'92-300CE - M104 Head Gasket - PeachParts Mercedes-Benz Forum

hispassion · #1 10-25-2009, 02:48 PM

Greetings!

Over the past week, I have been losing coolant intermittently with no sign of external leakage. Just yesterday, I confirmed my suspicion of a head gasket when the engine wouldn't turn over after a brief run to and short stay at the discount store. Yep, it hydro-locked, however after three tries the engine rolled and started, so I drove it home and parked it. I've spent considerable time researching this job on here, plus adding parts to my shopping cart at ********** and think I'm just about ready to tackle the job. That is after I move the junk out of the garage so I can work on it inside (HOA rules).

I feel confident and don't expect any problems, but did want to ask where there's a good place to get the cylinder head pressure checked and planed if necessary. Also, if the aluminum is porous and the head is junk, how expensive is a new (or rebuilt) head (approximate)?

The good part of this is I get to fix the oil leak at the timing chain cover, too! I'll post more as my work progresses.

Regards
Michael B.

dstorey · #2 10-25-2009, 11:59 PM

I think you should have towed it. With hydro lock it is locked therefore since what is in the engine won't compress you run the risk of something really expensive like a rod bending!

Don't even start it to get it into the garage. Have someone push it for you.

Good luck Go Cats

73Elsinore · #3 10-26-2009, 09:17 PM

Hi Michael. Best place to get the head inspected is to ship it to Metric Motors in the Los Angeles area. They are the experts on this head. Here is their site - http://www.mercedesengines.net/ They have rebuilt exchanges or they will rebuild yours. Prices are on the webpage. This is the outfit that the indies around here use.

They did my M104 head this past summer. Out the door it was $1175. Shipping each way was about $60. I had a total rebuild, surfacing, cleaning, welding to repair corrosion damage, etc. All my exhaust springs were out of spec so they were all replaced and I had one pitted valve. That number should be considered as your budget. You can expect to have some corrosion damage; the guy from Metric said all M104 heads have some corrosion damage normally. You can have them just do the cleaning and surfacing but if you are going to pull the head anyway, it is false economy to not at least have the seals and guides replaced.

You can get the head rebuilt (a little) cheaper elsewhere (not much) but MB engines are all these guys do and they know their stuff.

I know of a ton of other hints too on this project if you're interested. Read the write-ups you already listed as a starting point. This is not a weekend job for a DIYer; more like three weekendsor better because you will find things that you have to replace as you proceed with the work. So plan on parking the car for awhile. It's best to work slowly and methodically and work your way through it. Plus it takes time to wrestle with the shop manual because the manual is busted up into sections that are not at all interconnected.

Most important thing is to make sure you have the factory shop manual. Don't try to do this job without it. Just gag down the $65 for the manual against the cost of lost time and aggravation and possible busted parts. Or worse.

One of the most important tips is to buy the correct special head bolt tool. It is a Hazet #2752 triple square (XZN) bit from Samstag Sales or Chad's Tool Box (Google them). You have to get this particular one because the longer ones like you can get at Snap-On or Pep Boys are too long and they will not fit up under the firewall for the two head bolts near the firewall. Trust me - I learned this the hard way.

OK now I'm on a roll

. Remove the cams with the head still bolted on the block because it takes too much mustard to bust loose the cam bearing caps and the head will squirm around like a greased pig all over the bench if you try to remove them on the bench (unless you have a helper to hold the head or unless you bolt it down). Or leave the cams attached and send the whole thing to Metric as-is but they will charge you some labor to remove the cams. Actually this is OK anyway because then they can mike your cams and make sure they are all still in spec. Plus they can disassemble the advancer on the intake cam and clean it for you. There is a special procedure you must use when removing the cam bearing caps - it's in the manual.

Remove the head with the exhaust and intake manifolds still attached to the head. You will remove them from the head later when the head is setting on the workbench. This will save you tons of aggravation because a couple of the manifold bolts are dang near inaccessible with the head on the block.

Make a little temporary work stand to set the head on out of 2x4's that are set up on edge that is about the length and width of the bottom of the head. You use this to set the head on while you are working on it, i.e. while removing the manifolds. This makes it infinitely easier to mess with the head while it's on the bench because the manifolds hang down lower than the bottom of the head and this fact will make it difficult to work on the head on the bench (it will rock and roll and again will squirm around like the proverbial greased pig). Plus this also protects the delicate gasket mating surface of the head. Yeah, you are going to get it surfaced, but if you accidentally knock a 0.060" dent in the head gasket surface while futzing about with it, that is too deep to be machined out. You will use this little stand during removal of the manifolds and also when you bolt them back on the rebuilt head. If you want I can send you a photo of the one I made. Took me about 10 minutes to knock it together; best 10 minutes I ever invested.

And use an engine hoist to pull the head. Don't even think about doing this job without one.

These are tips that an advanced DIYer would use to ensure success and minimize errors and rework on this job. A pro who does this all day long for a living might do it differently, will know of shortcuts, and has tools that you and I have no access to.

