Possible S320 purchase
 

This weekend I'm looking at a 96 S320. Is there any weak points or problem areas on the 140 series that I should look for? It's got 138k on it and that's pretty much all I know about it.
Thanks for any input-
Ken

Well to start with head gasket leaks, cylinder head front cover leaks, and engine wiring harnesses cracking due to brittle insulation. Mass airflow sensors, throttle motors, too many things to list really. If it drives nice and no types of fault lights on the dash would be a good start. Should not have the 722.6 transmission, which even if it did to me is not a deal-breaker, it is just a misunderstood transmission, but this has the 722.5 which is not the filled for life trans.
Like any other Benz it depends on how well cared for it has been, so look for a stack of service records. I would be extremely shy around it if there are no records. Find out if there is a long list of owners or just a couple, and if they can name where it has been serviced, these things need to be cared for by people who know what they are doing, not a quick-lube place.

Ken,

I have two W140's my S320 is my favorite car...

The S320's are known for oil leak from the head gasket on the rear cylinder. Some may look barely wet(like mine), some may drip badly, and some blow the head gasket.

Also, the S320 was the last year of the all hydraulic transmission, and reverse gear is the biggest issue with the 722.5. One of the o-rings responsible for the reverse gear gets brittle and hard; No longer seals well. The o-ring gets worse as the transmission heats up, yet prior to loosing reverse. Reverse gear makes this clicking sound like you are on a roller coaster up hill. My S320 started to make the clicking at 125k, and reverse failed at 135k. I just finished rebuilding the transmission my self. The reverse should be quite. 722.5 like the 722.4 and 722.3 need additional cooling(a separate transmission cooler). While I've been barely driving my S320 after the transmission rebuild one of the transmission rubber cooler lines was brittle hard cracked, and sprung a leak. These cooler lines are behind the bottom front engine cover.

When you get your S320, do not go joy riding. Change out the heater tee on the fire wall. Replace the tee with a actual fresh new part from the dealer-no third party-ebay deals-used ones. The tee will break and spew coolant everywhere, and you have 30 to 60 seconds to respond before the engine is destroyed. The tee's should be changed at 70k to 80k. Mine broke at 125k, but I was lucky...

On the level of heater, test to make sure the heater and AC works. The Fan speed goes up and down. The heater is usually a stuck or damaged DUO valve. The Fan speed is a active voltage fan regulator that is known to fail.

This leads to the next question, I'd probably walk away from a car that the prior owner has replaced the entire head as the car has over heated on them. These cars are not the same after that happens.

The early engine wiring issue was solved after 1996, but the S320 still has a wiring issue(not in the engine). The problem is in the mirrors. Fold the mirrors(they fold electrically). If the mirrors stop(because the fuse popped), it is the wiring is bare, and shorting with other wires. You can usually see the bare wires while the mirrors are folded.

Obviously, no lights on instrument. Look at the oil on each of the dip sticks. Inspect the "radiator cap" the color of the coolant should not be GREEN or ORANGE...If it is green or orange, I would run not walk away from the car!



If the key is hard to turn, locks up some times. The tumbler/key assembly is about to fail, and when it fails it is a very VERY Expensive fix from the dealer(only!!) in the Thousands....

The rest of the stuff is peanuts.. Door lock does not work, windows do not go up, doors not suck in, trunk does not close, antenna does not go up or down, volume on radio jumps, sound sounds with static(its the amp), etc.. these are easy.

I hope you will DIY on the S320 because you will pay through the nose for service, as the W140 requires higher interval of service(it just has more parts to fail). Get a 2000 to 2002 E series if someone is going to service the vehicle.

If you can get PPI inspection, that will aid in your selection.

Best of luck,

Martin

Thanks Martin, always good to hear from a DIY 140 owner, sounds like you know your stuff!

Gilly,

Thank you for your comments, My S320 in 2006 was my first Benz, and I spent about 40hrs on the web just on the W140 reading the good, but more about the bad about the car in 2006..

When I got mine, I was ready for all the problems(and I had some major ones-Transmission and Bumpers) which arrived later in time..

I do it all. Work on transmissions, and paint. Like a friend of mine says" Once it's broken the only solution is to fix it?"

I'm learning here. I'm no genius-Just like everyone else..

Martin

I use green poly gycol, at 100%.,its better than mercedes stuff

I bought a 97 with 93k miles on it... i had looked at a number of them but this was clearly the one because of the service records.

I think the most noticeable fix was that the previous owner had the front control arms and rubber replaced.

i really need to take a look at the "t".

so far 10k trouble free miles.

I can't think of a better engine than the 104.

Mine also had the conductor plate replaced in the transmission among other things...

my only complaint is the stock wheels... i need to get some updated ones

I agree with old sinner, but 99 times out of 100 is the Benz found with green or orange used tap water is used too, and that is a big no no....Tap water is the killer to any aluminum engine leading to head gasket issues. Distilled water to fill the radiator and clean. This is also true for any Aluminum head to cast-iron block GM, Ford, Chrysler, etc...

The green stuff is better than the orange stuff, but better than the clear stuff. I do not know. Now Mercedes changed the coolant it is blue, I think...

Coolant and Cap need to be changed about every two years.

Martin

I have heard filtered "drinking" water is better than distilled water, something about the ions in distilled water. Worth researching anyways, but if distilled is better then do it, it stays in there a long time so should be no hesitation in buying water for your car if it's better for it, the stuff is cheap compared to the coolant (or the cylinder head!)

Xerex G05 also very good for these engines.

When I got my 124 K mile 97 SL320 ( R129 body ) I changed every coolant hose. New hoses at the dealer are priced reasonably so chasing parts at the corner store isn't worth it.

Are you going to drive the car in the winter? If not, bypass the heated window washer bottle and heated windshield bottom, this eliminates the need for some $ t hoses. Even if you are going to drive in winter, does it get cold enough for lots of ice and snow?

I would argue in favor of the heated windshield base and washer tank, but then again I am from Wisconsin, and also assume any car would be driven in winter unless it is a sporty car.

Thanks
 

Thank folks. I really appreciate all the information. Yes, it will be a DD year round.
Thanks again,
Ken

my s320 was my best decision,I get 29 mpg highway.Also with my NOS I out run a 500