Replacing Head gasket on 2.6L M103
 

My 190E 2.6 started having a slight coolant leak about 3k miles ago. I didn't make much of it thinking it was a leaky radiator/hose/etc.

Then it started consuming oil. Bottom line, the other day it overheated for the first time ever at ~185K miles. It was at or above the 120C mark for only a few minutes until I limped to work. I got back home with the engine running at 100C but within operating tempareture. It is quite obvious now that it is the head gasket (oily coolant, etc).

I wanted to junk the car (it has a bunch of other minor issues), but it is my first car and I love it. I figure it is not worth much, so might as well try and fix it myself.

10K miles ago I replaced the valve seals and valve cover gasket because it was consuming too much oil and my mechanic suggested it (I did the job myself and the car worked great but still consumed a but of oil, though much less than before).

Anyhow, I'm going to fix the head gasket. I don't expect to keep the car more than another 2 years/25K miles or so (it is my 2nd car and it has been a great winter car with WS-50's). Do I need to recondition the head? How do I know if it was damaged by the overheating?

Thanks for the help.

I wish I had found this site years ago. You guys seem awesome. Lots of great info. :)

I would stongly suggest finding a good/quality automotive machine shop to let them inspect/test and recondition the cylinder head. There may not be anything wrong with it but it is cheap/economical insurance.

Ok, will do. Just for personal enlightenment... reconditioning the head, I assume entails some kind of grinding/machining operation to ensure flatness across the mating surface to the engine block. Is there anything else to it?

Also, should I worry about the valve guides? I only replaced the seals when I did them.

If you're going to sell the car in 2 yrs. just replace the head gasket.

Cyl. head reconditioning can get expensive.

That was my gut feeling. Also, anecdotally, have heads been damaged by overheating the engine only a few minutes?

Ironically, it overheated on day when the tempreature outside was 3F.

I would only be guessing because one really doesn't know without thorough analysis, but given the short amt. of time, you may not have done much damage other than the gasket.

I wouldn't be concerned about damage to guides, but would be concerned about head warpage due to the overheating. For not too many $$$, a machine shop should be able to check the head surface for warpage.

I suppose having it checked is the right thing to do.

How much does it usually cost if they have to replace the guides, seals and smooth it out? In other words, go the whole 9 yards on the head, $250?

The answer to that depends on where you live.

If you're in a high $$ area like LA, labor gets steep vs. somewhere else.

You will need to call around your area for estimates.

I would call a few local MB dealers and maybe a few local independent shops and ask who they use for machine shop work. You don't want a guy who's done nothing but Fords & Chevies working on your MB head.

Find a shop that's done a lot of euro car work.

If the valve guides have never been replaced they are probably well worn and beyond the point where new seals will reduce oil consumption.

At a minimum, you need to pull the head, check the surface of the head and block for warpage, correct as required, and install the head with a new gasket to get it running. Then you can sell it.

If you want to keep driving it, the head will need to be refreshed. This consists of new valve guides, maybe new valves, reseating of the valves, and surfacing the head if it has any warpage. Overheating can definitely warp an aluminum head.

While the head is off, the mechanic should measure the bores for wear to determine the health of the upper cylinder walls. It's common for these engines to need a head refresh by 100-150K miles, but the bottom ends will probably go to at least 250K and usually more with decent maintenance.

Most shops will remove the head and sublet the head work to a machine shop. As stated, make sure the machine shop has experience with these heads. The mechanic you chose to pull the head can refer you to his machine shop, and then you can check them out.

Duke

If you need I can post the name of an automotive machine shop in Macon, Ga that you can ship it to and it should run around $250. Let me know if you are interested.

A good shop will perform what is called a Magna Flux inspection. They can see stuff you can't;).

I'll ask around. I'm in Boston. This $250 job includes a complete head job with parts? I assume shipping would be extra. I bet that gets expensive.

I'll be doing the gasket job myself and while I may (out of necessity) pay for a complete head job, I really rather not touch the block. The engine runs beautifully. No different than when it had 108K when I got it.

Magnaflux only works on ferrous materials such as cast iron.

