snatched from tight to loose.

 

A rebuild is going to be expensive especially if the head needs work and the crankshaft sprocket is damaged too. A reasonably fresh second-hand 2.8 AAA looks to be your cheapest option.

 

Best wishes

RB

[kerrly 0]

Thanks for all the feedback.

 

Just to give you a bit more information about the later cam chain set up , the car had a new engine fitted at VW in 2002 (the short engine is listed as £4600 +VAT on the invoice and along with all the other parts replaced comes to over £6500!

 

Having checked all the MOTs the engine has done around 100k.

 

Hopefully I should have the head off at the weekend and can go from there.

 

looking at this picture then, worst case now appears to be a snapped bottom chain which if the chain has then ended up wrapped around crank could have made a huge mess of the bottom end.

 

It would be an enormous shame if the bottom end is dead!

 

Ummmmm , I feel i can justify upper/lower chains/tensioners, HG, clutch, rebuilt head as i can most of it myself. Part of me thinks if I buy a cheap 2.8 it would be wise to do chains/tensioners/HG etc on that as well so I don't think I'd save a huge amount ,I'd be down on power and it would make the car less valuable come resale time.

[Jim 2]

A scenario that any VR6 owner would dread - good luck getting the car back on the road and hope it doesn't bankrupt you too badly! :(

[kerrly 0]

^ well that's the issue I can afford to spend some cash on it as I got it exceptionally cheap. I could even sacrifice the full heated leather interior as a means of funding an engine as this Corrado is a "daily" more so than a keeper.

 

The timing is so bad for me right now, I had planned on letting the tax expire on the VR6 at the end of March and getting my G60 on the road. The G60 still needs a few jobs like brake lines, rear brakes, waterpump/cambelt/charger belts a host of other service items plus MOT but it's just been relocated to a workshop that is 25miles from my house!!!! Hence no daily = no work on the other Corrado so I'm a bit stumped right now.

 

The more I spend on the VR6 the less likely the G60 comes out next month and to be honest I want the G60 more!!

[Roger Blassberg 0]

If I were you I I would first take off the gearbox /clutch /flywheel/bottom casing to see what has happened to the bottom chain sprocket.If it's worn, which may have been why the chain failed in the first place, you will need to budget for a new crankshaft.Be really scrupulous in inspecting this sprocket, if it is worn it will kill a new chain quite quickly and you will be wasting your time and money if you skimp on this detail. This will probably determine whether you decide to carry on with the current engine or go for a replacement. (Don't forget when inspecting it that there is one tooth that is filed partly off to give a timing mark, so don't condemn it on that evidence alone.)Of course the crankshaft from a 2.8 will go into a 2.9 as it is the bore diameter alone that differentiates the two capacities.

 

Good luck

 

RB

[coullstar 0]

Get a running 2.8, swap it in to get the car running then strip this one to check the damage. Converting to OBDII with a 2.8 pretty much yeilds the same power as the 2.9 OBD1 engines anyway.

[kerrly 0]

RB - thanks for advice especially regarding the crank - useful to know a 2.8 will work.

 

Coulstar: I don't think I can do a OBD2 swap in less i have a whole mk3 golf donor car available which further complicates things.

 

My current situation is I live in a flat with 1 reserved parking space, this has the mk2 golf in right now (no tax/test), then my brother puts his Corrado vr6 in one of the other residents spaces, my corrado VR6 is now dumped in someone else's space who may want to use it. I have two rented garages, one with my brother's mk2 polo (minus engine/running gear) and the other with the Polo running gear/engine and tonnes of other bits.

 

I was able to use my dad's driveway which until recently had my Corrado G60 stored on it, now that is not an option due to building work at my dads house so the G60 is 25 miles away in a lockup.

 

I can't buy another mk3 golf to park next to the corrado and do the swap in the car park, nor can the cars in the garages be moved hence I need to act fast an swap the bare minimum to get the car moving again.

 

really appreciate all your input though :-)

[Stonejag 10]

You may be able to get a look at the sprocket through the ggearbox inspection plate - should be two M7 bolts to remove from the plate adjacent to the dump at the timing chain end.

 

Stone

[Tigerfish 10]

You may be able to get a look at the sprocket through the ggearbox inspection plate - should be two M7 bolts to remove from the plate adjacent to the dump at the timing chain end.

 

Stone

 

Wouldn't the sprocket area be sealed off from there to prevent the the oil that lubricates the chains/sprockets from filling up the bell housing (and contaminating the flywheel and clutch with oil)?

[kerrly 0]

Got a chance to spend a bit of time on the car today, slow progress due to the hangover from hell.

 

Head is off.......... and the results are.....

 

Which meant it was time to look at the pistons...

 

No damage to any pistons was a very pleasant surprise. Plans now is to port match the head before sending it off to be stripped, new triple cut valves, stem seals and a light skim/clean up. Whilst that's being done, the flywheel will be lightened/balanced, new clutch sorted and strip the bottom end. At this stage im still completely unsure what I am going to find!!!!

 

I'd love to use now as an opportunity to put a 6 branch and set of cams in to but that would eat into the G60 fund too much.

 

Finally, as i'm going to start ordering parts what is the deal with the Mk4 2.8 24v Headgasket?