Spark Plug Fouling

[230slhouston]

Hi Everyone,

I need advice from the experts again. The more we tinker the more questions we have. Some history of my car, it was a 20 year sleeping beauty in a barn that I brought back to life. I would not say the car is perfect, it is OK. There is some oil smoke and oil burn but not excessive. When I idle and take of it blows some smoke, at start up it does and deceleration. In doing my tune up, the plugs look OK, I am not sure if the color is OK though. Except, the number 3 plug has some fouling on it. Pictures are attached.

Quesion to the experts, do you thing the fouling is worn valve seals/guides or seized rings? I have done 3000 miles on this set of plugs over the last year. The car has 77k miles, I believe are original since I have service receipts dating to the period when it was put into the shed.

Any advice?

Thanks
Maistran

[ja17]

Hello Maistran,

This kind of oil fouling on the bad cylinder can be caused by stuck or broken piston rings, dis-lodged intake valve seal and/or bad or loose intake valve guide. 

Remove the valve cover and carefully examine #3 intake vavle seal carefully. Use a flash light to see if the valve seal has moved off it's valve guide.

[230slhouston]

Thanks Joe.

I will remove the valve cover and take a peek to see if there is anything strange going on. Believe it or not it is a little cold in Houston. I will wait for the weekend to tackle this.

Maistran.

[230slhouston]

Joe and all the other Guru's,
I took of my valve cover and had a peek at the valve seals, the number 1.3,4 and 5 cylinder exhaust seals are out of position. They are high enough that you can see the valve stem below.

Question: there was no ticable fouling on the 3 cylinder, partial on 5 and 1 and 4 looked OK. Could there be something else like ring issues with 3 and 5?

Also can the seals be replaced in situ or must the head be removed. I also removed the head for a valve seal repair job.

Thanks,
Maistran

[ja17]

Hello Maistran,

Yes the seals can be replaced by a skilled experienced tech without taking  the head off in less than four hours. Doing it yourself is difficult and risky.  In addition,  90 percent of the time, just replacing the valve seals is only a temporary fix at best.   There must be some other issues with your cylinder head which have caused so many seals to jump off their guides.

If you have some history of the engine (mileage, service records, etc) you can make a more informed decision. How many miles on the engine? Any records of previous engine work?

[230slhouston]

Joe,
Thanks for the reply. My car was put into dry storage around 1989. Included in the trunk was receipts of repairs and I do not see any one for major repair to the engine/cylinder head. As far I can tell the mileage of 77K is original almost 40K was put on in the last 10 years until storage. This I can tell from the chronological receipts.

Could the valve seals be in the current state just from being stored for that long? Or, could the guides be loose?

I am pretty handy and overhauled these engine before but never attempted an in situ valve seal job. Are there any special tools to do this? I just don't want to drop the valve in the cylinder.

Thanks
Maistran

[ja17]

Hello Maistran,

Considering that your engine may have only 77K on the engine, I would try a valve seal replacement.  

The job is a bit tedius, but not all that difficult if you are a decent "wrench".   You will need to remove the valve cover,  and all the spark plugs. You will need a compressor and air connection to the cylinder for your shop air.  Most compression gauges come with a hook up hose that can be used if you remove the shreader valve. You must remove both rocker arms on the cylinder you are working on and charge the cylinder with air. Try to have the piston close to the bottom before hooking up the air since the air charge will move the piston down, turning the engine. The item which may be most difficult is a decent spring compressor tool to use to release the keepers on the valves. After hooking up the air smack the top of each spring/valve assembly with a soft metal hammer or plastic mallet to jolt the keepers  (they get stuck). Now use your spring compressor tool to depress the spring enough to snatch the keepers out. Intakes are easy. Exhaust are difficult since the springs barely compress enough to get the keepers out. Have a miniature magnetic pick up tool, some dental picks, tweesers, or other tools to help handle the keepers. Keep all parts in order and same location. Try to orient the pressure pads in the same dirrection and location during re-assembly.

No mystery on installing the new valve seals. Make sure the valve guides are still secure in the cylinder head before installing the new seal. Also check to make sure that each rotator is not siezed.  Dan Caron points out that the top of the  valve guide should be cleaned free of oil before sliding the new seal in place. An oily valve guide top makes it difficult for your new seal to stay seated apparently. I use the box end of the correct size wrench to push the seal onto the valve guide . Be especially carefull while re-installing the first keeper since the valve is still free until at least one is connected. Even up the spaces between the ends of each pair of keepers. Cover the chain gallery so you do not drop any parts down into the engine. You may want  to place a couple of old sheets on each side of the engine, in case you launch a keeper. They can be difficult to find. Make sure you do not interupt the air supply accidentally while work is in progress or you will loose a valve!

Finding a spring compressor tool will most likely be your biggest aquisition. Look at some of the choices in the "valve adjustment tour". Make sure you get the correct valve seals.

Keep us up to date.

[SteveK]

Maistran, I have a first class spring compressor tool and the 17mm valve adjusting crowfoot (bought them when I re-did my camshaft) if you need to borrow them. 

[230slhouston]

Thanks Joe and Steve.

