Spark plug hit by piston, valve? M103 engine
 

Photo below of spark plug out of M103 engine. Something has hit the end of the plug don't know what. Must have been a valve or piston, but how?

I just put head back on after doing heat gasket. Apparently I screwed something up. Before removing head engine was set at TDC for Cylinder one and cam grear sprocket was put back on exactly as taken off. Chain was put on at same place on cam gear as it was removed

What could have caused my problem and what can I do to fix it?


Edited: The spark plugs are all less than one year old but could it be that that one plug just goes to far in the hole that it threads into? I don't think I can shim it out since the plugs seat into hole, ie no washer.

I don't see how the piston can hit the spark plug unless the plug is too lorng or you had an object in the cylinder that does not belong.

Tom W

I checked cylinder before I put head on and blew them out with air to make sure they were clean. That said it seems I did something wrong or knocked something in there when I fitted head to block. Is there anyway to check without taking head off.

I put cylinder 3 in TDC and could not see anything in there with pen lite and also put a magnet in to see if I could get anything out, but no luck. I don't have a borescope.

Is there any way a valve could have hit the plug?

OK, let's see if we can figure this out.

First, when did you know something was wrong? Does the engine turn over? Did you realize something was wrong when you first cranked the engine over? Did the engine run at all after re-installing the cylinder head? Did you leave the spark plugs in the head for the duration of the job? Give us some details and we will figure out what happened!

First, when did you know something was wrong?
When I started the engine and I heard what thought was valve lifter noise.

Does the engine turn over?
Yes

Did you realize something was wrong when you first cranked the engine over?
Yes

Did the engine run at all after re-installing the cylinder head?
Yes, I was thinking maybe the valve lifters need to pressurize.

Did you leave the spark plugs in the head for the duration of the job?
Yes

The other plugs look fine?

I would work on the premise that there is an object in the cylinder. My favorite machinist has a little periscope he can put in places like that to look around, maybe you can borrow one.

Oh and in case you are feeling like a knuckle head I once dropped a 3" stud into a cylinder and forgot it was there and so when i cranked the engine over it fell in there and then pushed a hole in my piston. Ouch! That cost me about 2k to fix. I had to buy a piston and all new bearings plus have the block stripped and cleaned IIRC.

Just don't run it this way and you wont spread debris into your bearings. (like I did).

Tom W

Yes

This vehicle has 153K miles. The head gasket I installed is the vehicles 3rd; don't know if that's of any significance.

Maybe a bit of an 'out-there' suggestion, but is it possible that the spark plug was knocked while in the head but off the car, and the ticking noise really is just a lifter. :confused:

Good thought. Did you try replacing the plug?

Tom W

Well you must have gotten the timing off, I'd start by timing it.

Not sure what the chain drives on an M103, but getting the crank and cam on the timing marks would be a good start. Is the distributer driven off the chain?

Since pistons and valves are hooked together, even if incorrectly, and spark plugs can't move, I'd say that all the plugs would exhibit this damage if it was caused by a piston or valve. I think the damage was done while the head was off or there was something foreign in that cylinder.

Damage control.
 

Ron,

Something is wrong, be it major or minor. Do not run car until you have performed your checks.

Like Tony said, maybe you just whacked the plug while the head was off the motor.

Note to all: remove all plugs, injectors or other things from the head that you may have to before removing it. It is much harder to after the fact. I have a nasty scar from when I was 16 from pulling injectors off a VW diesel head because I was too much in a rush to remove them before pulling the head.

Regardless, you can not assume this as you have noises and a damaged plug.

Pull valve cover, pull all spark plugs, set crank and cam to TDC. Do the marks line up? Let's hope they do, if not timing must be reset, but more importantly, how many degrees/teeth are they off? I think 2 teeth out, and the valves are hitting the crowns of the pistons. Not an m103 expert. Let's assume timing is correct and continue.

Next you should assess if you have FOD (foreign object debris) in the cylinder. This could be a nut, rag, bottle cap, who knows what. A borescope would be ideal right about now. You could insert a fine magnet through the spark plug hole. May get lucky. Back track your steps. How careful were you? What are the chances you let something fall in? We all make mistakes, trace your steps.

If by whatever means you have did not find any FOD, crank the motor over by hand. Listen as you do this. Any strange sounds? Feel for resistance, does something feel choppy or abnormal in the motor?

