330d F30 bottom end failure - bent conrods?

[TedStriker]

Hi,

Bought a 2013 F30 330d with 78k miles and full BMW history a few months back knowing it had a bit if a ticking noise under load which I expected (hoped!) to be an injector fault. To cut a VERY long story short, have found low compression on cylinders 2 and 3 so got the head off hoping for a head gasket failure between the two. Nothing found but now I see that cylinders 1,4,5,6 have around 1mm of piston protrusion above the block, as per spec, but cylinders 2 and 3 stop a mm or so short. Oh dear.

So I'm thinking bent conrods - probably due to hydrolock at some point? Could anything else cause low protrusion?

Questions - I need to find someone who can take the job of fixing this in the Leeds/Yorkshire area. I don't know if the engine has to come out (remember head is already off), or even if I should be expecting any further damage to be found such as pistons/cylinder walls/crankshaft? Can you get away with just replacing conrods?

In my 20 years of tinkering with cars it's the first time I've had bottom end failure so looking for advice/a shoulder to cry on!

Attached picture is of cylinders 3 and 4

Cheers!
Ted

[Touring442]

It's possible, but so is a half arsed rebuild with wrong bits. 330d/335d's have the same conrods iirc but pistons differ between 30d and 35d, and F30 to E90 etc. You should find the piston part numbers on the crown once the carbon's cleaned off.

[Huskyman]

Whe you turn the crank do the affected pistons travel up and down the bore the same ammount as the good pistons? Have you measured the difference between Top Dead Centre and Bottom Dead Centre? Do it for all six pistons if you can and let us know what you find.

[TedStriker]

Huskyman said:

Whe you turn the crank do the affected pistons travel up and down the bore the same ammount as the good pistons? Have you measured the difference between Top Dead Centre and Bottom Dead Centre? Do it for all six pistons if you can and let us know what you find.

Without having any precision measuring equipment, I can say the following...

The two 'bad' pistons appear to have the same travel as the good ones. The four good ones bottom out 89mm below the deck and the bad ones bottom out aproximately 90.5-91mm below. This would seem to be in line with the differences seen at the top of travel.

[dhutch]

Which I guess is what you would expect, a change in stroke would be very hard to achieve!

What's it like to get the sum off these things?

[TedStriker]

dhutch said:

Which I guess is what you would expect, a change in stroke would be very hard to achieve!

What's it like to get the sum off these things?

A lot harder than it would be if it wasn't an xDrive!

Necessary preliminary tasks:

Remove starter motor.
Drain engine oil.
Remove oil dipstick guide tube.
Remove front axle differential (AWD).
Removing bearing support (all-wheel drive).
Lower front axle support.

I'm not sure why BMW says you need to remove the engine to remove the pistons/rods though - surely it's a case of head off, sump off, undo bearing bolts and push through top of engine?

The manual also says 'Individual connecting rod replacement is not permitted; they are classified by weight class.'. Is this critical?

[g3org3y]

Really sorry to see that, especially on such low miles with a FBMWSH.

Was the only symptom a ticking? No rough running, loss of power or 'check engine' light?

[TedStriker]

g3org3y said:

Really sorry to see that, especially on such low miles with a FBMWSH.

Was the only symptom a ticking? No rough running, loss of power or 'check engine' light?

Ticking which got louder under load, felt a bit down on power (but oddly not always).

BMW ISTA+ software flagged up smooth running correction codes on cylinders 2 and 3 and showed them both to be running weak on live test. No CEL or anything else.

As soon as I swapped injectors 1 and 2 over and the fault stayed with cylinder 2 I knew I was probably in for some bad news.

[helix402]

When I used to rebuild BMW engines that had been flood damaged piston protrusion was the main accurate test for bent rods. I’d go for a second hand engine or a set of rods. Whatever goes in it’s probably worth putting a new timing chain and all bottom end bearings in.

[TedStriker]

helix402 said:

When I used to rebuild BMW engines that had been flood damaged piston protrusion was the main accurate test for bent rods. I’d go for a second hand engine or a set of rods. Whatever goes in it’s probably worth putting a new timing chain and all bottom end bearings in.

Sadly second hand engines go for silly money, £2k or more and then there's fitting. Say I wanted to go cheap, but not so cheap that it won't last more than a few months, could I get away with a couple of rods, and big end bearings? How critical is it that I get a (new) matched set of all 6 rods?

Also, do you know if this could be done with engine still in the car?

Thanks

[helix402]

Last rods I did were a while ago, E39/46 era. These could be done with the engine in. As mentioned it should be possible in a F30, but I’ve not done it. Re 2 or 6 rods, ideally 6, two would probably be ok though I’ve only changed them in sets. (I wasn’t paying!)

[Shedding]

On a completely different car (mazda 2 litre turbo diesel), I replaced a piston and rod with a 2nd hand one from ebay. I didn't even replace the piston rings on the ebay piston as they looked fine. I did replace all big-end and crank bearings. I ran that car from 72k miles to 137k miles when the car died due to an unrelated cause. The engine was perfect. Maybe I got lucky.

[Charlie Croker mk2]

If you still haven't come up with a plan to fix it ? These guys in Rochdale are the real deal -- just for the record I do not have any affiliation with them .
https://www.facebook.com/Walkersofrochdale/?eid=AR...

[Touring442]

The inevitable shagged 35d on their website. They really are crap.

By the time you've farted about lying on your back trying to repair the engine it situ, you could just haul it out. This is a bit of a chocolate engine and there will likely be more wrongness inside.

[TedStriker]

Charlie Croker mk2 said:

If you still haven't come up with a plan to fix it ? These guys in Rochdale are the real deal -- just for the record I do not have any affiliation with them .
https://www.facebook.com/Walkersofrochdale/?eid=AR...

Have just dropped them a message. Let's see what they say. Not a million miles from me if they turn out to be the place to go to.

[TedStriker]

Touring442 said:

The inevitable shagged 35d on their website. They really are crap.

By the time you've farted about lying on your back trying to repair the engine it situ, you could just haul it out. This is a bit of a chocolate engine and there will likely be more wrongness inside.

Yeah engine out is definitely not something I can do on my driveway so maybe the best idea. Lots of labour costs though?

[Huskyman]

TedStriker said:

Yeah engine out is definitely not something I can do on my driveway so maybe the best idea. Lots of labour costs though?

You’ve already done a chunk of labour by pulling the engine, that could save you a bunch of labour costs. Ask the engine builder how much for you to send it down on a pallet and send it back to you?
Give your potential engine repair outfit a shout and ask them on costs.

[dhutch]

OP says engine our on drive is not practical, so far they have just pulled the head.

I don't know the labor cost for swapping an engine in a car like this?

[Huskyman]

dhutch said:

OP says engine our on drive is not practical, so far they have just pulled the head.

I don't know the labor cost for swapping an engine in a car like this?

I should read stuff with more care before posting... The OP needs to be frank with a garage that will take on the work and let them know what he’s done and get some quotes.
If the garage has experience of this work then they could give you a ball park on the time to remove the engine and their hourly rates, the cylinder head is usually installed when lifting the engine out as they attach the lifting gear to the cylinder head.

Edited by Huskyman on Monday 26th October 09:04

[TedStriker]

dhutch said:

OP says engine our on drive is not practical, so far they have just pulled the head.

I don't know the labor cost for swapping an engine in a car like this?

I've been quoted £500 labour for an engine remove and refit, which seems almost too cheap to me. Going to speak to Walkers Of Rochdale today and see what they say.