VR6 problems

[Serial 0]

Hi all,

 

I have some fairly major problems with my '93 VR6 ...

 

I got the car back in September last year and the engine has been fine apart from a leaky radiator ~6 months ago, now fixed. Recently however it's started to use more and more oil, now it will pretty much go off the bottom of the dipstick after 200 miles or so. There's *loads* of white smoke from the exhaust on startup which continues until the engine gets up to temperature, and then above ~3k RPM it really billows out. It recently started misfiring, or firing badly on Cyl 6, (tested by pulling the plug leads one at a time -- pulling cyl6 makes the least difference) I checked the sparks by cranking with all plugs removed, and there are good sparks on all the plugs. (all new plugs now, old plugs were pretty shot with no.6 being really mucky)

 

The PO did the bottom end (new rings) and the top end, but I'm beginning to think the valve stem seals weren't replaced -- hopefully this is the problem but I'd like to be more certain before I start dismantling things.

 

The only other thing I can think of that would cause the misfire is a dodgy injector, but I suspect that's unlikely to be the cause given the massive oil consumption & smoky exhaust.

 

So, I'm thinking of getting a compression test done to rule out the bottom end, then going for a head rebuild job, and maybe putting some nice new cams in (if the next group buy goes ahead!)

 

Has anyone else experienced this kind of thing before?

 

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[Reggit 0]

Is it using any water? Is your oil filler cap full of mayo?

 

If so I'd suspect head gasket failure.

[Critical_Mass 10]

Is it using any water? Is your oil filler cap full of mayo?

 

If so I'd suspect head gasket failure.

 

yeah going by what you've said id say head gasket too. What are your temps like?

[steve @ 0]

third plug from the left looks very clean -> suspect head gasket failure steam cleaning the plug.

[Serial 0]

That's the thing, I haven't needed to top up the water for months now and the oil filler cap is mayo-free. Both oil and water temperatures appear fine, water sits at around 85-90 when cruising and goes up to 100 in traffic, and oil temps are around 98-100.

[dinkus 10]

For reference:

 

White smoke = water

Blue smoke = oil

Black smoke = too much fuel/not enough air

 

If you're getting white smoke, then, it's gonna be water getting into the engine somewhere and the most likely place is the head gasket. It's a relatively easy thing to replace and will be obvious what it is as soon as you get the head off.

 

Make sure you replace all the head bolts and gasket if the head does come of though, they're not re-usable parts.

[was8v 0]

Get it compression tested both dry and wet. Maybe a leak down test if you can? That will tell you what is leaking head gasket /bores / seals in head.

[jamminvr6storm 0]

Id suggest a sniffer test too....

[Serial 0]

Cheers for the advice -- I think I'll take it to the local VW specialist and get compression, sniffer and leak-down tests done and then go from there. :)

[Kevin Bacon 5]

third plug from the left looks very clean -> suspect head gasket failure steam cleaning the plug.

 

Or lean running.

 

2 and 6 are the only correctly coloured ones.

 

3 and 4 are rich

 

1 is oiled to feck, bore wear

[gregulate 0]

Hi all,

Recently however it's started to use more and more oil, now it will pretty much go off the bottom of the dipstick after 200 miles or so.

 

Serial, did you sort this if so what was the problem - and more importantly how much did it cost to get sorted? My VR's drinking a litre or so of oil a fortnight recently, although no smoke coming from the engine.

[Serial 0]

No, not got it sorted yet unfortunately. :( Gonna take the head off in the next couple of weeks and see if I can spot the problem, just waiting to get the car into the garage that the landlord has been promising he'll clear out for the last 6 weeks or so :bad-words:

[Serial 0]

Well I've finally got the car into the garage and started taking the engine apart. So far I've removed the battery, headlights, grill, (with a view to removing the slam panel -- is this a good idea as I'm gonna have to take the intake manifold off?) spark plugs & leads, and the engine covers. It seems like there's a fair bit of oil that's dripped down the back of the block, not sure if this is from a leaky head-cover gasket or just from spills when topping up... Next stage is to remove the intake manifold and the head cover and have a gander at the cams... if there's nothing obviously wrong (not sure if I could actually tell by that stage?) then I guess it's head-off time... took a photo to remind me where all the wires go -- u can see the head bolt on the bottom right is full of oil...

 

21102008019.jpg[/attachment:2mx5tmps]

 

Tom

[tandino 0]

That will just be a leaky cam cover gasket weaping oil into the head bolts.

if your going to pull the whole engine then yes remove the front panel, if your just going to pull the head then no need.

[Serial 0]

Just did a dry compression test, here's the results:

 

Cyl1: 110psi

Cyl2: 120psi

Cyl3: 110psi

Cyl4: 120psi

Cyl5: 0psi

Cyl6: 117psi

 

No, that's not a typo, cylinder 5 showed no compression whatsoever, didn't even move the gauge! I think I've found the cause of the misfire -- now I'm wondering what on earth could cause it to have no compression at all...? I guess either a valve stuck open (is that possible?) or completely shot piston rings. I didn't get round to doing a wet comp. test, didn't have any spare oil around, so will see if I can do that at the weekend.