If all seems good, crank the motor over with the starter, plugs still out. A remote starter switch is ideal about now. That way you only activate the starter, no fuel or ignition, and can stand by the motor and listen. If all sounds good excellent. Also you can move about the engine bay listening to the motor from various vantage points.

All this time you will have the valve cover off. Now you can check to see if you are getting oil pressure to the camshaft, lifters, etc. Ensure nothing falls into the head while the valve cover is off.

Assuming all is well, I would do a compression test for grins. Good to know where things lie. If you can do a leak down test, even better.

If all checks out for the good, bottom it up and give it a fire. Listen carefully. Keep fingers crossed.


OK, now onto possible bigger issues. This is the 3rd head gasket in 153k miles? Something is not right! Warped head, poor installation, improperly milled head are all initial thoughts.

Here come the questions:

When starting the motor after this head R&R did you ever get oil pressure? If so how much?
Why was the head pulled the first time?
Did the car ever overheat?
How long did the last gasket last?
Was the head serviced by the machine shop when it was off the first time? (as it seems it was not this time?)
If so, was it checked for warpage and/or was it milled?

FWIW, if the head was milled too far down interference can happen. Seen it before on a 603. Also have seen a head that was not milled straight. Head gasket blew in less than 10 minutes on that one. That was an m103 also. A good machinist is worth his weight in gold!

Take a deep breath. Clear the mind, and approach this systematically. It may be something insignificant, but best to do your homework to be sure. Best case all is well, worst case the head comes off again.

Lastly, before cranking it over more, when you pull the valve cover, if there is no oil on the cam, followers, etc, you really should put some assembly lube on those bits. Standard procedure during assembly. STP works in a pinch, Motor oil if in an even greater pinch. Something is better than nothing. WD40 will not cut it.

Let's help Ron figure this one out ILUVMILS.

Hatteras, the distributor rotor is driven directly off the cam. It is not like the earlier motors.

you have given a good thorough descriptoin of all steps necessary. My only further comment is to ask how a valve can hit a spark plug if the plug is the right length? Seems impossible to me.

Tom W

A valve head could hit the proper-length plug, if it separated from the stem. But in that case, the engine is unlikely to turn over with the starter.

not the valve, FOD or the piston. head has been milled too much, piston comes up, hits plug. chances are slim of it, but may be possible depending on how the sp. plug is oriented. like i said, not an m103 expert.

When I saw the picture of the damaged spark plug, this was the first thing that came to mind. The more I think about it, the more sense it makes. That's why I asked if the plugs were installed for the duration of the job.

If there's any doubt about a foriegn object in the cylinder though, there are a few things you should do before installing a new plug and starting the engine. Using a borescope would be ideal, but since that's not gonna' happen, try this (I'm assuming you have an air compressor). Connect a piece of rubber vacuum line to an air nozzle. Put the vacuum hose into the cylinder and blast away. Keep a close eye on the spark plug hole to see if anything comes out. This may not get everything out (if there's anything in there), but you'll know right away if there's a problem. I've used this trick many times to clear debris from OM606 diesel cylinders, after drilling out stubborn glow plugs.



Incorrect engine timing can't cause piston-to-plug contact. Piston-to-valve? Yes. Piston-to-plug? No

As for the distributor, the ignition rotor is driven directly by the camshaft.

Thanks to all who have been kind enough to offer me advise and suggestions on how to deal with my situation.

Well, from reading and thinking about situation I decided I must have managed to get something in the cylinder that should not be there and the only way to know for sure and to assess damage was to remove head. So I did that.

Piston, cylinder and head and valve seat where damaged. The damage was caused by the small breather hose that goes from the intake manifold to valve cover which has those two metal clamps. The clamps did the damage. It is apparent I was not careful enough when fit the head to the block. This is the first time I did a head gasket replacement, so anyone else who does one for the first time I'd have to recommend just removing that little breather hose when you fit the head to the block, I suspect the pros remove it or are just more careful.

I do have a parts car, 1992 300 E with about 15K less miles on it than the engine I ruined in the 1992 300 TE. So everything should be the same except for the tandem power steering pump on the TE which runs the self leveling system.

I'm wondering if the transmission for the E model is the same as the one for the TE.

