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Old 04-11-2019, 03:53 PM   #1
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Default What can cause the oil level to go up in a Diesel engined car?

Learned folk.... anyone it any views or experience?

My friend has a 2011 polo 1.6 diesel engine. 70k on the clock FSH and serviced religiously as per manufacture requirements.

No one but NO ONE has opened the oil filler cap and poured anything in there. Take it as gospel.

A few months ago, it started smoking heavily. I’m talking plumes of smoke out the back and revving its pants off by itself. (foot OFF the accelerator and it was revving away on its own) so she turned the key off and the engine stopped and parked it.

We took to a local mechanic and he checked the dipstick and said it has DOUBLE yes DOUBLE the amount of oil that it should have.

He drained it all out, couldn't see any foreign or “shouldn’t be there” fluids, put half (or the required amount) back in and said “off you go, see how you go”.

It has been perfectly fine for many months since then. Not a hint of what happened. Oil levels are fine and hasn’t smoked at all.

How the hell did the level go up so high? Anyone any clues?
The only thing I can add is that at the time, She had been driving it extremely hard red lining it just prior to it doing that. So it would have been very very hot.

So what the hell happened? Anyone?
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Old 04-11-2019, 04:32 PM   #2
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A mechanic in a workshop I used to run knew Vauxhall engines so well he just used to refill engines during a service by counting the 'clicks' of the air operated oil pump that drew the air from the bulk tanks. He never checked the dipsticks. One day he came in with a hangover and forgot to drain the oil...just filled it up...same effect as above...
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Old 04-11-2019, 04:38 PM   #3
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On an older engine I’d say lift pump diaphragm split allowing fuel to enter the sump. On something new then I can’t be sure the exact route, but I’d be pretty confident in saying that it was diesel getting in somewhere.
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Old 04-11-2019, 04:54 PM   #4
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On something new then I can’t be sure the exact route, but I’d be pretty confident in saying that it was diesel getting in somewhere.
My hunch too. So here’s a question.... could it be a one off event? Ie some dIesel got in “somehow” as a one off freak event perhaps as a result of from red lining.

It’s been ages since it was corrected and there hasn’t been a hint.
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Old 04-11-2019, 04:56 PM   #5
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Quote:
Originally Posted by Manxdavid View Post
A mechanic in a workshop I used to run knew Vauxhall engines so well he just used to refill engines during a service by counting the 'clicks' of the air operated oil pump that drew the air from the bulk tanks. He never checked the dipsticks. One day he came in with a hangover and forgot to drain the oil...just filled it up...same effect as above...
I can see how that could happen. Except that the last oil change was 14 months ago and no one has been anywhere near it since.
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Old 07-11-2019, 12:44 PM   #6
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I’ve just been investigating DPF faults on a friend’s Vauxhall. Turns out that on them, if the DPF regen fails, the unused fuel from the process gets dumped in the sump. Maybe something similar? If the vehicle had been subject to loads of short runs then the DPF could have been choked up, causing failed regens and a rise in sump level and subsequent running on. The hard run could have cleared the DPF which is why it’s not reoccurred.
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Old 07-11-2019, 06:47 PM   #7
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I’ve just been investigating DPF faults on a friend’s Vauxhall. Turns out that on them, if the DPF regen fails, the unused fuel from the process gets dumped in the sump. Maybe something similar? If the vehicle had been subject to loads of short runs then the DPF could have been choked up, causing failed regens and a rise in sump level and subsequent running on. The hard run could have cleared the DPF which is why it’s not reoccurred.
Absolutely spot on. Bought a Jag x-type diesel DPF back in February and this happened twice. Cost me a small fortune in oil changes using the recommended Castrol oil. Put a Archoil DPF cleaner through it and make sure we swap cars so it gets a good flog on the motorway twice a week. no problems now for 6 months. Simple rule is, if its got a DPF you cant use it for short trips, it'll get cholked up and cost you a lot in mither. Know someone who is having the same problem in a small Peugeot van, didnt realise you cant use a modern diesel for short hops of a few miles constantly.
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Old 11-11-2019, 09:52 PM   #8
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I never knew that the fuel from the DPF can find its way to the sump. Then again I don’t know the mechanics and plumbing of DPF to the sump.

I randomly mentioned this story to the mechanic when I went took my own car for a regular MOT and he also said “could have been the DPF dumping fuel into the sump”
That’s three people who have said the same thing

Is it also fair to say that if said “DPF” diesel was dumped into said sump that you wouldn’t be able to tell from the fluid that you drain out if it is a mix of oil and diesel? (Cos they are already quite similar)
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Old 12-11-2019, 07:44 PM   #9
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Hello DEL,
It doesn't come from the DPF to the sump. What happens is the car over-fuels in order to raise the temp, to burn off the soot in the DPF when the pressure differential before and aft the DPF reaches a certain back- pressure. If this fails to re-gen , it will try again, and again in order to execute the regeneration. This over-fueling will get past the rings into the sump. If the level gets high enough, you can get a runaway diesel engine. ie you wont be able to tun it off because the sump oil will become that high it will create crank case pressure and push the oil/fuel mixture back into the cylinders so it self-fuels. This has been a big problem on some brands fitted with a DPF.
This it what happens https://www.youtube.com/watch?v=j4rMfrERpG8
In order to stop it you have to stall the engine ASAP as it runs of full revs. You can stall it by putting it in fifth or even reverse.
As a precautionary measure I would recommend that the oil is not filled to the top mark on the dip-stick but arround 3/4 up the safe range. Check the oil once a week, and if it begins it rise, then you know you have a problem.
Could also be a faulty injector. This will also cause the above mentioned run-away diesel.
Read this article https://www.oilem.com/blog/dpf-clean...-dpf-cleaning/
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Old 12-11-2019, 07:50 PM   #10
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Forgot to mention, I think the turbo seals can also lead to this.
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