Oil in spark plug wells

[MARCEDES]

Hey crew,

First Merecedes, first post, so please be patient with me

Bought my '74 W116 280SE two weeks ago and it hasn't skipped a beat. First drive to get her home took about an hour and she drove beautifully. Replaced a couple of small parts since (thermostat, radiator cap, coolant overflow bottle) and again has driven fine. Last week I drove her every day for about 40 minutes and a little stuttering started, particularly when taking off. I thought maybe the air filter needed replacing (which it does) so I put it down to that.

Yesterday, no good. Wouldn't start. After tinkering around a little, I've discovered a couple of my spark plug wells have oil in them. The plugs aren't swimming in there but it does seem that there's a weep at the top of the wells and this is running down to the bottom.

I'm thinking that this is why it's not starting. Any ideas on the best way to remedy the situation? The other wells that aren't wet with oil do have some considerable build up of, what I imagine to be, dust and oil but they're dry. My first thought is to some how degrease the wells but I'm apprehensive about spraying degreaser down there.

Any suggestions would be most helpful.
Thanks in advance.

[daantjie]

Welcome!

Oil pooling in the spark plug wells would usually point to oil coming form above, so think valve cover gasket as the easiest culprit.  If the gasket is toast, or not torqued down completely, then it will leak oil big time.  Best remedy is to pull all the plugs, then
the valve covers too, and replace the gaskets.
Plugs all need to come out, and I usually just use a good carb cleaner and liberally spray, and clean with lint free rag.  Painful work but necessary.  Be careful not to have the nozzle of the can of carb cleaner fly into the
spark plug hole, for obvious reasons, this would really suck!
You can also then run a spark plug thread cleaner (chaser) with lots of anti - seize compound to clean the threads, then clean again with carb cleaner to get all the carbon and crap off there.
Be sure to run the right plugs too.
Good luck!

[UTn_boy]

Adding to what Daantjie has already stated, please also note that each spark plug well has a drain hole.  These drain hopes exit on the right side of the cylinder head under the exhaust manifolds.  Mercedes put these drains here so if oil did seep in the wells the high tension leads wouldn't dead short to ground.  If these holes are clogged up, then figure out a way to unclog them, and as previously mentioned, renew your valve cover gasket.  Be wary of aftermarket kits for this.  They either don'y fit or they're short lived in life span. .......now that I think about it, the same can be said for most aftermarket products.  When buying aftermarket parts, always ask yourself if you want to do the job again in less than a year.  With regular use, that's about how long most aftermarket parts will last before they start to leak/fail. 

While the tappet cover is off, you might as well check your valve lash clearances.  This is very important on M-110 engines, and is overlooked/forgotten about 99% of the time.  Eventually, new camshafts and camshaft housing will have to be installed due to neglecting the lash. 

Your car will also have a transistorized ignition system.  So make sure that the low voltage points are set to the correct dwell, and that the ignition coil and ballasts resistors are in good order. 

Being that you have a 1974 280se, I'm assuming that you have D-Jetronic fuel injection.  If so, then this will open a whole other area of things to check and/or look out for.  Specifically, the manifold pressure sensor (MPS), the vacuum line going to it, the throttle position potentiometer, leaking fuel injector seals, and engine wire harness faults. 

Also, these early transistorized ignition systems don't respond well to the use of resistor sparking plugs.  Make sure that you don't have resistor type sparking plugs.  Non resistor types are still available from Mercedes, and I think NGK sells a somewhat close version.

[MARCEDES]

Welcome!

Oil pooling in the spark plug wells would usually point to oil coming form above, so think valve cover gasket as the easiest culprit.  If the gasket is....

Thanks for the info daantjie. Sorry for my lack of experience generally regarding this. I'll have to clarify a few things. Any information you can further pass on to me will be much appreciated.

Firstly, I understand the valve cover gasket to be beneath the top housing (valve cover?) on the engine block itself (sits in between the housing and the rest of the engine around the spark plug wells) - photo attached.

If I go ahead and remove the bolts (highlighted) and remove the top housing, I shouldn't have to expect any parts, springs, etc. flying off around the place when I remove the housing? Its just simply a lid effectively and reveals that section of the engine's internal components?

If this is the case I'd imagine that keeping the internal components of the engine dust free is a must but would it be ok carry out this kind of work outdoors as long as it's not raining or windy? I don't have a garage 

I bought this car going into the realisation that I'd need to do some work to it and I'm more than happy to. I just need a little more knowledge. Sorry crew!

Thanks too for your input UTn_boy. Would I be right in thinking the drain holes are around the area the arrow is pointing to?

I'm unfamiliar with what the valve lash is as well as the transistorized ignition system and your checklist of

manifold pressure sensor (MPS), the vacuum line going to it, the throttle position potentiometer, leaking fuel injector seals, and engine wire harness faults.

but thank you for your info just the same. I'll do some reading and check it all out.

Regarding the spark plugs, the guy I bought the car from said he'd changed the leads and plugs very recently (leads yes, plugs not so sure, will need to check them out once I manage to get the right socket to remove them). But I'm not sure what type they are and whether or not he knew.

[irvine]

Great advice, reminds me I need to replace my rocker cover gasket.

In regards to the drain holes beside the spark plugs, how would I go about cleaning these out??

Cheers,
Neil

[rumb]

I'd check out those spark plug wires, many aftermarket ones have different (wrong) resistance in them.



