[Aviatrix]

Hi all. I was wondering if you could advise what could cause my engine to misfire and do you know of a specialist garage who can diagnose it in Central UK please?

You're probably wondering what happened.

The season of the floods... Made a conscious brave mistake to go through a deep flood, hoping my air intake was as high as other cars. What a stupid decision that was!!! In first gear and at low speed I plunged into the unknown and the engine cut off at the deepest point which was as high as the door edge. Everything cut off. Had to be towed out. Luckily the garage managed to get her started by draining the water, changing the air filter and the oil servicing. She bursted the water out of the intake manifold too. Now she's juddering at cold start, has less power at low rpm and misfiring / coughing at about 1500rpm. Any ideas even if the obvious please?

[bishbosh]

I'd guess a bent conrod or two, giving lack of compression in the affected cylinder(s).

[Allworth]

Have you tried leaving it to idle for half an hour? If there is water in the system it will eventually leave.
If is is a damage due to thermal shock then there may be some irreversible damage to components.

[un1eash]

You've bent of broke valves or pistons at a guess. It won't be an easy or cheap fix as you'll need to remove the head.

As above start with a compression check.

[Danj94]

Liquids aren't know for their ability to be compressed. Usually the engine internals will fail before being able to complete the compression stroke and resulting in bent rods/damaged cylinders etc. Sounds pricey sorry to hear.

As above best start with a compression check and then perhaps weigh up the cost of repair vs a new engine or cutting your losses and moving on.

[Aviatrix]

I think she was idling for a bit at the garage when I went to pick her up.

Thanks guys, I'll get the compression checked. But if any rods, pistons, valves were damaged, would the engine even run?

[bishbosh]

Yes, because if only one or two conrods are bent, depending on number of cylinders, then it'd just misfire on the affected cylinders. So there could be compression, just not enough for proper combustion.

[planemad]

Hydrolocked - You most likely fooked the engine.
Normally you will need a new engine after this.

[Ennoch]

When you say door edge, do you mean the bottom of the door? Not that deep but you need to crawl through, and I rarely see people doing that. The BMW intake design doesn't help, it's shit. Lots of cars use what is essentially a u-bend with a drain hole at the bottom to help filter water out the intake tract but BMW in their infinite wisdom have a straight pipe to the airbox, and once water's in there there's only one place it's going. Water as others have said is incompressible so once it's in the combustion chambers it'll bend valves and/or conrods - if enough got in quickly enough that you stopped in the flood the engine is toast and I suspect it'll be time to call the insurers unless you're happy to stand on for the cost of either a new engine or a rebuild. I suspect neither will be cheap. You *may* have got away with just valves in which case a top end build would fix it but I wouldn't want to get your hopes up.

[sensible]

A costly mistake.

Hope your not featured on Tiktok with the numerous other dead BMWs that drive through the water with onlookers waiting for the inevitable clunk.

[Aviatrix]

Unfortunately, my garage made it available on TikTok.

https://vm.tiktok.com/ZGeUQBL6N/

Thanks all. Hope it's something small and I'm lucky enough to get away with it. Don't wanna get rid of the car. I agree, BMW's design is shit. Yes, bottom of the door edge and I was crawling in the water if that makes any difference. My insurance excess is £1000 so I'd rather pay that to repair the engine.

[TurboWeasel]

You drove through the water too fast, simple as. It's not BMW's fault or a bad design.

The intake is next to the kidney grille, so you basically caused a bow wave which tipped water straight into it.

The blame lays squarely at your feet I'm afraid, which is going to whack up your insurance renewal.

[Pond]

If an insurance claim is required, don't be surprised if they refuse it either.
Similar scenario with a colleague of mine. Lunched the engine on his L200 by driving through a small flood under a bridge. Insurance refused to pay out anything and cancelled his policy. They looked on it as 'willful damage'.

[Aviatrix]

I did not drive too fast at all. There were no waves whatsoever. And if insurance doesn't know about the incident, they can't do anything.

[TurboWeasel]

Of course you didn't. Completely standard 320Ds just get water into the engine 'somehow' when driving through sill deep water.

[xenon]

I thought you were planning to claim on insurance? They will know it's been flooded when they inspect it and / or the garage asks for repair approval. It would be very harsh to say "wilfull damage" as Pond mentioned; negligent perhaps. Amounts to the same thing I guess, I'd be surprised if insurance will cover but hope they do.

[Watsey]

My mum drove her Mini into a similar depth of water a few years ago, with the same outcome for the engine. It's very difficult to gauge the depth of murky water, even if the 'flood' has formed in an undulation of a road that you've driven literally hundreds of times before, and it's always easy with 20-20 hindsight to realise that you shouldn't have risked it.

The insurance company settled the claim (£6K; new petrol engine) without quibble.

[E60525d]

Happened to a family friend, drove through some deep water and wrote the car off. Insurance paid out very quickly

[TurboWeasel]

I suppose it should be the equivalent of home insurance 'Accidental damage' but I bet most car insurers will try and wriggle out of it.

My only concern is if it's on TikTok, an element of 'showing off' might come into play from the insurance company - which would steer it in the Wilful damage direction......thanks to the myriad Rufford Ford videos.

[Aviatrix]

Originally Posted by TurboWeasel

Of course you didn't. Completely standard 320Ds just get water into the engine 'somehow' when driving through sill deep water.

I'm gonna check to see if I still have the dashcam footage just for you.

[goram]

I managed to total my pride and joy at the time - an Alfa 159 SW - by driving through flood water. Totally my fault. The insurers were really good, but insisted on writing it off. I bought the car back off them, and had a new engine fitted, plus had enough money left over for some nice mods.

Once the work was complete I sent copies of it all off to the insurer who then removed the car off the ‘cat’ list.

Worked out well in the end, but it was really stressful for me at the time.

To the OP though, hope you get it sorted without too much drama 👍

[Allworth]

B/N 47 engines have a good seal ring on air intake pipe where it connects to an engine, with the actual air intake way above the bottom of a door level. You have driven too fast and too deep. You must change your ways. Now, I am thinking is not just engine that is malfunctioning, if you check American auctions they have thousands of write offs due to similar reason, because it can be whack-a-mole with such a car.
If you don't have a footage it will very hard to claim anything from insurance.