I have a 1987 260E with the same M103 engine, just different displacement. It was already using some oil when I bought it from the first owner 22 years ago. I’ve used the car as my daily driver and as long as I was driving on the highway it was fine as the oil just burned away, but oh boy, you didn’t want to get stuck in a traffic jam cause then the flames weren’t hot enough to burn the excess oil and the spark plugs got clogged resulting in the misfires in your video. Another tell tale sign is blue smoke from the exhaust when driving away after a few minutes idling. Misfires got worse, at some point it was using 1 liter of oil every 1000km. Then finally two of the valves burned. I got the head overhauled where the valve stem seals were also replaced. It’s been 40000 km since then and the engine still runs smooth without misfires. Later on I bought the W124 service manual on CDROM from Mercedes Classic center and learned this issue was already recognized somewhere in 1989 or so. There was even a recall in some markets where they replaced the valve stem seals free of charge. Needless to say that has been too late for my car…
M103 prechamber is the perfect term. When you showed the part I forgot their original purpose and thought it was a P0420 fix (02 sensor prechamber 😂) Very interested in long term results. Thanks for another great solution
Interesting take on the usage of oil Kent I'm looking forward to seeing your results also a trick to be used on oxygen sensors that give problems with the W124s.
I had an 86 300E for 20 years then put 370,000 miles on it The auto magazines touted this new M103 saying it was the first in-line six that was a rival in smoothness to the BMW I-6. It had only two flaws that I'm aware of One was its voracious appetite for head gaskets every hundred thousand miles to 150,000 miles That was because at the back of the engine block the coolant passage and oil passage were too close together. And I suspect overtime the cast-iron block and aluminum head would cool and retract it different rates. In any event the head gasket would develop a tear between the two passages and the factory went through three or four revisions The other was its need for valve seals every hundred thousand miles or so Since I was putting in head gaskets about the same interval the seals were just replaced but I was told it is possible to change them without having to pull off the head As far as your question I suspect that "fix" would keep the plugs from fouling but of course you're still going to get the oil into the cylinders Why not fix it right unless the engine has 500,000 miles on it ? I don't understand why he wants to buy an old engine and transmission and swap unless those are shot and then you're getting another old engine and transmission Anyway I loved that car I thought it really had the perfect dimensions for an E class Each generation has grown a few inches I haven't checked the dimensions between a W126 but I swear my W-211 is close in size to a short wheelbase W126 I really loved that E class even though my W-210 V8 gets the same mileage with 100 more horsepower It was the perfect dimension and if we're starting a pool I'll bet that the electrodes have very little oil on them
Another cause of misfires in this engine can also be from the little control module mounted on the inner wheel arch... 1990 260E. I chased a misfire at idle for a long time until this was diagnosed and replaced
Nice, simple, and effective troubleshooting. Thanks Ken! I've done the valve stem replacement for an OM617 using your kit. Is it really much different / difficult for the M102/3 engine?
It is more complicated than on a Diesel engine. If you don't have the right tools and know what you are doing, it is easy to drop a valve down into a cylinder. Then you do have to pull the head!!! Not a beginner DIY job.
I have a 1990 230e w124 (same engine but 4 cilinders) and 400.000km (around 250.000 miles) and recently it has begun to run not as smoothly as it has always been. I have changed the spark plugs, the wires, the gasoline pump, and the coil. Now it goes better but not perfect. I have seen this video and I would like to try with these prechambers. Where can I buy them. I write you from Spain in Europe. Thanks in advance!!
Hey Kent, thanks the usual helpful videos I am restoring a similar car that is 1991 SEL for my father would love if you can share links to vital stuff to buy whether parts , kits, or videos and I am looking for the gloves you recommended but could not source.
I have too many items to just send you links. Use the search box on my website and always start the search with "W126" so for instance, search. W126 suspension, W126 engine, etc.
I am using the best plug here for oil fouling. Adding a heat range will not do much on an engine that fouls out spark plugs due to oil in less that 2 days.
It is not as common on the M104. Are you burning oil? Do you get any blue/white smoke out of the exhaust after the engine has idled for a while? Pretty easy to confirm by removing the spark plugs to see if any are oil-fouled.
@ No oil burning that I’ve noticed, just an intermittent miss somewhere. I haven’t done any diagnostic yet, just preparing. I’ve replaced the ignition, but still a miss. I’ll dig in and look for oil!
You will have to explain what you mean by best. You would need to explain what you mean by old. You would need to explain who would do the maintenance. You would need to explain how much you would want to spend.
My E320 with the M104 straight six is still my favourite MB engine, even though it developed a head gasket leak around 300 000km. The body of the car was shot anyway (rust).
I have a 1987 260E with the same M103 engine, just different displacement. It was already using some oil when I bought it from the first owner 22 years ago. I’ve used the car as my daily driver and as long as I was driving on the highway it was fine as the oil just burned away, but oh boy, you didn’t want to get stuck in a traffic jam cause then the flames weren’t hot enough to burn the excess oil and the spark plugs got clogged resulting in the misfires in your video. Another tell tale sign is blue smoke from the exhaust when driving away after a few minutes idling.
Misfires got worse, at some point it was using 1 liter of oil every 1000km. Then finally two of the valves burned. I got the head overhauled where the valve stem seals were also replaced. It’s been 40000 km since then and the engine still runs smooth without misfires.
