oil leak in 94 c280

[Green Lantern]

so i just got a quote for the front timing chain cover and it came out to $800labor plus parts, oil, and coolant. is this a fair price?

94 c280

Joe.

[BillKerler]

Yes it is. The new head gasket (which is the culprit) has a special design to it...it's got a "ski lift" end to it towards the front of the engine. This prevents the gasket from shrinking with the high heat of this engine (which caused the oil leak problem). How the gasket for the front timing chain cover is installed is also quite a trick to get it right.

But wait until they start tearing apart your engine, the wiring harness will be the first problem if you have not already had it changed. A new harness is over $1000 cost.

With your engine tore apart, isn't it a good time to replace the water pump, the serpentine belt and the belt tensioner?

They should also inspect the timing chain and its tensioner although an inline engine's timing chain should last 300K+ miles.

[Sulaco]

He is right.

There were 2 (sometimes 3, depending on your VIN) fatal design flaws with the 94-95 M104 straight 6 that's in our cars.

Head gasket, engine wiring harness, and throttle body actuator (depends, once again). The wiring harness will likely be the first thing to go. They were manufactured using "bio degradable" insulation. After thousands of miles and years of heating/cooling/wet/dry under the hood (attached to an already-hot-running engie) breaks down the harness. The wires start crossing and shorting in ways they were never meant to cross. You'll experience rough rough idle, misfires, poor performance. Most notable is a CHECK ENGINE light that will never really indicate to what the actual problem is. Experienced Mercedes mechanics won't really bother on an M104 that hasn't had the wire harness changed.

The TBA was manufactured with the same wiring, depending on which TBA your car was delivered with.

The head gasket is as BillKerler explained. It's notorious for causing oil leaks. In alot of cases it lets the oil and engine coolant mix, which can cause LOTS of trouble with your engine. One key give-away that this is happening is a white-ish smoke coming from your tailpipe sometimes. It will also smell sweet (like engine coolant burning off). That's an indicator that engine coolant is getting into your combustion chambers--killing performance/mpg, decreasing longevity, likely ruining the O2 sensors, as well as damaging exhaust components.

To replace the headgasket, the entire upper half of the engine must come off. If you're still on your factory wiring harness, and it is still working fine, then it's about to be destroyed completely due to its fragile insulation. A new harness (last I checked) was around $790. Installing it yourself will save you about $300-500 depending on the shop you use. I did it alone in about an hour. There's a great guide around here somewhere on how to do it.

When my head-gasket finally blew the cheapest quote I received was $2,200 (though I just did it myself for the cost of the parts). So your shop's figure of $800 is entirely cheap (if not completely unrealistic). Beware the possibility that they already know exactly what's going to go wrong with your engine. They could easily end up quadrupling your bill once they've "fixed" the original problem.

However, if BillKerler and I have completely missed the mark and the head gasket is fine (which is highly unlikely), the simple changing of the timing cover gasket SHOULD NOT run $800. But that star on the hood typically means your mechanic saw dollar signs the minute you told him you had a sick Mercedes. But keep in mind, the aforementioned head-gasket oil leak is directly adjacent to where the timing cover gasket resides. It's a common error for inexperienced m104 mechanics to confuse the 2.

[JRE320]

I don't wanna hear that head gasket and wiring harness problem.
I've been thru that and my wallet is totally drain out. :( :( :dpress:

[Sulaco]

The GOOD NEWS is once you've fixed those issues, you've still got one of the most bullet-proof Benzes ever built!

Really, the m103 was one of the most reliable, stable engines ever made. The m104 is just an M104 with updated intake, exhaust, and fuel/fire control management (wire harness, TBA). Once you work out those factory flaws, you have an upgraded (and more powerful/efficient) m103.

[Green Lantern]

ok im scared now guys....this mechanic is my friends uncle, his uncle and his dad owns the shop so thats why the labor price is so low. ill give him a call tomorrow asap to ask him the price on changing HG, WP, and tensioners. also the wiring harness.

i really appreciate the help u guys/

[Green Lantern]

well, leak is fixed but now the bigger problem. wire harness is fubar'd. this freakin sucks since this oil leak problem already cost 1g. so another 800......damn

[Green Lantern]

so can anyone point me to where ican get a wiring harness?? from mercedesshop.com its 1029.00 for it :cry:

[Sulaco]

Hmm, looks like they've gone up in price. importeccatalog.com lists it for 1049.00

I'd try ebay or browse this board for more parts websites.

