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

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

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,

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.

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,

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.:D

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.

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.

Given the low cost of a timing chain you might want to change it anyway, even at this low milage.

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

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.

Just checked the price of a timing chain out of curiosity: $30.71

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.

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,

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.

Mike,
I think you have a point about low mileage being the problem although I always tried to drive it at highway speeds at least once a week.

I'm going to give the dealer a blank check on this thing and go with whatever the Tech decides needs to be done.

I just got my car back from Schumaker Motors in Scottsdale, AZ. The problem was the head gasket. They could find no other problems except for a soft hose and a cracked serpentine belt. They flushed the cooling system twice to make sure they got the oil out of it.

The head, chain, valves, etc. were all fine.

These guys are expensive but it's the most pleasant service experience I've had since I bought my first German car in 1957. What an amazing dealership!

Boy do I apprecieate the 300E after having to drive a Ford loaner for two days.

I wouldn't get too upset about the gasket failing at this mileage, either. I agree with the previous comments about low mileage.

Things like seals, gaskets and rubber bushings don't do too well with sitting.

The age in years of your car is more indicative of it's true age as opposed to the odometer.

As to the failure rate of the M103, I can't comment too much past the fact that I know lots of M104 owners with new gaskets, and not many M103 owners. But, that's just my personal experience. The M103 in our family is at 336,000 kilometers, and no leaks yet (touching wood!).

If it were my car, I'd spend the extra money to freshen the head even with the low mileage, since the majority of the expense is in R&R'ing the head anyway. All IMHO...

The Service Rep told me they saw more M104's with head gasket problems than M103's. The job is done. The people who did it had essentially a blank check from me and did whatever they thought was necessary. They didn't find anything wrong with the head. Maybe it's because this engine has had Mobil 1 15W-50 in it since the 1,200 mile mark.

My wife and I both thought the car ran especially well after we got it back but that may be because we've been stuck driving a
Taurus for three days.

Since we're down to one car, it won't be sitting around so much anymore.

I think the '93 has the M104 engine, not the M103. I'm not sure though.

Have a great day,

That's right.

1993 300E's have M104 engines - either the 3.2 or the 2.8 liter.

1993 300E's (3.2's) have the same vin #, engine #, and chasis # as 1994-1995 E320's. They just didn't change the badge as they should have. See my signature below.

1988 300E leaking coolant
 

Hi guys (Bud in particular!)

<*** thanks so much for the info Bud! I was just recommended by ******** (MB parts) an indy in Mesa (Hillprecht Auto) I'm gonna try for now...looks like my leak is coming from the back side of the water pump--maybe a seal I hope! I suppose he'll be able to tell if it is a head gasket since I have NO clue!! $538 for the replacement of the pump includes about 6 hours of labor and roughly $150-200 for the pump. Hopefully that does the trick!! Thanks again! Mike ***>>>

I have recently experienced a coolant leak coming from what seems to me to be the water pump area but being a non-techie I suppose it could be coming from a blown head gasket?? It ends up dripping off the oil pan right by the plug and I did notice some dried-up brownish streaks along that side of the engine so it must have been doing this for a while although haven't noticed it running hot except for last week when sitting idle with the A/C on for 10-15 minutes. Took off and it cooled down so figured it was from not driving it--maybe that was my mistake?!

Car seems to run fine for the most part with occasional rough cold start and rough idle once in a while--I attribute this to the fouling of 3 out of 6 of my plugs--this car too has only 72k miles on it and is using oil (about a quart every 500-1000 miles) and I figure the valve stem seals are ruined based on my research on this wonderful forum.

Also, realized tonite that I probably do have some sort of oil in my coolant overflow tank as the lower half has a kind of brownish tinge to it. I don't see signs of coolant in the oil as the dipstick oil looks crystal clear--is that how you check that? So could be ATF--how do I tell that?

In my research on the blown head gasket, I've seen the comment of checking for wet plugs and I'll do that in the a.m. but wanted to get this out there ASAP!

My question to Bud if you don't mind me asking was what Schumacher charged you to do the work?? I have heard not good things about them so was pleased to hear of your great experience but am definitely curious about your comment of them being expensive!

Lastly, I've seen such variation in the cost of doing the head gasket--anywhere from $1500-3500...sheesh, I don't know what I'll tell my wife if it is $3500!! :D :D well, even $1500 for that matter!!

