1986 300E High Mileage Maintenance

[brentsmith]

My 1986 300E is approaching 270,000 miles and I am looking for some recommendations. My wife and I love the car; I've done much of the maintenance for the last 20 years. The car runs well, but it has some real or imagined issues that I'd like to take care of:
1. Transmission runs very well, but has a minor leak at the front seal--let it go until it fails.....
2. Engine does not burn oil, but uses a quart every 300-400 miles (Mobil 1 15W50); leaks seem to come from the usual places--reseal the valve cover and the top front timing chain cover. My fingers are crossed on the head gasket and not sure how to test it.
3. Vacuum tubing is ratty--replace all of the tubing and air hoses. Any list of materials or diagrams around?
4. Original shocks and struts are on the car; the ride has suddenly gotten pretty rough--replace all the way around. Are there any additional parts to buy except for the Bilstein shocks.
5 I plan to replace all of the usual ignition components: plugs, wires, cap, rotor--and maybe the coil as well (I think it is original).
6. The differential has never been drained and refilled--refill with synthetic gear oil.

Does anybody have any comments or suggestions to add to this? I have used this forum over the years and appreciate all of the valuable help.

Thanks.

Brent Smith
Snellville, GA
1986 300E
2003 530i
2003 Boxster S

[carat 3.6 amg]

transmission oil and filter change?

[brentsmith]

Yes, I do need to do that too. It has been quite awhile, probably back at 210,000. The fluid appears okay because of the slight seal leak, but the filter will need changing.

Brent

[tbomachines]

I would recommend checking/replacing the timing chain, and inspecting the guide rails/tensioner for wear at that mileage.

[94Wagenmeister]

Sounds to me like you are every bit the enthusiast as the rest of us and doing everything you can to make it last a long, long time. I would add a visual inspection of the front end components especially the rubber bushings and also the flex discs (front and rear ) and center driveshaft bearing.

[04 Diesel]

How about valve guide seals?

[Hit Man X]

1. Trans has about had it at 270k, just run it until it fails.

2. 300-400 miles on a quart is large consumption. Do you foul out plugs? The gasket likes to leak from the back by the number six cylinder, the front cover, and also the side like my car. Also the front main seep with age. You may be up for another gasket at this mileage.

3. Just pick up some three and four way connectors plus some 3.5mm? ID tubing to replace the vac stuff. The breather and PCV hoses are self explanatory as are the idle control valve ones. May want to reseal the injectors (o-rings) and consider the AFM boot if very stiff.

4. The shocks/struts on there are long dead. Rears just bolt in, fronts have upper mounts and boots I would replace while in there last I can recall.

5. Ign components on the M103 do not last long, at least the cap/rotor/plugs in my experience.

6. Yikes on the diff. I would drain and refill... run for a while, then service again.



Otherwise do as the others pointed out and enjoy the car.



Oh, go hit the dealer and attain a high mileage badge.

I was once told, "there is a time to hang on and a time to let go." Maybe keep going with it like it is in search for a pristine 300 with low, low, mileage, that was very well taken care of??

[Ferdman]

Brent, every 30,000 miles you should be changing the transmission fluid & filter, plus the distributor cap, distributor rotor and spark plugs. If original you should replace the ignition wires. Oil changes should be at least every 7,500 miles. Differential fluid changes every 60,000 miles would be a good idea. Brake fluid should be replaced every 2 years, and coolant every 3 years ... or ph maintained at 7.

Based on oil consumption it would be a good idea to rework the head ... rework/replace the valves and seats, replace the valve stem seals. That will involve removing the head so the head gasket will be replaced too. While in there check for timing chain stretch and replace the timing chain guides (upper & lower).

New shocks/struts will restore the original ride/handling, plus you probably need to replace worn bushings and other deteriorated rubber suspension components. Definitely replace the upper strut mounts.

Definitely check the condition of the flex discs and the exhaust system rubber hangers. The brake hose at each caliper probably needs replacing also.

Inspect all coolant system hoses and the drive belt for cracks.