(I got really lucky and got mine on ebay for sixty five bucks.)

[BillKerler]

I could not bring myself to spend $1000+ on a simple wire harness that at best cost about $100 to make.

When you open the hood all the way, the black plastic tray running across the top of the engine bay under the wiper assembley is a trough that carries the 2 wire harness assemblies.

The bigger harness is the injection & ignition harness...it also carries wires to the temp sensors on the thermostat, to the warm up sensor for when to cut off cold idle and the the wiring to the electric EGR pump (located below the alternator). There are a few other odd connections, but that's most of it.

With a sharp razor blade, I cut open the black tape wrap around the bundles starting from the trough mentioned 2 paragraphs ago. I uncovered all the sins as the wrap was undone. It's horrible...so little insulation left. With Scotch high temp black tape I "created" my own new insulation.

I wish I could have justified a new harness and done it right...but it's been 3 years now and I haven't had a problem with my tape job. It took a good 6 hours to do it as clean as I could.

The real bear is the ignition wiring...there are 3 12volt + wires (black, black with white stripe and black with yellow stripe as I recall) plus a brown wire with red stripe which is the common ground. Each of the 3 coils needs a 12volt + and a negative ground connection.

From the wire trough, I used new 14 gage THHN mil spec 600F wire and soldered in new wire lenght pieces to each connector on each of the 3 coils. In other words, I cut the positive wires out supplied by Mercedes and used my own wire. Who cares about the negative wire with lost insultion...a ground is a ground.

Club202 is not a forum for doing "Rube Goldberg" hack fixes but I believe I spent less than $7 plus 6 hours of my time to permanently fix the problem. The wire Mercedes uses is great, it's the friggin insulation that sucks.

So sheepishly I suggest this as another alternative.

The smaller wiring harness primarily goes to the throttle body actuator and I have yet to have any problem with it or my cruise control or anything related to it.

[Sulaco]

I wish I had the guts to try that.

I've done some pretty intense things on my car.

But if my throttle body fails (as I suspect it will) I'm definitely doing what you just did.

[xvvvz]

There is a guy on the 202 forum at BenzWorld who refurbishes harnesses for a reasonable amount. I think he goes by doin12volt. You might get a quote from him.

[Green Lantern]

forgot to update that i got the harness for 760 from dealer and another 100 to install it. grand total is 2050 including the timing cover gasket change.

[Green Lantern]

$2200 later......oil leak is still there, minor but still there. after Wire harness change the car is now misfiring, fuel cutting off, and the tranny is now acting up. more on the tranny, on cold starts, if i drop the car into d, i have to wait for the tranny to "grab" and it'll slowly start to move and it'll jerk into gear. also at a stop, and trying to make a turn or something, the car will rev high like 3-4k rpm but go no where and it'll finally drop down and go. about the fuel cut, also on a cold start, the car will hesitate to shift and it'll bounce on the rpms like the car is getting no fuel.

im gonna go back and complain my @$$ off since i spent so much money and nothing got fixed except it got worse.

[Sulaco]

There's also a transmission harness that connects to the engine wiring harness. It connects underneath the driver's side fender. There's a chance it's gone bad, or they didn't connect it properly, I'd say.

But after the head gasket replacement you should have NO OIL LEAKS. That's just ridiculous. I would raise all levels of hell until they made up for that. You took their advice, followed their instructions, and PAID THEIR PRICE, and they didn't fix the problem. Business 101. If you advertise something for a price, you perform it. That's the nature of business itself.

Otherwise, you're the government.

[Green Lantern]

it was just the timing chain cover gasket that was changed...i asked them if the HG was fine and they said ti was so i went with it. now it probably is bad.

[Sulaco]

If it's a 1994-1995 C280, there's absolutely no way in hell, NO WAY, that your head gasket is fine. Absolutely preposterous. It's an inescapable factory defect that CANNOT be skipped. ALL the factory original head gaskets on the 1994-1995 m104 engines (C280, E320, CEL320, or anything else with the 2.8/3.2l I6 those years) were the same horrible design flaw. They must EACH be replaced. No doubt about it.

Now your shop is likely going to play dumb and play the trump card. "Oh yeah, you're gonna need that too. That's a totally seperate issue (like the wiring harness)."

[Green Lantern]

yea i had it up to here with them...i wanted the car fixed but turned out to be the worse... a HG problem. thanks sulaco. they better change that HG for me for parts only.