Blue smoke from exhaust at high rpm

[K Simmonds]

Beware just putting rings into an old cylinder. If you have the engine out, you need a machine shop to check the bores haven't gone oval shape. No new round ring will ever seal in an oval cylinder!

Oval check and look for scoring as well. If a bore has been damaged in its past, it could be the surface damage on the bore letting the oil out, not a worn ring.

Very good point there Steve, it's mandatory to check the cylinders are actually round before installing new rings.

If it's like he says on all cylinders then something has gone pretty badly wrong, the bores could be damaged as could the piston skirts.

[Bowie69]

If the engine has been running rich for a long time (very common on these Hitachi injectors, or with a failing O2 sensor) then they do wear bores like any other engine through fuel wash. Also, low mileage could mean lots of short trips = running with fuel enrichment for most of its life = bore wash.

Suspect this is your problem.

As above, you need at the very least to hone the cylinders, don't just slap new rings in and hope for the best. Wear like this can also scrap pistons, look carefully.

[Mikemul]

The weirdest is that all spark plugs are black so all cilinders are using oil ? This car I bought recently but wasn’t smoking. Do you guys have a link for a site to order the rings ? do you think a cast iron bottom block will become oval? if this is the case does it need other excess pistons as well?

[K Simmonds]

As above I suspect bore washing from over fuelling is the cause, I wasn't aware they were prone to this, it's about the only explanation that makes any sense.

Yes, cast iron blocks will go slightly oval over time with usage, it's really quite normal depending on what's happened and how mile's/km's has been covered with the problem, you won't know the extent of the damage until you pull it apart I'm afraid.

[Bowie69]

Black plugs = rich, not oil.

Gungy wet black plugs = oil, or possibly rich and oil.

[simons2]

Rich equals bore wash

[Tractor Dave]

And petrol smelling oil

[K Simmonds]

Yep, bang on.

I think we've sussed this one out, bore wash makes sense to me for a motor with so few km's to now be burning oil. The plugs will be black on all cylinders from over fuelling and/or oil as Bowie says.

This can have caused quite a lot of damage, I wouldn't be at all surprised if the piston skirts are scored and quite probably the bores, as I said you won't know until you pull it apart.

The fact it's only just started doing it may be in your favour, do not drive the car anymore, even if you fix the over fuelling as it will continue to to do damage now this has happened.

I wasn't aware 7A's were prone to to this otherwise I'd have put two and two together a bit quicker. It would have to be an awful lot of very short journey's to cause such serious damage, whereas if it's been washing the bore's all the time for a while then it make's total sense.

[Mikemul]

Black plugs = rich, not oil.

Gungy wet black plugs = oil, or possibly rich and oil.

the plugs are fully black and dry and some plugs have a coffee brown point on the middle of the core maybe was it some old stuff on the plug. But when it runs to rich it need to be smoking black from the exhaust right? I text the old owner and he told me he have tanked the car with a jerry can with a little bit oil on the bottom like 50ml or something maybe is this the problem ? He told me also that he change the piston rings but with the ones from a 2,3 10v with this part number 2c4927 the different between them are the first ring that is 1,5 at this and at the original 1.2 mm

[K Simmonds]

That doesn't sound good at, not the oil in the Jerry can bit, that doesn't matter. The stuff about rings! Why use 10V rings in a 20V engine? And why did they need changing in the first place?

That wet result would be enough for me to pull the head off and start having a look I'm sorry say.

[Bowie69]

Hmm, rings thing is a worry.

[Mikemul]

I don’t really know. we will see after rebuild. Do you guys have a link for the rings ?

[Mikemul]

Im started with removing the inlet manifold and was wondering all the inlet valve are wet. After 1week of driving. Maybe problem with valve stamps or is this normal?

[K Simmonds]

Hard to say from the photo, looks fine to me but I'm not there. Wet with what oil or fuel?

A little oil will creep down past the stem seals and guides if it need's new stems seals, which at this age it probably will. Also as we're pretty certain your cars been running very rich for some time then the inlet valve guides maybe a little more worn than normal due to the washing action of the fuel.

If the car passed a leak down test, which it appeared to, then failed a wet compression test that can only mean the rings are worn or damaged as the valves must be seating well.

I'm not saying you don't need new valve guides as well as stem seals, you may well do. However it's normally the exhaust valve guides that wear out first due to the heat. It will be interesting to see what they look like.

Once you get the head off and the pistons out all will be revealed.

[Mikemul]

Hi Guys I removed the head, there is a scratch inside the wall. Check the picture. Is this making the smoke?