[brentsmith]

Thanks for all the suggestions. Over the years, many (not all!) of the items mentioned have been regularly maintained or replaced. Early on, the dealer did much of the more difficult work, but I have used two very good local Benz specialists in the last 15 years. I have a set of factory manuals and still do everything that I can do myself.

Some comments and updates:
1. The front struts (Bilsteins) are on order; I didn't order new mounts, but I will today along with the rear shocks.
2. Caliper brake hoses are probably original and I will replace them.
3. I'll definitely do the differential soon.
4. The flex discs were replaced years ago, but are probably worn out again.
5. Cooling hoses and drive belt are pretty new.
6. I agree with "a time to let go", but my wife and I like the car and feel like it is part of the family, so until something catastrophic happens, we'll continue motoring along............
7. My biggest unknown is the engine. The plugs actually look pretty good. No fouling. I just cleaned the engine and I hope to see the leaks a bit better. I could do the valve cover and maybe the valve seals myself. Ditto for the upper front cover. However, it might be wise to get my independent to do all of this while replacing the head gasket and inspect the rest. It's tough though, because I'm cheap.

Again, thanks to all!
Brent

[lee polowczuk]

you just have to realize that the car is probably only worth 600.

i have sold two 300e's with 200-215k on them for 1200. (both needed tires or little nitpicking things)

That's as far as i am taking one.

[tbomachines]

Originally Posted by lee polowczuk

you just have to realize that the car is probably only worth 600.

i have sold two 300e's with 200-215k on them for 1200. (both needed tires or little nitpicking things)

That's as far as i am taking one.

These cars are extremely undervalued, I think anything aside from a pristine w124 would be statistically a money pit--meaning over the next 10 years or so you'll spend much more than its worth. That being said, I would take my 300E over almost any new car I've been in and driven (obviously costing much more, not having depreciated) even though I've got a total of over $4k in it and could realistically sell it for half that. The glass half full version is that these are such a bargain for us nuts! And the cost per mile factor is actually pretty low as well in comparison to newer more expensive cars since the initial investment is so low. Just my (somewhat biased) $0.02

[pawoSD]

300-400 miles per quart is ultra bad. Its either inhaling it through the valve stem seals(and thus burning it) or it is leaking a LOT. My M103 with 154k on it uses less than a quart per 5000 miles....and thats despite a couple minor leaks. When I got it, it was using around 1qt per 750 miles due to bad stem seals.

At 270k that engine needs minimum new valve guides/stem seals and maybe the valves themselves, and probably several other seals/gaskets replaced. Getting the engine up to snuff will cost significantly more than the car is worth, and thats just to do the engine....

[brentsmith]

I appreciate your opinion on the maintenance items, but I plan on keeping the car. It is midnight blue (original factory paint that takes a nice wax) and the interior is almost perfect. Everything works: climate control (I have the receipts to prove it), all the lights, cruise, you name it. The car has been looked after and garaged.

Now, it probably is worth $600 as a generic high mileage car. However, it has more value to my wife and me. For instance, what would be the cost of its replacement? And, frankly I don't buy high mileage cars. I buy well-maintained very low mileage cars, maintain them and drive them until they really fail.

As a 64 year old engineer, I have been a gearhead all my life, starting with a 1950 flathead V8 Ford (at 14 years old) through numerous English sports cars to now owning three German cars.

Again, I appreciate the technical advice..........

Brent

[lee polowczuk]

as long as you have working a/c and a good transmission...keep it...

i guess what i was trying to say is that i have sold mine in good working condition....only to "trade up" to another one with lower mileage at very little cost.

i guess the most recent example was selling my son's 300e with 216 for 1200...and buying a much newer --1992-- 190e with the 2.6 for 2k. It was overmaintained by an 85 year old owner and had 71k on it....

i have opportunities to buy other similar bargains by being patient....

i would be patient and start looking for another and keep that one as a spare.... it could take you 6-12 months to find one... less in states like Florida.

Don't do the valves.... a stem seal kit costs about 20 dollars and takes about 5 patient hours to do the job.... your car should burn about a quart every 12-1500 miles then.... or a quart between 3k oil changes.