Any 300 E experts out there? - PeachParts Mercedes-Benz Forum

sailnlass · #1 06-16-2003, 06:24 PM

I purchased a 300E 1987 w/ 96k on it, I love it, but a few things.

First
the idle is slightly bumpy, I ran it by a european mechanic he said
something about a vaccum hose replacement.
>
> Second, when idleing, the temp of the engine goes hot, not red line but
almost, then cools right down when I am moving.
>
> Third, the oil lamp went on when I was in a few turns, i checked the oil,
it was a little low so a quart went in...does the 300E just use oil? There
are no visible leaks...and no oil under the car....
>
> Any advice would be helpful. Also some manual suggestions...

>
> Thanks

This reminds me of when I kept my 64 Bug alive......

Benzmac · #2 06-16-2003, 07:43 PM

Install a new thermostat and make sure the fans are working correctly. The Auxillary fan should come on when it is hot and the A.c is on at idle.

stevebfl · #3 06-16-2003, 08:17 PM

The 103 motor does have a tendency to use oil through the valve guide oil seals. I wouldn't worry about it if the consumption was less than a quart evey 1000 miles.

The subsequent formation of carbon has caused some amount of idle problems. As your tech pointed out, vacuum leaks can cause single cylinder lean misfires. Check the archives for vacuum leak diagnostic techniques.

psfred · #4 06-16-2003, 10:42 PM

The oil light comes on at one quart low. Mine uses about one quart on 1500 miles or so -- my Mother drives it, so I'm not too sure, but it's not much.

All the rubber vac lines are probably rock hard or melting with age, replace them all. Will make the tranny shift softer, too.

High temp at idle in traffice (the line above 80C or so) that drops quickly makes me think of bad visco clutch. Mine is, and will be replaced this week when I do a new belt and fix the AC (hopefully the expansion valve is the only leak....). You can test the visco clutch by listening when the temp is up -- you should hear it blowing, it makes more noise than when it's not locked up. Should also move much more air. If you then shut the engine off while watching the fan, it must stop within one revolution. If not, the clutch is bad and needs to be replaced. Takes two "special" tools -- an 8mm allen on a flat bar (or in a flattened pipe like we made) and a 4mm allen or 1/8" wire to lock the clutch to the carrier so you can unscrew to hex socket bolt.

Peter

sailnlass · #5 06-17-2003, 07:44 PM

On the Oil question, if no sign of leak, no oil anywhere under the car, I have done the newspaper test under the car, etc....

Could it be maybe b/c the engine is running hot b/c of the thermo or bad visco clutch?

Thanks Guys...

kfuller · #6 06-17-2003, 11:48 PM

I have a '90 300e. Not sure what differences there are but here is what I know about mine:

1) Most noticeable fix for my rough idle was replacing the engine mounts, although distributor cap, rotor, and plugs (gapped wide) also made a diff.
2) Mine too burnt about a qt of oil every 1500 - 3000 miles. No smoke. No leakage for a long time, then head gasket. No oil loss at all now and I think what I had before was from the valve guide seals (which can be replaced without pulling the head if I recall correctly).
3) My car has a mark between 80 and 120 deg. The 120 spot has a white mark adjacent to a redline mark at 120. If yours is getting anywhere near 120, I think that you have a problem -- possibly the aux fans are not running. If this is the case, you should get this checked as substantial damage to the engine may occur. Normally my aux fans kick in around the temp indicated by the mark between the 80 and 120 mark. Once the fans kick in, the temp lowers quickly several degrees and then the fans cut out until the temp rises to the mark again.

Ken