Hope this helps! Pete

bbarcher · #4 10-26-2009, 10:48 PM

While you have it apart, there is a small hose you should replace, and it is hard to get to with the intake installed. If it starts leaking after you do all this, you will be upset. It is referred to in the online parts catalogs as "Cooling Hose", and is MB part number 104 203 03 82, WorldPAC SKU # G2021-71771. I purchased a new hose through Carquest using the SKU. It was 7.59 with tax. The hose is under the intake, near cylinder #5, and it connects to the oil cooler on one end.

Also, if you take off the dipstick tube, place something over the hole to prevent anything from falling into the oilpan.

hispassion · #5 10-27-2009, 09:44 AM

Thanks guys! All good stuff here. Busy week at work, so more later as time allows. Gawd, I hate driving my wife's commuter car...

latief · #6 10-27-2009, 10:02 AM

http://www.benzworld.org/forums/w124-e-ce-d-td-class/1460479-started-my-head-gasket-repair.html

hopefully this will be helpful.....

hispassion · #7 11-02-2009, 12:39 AM

Well, I got the garage cleaned out and the 300SL moved over to provide room to work. This was quite a task, because there were storage boxes to the ceiling and there were no wheels, shocks or struts on the SL.

Then today, my wife's car needed a belt tensioner, so I had that to fix before pushing my 300CE into the garage. After opening the hood, I pulled the dipstick and saw chocolate milk colored oil. Seeing that is never a good thing, so I decided that the teardown and inspection should begin tomorrow. I had had enough for one (actually two) day(s).

Thanks again for the input guys. I'll post pictures as I go along, too.

More tomorrow!
Michael B.

hispassion · #8 11-03-2009, 01:03 AM

Well gents, I started the teardown. All that's left before I pull the cylinder head are the manifolds and the timing chain. Also, I found the oil leak. Seems someone before me was a little over-zelous with the silicone goop causing the gasket to split. As well, the distributor shaft seal was leaking and looks like the sealing surface hadn't been cleaned from the previous time.

Will be back after I get the head off, which will be a couple of days given my current schedule.

Michael B.

hispassion · #9 11-03-2009, 09:13 AM

Does anyone know the socket size for the crankshaft bolt? This would be handy to know before I go to the store. Thanks!!!

73Elsinore · #10 11-03-2009, 10:05 AM

Quote:

Originally Posted by hispassion

Does anyone know the socket size for the crankshaft bolt? This would be handy to know before I go to the store. Thanks!!!

Socket size is 27mm.

Do not pull the manifolds off. Remove them with the head. Do you have the factory shop manual?

Kestas · #11 11-03-2009, 10:15 AM

Silicone on the upper timing cover seal is a no-no. I believe the seal should float across the surface from thermal movement. It also appears that the seal may have rolled during reassembly and never gave a good seal.

When the head is off, it's a perfect time to remove and clean out the egr tube that runs behind the head.

suginami · #12 11-03-2009, 10:42 AM

Quote:

Originally Posted by Kestas

When the head is off, it's a perfect time to remove and clean out the egr tube that runs behind the head.

Yes, that tube gets plugged up with oily pcv vapors. You should consider replacing it with a new metal tube. The new tubes are redesigned to stick in a little further inside the intake manifold, apparently preventing blockage in the future.

Ferdman · #13 11-04-2009, 09:30 AM

Michael, when you're replacing the upper timing chain cover U-shaped seal spend the money for the black sealant at your local MB dealer. Use a dab at both ends of the seal only ... the rest of the seal remains dry. Be patient so the seal doesn't roll over or get pushed out of place when positioning the cover.

Kestas · #14 11-04-2009, 01:29 PM

I practised laying the upper timing cover in place a few times before going ahead with the permanent install. This way I could install it in one shot and not make a mess with the loctite.

hispassion · #15 11-15-2009, 07:03 PM

Well, it took longer than two days because of my busy schedule and not feeling well for a few days when I could work on it.
But the engine is now apart and it was clearly #6 that was leaking as this was the cleanest piston top.

And as you can see, the combustion area is relatively clean.

Plus, I think I found the reason for the coolant consumption.
Pay close attention to space between the water jacket and sealing area just above the valve.

It doesn't look like a crack, but if it's just a steam trace I hope that it's not too deep and can be planed out.

Does anyone know about Bill's Cylinder Head Service in Phoenix? It doesn't look like he has any web negatives that I can find. Though I can send the head to Metric Motors in L.A., I would prefer to drive it to a local machine shop in Phoenix (if I can feel confident about it).

While taking it apart, every connector on the upper engine wiring harness broke. The wires are somewhat pliable, but the black tubing and connectors are very brittle. Any idea where to get a replacement harness?

Also, the timing chain guides have worn grooves from the chain, so, I think I'm going to replace all the guides too. This means removing the lower chain cover to access them. Anything special I need to know while doing this?

73Elsinore; you asked if I had a shop manual. Well, not the printed Mercedes shop manual used by techs, but I do have a couple of other manuals (Haynes 3253 & the useless E-Class Owner's Bible) plus I do have the 124 Service Manual Library on CD. Is there one in particular that you recommend?

Thanks all for your posts and help...
Michael B.