Seals or Valve Job? - PeachParts Mercedes-Benz Forum

#1 07-17-2002, 12:51 AM

How can I tell if my 1983 240D 4 speed needs new valve seals ($450) or the complete valve job which will be many, many more dollars? Miles are 139K, and I am burning 1 qt of oil every 463 miles, calculated in my pda every fill-up (sidenote getting 26-27 mpg each tank). Any suggestions or tests I can have done to pin down the culprit and solution to the big clouds behind my car? I have to say, every car behind me on the road seems to move into other lanes very quickly!!

Thanks,

Tim

kweimer · #2 07-17-2002, 01:38 AM

$450 for valve seals? Replace these yourself and save about $400. Replacing the seals will at least eliminate seals as the problem.

leathermang · #3 07-17-2002, 08:25 AM

Kweimer is absolutely correct. I can't believe they quoted you such a high figure and you won't either after you get through doing it yourself. The valve stem seals are about $12.... not per cylinder...$12 total for a five cylinder....The tool shown for installing them is just an offset pusher....

The main thing to be concerned about is having the little plastic sleeves which you put over the threaded portion of the valve stem... so you don't mess up the inside sealing surface of the stem seal... one package I bought did not have them...this was about 3 years ago, and I did not know that they should be included with the seals.... the latest does... they are usually clear with lines printed on them...don't try installing without them.

The rest of the job is a pain... but just because you want to be methodical about clearances when going back together with stuff... good luck, Greg

#4 07-17-2002, 10:01 AM

Thanks for the tips. While I am fairly good at keeping the IRS at bay for the company I work for, and I do know the difference between a hammer & a wrench, I would not put myself in the excellent mechanic area. While I'm not afraid of trying jobs, I don't want to kill my beloved car either. Step by step, how difficult is it to replace the seals and do I need to adjust the valves afterward? Any special tools I need? Living in the bay area I thought $450 was reasonable after another indy Mercedes shop said it would be 5-600 (I obviously have become numb to reality in pricing). I still have a hard time with Levis now costing more than $8 when I was a lad!

leathermang · #5 07-17-2002, 10:18 AM

First, buy or borrow the factory shop manual and a Haynes manual for your car. Also, you must read them... I know of people who have them but don't read them... You are totally taking away the items which constitute a valve adjustment.. so yes,,, as you put it back together you will be doing a valve adjustment. The offset installer tool, bent valve adjustment wrenches, spring retainer wrench,new valve cover gasket,feeler gauges,the seals and the protective sleeves....would be my off hand recommendations for stuff to have on hand before starting...I know what you mean about the jeans... I switched to Walmart Rustler @ $10 to $12 myself...

#6 07-17-2002, 03:13 PM

I was just speaking to another mercedes guy and he said my oil burning could be a bad diaphram in the vacuum pump, pushing oil into the cylinders. What do you think? I don't have any oil in the air cleaner as blowby. I also forgot to say the engine compression is 400, 400, 400, 380. Could a bad vacuum diaphram cause oil burn? Car starts and shuts off fine, all vacuum acc. work fine also. Thanks for your help.

kweimer · #7 07-17-2002, 04:36 PM

A bad diaphram can cause oil to be sucked into the intake manifold, however, a bad diaphram is usually accompanied with other symptoms such as hard brades due to less vacuum to the brake booster and you will frequently notice rough running of the engine because of the excess oil getting to the cylinders. Check for a bad diaphram is easy: Disconnect the line from the vacuum pump to the intake manifold at the vacuum pump---look into the pump fitting and the end of the line you disconnected---if you see black engine oil, you have a bad diaphram. Regarding your oil comsumption, make sure you don't have any oil leaks. Two common locations for leaks are where the oil filter bolts to the engine block and the bottom of the oil cooler next to the radiator. The oil cooler core tends to rust at the bottom leaving you with small pin-holes.

#8 07-17-2002, 07:10 PM

I don't have any oil spots under the car and can't see any oil on the cooler and the car runs fine. I will check the vacuum hose though just to be sure, but I don't think its the vacuum. The quest continues!

leathermang · #9 07-17-2002, 09:57 PM

The valve stem seals are by far the most likely culprit...

#10 07-17-2002, 11:36 PM

No oil in the vacuum line. On to the valve stems, I do have the repair CD and Haynes, for guides. Thanks for the help!

Tim

stephenson · #11 07-18-2002, 01:14 AM

Tim,

Perhaps it is age on the seals ... isn't this a bit odd for such a low mileage engine? Maybe they are hardening?

How about an option that might help - might not?

I am assuming you are using non-synthetic oil ... how about switching to synthetic and running the living bejesus out of it for about 5000 miles? Might soften the seals ...

As John Belushi said, "don't cost nuthin."

#12 07-18-2002, 09:56 AM

This is why I love this site, so many excellent ideas to solve our benz problems! My 240D does have nonsynthetic running in it. Putting syn oil may cause the seals to soften and swell but there seems to be a huge debate on this site about the virtues and ills of syn oil and switching to it. But this might be a great experiment to try before I replace the seals.

stephenson · #13 07-18-2002, 11:01 AM

Tim,

While this note may sound like a continuation of the "great oil debate," my opinion is that the debate has been over for about 10 years ... many simply have not picked up on it.

You will obviously find my comments and those of many others to be interesting material ... I still do. But, I gotta tell ya, other than the cost versus goodness debate (while I admit is still not absolutely clear unless you own your car for a LONG TIME), the technical issue debate is over.

A new debate we will be seeing in America is likely the one the Europeans have gone through over the last 10 years - another simple, but incredibly interesting debate ... do you need to change your oil as often with better engines, better filters, better oil and in the presence of relatively inexpensive testing? Add in environmental issues and now ya got a great topic.

Your can should not be using much oil ... give the synthetic a try ... don't panic with a couple of drips ... pan the garag floor and keep driving it - what have you got to loose?

kweimer · #14 07-18-2002, 01:00 PM

Well, here's my two cents worth on the Great Oil Debate: I use Mobil Delvac 1300 Super 15W-40 (not a synthetic oil) and change oil and filter regularly---every 10,000 miles.

leathermang · #15 07-18-2002, 02:08 PM

I use Delo400 straight 40 wt and change it and filter every 3000 miles.