Sorry to ramble and THANKS to all of you for your help--it has been invaluable over the last year or so! Mike

Mike,
I was charged the following:
- Labor...$1,140
- Head gasket set...$148.52
- Cooling syst cleaning compound..$18.70
- Coolant...$17.00
- Hose and Clamps....$15.75 (short hose to water pump while they had it apart)

They had the car for three days and provided a free rental car while they had it.

The job they did seems to have been excellent. No problems so far. They checked the head for warping and no other parts needed replacement even though I told them to correct any problems they found.

The parts costs are high but I'll be going back to Schumacher for anything I can't do myself. My experience with those guys was outstanding.

The most important thing is that they do a lot of head gaskets so they know what they are doing. Besides, you are treated like a king...lots of goodies and drinks:D

103 head gasket questions.....
 

We have a '93 300TE 4Matic with 270,000 miles. This is a 103 engine. The engine has minor oil "seeps", our very good "indie" has used a flourescent dye in the oil to locate all the areas. I use about a quart of oil every 5000 miles, I use Castrol 10W50 and change every 5M miles. The seals were done at about 150M, engine runs fine, the problem is the drip wherever I stop the car. We can't find another car we would rather have so the problem is whether to have the gaskets replaced, along with other work while they are in the job. After reading the various gasket comments I get the feeling maybe we should leave this alone and tolerate the drips until it gets much worse. Taking the head off might be opening a can of worms. I'd like to hear any comments. We have replaced the waterpump and alternator, the powersteering pump has a minor leak. Thanks for your comments. srharvey

Sharvey,

Since you have a M104 engine- It is apparent by the responses that the sign of needing a headgasket is oil in the coolant.

The external oil leak is probably the front cover needing to be re-sealed which is not very expensive.

To the list: So you guys don't consider a M103 headgasket leaking oil externally as a "head gasket failure". Only when there is mixing between coolant and oil?

I'll put valve seals in mine this year and see how things go. From what I see in Texas, you need to make sure the aux fan comes on when the coolant gets hot.

Michael

If you have a leak in the rear corner of the engine, it's the head gasket. If you plan to keep the car for any length of time, I'd have it repaired before it gets worse. If you get to the point where there is oil in the coolant, you will have to add the cost of a coolant system flush not to mention any other possible problems that could arise.

Make sure you have it done by a highly experienced person/shop. If they don't do it right the first time, you will just have more cost and grief down the line. When they have the head off they should replace anything that's difficult to get to like the serpentine belt and the short hose between the head and the thermostat housing.

Done correctly, you will not have any more problems. I believe they changed the head gasket to correct the problem.

Not saying that I am doing the correct thing, but I have been driving my '92 300E M103 with a very slight head gasket leak for now going on 130,000 miles. I have crawled under the engine and watched the leak.

There is no contamination of coolant. I have to watch coolant levels and oil levels about every 500 miles. It's not burning oil, it's just leaks a little.

I will eventually get around to having the top end re-built and head gasket replaced.

Steve

MB agreed to change (on warranty) the valve seals on my engine (I was aware that better seals went into production after my car was built.) to, hopefully, improve oil consumption, which was about a quart every 2K miles, however I elected to wait until just prior to the end of the four year/50K mile warranty, and at about 48K the head gasket began to seep coolant toward rear of the exhaust side, so they pulled the head and completely rebuilt it - all new guides, new exhaust valves, and, or course the newer viton seals.

The engine seemed to pull a little stronger at the top end after the rebuild, but interestingly the oil consumption was about the same, and has maybe degraded to a quart every 1500 since then.

Bottom line as Larry said is that head gaskets that seal materials with different thermal expansion characteristics will not typically last as long as if both head and block materials are the same, and it's a matter of the number of thermal cycles, not miles, so a car that sees low average trip mileage between cold starts is going to have the head gasket go in fewer miles than a car that has high average trip mileage.

Owners of vintage Alfa Romeos consider changing the head gasket at least every 50K miles, if not sooner, as "normal maintenance".

Duke

I agree with the previous comments about the age of car and not the miles driven as contributing factors in failures of certain engine parts.

When I bought my 88 124C/103 four years ago, it only had 41,000 miles on it.
Nothing at all for a 13 year old car. But a PPI revealed a leaking head gasket (yes, at the rear of the head, external only) which was replaced at the time.

A year and a half later (at 55,000) valve seals replaced to cure heavy oil consumptiion.

I can't compare the engines. But I have no gripe with my 103. Trouble free car. Get in and Go.

Parting thought: Consider a coupe or cabriolet if your single or getting a second car. Rare bird and dynamite looks. ;)

It just occurred to me that this thread is ANCIENT!

Duke