Diesel Car Drivers READ THIS!

[DarrenHW]

Yesterday my brother experienced a phenomenon known as Diesel Engine Run Away (http://en.wikipedia.org/wiki/Diesel_engine_runaway), whilst driving to work his car "spluttered", dropped power and started pluming white smoke out of the exhaust. He pulled onto the hard shoulder, turned the ignition to stop, removed the key and to his complete disbelief the engine continued running :eek:!

He got out of the car and (unfortunately for the car) his first thought was for the safety of other drivers as the smoke had reduced visability on a busy dual carriage way to less than 10 meters. He's one of those guys you see setup in road works digging the road up, (I don't know what his job title actually is as he refers to himself as a "Shovel Operative" which considering the amount of certificates, qualifications and responsibility he has to take on for the job I think he's selling himself a little short) so set himself up at a safe distance to direct traffic and called the emergency services. By the time they got there the car had stalled the smoke was clearing and there was very little for them to do.

Preliminary investigation suggests this was caused by a failed Turbo Oil Seal, 1 small seal has led to the complete destruction of the engine (well beyond economic DIY repair anyway) by using oil as fuel and running the engine dry until it ceased. As to whether your Diesel Car could be affected by Diesel Run Away, depends on engine technology and luck. Had my brother put the car in top gear and applied the brake the engine "should" have stalled and apart from a Turbo rebuild could have lived for another *****miles.

If you are affected by this, put the car in top gear and (if safe) apply the brake, this could result in damage to the clutch and / or flywheel which whilst still a very expensive repair (especially if (and most likely) your car has a Dual Mass Flywheel) but far cheaper and quicker than a new engine / rebuild.

So there we have the sad story of my brother's Volvo a car that had been loved all it's life, we bought it with a full service history and continued with the routine, using (the correct grade of) Castrol GTX, good quality filters, replaced gaskets and o-rings whenever we were in their vicinity, if only we'd spent a couple of quid on a Turbo Oil Seal :doh:.

RIP Volvo V40 :deceased:

[Marco]

Nightmare, dude... He'd certainly gotten his use out of it, though! Question is, what will be his new jelopy? :)

Marco.

[DarrenHW]

Yes, can't argue with that, cost per mile is less than 1p! Volvo V70's still on the cards, just a matter of finding one, nothing worse than rushing into a car purchase. Off to check out a (Bright Yellow :lol:) Hyundai Coupe shortly to keep him on the road until we source a V70.

[walpurgis]

Turbochargers are not good. The whole idea of free gas flow goes against bunging a turbine right in the path of escaping exhaust gases. A supercharger is more logical and works from low RPM. Turbocharger seal failure is not uncommon, it can fail on the intake side or the exhaust side of the unit. A new turbo is not cheap and at worst a new engine is needed.

[CageyH]

In my experience, Castrol GTX is pretty shocking. There are better oils for the money.
When my dad used to run a Nova, it used to pink (pre-detonation) like mad. We changed the oil to something else (at the advice of a mate who used to work in a Vauxhall dealership) and the problem went away. I have never used it since.

This does not have much to do with Diesel engine runaway, but just something to bear in mind,
Have a look at Opie oils. The guy who runs it is pretty knowledgable when it comes to oil, and I am pretty sure you can find something much better at a similar price.

[MikeMusic]

There was a guy on the radio (I wa told) telling us all how horribly polluting diesel engines were
Particulate size I believe

Mostly for breathing so being a cyclist I'm less keen than I was on diesels

[Clive]

Regulations have made the manufacturers reduce particulate size from exhausts. The trouble is this means the fine particles are even more invasive than the larger lumps of soot.

[The Barbarian]

Classic cars are so simple & easy in most cases

:eyebrows:

[MikeMusic]

Regulations have made the manufacturers reduce particulate size from exhausts. The trouble is this means the fine particles are even more invasive than the larger lumps of soot.

Think that may have been his point.

He was quite serious that diesels should be banned

[walpurgis]

There was a guy on the radio (I wa told) telling us all how horribly polluting diesel engines were. Particulate size I believe

Hence the dreaded and troublesome DPF fitted to modern diesels. Just more to go wrong. Diesels get more and more complex. Shame, they were so simple originally.

[walpurgis]

Classic cars are so simple & easy in most cases

:eyebrows:

I like 'classics' and they are generally easy to work on, but you have to be aware of the inevitable rust and repairing it, unless you want to pay 'concours' prices for a mint example that you're not likely to want to use day in day out. Also, old cars are pretty bad on fuel by modern standards. Even a 998cc Morris Minor will have a job to nudge 40mpg, an 850 Mini may better that a bit. A 1275 sprite will do about 35mpg and an MGB may just hit 30mpg.

They may be tax free if you buy earlier models, but then so is my new car which does 70mpg and is dirt cheap to insure.

[CageyH]

Classic cars are not great for low emissions either.
They have no cat, no Lambda sensor, no ECU and hence no closed loop fuelling.

[walpurgis]

Classic cars are not great for low emissions either.
They have no cat, no Lambda sensor, no ECU and hence no closed loop fuelling.

