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Discussion Starter #1
I had a small engine fire at the weekend, and although the damage is not great, the reason is not obvious, and before I start repairs, I’m trying to track down what the cause might be.

Symptoms were brief and straight forward. I was driving slowly, heard a dull pop, engine lost power, and extremely quickly noticed smoke. Stopped almost immediately and turned car off. Lifted bonnet a crack to see if flames but none, open the bonnet and lots of smoke and noticeable heat! Not coolant steam, but smoke.

In the time it took to retrieve a fire extinguisher, small flames at the back right side of the engine behind the cover. Extinguished and disconnected the battery.

I’ve inspected the damage today, easy to see removing the engine cover and pollen filter tray.

On the right, oil separator melted, breather hoses burnt, vacuum pipe burnt, injector loom plastic cover melted, possibly harness damaged. Engine cover melted, then in the centre there seems to be a high current connection bolted to the back of the engine which is melted. Inlet manifold is damaged on the last tube.

Nothing else seems damaged, and on the left, the fuel pipe to the rail is fine.

I reconnected the battery to see if anything amiss, but no smouldering, and turned the car on. Usual set of lights and stuff on the dash. Finally tentatively cranked the car which cranks fine , and tries to start (clearly won’t with major vacuum leaks and possible injector loom damage). There is a strong smell of fuel though, and no obvious leak.

Does anyone have any experience of the same, or any ideas of what might cause such a fire? Other than the high current connection, there is not much there, and a fuel leak I suspect would be a bit more catastrophic!!
 

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Discussion Starter #2
Bumping this to see if anyone has any kind of idea or experience at all. I am limited to what I can take to pieces at the minute as I am claiming on insurance and don't want to disturb anything until the assessor has been to take a look. They are sending out a fire expert who might have some ideas.

All I can think of is as follows:
  • Spark plug has come out for some reason meaning a small amount of fuel has got out and ignited.
  • Fuel rail has developed a crack (although I think the impact of this would be more of an inferno than the small fire I had
  • Electrical connections got fried (but there is only one big electrical connection there and no other wiring is obviously damaged or burned
Looking for ideas from other L322 experts on what is at the back of the BMW V8 that could cause sparks or sufficient heat to ignite as I cannot see anything. All I can observe on the rear of the engine, RHS, are:
  • Oil separator
  • Oil breather pipes
  • High current battery connection
  • Brake server vacuum hose
  • Non-supply end of the fuel rail
  • Injector harness
The most badly damaged parts are the oil breather hose and separator.

Engine cranks fine, with a smell of fuel, but no obvious or visible petrol leaks.

Anyone in L322 land with any thoughts on this to give me a lead?
 

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You got my attention at "engine fire!"

How and why should be left to the people who know more than I do.
 

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Discussion Starter #5
Indeed :)

I have been doing a bit of internet research. Not always the most reliable source, but interesting reading and maybe there is experience to comment on what I found today. RSW do a couple of videos on YouTube about replacing the PCV valve on the 4.4 v8. I was looking at these as the oil breather pipes have been destroyed and the PCV valve and oil separator damaged.

I noticed on the videos that there is a flexible heat shield pad wrapped around the oil breather pipes. This shield was missing on mine, and I am guessing it is there for a good reason. I also read on several forums that the oil fumes eventually rot the breather pipes and they can collapse and tear. Failure of the pipes or PCV can cause engine running problems. So one question to the knowledgeable people here (as I am just getting up to speed with this engine), is does any of the above hold water?

So one theory I have is that the breather pipes were old and rotted, and with there being a reason for a heat shield likely to be heat build up in that area, maybe the breather pipes failed causing a loss of power, and the fire was caused by hot oil fumes igniting.

Has anyone else had to replace the oil breather pipes and observed a heat shield wrapped around them (its like one of those wine coolers you freeze and wrap around a wine bottle with velcro).

I am pretty mechanically experienced although still learning about the M62 engine (lots of experience with Alfa engines, my other passion, Rover V8s from the P38s I own, 300tdi, and the D3 2.7 V6). Hoping there is experience to comment on the oil breather system, hoses failing and causing a loss of power, the heat shield in that area, and likelihood of oil fumes igniting.

What do you think? Maybe the best of this post if to give a heads up that this might be the source of an engine fire if the pipes fail.

This is part 1 of the RSW video (good US outfit - very helpful when I was learning about my D3)


And now, looking for all the bits to repair the car. Inlet manifold, injector harness, oil pipes and separator, servo vacuum pipe, various other pipes off the back of the engine. All seem available used at decent prices on ebay.
 

