Renault Scenic - Excessive Blue Smoke

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Sat 4 Jun 2011 19:23
Renault Scenic - Excessive Blue Smoke - Bazeybee1

Renault Scenic 2001 1.6 16v. 85000 miles

Just had head done after cambelt failure, but am getting a lot of blue smoke after engine warms up. Ok when starts from cold.

Any ideas

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Sat 4 Jun 2011 21:44
Renault Scenic - Excessive Blue Smoke - Peter.N.

Could be that the carbon round the top of the pistons had been disturbed and has reduced the seal, if so should improve as you get some miles on it. Is the oil overfull, have you checked the level? When does it smoke? after going down a hill, when you accelerate hard?

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Sat 4 Jun 2011 22:02
Renault Scenic - Excessive Blue Smoke - unthrottled

Should be very little carbon on the piston crown of a modern engine.

Unfortunately, it's almost certain that the valves were bent when the cam belt snapped-bending the valves and damaging the valve guides pr valve stem seals. I suspect the engine pulls oil down past the guides under high manifold vacuum conditions.

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Sun 5 Jun 2011 12:39
Renault Scenic - Excessive Blue Smoke - Bazeybee1

Hi and thanks

New valves and seals were fitted at the repair, do you think it would still pull oil through even with new seals. My only other thought is the piston oil seals but engine is low mileage?

Thanks

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Sun 5 Jun 2011 13:20
Renault Scenic - Excessive Blue Smoke - unthrottled

You can get the garage to do a wet compression test to see if the problem is with the valves or the piston rings. I still think it's the valvetrain end. Too much of a coincidence. I'm sorry that you've spent so much money on a repair for it to not be working properly.

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Sun 5 Jun 2011 14:22
Renault Scenic - Excessive Blue Smoke - Peter.N.

unthrottled - you can tell how old I am!

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Sun 5 Jun 2011 15:02
Renault Scenic - Excessive Blue Smoke - unthrottled

Not old Peter, just 'experienced'! You're right, back in the the day, you'd pull the head of a petrol engine and the piston crown and valves would be caked in carbon.

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Sun 5 Jun 2011 17:04
Renault Scenic - Excessive Blue Smoke - Bazeybee1

Many thanks, will get in touch with a garage tomorrow and get it checked.

Will definately let you know how I get on.

Note:its only other people who see you as old, your eyes never do!

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Sat 25 Jun 2011 18:52
Renault Scenic - Excessive Blue Smoke - Bazeybee1

Well back again to continue it turned out to be the valve stem guides must have got damaged and were leakingh oil through. Any way managed to get another head of a 65K engine and fitted it with new gasket and bolts, the problem being I am now getting white smoke, just cant win with this engine. not too bad at first but again more as the engine warms up. Just wondering if I should have got the head skimmed?

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Sat 25 Jun 2011 19:18
Renault Scenic - Excessive Blue Smoke - madf

I'd get a new garage which is competent: the current lot must be a bunch of chancers.

Aluminium heads should ALWAYS be checked before re-use.. especially if second hand. A skim is cheap £50ish. And anyone semi competent checks valve seats and guides after a head blow up. Basic ABC stuff.

Your garage are plain incompetent,

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Sat 25 Jun 2011 19:55
Renault Scenic - Excessive Blue Smoke - unthrottled

I've not bothered skimming the three heads I've changed-all of them sealed just fine. If the head face is straight, it doesn't need skimming. A few thou can easily be absorbed by the head. If it's warped by more than a few thou, skimming won't help since that's all they take off anyway.

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Sat 25 Jun 2011 19:18
Renault Scenic - Excessive Blue Smoke - Fernando P

Yes!

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Sun 26 Jun 2011 06:50
Renault Scenic - Excessive Blue Smoke - 1litregolfeater

Yes I'd be a bit wary, valve guide damage is rare, more likely they didn't fit the new bits right. You shouldn't see any smoke at all, are you sure it isn't steam from "the normal combusion process". Check if you are losing coolant!

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Sun 26 Jun 2011 11:32
Renault Scenic - Excessive Blue Smoke - Bazeybee1

Hi starts as you would expect when cold with a small amount from exhaust but as engine gets warmer when you rev it you get a cloud come out the exhaust.

Not sure where to go next or maybe just sell as spares

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