 

Also I noticed a loud tapping sound coming from somewhere near the throttle body, which increased in rate with engine rpm, got a bit quieter with higher rpm as well... i've never noticed it before...

[Roger Blassberg 0]

Those readings seem generally low to me. Especially nr. 5 obviously. Maybe you have a broken valve spring or a massive cylinder head gasket leak to atmosphere/water jacket. Is the cooling system getting over-pressurised, even when cold?

 

Best wishes

 

RB

[was8v 0]

The Bentley manual states when new the compression should read 11-13 bar (159.5 - 188.5 PSI) and the wear limit is 7.5 bar (108.8 PSI ) with engine at 30 degrees(F?)

 

So your cylinders are all down but not down to the wear limit. Did you do the test with the engine hot or cold? With it cold I'd expect them to be down a bit on the above figures.

 

Cyl 5 is VERY worrying though! Unless something is wrong with your procedure it sounds like the head needs to come off. Normally a wet compression test will help determine if the head or block is the likely culprit.

[Serial 0]

The engine was pretty warm when I did the test, the oil temp was showing around 60C and water temp a little lower... The thing is I'm not losing any coolant and the cooling system doesn't appear to be getting unduly pressurised... main other symptoms are massive oil consumption and smoky exhaust.

 

Just off out to the garage now, gonna do another compression test, this time I'll do a wet test as well. Then I think I'm gonna strip it down to the point of taking the cam cover off and see what's what...

 

Cheers for the advice & info as always :)

 

Tom

[Serial 0]

Just done another compression test. The first figure is the dry test, the second is the wet test, both in PSI.

 

Cyl1: 111, 120

Cyl2: 122, 143

Cyl3: 110, 129

Cyl4: 125, 147

Cyl5: 0, 0

Cyl6: 120, 138

 

So it seems like I have some bore wear across most of the cylinders, and some still unknown problem with cylinder 5. :scratch:

[was8v 0]

With figures like that I'd be tempted to drop another engine in, a known good 2.9 engine or low mileage late 2.8 (theres been lots on here recently and ebay going VERY cheap, like under £350). Thats the easiest and probably cheapest thing to do.

 

If you take the head off you are into paying £££ for at least a head refurb and possibly bottom end rebuild. I would say thats not viable given the prices engines have been going for. If you are going to keep the car forever or are going for a supercharger upgrade at some stage then it may be worth rebuilding what you have so its known good.

 

You can always whip the head off to inspect the bores and keep your eyes open for an already rebuilt head going cheap?

[Serial 0]

Took the inlet manifold off -- inlet to cyl5 had a few cc of a whitish mayonnaise-like substance in the bottom of the tube... the worrying thing was it also had lots of little 'crumbs' of blackish metal spread around in there as well :( Seems like some important piece of metal may have disintegrated at some point :pale: Next step -- I think I'll remove the cams and see if there's anything obviously wrong with the tappets or the tops of the valves..

 

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Regarding engine swaps, the previous owner did actually rebuild this engine about 10,000 miles ago.. It's a 2.8 block rebored to 2.9, and the head was skimmed, valve stem seals were replaced and the valves were lapped back in. The original pistons were reused with new rings. So... given that this has happened to a 12v VR6 in that length of time, I wouldn't really want to swap it with another relatively high mileage engine of the same type -- if I'm gonna swap engines I think I may go the whole hog and get a 24v... an R32 lump sounds like a brilliant plan to me :D

 

cheers

 

Tom

[Serial 0]

Finally got the head off today and the exhaust valve on cyl 5 appears to have exploded?! See photo... That'll explain the crumbs of metal kicking around the inlet manifold, and the total lack of compression on that cylinder... and I'm guessing the bits will have pretty much ruined the cylinder wall -- I haven't measured them but cyl5 seemed more rough than the others. :sad:

 

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[CorradoVR6-Turbo 0]

thats typical exhaust valve burnt away,probably wont have touched the bores as its malten metal blowing out the exhaust....is the bore scored?

[Serial 0]

I think some material definitely got into the cylinder, there's quite a bit of melted metal on the flat surface of the valve and I found lots of crumbs in the inlet manifold (see prev post) The cylinder wall seems a bit rougher than the others but there's no obvious deep scoring...

[Serial 0]

OK after quite a long wait for money, parts etc. I have finally started the rebuild of my VR6. I decided to get the original block bored out to 82.5mm and fit Wiseco forged pistons, also got my hands on ARP head, rod & main fasteners so I won't have any worries if (when!) I decide to stick a turbo on at a later date.

 

Thanks to Adrian at Impulse in Rochdale -- he's been very helpful, great service getting the block rebored and lots of useful tips & advice for the novice engine builder like me! :salute:

 

Here's some pictures of what I got up to this weekend:

 

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2.8l 24v Climatronic system.pdf22082009173.jpg[/attachment:199s4r8t]

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