New to Mercedes, 89 300e issues

[244brick]

I bought this car last Sunday, and ran beautiful and smooth as can be other than a very slight rough idle. Probably just needs a tune-up.
Mileage unknown, speedo cable broke at 79k.
I've babied this car from day one, yet the day before yesterday (3 days into ownership) the problems start showing up.
First 3 days, this car didn't have any mechanical issues. Then out of no where, it started getting rough on gear selection. Reverse takes about 2 to 3 seconds to engage, and when it does it is very abrupt and hard. Drive has a little faster reaction but the same thing. Loud clunk and a jerk.
It may just be me, but it seems like at slow speeds (nearly idle speed), it takes longer to shift than it used to. Also I only feel it shift twice, but I've read about these transmissions starting in 2nd?

It overheated yesterday sitting in one spot for about 10 min. Driving, it cools excellent. Even when it sits for a few minutes it seems fine, then eventually temp starts to rise and coolant starts building pressure and spraying out of the cracks on the coolant resovior. The condensor fan does not work but the mechanical fan spins great.

Issues the car had when I bought it, were oil pressure needle stuck at 3 on or off. Brake pedal seems stiff, as if there were a vacuum leak from the booster but there is not. Srs light blinks on every now and then.

I need some technical advice to help me sort these issues out. I am quite bummed because the car is lovely. Thanks in advance,
Drew

[stormyc88]

Hi Drew,

You are correct, the transmission is set to start in 2nd gear, so only shifting twice is normal. As far as the rough reverse/drive engage goes, maybe check the fluid level? my own 300e was never exactly "smooth" when it engaged reverse/drive, there was always a solid clunk but nothing alarmingly jarring. And it was the same before and after it was rebuilt.

Overheat problem: check the fan clutch. they are a common high mileage failure point. procedure to check it is (someone double check me) get the car up to operating temperature for a while, shut it off and let it sit for maybe 5 min, open the hood and spin the fan with your hand. if it spins freely, the clutch is shot. if it does not spin freely, then it is good. I think you can also try this procedure when the car is cold, in the morning. Other overheat causes could be thermostat, worn out water pump, somewhat plugged radiator, or the auxiliary fan not coming on when the coolant temp reaches 105C.

Oil pressure guage: the oil pressure sender, located under the oil filter is a common failure from what I've heard, although I dont know if it would make the guage stick on 3. There could also be a broken wire or something or even the guage itself is broken. good used instrument clusters are pretty cheap on ebay if you want to try swapping in a different one..

Speedo cable: it broke? i guess that means you dont know how fast you are going? might want to fix that...i dont think they're too expensive.

Brake pedal: check the vacuum line that goes from the intake manifold to the booster and make sure the connections are tight and that the line is not cracked or anything. The booster itself could be shot, too, I guess.

SRS: I have no idea. Sorry!

Tune up: please make sure to use only OEM ignition parts (Bosch/Beru). I personally only use bosch parts including the hard-to-find H9DC0 plugs, available thru peach parts!. Note: a rough idle on these cars can also be caused by a dirty/lazy idle control valve, and the hoses that go to and from this valve are a common failure point as they dry out and crack, causing vacuum leaks at idle.

i hope this helps! please note that I am not a professional technician, i am going off of my own experiences owning my 300e for 10 years, and doing tons of research about it reading the manuals and the posts on this forum. There are many helpful people on this forum who will be happy to give their opinions as well. Welcome to the mercedes world! The 300e is an excellent car that will give you many happy miles, as long as you give it the care and feeding it needs.

-Chris

[ps2cho]

A slow reverse engage is a warning that reverse is about to go...be careful! Search 722.3 no reverse. It happens to all 722.3's anywhere between 130-250k depending on fluid change intervals and driving style.

