1979 6.9

[otahir01]

Hello Everyone,

I recently purchased a 1979 6.9 with 91k miles and am having some issues with it so I figured I'd get your insight on the matter.

1) Today I found a few drops of water accumulating inside the cabin at the driver's side footwell (AC problem?). I drove the car later on and the problem did not repeat even though the AC was on.

2) The parking brake light came on yesterday and flickers off and on when I go over bumps. I checked the manual and it says that the brake light will stay on if the brake fluid is low. I can't find where the brake fluid container is on my car to even check but I am guessing that the problem has more to do with electrical issues than with fluids.

3) From time to time I hear strange noises like a clunking sound from the under the hood coming from the passenger side or an osscilating/whirring sound that comes and goes (not specific to during braking or accelerating etc)

4) Minor oil leak

All in all the car is in pretty good condition other than some minor fading of the paint. If anyone has any ideas or suggestions I'd really appreciate it.

Thanks

[Phil OBrien]

Hello otahir01,

Do you have a euro or american 6.9?

1. It could be a number of things. Have you checked to see if the heater core line is dripping into that area? It could be the AC, and it could be bad seal (door or other), or it could be the sunroof drain tube. Did the leaks come after you washed the car or it rained?


2. That sounds like a fuse issue to me, but check the fluid first. If you have a LHD car the reservoir is located on the drivers side firewall and it will be connected to the brake booster ( the cylindrical thing). If the fluid checks out ok, remove each fuse one at a time, clean them, and clean the fuse box connections. I recommend using a dremel and a wire brush attachment. One the fuses and fuse connections are clean, apply electrical connections grease to them. Also, beneath the battery plate is a connection junction that I recommend you clean as well.


3. Sounds like you have a bad motor mount, tranny mount, driveshaft bearing, or idler arm. If you are not familiar with these, take it somewhere and have them check it.


4. Where is the oil leak coming from?


Check out www.m-100.cc

Phil

[Don350SDL]

#2 is more likely the park brake pedal vibrating over bumps. To verify, use a stiff rubber band (or a few) to pull the lever to the disengaged (up) position and hold it there, then drive around and see if it's "fixed". If so, the switch needs adjusting (it might not be adjustable though) OR you just have a weak spring holding the park brake pedal upwards - you can leave the rubber bands there until you figure it out.

The brake fluid reservior is in the engine compartment, high up against the firewall, just in front of the steering wheel. Use extreme cleanliness when opening it for any reason. If the fluid is anything other than a light golden color, it needs to be replaced.

Don

[otahir01]

Thanks for the feedback,

My car is an American 6.9.
As far as problem #1, the water droplets appeared without washing or anything and to be specific, I found them on the driver's side where the driver's right foot and accelerator would be but the problem has not reoccurred. The previous owner states that the drain may be blocked but I have no idea where that is. The AC was worked on/replaced recently before I bought the car so I may consider taking it back there if I have to.

Problem #2: I checked the brake fluid today and it was brown. Is this something I can change myself or do I have to go to a dealer? If it has to go to a dealer, does it have to be a Mercedes dealer for something like this?

Problem #3: Before I bought the car, the previous owner replaced the suspension control valve and replaced the front sway bar pull rod, do you think that has anything to do with it? The problem doesnt happen that often so I'm not sure if its anything to be worried about.

Problem #4: Forgot to mention this one before, steering is really shaky and vague but managable once you get used to it.

Thanks for your help and suggestions

[Phil OBrien]

If you have the mechanical ability, do as much of the work as possible. The brake fluid could be done by anyone, just make sure you use the right DOT rating. One thing I forgot to mention on the previous post is that on the brake reservoir there is a button/pin and if it's sticking out, the brake light will come on. Push it back in and it resets it it was some sort of early safety warning system.


The bad steering could be a few things:

worn tie rods
needs wheel alignment
worn idler arm
worn steering column link
worn steering shock

[otahir01]

Hey Phil,

I took the 6.9 into the shop today and the guy took a look and showed me some things that were wrong. He has worked on 6.9's in the past and seems well educated on how to fix them and old benzes in general. He quoted me a price of $650 after negotiating to replace the following:

1) Replace Brake Lines & Fluid
2) Do a valve adjustment and replace the gaskets
3) Change Shifter Bushings etc
4) Replace Tie Rod Assembly on the Right side
5) Replace Steering Coupling

The guy seemed pretty straightforward and honest. What do you think? Also, I get a vibration when the car is stopped, he said that the engine mounts and tranny mounts would need to be replaced eventually but not at this time and that he could do all that for $350 installed. Any thoughts?

[Hanno]

sounds fine, but the valves are hydraulic, no adjustment possible except by replacing the lifters. As a previous post suggested, best resource for M-100 engine cars (600, 6.3, 6.9) is www.m-100.cc

[Phil OBrien]

You can adjust the valves on the 6.9, you do not need to adjust them as often because they are hydraulic. The price does not seem bad, but once you replace a tie rod you need a wheel alignment. I suggest working in phases on your 6.9 and each phase concentrate on a specific area of your car. For example, on the steering I would replace the tie rod assemblies, idler arm, steering shock, steering coupling, power steering fluid/filter, any hoses as needed, and the two belts. All these parts can be purchased for under $200 total if you know where to look and can easily be replaced if you have some mechanical ability. After those are fixed I would do the wheel alignment, and then move onto the next area. 116s are very reliable cars when maintained, so once an area is "fixed" you will not have to worry about it again most likely for another 28 years (or the age of your car).


Phil

[otahir01]

Thanks for your help everybody, I really appreciate it.

A couple more questions

1) I am a med student and am normally pretty busy but this summer I want to work on the car and do whatever I can. I have minimal experience working on cars but am willing to learn. Are there any books that you'd recommend that specifically tell me how to fix things on the 6.9?

2) Today I put the car in park (on a flat surface) and the car rolled back about 6 inches while making 2-3 clicking noises (car was off) and then finally became stationary. The guy at the shop told me that the tranny and engine mounts are shot (he will replace them all for 350 installed, good idea?) do you think this somehow has anything to do with it or is this a problem with the recent installation of the shifter bushings?

3) I sent the car in and had the AC drains flushed out twice because the first time didnt get the job done. After the second time, it still seems to be having the same problem (water drops coming into the cabin). Any idea what it could be?

I'm sure the longer I keep this car, the more things that will come up. Thanks in advance for all your help everyone

[Phil OBrien]

1) There are two books I recommend:


http://cgi.ebay.com/ebaymotors/Repair-Manual-Book-Mercedes-Benz-350-450-sl-sel-107-116_W0QQcmdZViewItemQQcategoryZ34227QQihZ020QQitem Z300112450207QQrdZ1

The other one is a Chiltons that covers all Mercedes 1973-1980. A big chain book store should have them, and Autozone has the one in the link. Also, the one in the link is for the 4.5L engine, but 95% of the things you will fix on a 6.9 will be exactly how you fix it on a 4.5L.


2) The clicking noise means that it was not completely in gear (P). It is probably somehow related to the shifter bushings - maybe it needs to be adjusted a bit more. You should fix this ASAP, I once had a problem similar to this on my reg 450SEL. I put it in park on an incline, got out of the car, went up to someones house, turned around to see that it was rolling quickly towards an expensive Audi! Luckily I was able to run down and stop it in time.

3) Remove the carpeted panel that covers part of the steering wheel and the panel underneath it. You should be able to see the climate control mechanism and see exactly where the water is coming from.


Phil