I suspect I have a bent valve !
 

I had an alcohol misting nozzle in the air cleaner, which I found later has a metal insert in a plastic body. Somehow this nozzle has been ingested into the engine. Needless to say, the engine has developed a new sound.
It sounds like it has a bad tappet rattle (OK, cam follower rattle).
I have removed the inlet manifold and the missing nozzle is not to be found.

I believe the ingestion happened while ascending a steep road near my home.
The engine suddenly started to have the tappet rattle.
I re-checked my valve clearances but found them to be within spec.

Is my diagnosis a probable scenario?

I will download the relevant sections od the FSM from the skinnerbox site tonight.

Looks like I will need to buy a top overhaul kit.

Pardon my lack of knowledge, but what is an "alcohol misting nozzle" is this some type of pre-start aid, like glow pluggs?

With an aluminum head, and something banging around in there, I would cease running the engine at all as aluminum is very soft and anthing banging around in there will hack the hell out of the head!

Steve............ :)

No, I tried getting a bit more power from my non-turbo 300D.Steve, this is the OM617 engine, and has the cast iron head. I have stopped using the car, as even though the head is iron, the pistons are aluminum, and unfortunately, I think I have a bent valve. I doubt that the remains of the nozzle will be found in the engine.


Anyone wanting to lay odds on which cylinder has the bent valve?
Bonus if you correctly identify whether the exhaust of inlet valve is the one.

Lets see, it would be trying to escape throught the exhaust valve, but, if it is banging around in there, aimed and timed just right, with intake valve open, wanggg-ohhh!!!

Thought I saw you to mention a 201, but was mistaken, sorry! You still haven't answered my question about "alcohol misting nozzle" I've never heard of one! :confused: :confused:

alcohol misting nozzle
 

An item that claims to boost power but does little good IMO.

A cylinder leakage test will confirm a bent valve. We use a boroscope to inspect the interior of the cylinder and piston top when an engine injests something.

I have seen debri imbedded in a piston top that was hitting the head and making noise, like a small screw or washer. When the gods smile upon you, the debri can be removed through a spark plug hole or through a diesel injector hole. Leaving a sharp spot on the piston can cause you grief in a gas or a diesel engine.

Using water and or alcohol injection, even in a turbo charged diesel engine, has little effect. Back in the days before anti-knock sensors the water/alcohol injection systems worked marginally well for hot rod gas engines by slowing the flame spread in the cylinders.

Tony,

Does your engine miss-fire on one cylinder at idle? If you had a bent or broken valve, you would have low compression on one cylinder that might cause it to miss- fire. If you have good compression in all the cylinders, you don't have a bent valve. If the valve clearances are within spec, I doubt you have a bent valve.



There is practically no clearance between the and the pistons. Anything that got into the cylinder would be pushed into the piston because the aluminum piston is softer than the iron head. Try a borescope to see if there anything in the piston.

P E H

Thanks all for your comments.
A mechanic friend of mine suggested that the offending item may be impaled in the piston crown and contacting the head at each TDC. I will ask around to see if someone has a borescope.
The engine idles and runs smoothly, but seems to have lower power than before.

ALCOHOL MISTING.
I had the alcohol misting installed in a Mazda 2.0 litre Diesel car, with excellent results, giving a 10-20% power boost at WOT. This system consisted of a 12v water pump (washer pump) with a microswitch on the IP to close when the pedal hit the metal, turning the pump on and misting denatured alcohol into the inlet manifold. As the injection only happened at full power, the alcohol usage was minimal, but it gave an improvement in diesel economy due to greater power and shorter acceleration times.

I installed this in an effort to improve the OM617, non-turbo, power output.

If I remember correctly how the alcohol works it was to raise the cetane level. The system has never had much of a following for some reason. One thing that was discovered with the alcohol was the small amount of water in the alcohol will clean a combustion chamber carbon depsosits out like you would not believe. That said the water mist system has been used off and on over the last 50+ years in trucking industry for cleaning engines of carbon build up.

I have personally seen it done to high compression gas engine back when I was a kid at the local Ford dealership. They just started the car and run water from a hose into the carb in the same way you do with carb cleaner, keeping the engine running all the time. Under the exuast pipes of a 406 CI Ford V8 it would leave a black nasty puddles. I had often seen it done in the big truck shop, but had not realized what they were doing at the time.

Seems like the problem with doing that was it could not be done for long periods at a time due to cylinder wash or something of that sort. Maybe not allowing enough upper cylinder lubbing.