These are good: Karlyn

http://www.autohausaz.com/search/product.aspx?sid=fvcfdozjj1unwmbao4hfds55&makeid=800016@Mercedes&modelid=1193396@280SE&year=1977&cid=25@Ignition%20Parts&gid=7228@Spark%20Plug%20Wire%20Set

[rumb]

This thread has some good pictures of a M110 head.  it is actually 3 parts to it.  1, the valve cover, 2, the cam box, 3, the actual head,  then below that is the block.

http://www.peachparts.com/shopforum/vintage-mercedes/322616-m110-cylinder-head-rebuild-pictures.html

[s class]

Generally the spares-shop type plug leads simply don't work.

In our shop we fit a lot of the KarlynSTI/Bremi sets, and they are excellent.

[TJ 450]

For the oil leaks, I'd be buying a rocker cover gasket set... I see you're in Perth. These can be bought locally through Lintrex in Welshpool/Os. Park or if you need other things like the leads, online parts stores and eBay (quite likely, as even the new ones could be damaged if someone was heavy-handed with them... it's easy to rip the wire out of the plugs on the spark plug end if you're not careful). The rubber pieces around the plug holes go hard and start leaking.

Worst case, oil leaks can be from the lower gasket between the head and separate cam box, but unless its a huge leak there I wouldn't worry about it so much.

When you pull the leads off, if the wires are loose in there or can be ripped out easily they are faulty.

It's hard to clean out those holes, but you can flush it out with carb cleaner and pick the sand out with a rag on the end of a screwdriver or compressed air.

I also second the notion of adjusting the valve clearances, there should be a sticker on the cover showing the clearances. If it hasn't been done in a while it can be a real bastard turning the adjusters... I'd be adjusting once a year or thereabouts depending on how many km you do. I think it's supposed to be every 10k, but it will be in the manual.

Btw the M110 isn't quiet in the top end, so don't be concerned about bit of tappet noise.

Tim

[daantjie]

To come back to the removal of the valve cover and precautions to be taken.
Indeed you must be careful to remove all the nuts, and spring washers underneath (some of them might be missing), BEFORE you try and lift the cover off.  The reason for this is that a rogue nut/washer can drop into the engine as you do this and
then you are up the creek trying to fish it out!  Also be prepared for the cover to be a bit stubborn to come off.  You can try GENTLE taps with a rubber mallet to break the seal if it does not want to come off but be very careful not to damage the cover.
Overall cleanliness is of course good to observe, but I have done all my work under a car port so it can be done sans garage.  Not ideal but not bad either.  I try and cover as much of the surrounding area with a cover, could be an old shower curtain or such, works quite well.
Just be methodical in where you place your tools and such, it can be very easy to drop a tool on the fender and nick up the paint.  Fender covers are a cheap and great solution to this little problem:)

[MARCEDES]

Thanks rumb and s class for the info. Will look into that. I was chatting with a mechanic acquaintance this afternoon and he thought it might be that there's no fuel injection. Sound plausible?

Thanks for the info too, TJ 450. Good to know another local supplier in Lintrex. I'll give them a call. Not sure that its a leak from the lower gasket as it seems to be weeping down from above the spark plugs and in to the wells (unless I've misunderstood you). There is, however, a fair leak on the driver's side of the block where the arrow is pointing (see photo). Do you know if that's where the holes you and UTn_boy are referring to? Maybe that's just the possible dead valve cover gasket though.

Regarding the valve clearances, sounds totally out of my league but always willing to give it a shot with the right info. I'm sure I could find a thread to help.

And thanks daantjie. I'll be sure to follow those guidelines. Very helpful tips.

[s class]

Leaks at the valve cover gaskets are common on 110 engines because :
a) the valve cover has to be taken off an M110 quite often (every time valve clearances are done)
b) guys overtighten the nuts holding the valve cover, distorting it and crushing the gasket.

[MARCEDES]

Good to know s class. So when re-tightening the nuts, just finger tight?

[rumb]

5nm

http://handbook.w116.org/Engine/110/05-210.pdf

There is a great manual in the Library top right screen

[UTn_boy]

Thanks rumb and s class for the info. Will look into that. I was chatting with a mechanic acquaintance this afternoon and he thought it might be that there's no fuel injection. Sound plausible?

Thanks for the info too, TJ 450. Good to know another local supplier in Lintrex. I'll give them a call. Not sure that its a leak from the lower gasket as it seems to be weeping down from above the spark plugs and in to the wells (unless I've misunderstood you). There is, however, a fair leak on the driver's side of the block where the arrow is pointing (see photo). Do you know if that's where the holes you and UTn_boy are referring to? Maybe that's just the possible dead valve cover gasket though.

Regarding the valve clearances, sounds totally out of my league but always willing to give it a shot with the right info. I'm sure I could find a thread to help.

No, MARCEDES.  Where your arrow is pointing is another common leak point.  This is where the camshaft box and cylinder head meet.  The exhaust manifolds are connected to the cylinder head, and the drain holes terminate UNDER where the exhaust manifolds connect to the cylinder head.  Between the cylinder head and the engine block, essentially. 

The M-110 engines, at least the early ones, came from the factory with no gasket between the camshaft box and cylinder head.  They ALL end up leaking profusely, and the addition of the gasket becomes necessary.  Hopefully, this has already been done, but with oil leaking from this area It doesn't sound like it. 

And thanks daantjie. I'll be sure to follow those guidelines. Very helpful tips.