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Sorry for the incident. I think the shield you are talking about is a cold weather shield that wraps around the pcv breather tubes and warms up them up so they don't get clogged. There is a plug for it back there. Most L322s don't come with that shield, mine does not have it either. I honestly do not think that a collapsed breather pipe would ignite due to heat and fume in that area. I would think that you would have experienced early signs of performance issues before any castastrophic failure such as fire. Speaking for myself, I think it is hard to speculate on the cause of fire without seeing the damages under the hood physically but still even then most of us are not experienced in L322s catching fire I don't think. This same engine was used in BMWs so I guess you can expand your search to those forums too.
 

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Discussion Starter #7
Thanks for the thoughts.

This isn't really about speculation though, it is about using the experience of others. I am new to the L322 and 4.4 BMW engine, and am asking for experience of what might be flammable at that end of the engine given that as a newcomer I can find very little with the experience I have from other engines and cars.

But no worries, looks like there isn't any experience of what lives on the back end of the engine, and having now had time to take a more detailed look, the only source of potential flammable materials are the oil breather system and high current electrical connection.

As Sherlock once said, once you have eliminated all of the possible clues, then the improbable ones are the culprits (or something like that). I have decided against an insurance claim and will strip the damaged parts out this weekend to see if I can learn more and share the experience here.

At the very least, it is a risk other owners might need to look out for.
 

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I've had plenty of rovers that profusely leaked oil everywhere 1969-2001. All of them. None have caught fire from the oil, including valve covers leaking above the exhaust manifold. All my british cars have leaked. That's what they do. Only fires I've heard about have been fuel, or elect. Jaguar e-type's have been known for the wire harnesses shorting out and burning the car to the ground in minutes.
 

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Discussion Starter #9
Whilst that’s good news, oil does burn. And as mentioned above, this is not oil, it’s oil fumes, vapourised oil that can be more flammable than oil.

Some good reading on a few BMW forums, and the insurance assessor today and this does point to a failure of the PCV causing breather pipes to burst and the fumes to ignite. Not 100% sure this is the reason but as there is nothing else there to ignite (no electrics or fuel) this is the most likely reason being attributed.

Just to note that I too have had multiple vehicles that have posed oil leak issues. Petrol and diesel D2s, D3s, Defenders, P38s, and many Alfas aging from late 80s to current. Per my previous comments, once you have eliminated the obvious, you have to look at the less plausible and as I’m still building experience with the L322, I’m quite looking forward to stripping it and seeing if I can find what really went on.

I’ll feed back here as it does seem no one else has experienced the same!
 

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Looking forward to hearing about your findings, so we can maybe in the future avoid having to search the forums for "L322 engine fire" Thanks for sharing your misfortune with us.
 

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Discussion Starter #11
Sorry for the big pictures. After spending the morning stripping out the damaged parts. Here is what it looks like.

Oil separator is totally destroyed, per previous comments, suggests that the seat of the fire was right here. The pipe from the oil separator to the sump drain is also burnt, and no clue what the source of ignition was, but can be clearly seen here that the fire started in this area. With a number of related issues on a few BMW M62 forums, this does suggest making sure that the separator, PCV valve, and associated pipework are all in good condition. Note that the high current cables behind this are all intact. The harness armour has been melted a tiny bit, but the insulation on the cables has not been breached all the way down the cables to the starter.

Second picture, the last RHS pipe on the inlet manifold has been breached. I removed the PCV valve to see if any clues to failure, but enternally it has been charred and melted.

Third picture, the valley cover started to burn, and took out the small pipe from the PCV drain to the metal sump drain pipe. Unfortunately the heat has also damaged the O ring seals from the coolant pipes into the rear manifold, so this needs to come off and have new gaskets and O rings. Easy job but a bit of a pain. Easier than the similar set up on Alfa Busso V6s.

4th picture is the injector harness, showing damage to the outer casing, and clearly showing insulation on a couple of wires being breached. Lots of used harnesses around at a reasonable price. Just a pain to put back the cables that go under the car. 3 go over the transmission to the LHS for 2 lambda sensors and the Gearbox connection. It was a struggle feeding these through to come out, so not sure yet how to put them back!!

Final picture is the RHS end of the fuel rail and final injector. Probably shows how lucky I was to get the fire out quickly. The injector was starting to melt, and the fuel rail was getting hot with pressurised fuel in it.

I am still not 100% on what caused this lot to ignite. I will carefully check the high current starter harness and ensure there are no shorted, as well as double armour it. With this in mind, it is clear that yes, oil and oil vapour do burn, and whatever cause it to ignite, the seat of the fire was clearly in or very near the oil separator.

My suggestions are:
  • Ensure there is no chance of the starter circuit shorting in that area
  • Make sure PCV and breather hoses are all intact and in good condition
  • Make sure no oil leaks from the separator, head, cam covers etc in that area.
Of note, the engine appears oil tight and no signs of oil leaking in this area.


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JACK'S GRANDAD
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No idea where you are at, but I have a '04 parts rig here in Mo.
 
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