Aluminum heads can be checked for cracks with various dye penetrant methods. One common one is Zyglow.

Duke

LOL - oh yea, al is not drawn to the magnet is it;).

I had my test procedures mixed up. Been working on too many 617's. Thanks for setting me straight. A good automotive machine shop will perform a dye penetrant test to look for cracks that are not visible using the naked eye.

Inspect the cylinder bores with the head off and if the cross hatching is evident I'd leave the bottom end alone.

Mister Zulu... starbase 129... warp 6
 

If your rings are passing oil as a result of an overheat... your heads are almost assuredly warped.

Rings are steel, and lose spring much less quickly than the time it takes to warp your aluminum heads. If the steel bought it, the aluminum did too.

If they are passing oil due to age, well, the check procedure is the same anyway.

Check your head carefully with a steel rule at all angles across the sealing surface. If you can see a discrepancy, it really needs to go to the shop. If not, it probably still needs to go to the shop, but your labor is cheaper than theirs, and if it is too warped, the new gasket will just leak or blow again. Head gaskets not very expensive. Another thing to remember, is that your head bolts stretch (regardless of if they have stretch designed into them) and should be replaced and torqued in exactly the manner prescribed with your new gasket.

At so many miles you will need valves and guides with your dye and grind. Not cheap.

I still have my first car, it's on its third engine and has 240K miles. But I can let it sit for 2 months, get in and tap the gas twice and she starts right up.
I sympathize with your wish to keep the car, if you decide you want to do so, I'd follow the advice you see here. Get the block checked or buy the tools to check it, it's easy to do (and you can never go wrong buying tools), and get the head fully redone at a good shop. You'll smile everytime she manages to start I'm sure.

Up until the car overheated, the engine ran beautifully. On the way home after the event, it also ran great. I have not used it since.

If I don't want to spend many hundreds of dollars, would it be good enough to have the head checked for warpage and resurfaced and then installing it back with fresh bolts and gasket, or am I potentially risking a terrible situation by not inspecting the valves? Remember, I dont see me keeping the car for a very long time.

I have an 330i already and I kept my 190E as my second car until we have kids in a couple of years and get a wagon. I was actually considering junking the 190E (aftyer the overheat) and getting a 94/95 E320 wagon.

I'm just not convinced on spending several hundred dollars on the head job. But if you guys think there is too much risk in leaving the valvetrain unattended, then I will do it I guess.

Thanks for all the help guys. :)

You never know how much, if any, damage there is to the head until it's removed. Assuming you're going to remove the head yourself, go ahead and remove it, and if there's bad news, just donate the car.

If your plan is to take the car to a shop, you might be better off donating the car now or selling it as-is with a blown head gasket and be done with it.

Duke

For a frame of reference, my 3.2 inline six DOHC 24 valve head at the machine shop that services the local dealer is running $695.00 with valves and guides extra.

That is for a COMPLETE head job labor? How much are valves and guides on an M103 head? :confused:

bi-valve sponges and their role in reef building...
 

Not doing the valves will not kill you for 15-25K miles more use, most likely.

Valve related problems can include:

Surfaces of the valves being too thin and as a result getting very hot which can cause them to burn and give you poor (no) compression, also wear in the guides can cause mis-seating which can also cause a valve to burn. The place where they valves meet the head is critical, as valves reach unreal temperatures, and if they cannot dissapate heat through the valve seat evenly, they will DIE.

Deposits on the back of a valve can cause performance issues, as the air/fuel mixture does not travel easily or most completely into the combustion chamber as a result of them.

From a German mechanical or engineering standpoint, at your mileage it would be heresy not to do everything. Your car after all probably needed it a long time ago, even before your overheat, for purposes of durability and efficency.

But in reality, you can probably slide. As duke said, you'll need to pull the head before you know any of it for sure.

must be the mechanical engineering coming out in me:). I don't think I've got no German ancestry;).

Thanks. I'm leaning towards just having the complete head job done as long as it is not insanely expensive. Like I said there are other things wrong with the car, hence the dilemma. If it were just the gasket/head issue, I'd do it in a heartbeat.

Right now, I need to get the engine in working order and then tackle all the other issues (minor, but many).