Later on I bought the W124 service manual on CDROM from Mercedes Classic center and learned this issue was already recognized somewhere in 1989 or so. There was even a recall in some markets where they replaced the valve stem seals free of charge. Needless to say that has been too late for my car…
M103 prechamber is the perfect term. When you showed the part I forgot their original purpose and thought it was a P0420 fix (02 sensor prechamber 😂) Very interested in long term results. Thanks for another great solution
Interesting take on the usage of oil Kent I'm looking forward to seeing your results also a trick to be used on oxygen sensors that give problems with the W124s.
Never seen this before. Great idea. Your videos are really appreciated.
Thanks!
I expect good short term results, possibly long term.
Maserati uses a pre-chamber setup like this on their MC20 engine. Works brilliantly from what I’ve seen.
Mercedessource Kent, I have used the anti foul on my 1952 continental in M62 army truck they do help the spark plugs from fouling as bad.
I had an 86 300E for 20 years then put 370,000 miles on it
The auto magazines touted this new M103 saying it was the first in-line six that was a rival in smoothness to the BMW I-6.
It had only two flaws that I'm aware of
One was its voracious appetite for head gaskets every hundred thousand miles to 150,000 miles
That was because at the back of the engine block the coolant passage and oil passage were too close together. And I suspect overtime the cast-iron block and aluminum head would cool and retract it different rates. In any event the head gasket would develop a tear between the two passages and the factory went through three or four revisions
The other was its need for valve seals every hundred thousand miles or so
Since I was putting in head gaskets about the same interval the seals were just replaced but I was told it is possible to change them without having to pull off the head
As far as your question I suspect that "fix" would keep the plugs from fouling but of course you're still going to get the oil into the cylinders
Why not fix it right unless the engine has 500,000 miles on it ?
I don't understand why he wants to buy an old engine and transmission and swap unless those are shot and then you're getting another old engine and transmission
Anyway I loved that car I thought it really had the perfect dimensions for an E class
Each generation has grown a few inches
I haven't checked the dimensions between a W126 but I swear my W-211 is close in size to a short wheelbase W126
I really loved that E class even though my W-210 V8 gets the same mileage with 100 more horsepower
It was the perfect dimension and if we're starting a pool I'll bet that the electrodes have very little oil on them
Another cause of misfires in this engine can also be from the little control module mounted on the inner wheel arch... 1990 260E. I chased a misfire at idle for a long time until this was diagnosed and replaced
Would an Infrared Laser Thermometer aimed at the exhaust manifold tell us which cylinder is not firing?
Nice, simple, and effective troubleshooting. Thanks Ken!
I've done the valve stem replacement for an OM617 using your kit. Is it really much different / difficult for the M102/3 engine?
It is more complicated than on a Diesel engine. If you don't have the right tools and know what you are doing, it is easy to drop a valve down into a cylinder. Then you do have to pull the head!!! Not a beginner DIY job.
What are some other signs of valve stem failure? Black smoke??
The most common one is after you sit for 5 minutes at a long traffic light idling, then take off and see a big cloud of white-blue smoke behind you...
Those are awesome engines but they really like Head Gaskets as well.
great content Kent
Thank you for this video!
I have a 1990 230e w124 (same engine but 4 cilinders) and 400.000km (around 250.000 miles) and recently it has begun to run not as smoothly as it has always been. I have changed the spark plugs, the wires, the gasoline pump, and the coil. Now it goes better but not perfect. I have seen this video and I would like to try with these prechambers. Where can I buy them. I write you from Spain in Europe. Thanks in advance!!
Hey Kent, thanks the usual helpful videos
I am restoring a similar car that is 1991 SEL for my father
would love if you can share links to vital stuff to buy whether parts , kits, or videos
and I am looking for the gloves you recommended but could not source.
I have too many items to just send you links. Use the search box on my website and always start the search with "W126"
so for instance, search. W126 suspension, W126 engine, etc.
As a question could you go up one heat range in thr plugs? Not a mechanic.... but this is often used in 2 stroke outboards that run slowly on rivers
I am using the best plug here for oil fouling. Adding a heat range will not do much on an engine that fouls out spark plugs due to oil in less that 2 days.
Great video. Having the same engine myself with quite similar issue. Do you maybe know where to buy anti foul adapters?
Here is the link to purchase: mercedessource.com/store/m103-6-cyl-engine-spark-plug-oil-non-fouler-kit
👍🏻👍🏻👍🏻
Is this problem present on M117 V8 engines also?
Quite rare and usually only on very high-mileage engines.
Is this also an issue on the M104? I have an intermittent miss in a ‘91 300SL that I was going to tackle in a week or two…
It is not as common on the M104. Are you burning oil? Do you get any blue/white smoke out of the exhaust after the engine has idled for a while? Pretty easy to confirm by removing the spark plugs to see if any are oil-fouled.
@ No oil burning that I’ve noticed, just an intermittent miss somewhere. I haven’t done any diagnostic yet, just preparing. I’ve replaced the ignition, but still a miss. I’ll dig in and look for oil!
What is the best model of old sedan mercedes car I can buy today?
You will have to explain what you mean by best. You would need to explain what you mean by old. You would need to explain who would do the maintenance. You would need to explain how much you would want to spend.
Where do you get them? & what are they called?
Here is the link to purchase: mercedessource.com/store/m103-6-cyl-engine-spark-plug-oil-non-fouler-kit
why change prechambers and not the valve stem seals?
We did not change the "prechambers." We added them.
I think it is a good idea to try this
👍💪
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My E320 with the M104 straight six is still my favourite MB engine, even though it developed a head gasket leak around 300 000km. The body of the car was shot anyway (rust).
Rust bucket manifold
My apologies for showing that in the video. I will remove it today and get it powder-coated.
@@Mercedessource 😂
@@Mercedessource😂
Good one Kent!😂