Yes that's true, but in comparative terms they don't pose much of a problem. There are far fewer about and most do limited mileages.

[AlexM]

Diesel engine runaway is quite common, and is usually caused by a blown turbo allowing engine oil to be ingested into the inlet side of the engine. The engine runs using the oil as fuel, and doesn't respond to the fuel pump being shut down. It will run on until the engine oil is all gone, and then you loose the big ends... very expensive. The engine governer won't be able to slow the engine, so it will rev into the red also.

You can stop the engine by blocking the air intake, but often this is inaccessible or trunked into the inner wing. You would have to be brave to put your hands into the engine bay of a car that is revving over the redline. Perhaps a spud up the exhaust would have the same effect, or stall the engine out with the brakes in top gear.

[anthonyTD]

Hi Alex,
I was just about to post the same thing [Block the air intake] then i saw your post! The only things a diesel needs to run is fuel and air,if the turbo seals go, it has fuel, the engine oil, so' the only other thing you may have some control over is the air it can get! On modern cars its not always apparent where the air intake is though!
A...
Diesel engine runaway is quite common, and is usually caused by a blown turbo allowing engine oil to be ingested into the inlet side of the engine. The engine runs using the oil as fuel, and doesn't respond to the fuel pump being shut down. It will run on until the engine oil is all gone, and then you loose the big ends... very expensive. The engine governer won't be able to slow the engine, so it will rev into the red also.

You can stop the engine by blocking the air intake, but often this is inaccessible or trunked into the inner wing. You would have to be brave to put your hands into the engine bay of a car that is revving over the redline. Perhaps a spud up the exhaust would have the same effect, or stall the engine out with the brakes in top gear.

[AlexM]

Blocking the exhaust will have the same effect - doesn't need to seal completely, but the engine will quickly stop due to rise in compression and having the combustion chamber full of exhaust fumes. Might be difficult to achieve though... I don't carry a selection of potatoes or a rubber bung around in my car!.

[CageyH]

It's a good idea to block the exhaust, but it's usually really hot. Top gear, with brakes full on would be my favourite, and probably the quickest to achieve.

[anthonyTD]

No good if you have an auto, as it will just click down a gear!!!:eek:
. Top gear, with brakes full on would be my favourite, and probably the quickest to achieve.

[Dan W]

Turbochargers are not good. The whole idea of free gas flow goes against bunging a turbine right in the path of escaping exhaust gases. A supercharger is more logical and works from low RPM. Turbocharger seal failure is not uncommon, it can fail on the intake side or the exhaust side of the unit. A new turbo is not cheap and at worst a new engine is needed.

A supercharger isn't anywhere near as efficient or effective hence why very few supercharged cars exist compared to turbocharged. A supercharger is always running and takes a lot of bhp to make bhp. A cleverly designed turbo these days has zero lag and is making boost right through the rev range. But I agree, they fail at a high rate. Also going back to the first post, putting it in gear and trying to stall the car doesn't always work, trust me! The only sure way is to blocked the intake and stave the engine of air. Easier said than done though when it's screaming its nuts off!

[hal55]

I don't quite get it - with the electrics shut down there should be no spark to ignite the oil, or is just the cylinder heat enough to continue igniting it? Condolences on the loss of the car.

Hal55

[walpurgis]

I don't quite get it - with the electrics shut down there should be no spark to ignite the oil, or is just the cylinder heat enough to continue igniting it? Condolences on the loss of the car.

Hal55

The fueling and ignition on a diesel is (normally) mechanical and not dependant on electrics to continue working (or go into runaway).

[hal55]

Guess that explains it - thanks for the info.

Hal55

[AlexM]

The diesel or engine oil burns as a result of heating during the compression stroke, so it is purely mechanical. When a dies is running away, it is running on its own lubricant, not fuel, so you done even need a live fuel pump or fuel flow to the engine.

[Reffc]

Despite your brother's ill fortune, this (runaway) wouldn't appear to be a very common problem. I've certainly not come across it on Volvo 5 cylinder diesels. I spoke with my local friendly mechanic about this and other potential problems before buying my current Volvo and his advice was "buy Merc or Volvo diesel autos for the most reliable motors on the road". I know of V70 driver (D5 185BHP model) with over 400K on the original engine, several Volvo 850 T5 petrols with over 300K and still sweet as a nut and rate their 5 cylinder engines as amongst the most reliable going. Turbo seal failure can occur on any turbo engined cars but that doesn't make all turbos bad. It can be down to plain bad luck. BMW drivers of post 2005 cars can tell you that their problems (swirl valves) affects a huge number of expensive newer cars and turbo failure on those has been a common problem (avoidable with some simple mods apparently). As a cyclist, I'm also aware of polluting motors but many diesels these days burn very clean indeed, and the D5 is one of those. It has a very effective diesel particulate filter (CAT) and the exhaust looks clean as a whistle. Even so, it has been superseded by 4 cylinder 2 litre power plants which are even more complex for euro compliance. Modern engines, especially diesels have become mind bogglingly complex though so I guess more scope for unreliability down the line with some.