M102, 103 & 104 head gaskets almost seem predictable! - PeachParts Mercedes-Benz Forum

Greg in Oz · #1 08-02-2004, 10:11 PM

I have been servicing my father's W124 '93 E320 coupe (3.2 M104) for him. One thing he wanted me to look for was the source of the oil leak under the back of the motor. You guessed it! Rear, right corner of the head gasket. Nothing in the coolant yet, just a slight annoying external leak. I don't know how long before it really will need attention. Our '90 300TE (3.0 M103) went for a couple of years with a worse leak than this before oil appeared in the coolant and I had to pull the head. That was when the car was about 10 years old with 145,000km. Early this year I helped my brother do the head gasket on his '92 180E (1.8 M102). 11 years old and 93,000km. Now the E320, 11 years and 136,000km. There almost seem to be a predictable pattern to this. Just as well I purchased my '90 190E 2.3 at 13 years and 211,000km with the head gasket previously replaced. Hopefully I won't have to do that one as well.

For those who are familiar with head gasket replacement on the M102, 103 and 104, how do they compare? I have done the job on the M102 and 103 and apart from the occasional stubborn item, the jobs were not difficult. How about for the M104? Any tips? I found with the 102 and 103 it was easiest to lift the head with exhaust manifolds attached but with inlet manifold left behind in engine bay. They are KE whereas this 104 is HFM so that might change things. I suspect my father might ask me if I can do the job. I have yet to break the news to him. I am getting to know his car well. This year alone I have done the water pump, belt tensioner and damper and have just finished fitting new front discs and pads in addition to a routine service. The car now travels only about 10,000km (6,000 miles) per year.

Gilly · #2 08-02-2004, 10:18 PM

On the M104, you can let that leak go as long as you can stand the mess, it normally won't allow oil into the coolant or vice-versa. The M104 isn't much tougher than the M103, in essence the M104 is much like a M103, except for the dual cams. You have to be careful to reinstall the intake cam sprocket (adjustable) correctly, other than that it will seem very familiar. Fuel injection harness is of course an added concern also, easily removed and set to the side.
With the M103 I feel it's important to do that head gasket replacement as soon as the oil is noted in the coolant.
I've seen alot of M102's self-destruct for various reasons, usually seemed related to plugged pre-cats, but few head gasket replacements.

Gilly

Kestas · #3 08-03-2004, 08:58 AM

Considering head gasket repair is inevitable on these engines, I wonder if the weight savings by going from cast iron to aluminum for the head is worth it. Aluminum head on a cast iron block is difficult to seal because of thermal expansion mismatch. A cast iron head can give virtually trouble-free service as long as the valvetrain doesn't need reconditioning.

Greg in Oz · #4 08-03-2004, 09:31 PM

Gilly,
Thanks for the reassuring advice. I would rather not have to tackle this and unless oil appears in the coolant or the oil leak gets very messy I will be tempted to leave it alone. As yet it is not even leaking from the front timing cover in the usual location, I thought this was where they were inclined to leak first. When I did the job on our M103 a few years ago it was leaking front and back and I caught it just as oil started to appear in the coolant, unlike my brother who drove around for about months with oil in the coolant of his M102 before asking me to help him fix it. I do remember once looking at a 300CE-24 with plenty of oil in the coolant reservoir though. I hope this was an exception or did the early M104 (3.0 KE) have a different head and gasket design to the late M104 (2.8 & 3.2 HFM)?

Kestas,
I remember you tackling this job on your E320 a while back. If I have to tackle this job down the track, hopefully you might have some good advice. What you say about alloy heads on iron blocks is true. I have never had a head gasket problem with engines with iron heads. Imagine how heavy an M104 would be with an iron head though! With the M102 and M103 I was able to single handedly lift the alloy heads off and on myself, although the 103 probably nearly gave me a hernia! For the 104 head an engine lift might be in order.

Thanks,
Greg

Kestas · #5 08-04-2004, 09:29 AM

The instructions say to remove the head with the manifolds attached. It's easier and faster this way, but you have to have a hoist. Even with two guys, somebody may hurt themselves or do some damage under the hood from dragging the head off the engine. I would have to guess it weighs 100-150 pounds.

I tried to remove the manifolds first, and would have been successful, but one of the bolts was hopelessly stuck -- overtorqued at the factory. Besides, a lot of the bolts were difficult to access. I have an engine hoist, but it was easier for me to use a winch and one of the reinforced beams in the garage to lift the head off, then roll the car away from underneath.

It's a good idea to clean out the egr tube while the head is off. It's easy to remove it and give it a good cleaning at that point.

732002 · #6 08-04-2004, 09:55 AM

Don't all cars now have aluminum heads and they
don't fail at the high rate that MB's do. Does the
length of a I-6 head have something to do with
the failure vs shorter heads on V6, I-4, boxer etc?

Dave

91 190e 2.6 90K, on 2nd head gasket.
73 bmw 2002, Head cracked after 25yrs
96 Subaru 120K, still on 1st head gasket

Kestas · #7 08-04-2004, 10:57 AM

I'm sure the length has something to do with the problem. After all, the whole issue is mostly the difference in thermal expansion between cast iron and cast aluminum, which is roughly 2.2 to1. The fact that aluminum transfers (absorbs) heat more quickly than iron means it expands faster than iron during warm-up, thus making the problem even worse. This micromovement over the years takes its toll on the head gasket. I imagine some manufacturers use better head gaskets.