[Ferdman]

Drew, it sounds like the 1989 300E you bought has been neglected. I have the following recommendations:
1) Fix the odometer so you can track mileage.
2) Replace the coolant expansion tank.
3) Replace the thermostat.
4) Recommend changing all fluids and filters: oil/oil filter, transmission fluid/filter, coolant (50/50 mix), brake fluid and differential fluid ... unless you have records showing that they have been done recently.
5) Replace the viscous fan clutch if the fan is not operating properly.
6) Repair the auxiliary fans.
7) Replace the distributor cap (Bosch), distributor rotor (Bosch), distributor O-ring seal, ignition wires (Beru) and spark plugs (Bosch). Use dielectric grease inside the ignition wire boots.

Unless you are an experienced DIY'er you probably should have a reputable independent MB-trained tech work on your car. Expect an appreciable repair bill. MB automobiles are a pleasure to drive, but they require routine maintenance.

[JohnM.]

SRS light might be the steering wheel clockspring. Mine just started doing the same thing, but only when it's 110F or hotter outside...

[Gilly]

The abrupt/hard shift into reverse and drive could also be a worn out flex disc.

It may take longer to upshift when cold due to the upshift delay solenoid, this would be normal, on a cold start in the morning for several minutes afterwards. It does htis to help warm up the catalytic converter.

[Slow Joe]

I had all the same issues with my 86 300E. The coolant issue turned out to need a new heater core. Pain in the ass to swap out, but no more coolant issues. I noticed you have a 244 brick. Are you on TB?

[244brick]

Thank you for all this awesome feed back! Everything so far checks out, fan clutch is shot. Transmission fluid was a bit low. I added a little over a 1/4 qaurt of dextron VI (III was not available). t It seems to be a bit smoother I guess. Is it safe to flush a higher mileage transmission?
If I treat this worn reverse issue, will the Peachparts clutch & seal kit be enough to repair?
Found a few other things that need attention, so I will be surfing through the parts catalog.
I've been searching for a good write up for the fan clutch replacement, if anyone can point me in a more specific direction.
I have one other issue that I haven't really looked into yet. Terminal C in the fuse box looks a bit toasted. No melted plastic or anything. There was no fuse there when I bought, and when I put one in nothing changed. My power door locks still don't work.

I am a DIY owner. I have a few years of experience working on european cars. I rebuilt a transmission in a diesel w123 with guideance, so I'm not really intimidated about rebuilding just only the front half.

Slow Joe, I am indeed on TB: cfl940. I'm prepping the 240 currently for a B6304 swap.

[p7fan]

A little roughness at idle along with delayed shifting; might want to check for a vac leak to the modulator. Might get lucky....

[lorainfurniture]

I've had the slow reverse thing going with my 300e for 5 years now. I wouldn't worry too much about that.

The clunking is probably the flex discs. The front one is the first to go bad. Look at those ASAP..

It should hold out for much longer before overheating. Even without a fan working. I would do a coolant flush, and definitely get the aux fan going. The mechanical fan helps, but the electric one will keep you from overheating.

Oil pressure Sensor is tapped right off the oil filter housing. Trace the wire as its likely the culprit. I highly doubt the sensor failed. I would bet the wire is to blame.

Stiff brakes are a vacuum issue. If you don't own a mighty vac, I'd buy one. The car will run much better when there are no vac leaks.

Good luck

[timmyr]

Originally Posted by lorainfurniture

I've had the slow reverse thing going with my 300e for 5 years now. I wouldn't worry too much about that.


Good luck

same here, but for the past 3 yrs. i always give it plenty of time to engage reverse, and make sure to go easy on it when using reverse, and so far so good.


i would suggest that you inspect the fluid next. fortunately for us , these cars have transmission drain plugs, find a clear plastic container, remove the transmission pan plug for a second or two and collect the fluid in the container. now you can inspect the fluid, check to see if it smells burnt,and also check and compare the color of the fluid with new ATF. if it doesnt look/smell new replace the fluid(6.6quarts) along with filter. speaking from experience , changing out the fluid improved both gear engagement smoothness as well as shift quality.


if it were my car, i would avoid flushing the trans.
these transmissions have torque converter drain plugs, so if and when you decide to change out the ATF, just drain the converter and then the trans oil pan, this will allow you to change out roughly 85% of the ATF.

good luck