Hydro locked 330I

I am considering buying my son's 2002 330I He hydro locked the engine trying to get through some flood water and being active duty military he would rather just settle with his insurance company and move on... I love the car and should be able to buy it from him for less than 4k.

The engine was relatively cool when he hit the water (about 400 yards from where he started it) and the rpm's were low when it locked... I pulled the plugs, discharged the water and drove it to a credible local shop. There is a distinct ticking sound coming from the engine that sounds like a bent valve. The mechanic that looked at it says that its at least one bent rod and the noise i hear is the rod tapping the edge of the block skirt and that in his experience he has never seen a hydro lock bend a valve.

I am an above average shade tree mechanic (old school gear head) but have no experience with these engines. My questions are..

Does it sound likely that the mechanics diagnosis is correct?

Are these aluminum blocks really so delicate that they strip head bolts easily?

Suggestion:
Pull the coil wires off the plug of the cylinder you think is knocking, then start it up and see if the noise changes. If the noise diminishes with no load on it, it might not be the rod. BMWs have very strong bottom ends, it takes a lot to damage them. The "stripped head bolts" issue usually occurs after someone drove the car while it was overheating....one episode like this can be The Kiss Of Death to a BMW engine....the head can warp or crack, the block can become annealed (softened) from the heat to the point where the rod bolts can no longer be torqued to the correct value, etc. Bad JuJu....

BTW, the car is Silver, sport pkg., 5 speed manual, sun roof... loaded with only 84,000 miles

Originally Posted by Fast Bob

Suggestion:
Pull the coil wires off the plug of the cylinder you think is knocking, then start it up and see if the noise changes. If the noise diminishes with no load on it, it might not be the rod. BMWs have very strong bottom ends, it takes a lot to damage them. The "stripped head bolts" issue usually occurs after someone drove the car while it was overheating....one episode like this can be The Kiss Of Death to a BMW engine....the head can warp or crack, the block can become annealed (softened) from the heat to the point where the rod bolts can no longer be torqued to the correct value, etc. Bad JuJu....

Thanks my friend, That makes perfect sense in all respects. From your experience is it best to drop or pull these engines for these kinds of repairs... or is it possible to get the necessary access with it in the engine bay?

Let me rephrase that question...

Assuming the worst and I need to replace a bent rod or two, will I be able to pull the head and get the pan off to get access to the rod bolts without pulling the engine?

Am I correct that these engines mount to a subframe of sorts and are best dropped out the bottom?

If there is a thread that would help me, I would appreciate any help in finding it. I have a lot of mechanic experience, access to a shop with a conventional engine hoist and am not scared of any project.
4 years ago I built a '85 4runner with a chevy 4.3 swap/700r4, megasquirt, edis 6 ignition etc.. (did everything but the machining) that I take to Colorado every summer to drive the off road trails at 10-14k feet.
Just have NO experience with the Beemers and could really benefit from some general direction before I dive in to learn the details and spend any money on service manuals.

Thanks in advance for any help!

It is doable, but very difficult. I usually drop the engine out, and put it on a stand. The oilpan is a bear to remove on the car, and it is much easier to drop the engine through the bottom. Make sure to buy the correct timing tools also. As fastbob said, the only time you have to worry about stripped threads is when it overheats.

Originally Posted by Jimmys 530i

It is doable, but very difficult. I usually drop the engine out, and put it on a stand. The oilpan is a bear to remove on the car, and it is much easier to drop the engine through the bottom. Make sure to buy the correct timing tools also. As fastbob said, the only time you have to worry about stripped threads is when it overheats.

You guys are great, Thanks for the fast response!
This is a really sweet car and it would be a shame to see the insurance company get it.

Originally Posted by jpdunn101

...I am an above average shade tree mechanic (old school gear head) but have no experience with these engines. My questions are..

Does it sound likely that the mechanics diagnosis is correct?...

Hope for the best, but expect the worst. Plan on buying a replacement engine, and be pleasantly surprised if it is not necessary. You may want to try and look inside the cylinders with a boroscope, to see if you can tell what damage occurred.

I am sorry to be the skunk at the party. The BMW M54 engine (your engine) is a technical marvel, but it is very complex to repair. The valve train and timing chain setup is not for the inexperienced. I recommend buying a Bentley BMW E46 repair manual, and review the engine section.

Many many have removed the oil pan from beneath. It's not a miracle.

Yes, used engines are sometimes the best idea.

Gotta agree with the mechanic; hydro locking isn't going to bent valves; but it will bend or break rods. Valves would have to be closed in order for the engine to lock (otherwise the water wouldnt try and compress; it would just exit between the valve and the valve seat).

When you get the pan and the windage tray off, look for witness marks on either side of the bottom of the bore. Or just turn it over by hand and see what's up.

Bought the car today for way less than what I thought and no salvage title required and
ordered the Bentley E46 service manual.

Ran compression tests and it looks like #3 is the culprit with only 95psi and listening closer i'm sure its the bent rod tapping the edge of the block skirt.

Time to tear it down and see what I find!

Originally Posted by jpdunn101

Bought the car today for way less than what I thought and no salvage title required and
ordered the Bentley E46 service manual.

Ran compression tests and it looks like #3 is the culprit with only 95psi and listening closer i'm sure its the bent rod tapping the edge of the block skirt.

Time to tear it down and see what I find!

Good luck ! Keep us posted.

Have fun also, don't be surprise if u have a bent crank...

Originally Posted by TrippinBimmer

Have fun also, don't be surprise if u have a bent crank...

I thought about that possibility... man, I sure hope not!

Well I pulled the engine and got it on a stand... 5 bent rods

Good news is...leak test on the head was good, the engine is very clean, the crank is straight, the rod bearings and journals are in great shape.

Parts are on the way!

Originally Posted by jpdunn101

Well I pulled the engine and got it on a stand... 5 bent rods

Good news is...leak test on the head was good, the engine is very clean, the crank is straight, the rod bearings and journals are in great shape.

Parts are on the way!

Nice. Are you willing to post up some photos of the carnage? I'm curious what bent rods look like... congrats on getting the beast rebuilt!

Originally Posted by numindast

Nice. Are you willing to post up some photos of the carnage? I'm curious what bent rods look like... congrats on getting the beast rebuilt!

I would have to second this as well.

5 bent rods.. two of them were tapping the block skirt during rotation.
The moral to this story.. hydrolock is BAD!

I would just pick up a new used motor...

Nice pics! That's impressive. thanks

Originally Posted by TrippinBimmer

I would just pick up a new used motor...

Where's the fun in that?

Got time? Make a project out of it!

Proves water is stronger than steel.

Originally Posted by GoForthFast

Got time? Make a project out of it!

Proves water is stronger than steel.

I enjoy working on engines.. I have rebuilt 3 in the last five years and I was dying to get into a double overhead cam with variable valve timing.

I have the shop, tools and time so why not save a couple thousand and know what you have.. an engine with fresh bearings and rings.

Originally Posted by jpdunn101

5 bent rods.. two of them were tapping the block skirt during rotation.
The moral to this story.. hydrolock is BAD!

I'd say that's pretty impressive. 5 bent rods, and yet the crank and bottom end are still fine.

Good luck with the rebuild.