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Author Topic: Bwj Oil Consumption + Leak down test question  (Read 333 times)

Offline Ash_89

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Bwj Oil Consumption + Leak down test question
« on: May 26, 2021, 05:18:41 pm »
Im getting a fair amount of blue smoke when coasting down hill also when pulling away from a stop.
Oil consumption 3/4 a bottle a month to keep it around 80% on the dipstick.

Compression and leak down test done
Oil cap leaking past 20psi on test

Engine BWJ 90k miles
Stage 2+
De cat exhuast
Rev R Pcv 2 years old

Im thinking due to the air passing up past the oil cap there is a leak on one of the pistons, can this also sometimes be due to a blocked/ under performing Pcv system?
I was due to take the car on track next month and am in two minds now incase I totally kill it.

Offline Clarkj93

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Re: Bwj Oil Consumption + Leak down test question
« Reply #1 on: May 26, 2021, 05:22:41 pm »
How many miles is costing you 3/4 (of a litre?) Bottle per month? On standard 5w30 oil consumption can be pretty high on these cars as standard.

Offline Ash_89

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Re: Bwj Oil Consumption + Leak down test question
« Reply #2 on: May 27, 2021, 08:33:07 am »
I am doing about 1400 miles a month 5w40 quantum, I have ran that oil for 3 years now.
Its more the oil cap leaking on test and the blue smoke that's bothering me :/

Offline Pudding

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Re: Bwj Oil Consumption + Leak down test question
« Reply #3 on: June 05, 2021, 12:36:18 am »
Assuming the cylinder was on TDC and the valves are sealing OK, that amount of air blasting out of the oil cap can only mean one thing - a knackered piston.  Likely a cracked ring land.  Very common on remapped engines.  Running that much boost pressure on stock pistons is a ticking time bomb.

Not a GTI piston, but an example of what it looks like.  A hot compression test doesn't always tell the full story as the heat expansion can close the gap and the top compression ring is still doing it's job, but combustion pressure when the engine is running will blast through that gap very easily, and oil will also find it's way into the combustion chamber equally easily on over-run and idle.

This is why I've stuck to Stage 1.  Even that is on the ragged edge for lifespan and operating outside of the original design parameters.  Unfortunately with these engines, it's a case of when, not if, when running Stage 2 and higher.


« Last Edit: June 05, 2021, 12:40:36 am by Pudding »


2007 ED30 | Ohlins Coilovers | Revo Map | Plus some other stuff | Is all a GTI needs :-)

Offline Ash_89

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Re: Bwj Oil Consumption + Leak down test question
« Reply #4 on: June 07, 2021, 11:14:50 am »
@Pudding

I had the tests done at a decent garage but still waiting for the compression results. I had asked for
full compression test plus leak down test, All that was on the report was oil cap started to leak at 20psi.
I am hoping the garage doesn't say well you didn't ask for the results to be wrote down.
I have a track afternoon booked next week typically.

Cheers for the reply by the way  :happy2:

Offline Pudding

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Re: Bwj Oil Consumption + Leak down test question
« Reply #5 on: June 11, 2021, 08:46:57 pm »
Fingers crossed it's not a busted piston!


2007 ED30 | Ohlins Coilovers | Revo Map | Plus some other stuff | Is all a GTI needs :-)