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M103 Head Gasket Questions
It looks like I need to replace the head gasket on my '91 300E. The coolant has an oily feel and there is a oil blown back over the transmission that appears to be leaking from the head at the rear.
This car only has 54K on it and has had annual coolant changes using 50/50 MB cookant and distilled water. I can't believe that I've got this problem. I'm going to take it to a respected MB dealership but wondered what I should insure they do: - Cooling system flush w/MB cleaner? - New timing chain cover gasket? - Chain guide? - Tensioner rail? - Other? TIA, Bud |
#2
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Hi Bud:
If I was to change my timing chain cover, I would want to change the chain itself and the tensioner too. I don't know if you need to go that far. Also a valve cover gasket will be a good choice too. When I did my head gasket, I also did the valve seals. Motor uses a lot less oil now. Hope this helps. Aloha, Eric
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1987 260E Charcoal Grey 157,000 Miles 1987 260E Forest Green 120,000 Miles |
#3
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These engines have a ratcheting tensioner. If this engine had many more miles then I would change the chain because the engine is apart. With such low mileage and apparent frequent oil changes, I would replace the chain if close inspection warranted. I will be shocked if it does.
Your description sounds much more like what would be expected from a 104 engine, but it could certainly happen to a 103. Since you have maintained the cooling system AND the oil is apparently coming from the head, then you are probably correct. The thing to do is wash the area THOROUGHLY and ensure that the oil is coming from the head gasket before attacking this job. Have you checked the transmission fluid level to ensure that you are not getting A/T fluid in the coolant? Good luck, |
#4
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I'll let the dealer do the final diagnosis but it seems more like engine oil rather than ATF fluid in the coolant. I use 15W-50 Mobil 1 and the stuff has a unique texture.
As for the chain, the car has had frequent Mobil 1 oil changes since the 1,200 mile mark. It doesn't use a drop of oil between changes. I suspect the chain is in good shape but I'll leave it up to the dealer to decide about replacing it. I can't understand why Mercedes didn't have this problem fixed by 1991. Incidently, I had a 1984 190D that had a leaking head gasket. The dealer wanted $600 to replace it. I had him retorque the head and drove the car for another 11 years with no problems. I doubt that will work with this problem. |
#5
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Bud,
There is irony in your comment saying that you can't believe that MB did not have this fixed by 1991. Actually it is opposite. The M103 engine rarely blows a head gasket relative to the later M104 engine which is much more frequent. In addition to that, There are no aluminum head/iron block engine models that I know of that do not experience a dose of this from time to time. The cast iron expands/contracts at a much different rate than aluminum, so things will sometimes happen. Best of luck, |
#6
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Larry,
The archives seem full of examples of this problem on M103's and even at relatively low mileage. It's also mentioned in Stu Ritter's new book as a common M103 problem and in other places. What's disturbing is that this car has probably never had coolant temps above 105C and never had tap water in the coolant. It's not the money that gripes me because just the tags and taxes on a new E-Class would more than pay for it where I live. It's the idea of somebody taking the engine apart and the inconvenience of finding a reliable shop and getting it fixed. I suppose the bright side of it is that I didn't have a BMW V8 that had to have a short block installed because of cylinder etching or a Lexus V6 having to be stripped because of the gelling problem. My brother-in-law has got it figured out. I told him that he was spending a fortune having to replace his Cadillacs every few years because they didn't last. He said he'd thought about getting a Lexus or Mercedes but then he wouldn't have an excuse to buy a new car every four years. |
#7
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Based on what I've seen on my old 1989 260E (103 engine) the timing chain and guides should still be in new condition at your mileage.
I never had a problem with a leaking head gasket in 235K, although I had to replace it last summer when the valve guides needed attention. I just hope the replacement head gasket will be as good as the original. That was the first time I had the valve cover off the car in 11 years of ownership. |
#8
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I concur with Larry.
This forum is full of techs commenting and disagreeing with us when we say that M103 head gasket failures are common. The techs always say that in their umpteen year experience, head gasket failures on M103's are rare. M104's have the common head gasket failure. Plus, even in Stu Ritter's book, he points out and shows in pictures why the gaskets fail, and comments that the leak is manifested by an external oil leak. It is very rare to see an internal leak of coolant in the oil. Your problem to me sounds more characteristic of ATF fluid leaking internally into the coolant. It happens and usually surprises owners that this is even possible. Last, this also comes up from time to time. but the techs also always say that M103 and M104 engines never require a replacement of a timing chain. They just don't do it. The chains are short, don't change direction multiple times like they do on the V8's, and the tensioner does a good job of keeping the chain tight. You may change out the tensioner and the guide rails, but the chains are not a replacement item.
__________________
Paul S. 2001 E430, Bourdeaux Red, Oyster interior. 79,200 miles. 1973 280SE 4.5, 170,000 miles. 568 Signal Red, Black MB Tex. "The Red Baron". |
#9
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Given the low cost of a timing chain you might want to change it anyway, even at this low milage.
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#10
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Quoting page 139 of Ritter's book...'At the rear of the gasket, water and oil channels pass very close to each other. It is here that the gasket develops a crossover between these channels. If the gasket fails in this way, oil is visible in the coolant.'
I've got oil in the cookant. I've also made an appointment with Schumacher Moters in Scottsdale to have them look at it next week. The Service Advisor said they probably do one of these a week. They are going to be expensive but they're giving me a loaner and a 1 year, unlimited mileage warranty. Maybe they'll find something else but I doubt it. Thanks to all for the feedback. Bud |
#11
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Whatever it is, if the head comes off for a gasket replacement, by all means, spend the extra few hundred dollars to get the head rebuilt with new valve guides and valve seals. You can actually replace the seals with the head on the engine, but you can only replace seals with the head removed.
Valve guide wear is much more common on M103 engines than M104 engines, too.
__________________
Paul S. 2001 E430, Bourdeaux Red, Oyster interior. 79,200 miles. 1973 280SE 4.5, 170,000 miles. 568 Signal Red, Black MB Tex. "The Red Baron". |
#12
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Just checked the price of a timing chain out of curiosity: $30.71
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#13
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Your low mileage may actually be part of the problem. You have an 11 yr. old car that's been driven only 54,000 miles. Things dry out when they sit idle for extended periods of time and that can cause leaking.
As Stu Ritter said, 103's leak at the right rear corner. There have been many posts here that indicate the 103 chain is more or less timeless. If the oil has been kept clean I'd doubt you'd need to change it. New valve stem seals and a head gasket will drop any oil consumption you may have been experiencing way down. |
#14
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The main reason for 103 chain durability is the ratcheting tensioner. It uses oil pressure as do others, but as the chain loosens the plunger "ratchets" to keep the chain tight, even after the engine is shut down. Since there is no looseness during that cold start up, it does not hang up on "stuff" causing things to break.
Have a great day, |
#15
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Here's an M103 HG fan
Hello Bud:
I know how you feel about your head gasket. I have a '93 190e that had 73k on the clock at the time, and mine failed. I was rather surprised as well, but my mechanic said that he has seen a number of these. I guess all you can do is pay the $ and get it taken care of. If you do what the others have suggested (guides and seals), you won't have to touch your engine again for a way long time. My mechanic advised me to just do the valve seals for now. The guides on my car were still in excellent shape and did not require attention. Best of luck to you on your repairs; hope they can get it finished for you soon. Peace, Michael. |
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