Hopefully I can swap engines without screwing anything up. I'm not a professional mechanic but I've got a good bit of experience and feel pretty stupid for not being careful enough when I reintalled the head.

Dude....I feel for you. I've made plenty of mistakes over the years, so I know how you must feel, but don't sweat it. Maybe there's hope. What kind of damage did you find? If the piston didn't crack, the damage may be limited to the cylinder head. If so, it's possible it can be repaired. If a valve seat didn't get hammered it might be easier than you think. Don't make a bad situation worse. Assess the damage and proceed accordingly. Keep us posted.

I would get an experienced machinist to look at it. Sometimes things aren't as serious as we hobbiests think by looking at it.

Good luck.

Tom W

Attached are photos of my mess. Note cylinder is scored.

ron...there was a guy on here selling a head that he rebuilt.... i think he was looking at 350 shipped.

I know i was very interested in it.... but just don't want something that big taking up room.

his name is hihosilver

Oh well. I think it's time to go with plan B. Best of luck. :)

Ron,

Mistakes happen to everyone. I installed a cam timing gear backwards on my old 220Sb and drove the car for half a semester in college before it reared its ugly head. We all have our stories. In the future, I am sure you will ensure the bores are clear of any debris. Chalk it up to a learning experience.

Looks like your cylinder head may be salvageable, but that is a nasty score in the block. If your spare motor is nice, looks like it will be the best way to go.

My spare motor will come from wifes 1992 300E with 135k miles on it. We have had that car from about 9 years having bought it with 60K miles on it. The car was totaled earlier this year when it was hit from behind, really not much damage but trunk lid will not close.

The 1992 300 TE was purchased about 2 years ago with 133k miles on it. I basically restored it, everything worked perfectly including the new evaporator which I changed out shortly after I bought it. The wagon had it's original head gasket replaced once before but I don't know at what mileage. I had even changed valve stem seal which stopped it from burning any oil.

I'll need to figure a plan for removing the engine, i.e., the block.

I would kind of like to reuse the intake manifold and fuel distributor and associated fuel stuff.

Should I start taking assesories off what remains until there is nothing but the block to take out of car?

[QUOTE=Ron in SC;1693584
I'll need to figure a plan for removing the engine, i.e., the block.

I would kind of like to reuse the intake manifold and fuel distributor and associated fuel stuff.

Should I start taking assesories off what remains until there is nothing but the block to take out of car?[/QUOTE]

Ron,

I would suggest you remove motors as whole assemblies, swap bits around as you like with the motors out of the car, then reassemble. Also with the motor out, it is an ideal time to clean the motor as well as the engine bay, replace any seals, gaskets, etc, that would benefit from such. With the motor out of the car, things become considerably more accessible and simpler to work on. Make the most of the opportunity so that you do not have to dive back in there for a long time to come.

I would suggest you remove motors as whole assemblies
Would that include the transmission too?

As far as the wiring harness goes I've removed most of the connectors on top of the intake manifold. Do I remove the harness connectors under the engine and leave the harness with the body of the car or do I disconnect it from behind the battery?

The motor that will go in wagon had head gasket replaced at 101K miles and waterpump at 81K miles, motor now has 135K miles so I should be ok with that. It also has a new mercedes a/c compressor installed just a few years ago.

If it is a known good tranny attached to the motor you are going to use I would keep it attached and install as a unit. That way you are not disturbing the seals around the torque converter.

Sorry it turned out so badly.

Been there, done that too.

Tom W

exactly, If you're planning on doing this in your driveway, i.e. on your back, pull the engine and trans as one unit. Use a load leveler so you can tilt it to clear the core support! As I started reading the thread I was going to guess one of the guide pins got into the cylinder but I guess those hose clamps can be just as nasty!

ron... are you really going to attempt this yourself?

Yes, that's the plan. Of course it's subject to change. My new detached garage is not completely done and lift is not in so I may have to have my friend who owns MB shop lift motor out of donor vehicle and place it into wagon. I can for sure remove motor from wagon and transmission if necessary. I can do all the other stuff.

I don't have a lot of time to work on car because I'm doing finishing type work on the house addition and then I'd like to get back on garage (photo below) to do painting and other work to finish it up. Basically the engine change project is not the highest of priorities.