'99 E300 D - Cracked Head?
 

While waiting at idle for traffic signal, vehicle was inundated by water wave from passing truck. Engine stalled and subsequently ran rough on restart.

Inspection revealed soaked air filter and water droplets in turbocharger air intake.

Compression results:

Cylinder -

1

210 025 with OM 606 962; 95K miles.


While waiting at idle for a traffic signal, the vehicle was inundated by a wave from a passing truck. The engine stalled and subsequently ran rough on a hot restart. Subsequent restarts from cold resulting in a smooth idle for approx 180 seconds, followed by missing and white-grey exhaust smoke. The final restart from cold resulted in an immediate miss, greyish-black exhaust smoke and Check Engine warning light illumination.

Initial inspection revealed a soaked air filter and water droplets in the turbocharger air intake.

Compression results:

Cylinder -

1 25 bar

2 < 10 bar (air could be heard escaping from cylinder 3 injector port during cranking)

3 17 bar

4 21 bar

5 27 bar

6 26 bar


Cylinder head removal revealed no visible cracks and no head gasket defects. Injectors for cylinders 5 and 6 were coated at the bottom with motor oil; the corresponding prechambers were also soaked with motor oil; the upper cylinder walls of cylinder 5 displayed motor oil as well.

The motor was asymptomatic prior to water ingestion. Any ideas as to the source of motor oil in prechambers 5 and 6? Where does the OM 606 head typically crack?

The insurance company is requesting visual proof of a defect before authorizing head replacement. But no cracks are visible at room temperature. Head gasket replacement alone will not remedy the prechamber oil problem and may or may not remedy the low compression in cylinder 2. Would rather have definitive proof of all faults before proceeding. Is magnafluxing the head warranted?

Cyl 2 and 3 are out of balance with the others which are relatively close, so i'd take a look at the head where those cyl's are, did you hydro-lock the engine? or were you able to start up right away?

Has the head been properly (UV) crack tested or has it just been a clean & visual inspection?
What are the pistons like? do they all come up the bore to the same height?
Your description doesnt convince me of a cracked head. The air escaping from #2 is unlikely to be anything more than a loose injector. What was the heat shield like?
I think you have a long way to go before one would say a new head is required.

If I wanted to jump straight to the most alarming possibilities, I'd suspect damage from water compression before I'd suspect a head crack. Just can't quite imagine how a water sousing would cause a head problem, but I can easily imagine that if a *HUGE* slug of water went through the intake, into an open cylinder through the air intake, and then the thing tried to compress it as the piston came up, with both valves closed, I can imagine it bending a rod or doing other bottom end damage from attempting to compress a liquid.

I'm not suggesting that's what has happened either. But, it might explain the low compression on that cylinder, and it comes closer than a head crack to what my "instinct" suggests water ingestion would cause.

However... I don't usually know what I'm talking about :-D Just throwing the theory out there for the smarter ones to digest.

ussually a bent rod..

With the head pulled measure each piston in the block. sometimes a bent one will be cocked a bit- not a lot- in a gaser it can be 0.010-0.05 inch or so.

944's are bad about it.

Michael

Pressure testing at the head shop will reveal any cracks in the head, which might or might not be weldable. I'd bet against cracks.

The hydro lock issue could be big--you might have been "lucky" and just blew the head gasket in the process, hence the lack of other obvious damage.

With regard to the bent rod possibility, you'll need to measure each piston at top and bottom dead center. the edge of the crown of the piston will stick about a 1mm or so above the top of the head at TDC--if there is any variation between pistons, a bent rod could be in your future. . .

Far as the oil, with the injector down the center of the valve cover, anything in the injector bore is going in the cylinder when the injector is removed. As you turn the engine over to check the piston heights I'd be more concerned if you ended up with lots of oil on the cylinder walls. . .

G

Correct me if I am wrong but this motor has an aluminum head. I thought aluminum could not be "magnafluxed" nor successfully welded. It can be pressure tested though and if it is bad a new head is the only real solution. My guess is the hydrolock theory is correct and the damage is more extensive. If it were my car I would just look around for a used engine - there are probably several around.

Short of that, with the value of these cars down to where it is probably very close to totalled the insurance company may opt for that rather than pour money down a rathole.

Magnaflux is a ferrous metal procedure--Dynaglow (UV) and xray are the only non-ferrous NTD techniques suitable for crack detection.

sorta right. aluminum heads cannot be magnafluxed (they aren't magnetic) but uv and xray work well. and aluminum is much easier to weld than cast iron...

Having done a double rod replacement on a hydra-locked 606 turbo, my guess would be bent rods on 2 and 3. Not sure about the air noise though. Kind of odd two next to each other. I am not sure of the firing order. Mine were 3 and 6. If you want proof for the insurance company, show them the rods once they are out of the motor. My number 3 looked hideous and and number 6 was still visually bent.

Like previously said, measure the deck clearance with the head off and that will tell the tale.

As for oil in #5 and #6, that is from the crankcase ventilation hose leaking oil and draining into the injector ports.

Keep us posted. It is not too bad to do the rods now that you have the head off. You will not be able to fully get the oil pan out of the way, but with the motor jacked up you are able to get the end caps off the rods.

Two rods are $500 approximately.

Huh?

Use a dial gauge or some reliable system to check and compare piston heights. Thats if the difference is not obvious. I suspect you have not done so with the head off because of complcations with the timing chain yet. You still have to do this though.