Faulty VR6 engine questions- Fouling plugs

[IainX 0]

Hey guys,

 

Afraid im a bit of a noob when it comes to the VW scene as I am, for my sins a BMW nut :camp: so most of my attention tends to go to my e46 M3.

 

However i have been offered a very minty VR6 Corrado, and now my e30 project is complete and soon to be sold i am tempted.

 

The car its self is in exceptional condition and is a 94 2.9 12v with 100k on the clock.

 

There is however a rub, the heater matrix has failed, no bother as i have done two of them previously on mk3 gti's and the engine will barely run and the exhaust is very smokey with significant soot deposits.

 

All of the plugs are fouling badly and there are apparent traces of oil in the inlet.

 

The owner is under the beleif that the headgasket is at fault, but to me this is improbable.

 

My guesses are (please excuse me if this is wildly inaccurate as my vr6 specific knowledge is zero)

 

1) The breather system is blocked leading to overpressure in the crank case and is leading to oil being forced passed the seals or/and into the inlet.

 

2) The valve stem seals have failed on all cylinders and this is causing the fouling

 

3) The rings have failed or the block is worn, this is feel is unlikely as the engines initial start is fairly quick leading me to beleive that compression is good (though i have not compression tested to confirm this)

 

 

Is option one viable? the other too seem rather severe considering this is a one owner car with full VAG service history, or rather it seems pretty crap that a 100k engine should be suffering such major failures.

 

If its either fault one or two, im in! if its probably option 3 I am OOOOUUUT!

 

Many thanks for all your help in advance!

 

Iain

[IainX 0]

Sorry to push on this guys but i am likey to be getting an acceptance or denial on my offer quie shortly so it would be good to get some thoughts on this if possible?

[Serial 0]

Oily plugs is generally a bad sign, and if it's smoky from the exhaust as well then I reckon it'll be either rings/bores or valve stem seals. There's usually a coating of oil in the inlet/throttle body area as the crankcase vents back into the intake just before the throttle valve.

[IainX 0]

Oily plugs is generally a bad sign, and if it's smoky from the exhaust as well then I reckon it'll be either rings/bores or valve stem seals. There's usually a coating of oil in the inlet/throttle body area as the crankcase vents back into the intake just before the throttle valve.

 

If its likely to be the stem seals then i am happy to take the car, i can have the head off and new seals on in a few days so thats no bother.

 

Im not interested in finding that the block being scrap though :? with all the plugs being fouled is this not more likely to be a stem seal issue? Would be odd for all the bores to run out at the same time would it not?

[Serial 0]

Bores 1 & 6 do tend to wear faster than the others due to poorer cooling, but it's not impossible it's been overheated at some point and all the bores have worn.

 

Worn stem seals can produce a puff of smoke from the exhaust when you accelerate after overrun, this is one way to diagnose them.... failed rings or worn bores I guess can only really be diagnosed by a compression test or visual examination...

[IainX 0]

Bores 1 & 6 do tend to wear faster than the others due to poorer cooling, but it's not impossible it's been overheated at some point and all the bores have worn.

 

Worn stem seals can produce a puff of smoke from the exhaust when you accelerate after overrun, this is one way to diagnose them.... failed rings or worn bores I guess can only really be diagnosed by a compression test or visual examination...

 

Hmm, difficult to say as the plugs are so fouled that the car doesn't really drive and i don't really have the option of going back and poking about further at the moment.

 

What sort of psi readings would be considered normal on the vr6? 200psi?

[Serial 0]

There's some info on compression test figures in this post

 

http://www.the-corrado.net/.archive/forum/viewtopic.php?f=1&t=67231&p=781585#p780935

[IainX 0]

There's some info on compression test figures in this post

 

http://www.the-corrado.net/.archive/forum/viewtopic.php?f=1&t=67231&p=781585#p780935

 

 

Thanks, most helpfull.

 

Looks like its most likely to be a stem seal issue from what i have been reading, but i will comp test it first to be sure.