But if you look at the wall thicknesses at the problem area and how thin they are, you would understand why the head gasket leaks as quickly as it does on the M104 engine. I do not consider the design 'robust' in that area.

#8 08-04-2004, 11:21 AM

I have only done a 103. On the 103 it was VERY easy to remove the head while leaving the manifold in place. On the 104 I can see that it might be easier to leave the manifold in place and use a chain hoist.

That said, my brother in law, who is an MB dealer tech, says that it's a wash on either engine. That is, leaving manifold on or taking it off is about the same either way. For me, I can't imagine taking off the head with manifold attached on a 103. Looking at the 104 manifold I can see why you would do that.

He also said that because they are a dealer they have to always recommend doing the head gasket if the oil leak is present, but that it really doesn't hurt anything if you can stand the mess.

Have a great day,

Gilly · #9 08-04-2004, 11:28 AM

Quote:

I do remember once looking at a 300CE-24 with plenty of oil in the coolant reservoir though. I hope this was an exception or did the early M104 (3.0 KE) have a different head and gasket design to the late M104 (2.8 & 3.2 HFM)?

I would say it's an exception. Pretty rare, but I'm sure it would be a possiblity, especially in the case of a severely overheated engine or a crack in the head or block, or just an unusual type of gasket failure. I believe MB changed gasket designs a few times, but if you were to order a gasket today for an early or late M104, I believe it's the same part number.

Gilly

Greg in Oz · #10 08-04-2004, 07:42 PM

Kestas,
I can appreciate that if you get delayed by difficult bolts then there is sense in lifting the head with manifolds as an assembly. As I know Larry agrees, I found the M103 very easy to do leaving the inlet manifold in the engine bay, despite shop manuals suggesting otherwise. Strangely, on the M102 access was not as good around the inlet manifiold and this slowed progress a little. Obviously the M104 with HFM is quite a different arrangement. I like disturbing wiring as little as possible although fortunately this E320 has already had the engine harness replaced (the first major repair after my father purchased it). Aussie versions did not get EGR so that's one less area to give trouble. None of our 102, 103 or 104 had EGR althought the early 104 with KE did get an air pump. We on the other hand got the troublesome and expensive to repair 5-speed auto in all the 124 coupes with the M104. Many have been retrofitted to the 4-speed. Dare I say, this is one area that has not given trouble on my father's car yet.

Dave,
I think what you say re the length of the I6 plays a big part in this. Here in Oz we have a locally manufactured Ford with a 4 litre I6 OHC with alloy head and iron block. I know many of these also suffered head gasket problems. Shorter engines do not seem to have as many problems, although some I4s (including the M102) still do. As Kestas mentions, most of the problem on the M102, 103 and 104 results from small area around the high pressure oil feed, not combustion chamber failure as with some other makes.

Larry and Gilly,
I certainly won't be rushing into this unless oil appears in the coolant which as Gilly suggests is less likely on the 104 or unless it just gets so messy that my father insists on it. Whilst he enjoys keeping his cars clean, he is not as fussy with the engine bay and underside as I am with the 300TE and 190E (which are daily drivers that I enter in concours).

Thanks all for the replies. I'll let you know if the situation changes and requires the work to be done.

Greg

Silver Streak · #11 08-05-2004, 11:56 PM

My 92 300E 126,000 kms. ( 75,000 miles ) has the classic leak...no oil in coolant yet, but just had into a shop, where the teck showed me how close the oil had come to the cat....advise given...get it fixed, or watch it on long drives, as the oil will one day meet the cat and it may ignite !! Any Comments ?

Greg in Oz · #12 08-06-2004, 02:35 AM

Quote:

Originally posted by Silver Streak
My 92 300E 126,000 kms. ( 75,000 miles ) has the classic leak...no oil in coolant yet, but just had into a shop, where the teck showed me how close the oil had come to the cat....advise given...get it fixed, or watch it on long drives, as the oil will one day meet the cat and it may ignite !! Any Comments ?

You raise a valid point but fortunately Dad's E320 is nowhere near that bad yet. It is just a slight run down the right side of the engine that drips off below the torque convertor and leaves a small patch of oil in his garage. When the head gasket got bad on our 300TE it was much messier than this with the oil in the coolant eventually forcing me to repair it. I must say that I do enjoy an engine without a single oil leak.

suginami · #13 08-06-2004, 12:51 PM

When the head gasket on my 3.2 liter M104 was leaking, I let it get so bad that oil was pooling on the floor of my garage.

The exhaust manifold was getting so covered in oil that it would smoke a bit at start-up burning off the caked oil.

When I finally took it in for replacement, the whole undercarriage of the car was covered in oil.

The catalytic converter was also covered in oil, essentially ruining it. I failed the next smog test and had to replace it.

samiam4 · #14 12-08-2005, 11:50 AM

I don't think it's the I-6 design,

Have you worked on the 80's BMW's with 4 cylinders? They are known for headgasket problems too! I think the sealing area in the gasket around the feed through just doesn't have the surface area as the gaskets age.

Gasket design changes have made improvements. V8's don't suffer the same failures but they have more meat around the oil-feed through in the block.

Michael

Strife · #15 12-08-2005, 12:39 PM

I had Pontiac J2000 and Buick Skyhawks with the infamous 1.8 OHC engine, aluminum head, iron block. You had to use magic sealing materials on it and torque in order and absolute precision. First one blew at 38K; second at 140; the J2000 blew at 90; I called up a GM mechanic and asked him if I had done anything wrong, only getting 100K out of my repair.. He said, probably not, no one had ever gotten that many miles out of it before...