Steve, I sent you a PM.

Regards,
Maistran.

[230slhouston]

Folks,
Any idea were I can buy the valve stem seals, any recommendations?. I looked at Autohausaz.com and see they have kit. Anyone has any experience with these sets?
The email Link is:
http://www.autohausaz.com/search/product.aspx?sid=pdtv4355fg3urpumq2p35xey&makeid=800016@Mercedes&modelid=1342628@230SL&year=1966&cid=20@Engine Parts, Seals %26 Gaskets&gid=5504@Valve Stem Seal Set

Thanks
Maistran

[Benz Dr.]

I don't see which engine you have in any of these posts. If it's a 230SL, they have different seals than 250 or 280SL's. 230 seals are harder to find and very exspensive. I use a proper valve seal installation tool. If you damage even one of them you will have to buy a complete kit as they are only sold that way.

Frankly, if your car was in my shop the head would already be off the block. 77K miles is more than enouigh for the valve guides to be worn out. A seal replacement is temporary at best. You have will have little or no idea if there's any loose guides, water port cavitation, worn out ball studs, worn valves, worn guides ( very likely ) or warped head. With the head off you will be able to see if there are any broken or seized rings by looking at the cylinder walls.

You can do the seal replacement but I've found that one problem often leads to another. Something made the seals pop off. Maybe they were installed improperly which leads me to wonder if otherr things are worng. It's winter ( 15 F ) so now is the time to look at this.

[Atazman]

I installed the AutoHauz valve stem seals on my 250 SL 11 months ago.  At that time, also had the head off and did valves, guides, etc.  So far-----so good.

Prior to removing the head, I was going to replace just seals, but found one intake valve guide loose in the head.  I knew additional work was needed.

Good luck.......

Don

[al_lieffring]

earlier in this thread, the question was asked why if more than one cylinder had loose valve seals  shouldn't  more than just the #3 cylinder be fowling plugs.

Oil that leaks past the exaust seal/guides goes directly into the exaust, and will make smoke, but not get into the combustion cahmber and show on the spark plugs. Oil fowling will more likely be caused by intake guides/seals.

I have changed valve seals from the top on lots of MB engines and rarely ever got results that made it worth the effort. It was the kind of patch up repair that car traders would ask for to get top dollar out of a klunker. I agree with Dr. Dan, take the head off and replace the guides.

[Benz Dr.]

 WOW!  Someone around here agrees with me!

[ja17]

Hello Dan, and Al,

I think we are all in agreement somewhat.
My quote..."90 percent of the time, just replacing the valve seals is only a temporary fix at best.   There must be some other issues with your cylinder head which have caused so many seals to jump off their guides."

Now the 10% odds for success are not good for the pros which have  to charge a customer for seal installation and parts with only a small chance of success. Chances are you would have an unhappy customer coming back in a week or two wanting some kind of warranty.  Yes a complete head reconditioning has a much better chance of success.

On the other hand if Maistran wishes to do it himself, he is out the price of parts and about four hours of tedius work. He can always abort and continue taking off the head. Sometimes it is not just the results but the journey which is the reward.

[230slhouston]

Thanks Joe, Al and Benz Dr,

All your input is immensely valuable. I do at some point plan to overhaul the engine and do a full resto paint job, I will be needing a lot of expert advice. That is why I am OK with just doing the seals for now. If it works even partially, then I buy a little more time before doing a complete break down and resto.

The worst I can be from a dollar point of view is the cost of the seals and my sweat. Actually, I can drive it as is for now but have itchy fingers and want to experiment a little. Lets hope I am the 10% jackpot winner. Once I start and find out there is more issues then meets the eye, my resto starts a year earlier and the financial director will have to release some cash earlier then she planned.

Does anyone know where I can get the seals and part numbers? My car is a 66 230sl.

Thanks again,
Maistran.

[ja17]

Hello,

Dan Caron, Dave Gallion, Gernald (SL Tech) are active on this site and sell parts., and Bud's (Dave Latham) and K & K Manu. have also supported this group and sell parts.  Al Lieffring is also a great asset, but I am not sure if Al is in the parts business?.  These guys make life easier for all the rest of us.
Tom Hanson of the MB Classic Center is very helpful and knowledgable but not active with our group yet.

There are many others, but not many others with as much knowledge or assistance.

[230slhouston]

  Quick update....

I installed the seals today. This was a fairly easy task with the right tools and advice. First time I did seals in situ. I started her this evening and she sounds beautiful now that the valve clearances are set as well. I could not see if it was blowing any smoke since it was dark already. But certainly did not smell oil like usual. To early to tell. Tomorrow I will set the timing/dwell etc and take her for a ride - can't wait for the morning.

There were some seals actually broken and brittle - I am not sure if this indicated some other issues but will monitor this. I will post pictures of the seals tomorrow.

All in all a fun day. 
Thanks everyone for your advice.

Maistran.

[ja17]

Hello Maistran,

Impressive accomplishment!
sounds like you will see some improvemnt. If the problem turns out to be old, brittle and damaged seals, you may luck out!
You may have some oil saturated in the packing of the exhaust system. It may take a good drive before it all burns out.