We have just bought ourselves as a family car a 1990 model 300te. It is the first Mercedes I've owned and I am trying to find out as much as I can about these cars as possible to avoid getting ripped off. The car is driving great but the only problem I am having is it occasionally doesn't start first go and seems to have high fuel consumption compared to other cars I have owned in the past. I am only getting about 200Miles or 340km to a full tank of gas. Is this normal? The car was very neat body wise and interior wise but mechanically it needed some attention. I ended up renewing the fuel injectors, fuel distributor, valve stem seals, new rotor, distributor cap and leads. It drives 100% apart from those two problems.

 

My wife and I have owned our '90 300TE for almost 5 years now and I can assure you that the W124 is a great car and the 300TE would be among the finest wagons ever made. It is our second MB wagon (replaced an '80 300TD we owned for 4 years).

Regarding fuel consumption, you don't specify the driving conditions. On short trips around the suburbs of Sydney, ours uses around 15 l/100km. Open road driving at around 110km/h usually returns around 10.5 l/100km.

For further information about your car, search this forum and you may also like to search
http://www.benzworld.org/forums/
and
http://www.mercedesshop.com/shopforum/index.php3
The Mercedes-Benz Club of Victoria would also be worthy of consideration since I notice you are in Melbourne.

 

Greg thanks for the reply. Yes I will be joining the mercedes club of Victoria because I feel I have become obsessed with finding out info about this car. I actually bought the car from Sydney because I had problems finding a 300te Update for a decent price. Of course even though I got the car checked out by a pre sale car inspector and not knowing what I know there was a few things that needed to repaired. One thing I am slightly dissapointed in is most MB workshops assume you have a blank cheque when it comes to mechanical repairs because most Merc owners are willing to pay the high price. Even though I have done the Valve stem seals can anyone tell me an easy way to check if the valve guides are worn becuase most places won't guarantee just replacing the stem seals.

 

Hi Chris,
the fuel consumption seems absolutely on the high side. It should be around where the other poster said. But even drinving short distances around the town should not be more than 12-13 liters per 100Km. The starting hesitation can have several reasons. One of them is that the backflow valve of the fiuel pump is worn, and allows pressure loss in the fuel system when parking. Then, when you try to start the fuel pump has to increase system pressure first before the engine starts properly. Another option can be, and this leads to higher consumption also, that the electrically operated cold start valve (right on top of the head blue plug) is leaking. This valve is only briefly activated during the cold start sequence and then shuts off. If it leaks it always allows fuel to enter the manifold and makes a richer mixture, consumes unnecessary fuel, and, due to the rich mixture, causes bad starting, especially when the engine is still hot or warm, and the richer mixture is actually not required.
Otherwise I would state the car is worth every $ spent. I own 2 of them both well over 300.000 km no significant problems what so ever, one is a '90 and one is a '86.
In order not to get ripped by garages, you need to get yourself a DIY-CD or a manual for DIY, and then you are save.

 

Bamberger thanks for your quick reply. The first reason you point to is the backflow valve on the fuel pump. Is this a replacecable part or do you have to replace the whole fuel pump. Has the 300te got one or two fuel pumps and where are they situated. Is there any way of checking this?....The next part you refer to is the cold start valve..Where exactly is this situated and is there any way of testing it or do I take the chance and change it...It seems that these forums are priceless when it comes to information. I will definetely be bying the service manuals soon as I found out where they are available here in Australia.

 

Hi Chris,
the backflow valve is something which cannot be checked simply because before you take it out and test you better replace it. However you can do some trails to narrow down whether the valve is causing the problem. When you start the car after the car was sitting overnight in the garage and the outside temp. and the engine temp. is say around 20 Celsius or slightly above. Turn the key and try to start the engine. If it starts immediately it seems all may be ok concerning the fuel pump valve. If you need to turn the key twice or more it somewhat calls for the valve problem. The reason is, when ever you turn the key in the position just before the starter kicks in, the fuel pump starts pumping for 1-2 seconds (and you'll hear it). If the valve is worn the second try just brings up the fuel pressure to get the engine starting. Actually the pump (its only one pump) consists of the valve as a seperate part and the (normally BOSCH) pump. But I dont know where to get the individual parts. So I had the problem by just replacing the pump and the valve which comes attached. Messy job! Caution dont get anything but BOSCH. There is also a Pierburg replacement available, but this thing is a "singer" and even at higher speeds you'll notice the anoying sound. The pump and filter assembly sits underneath the car floor, just below the rear seat on the Australian driver side. When you plan to replace the pump just do the filter also.
The cold start valve sits right on top of the rigth side of the cylinder head between cylinder 3 and 4. You have to remove the airfilter assembly to see it. To check the valve is simple. Carefully try to pull it out of its sealing, dont knick the fuel line! pull the electrical plug. Turn ignition on w/o starting the engine, so fuel pressure builts up. There should be no fuel coming from the valve. Then you can apply 12 V to the valve plug and it shall open and spray fuel. Careful! just hold the valve into a can to limit the mess. After removing the 12V supply the valve should close and be tight, and no fuel shall drip from it any more.
All in all this are only 2 of plenty other possibilities causing high fuel consumption and hesitating starts. But remote diags are somewhat difficult, but may be it works for you.

 

Chris,

Once you join the club, you will not only learn more about your car, but you will learn where to get parts and service for the best value for money.

Regarding fuel consumption and difficult starting, it may also be worth checking the over-voltage protection relay (OVP) behind the plastic panel behind the battery. If the relay, or the fuse on top of the relay fails, the car will still run in limp mode without any electronic management of the otherwise mechanical fuel injection. It is surprising how many KE-Jetronic cars are getting around as just K-Jetronic because of this fault. It is just another thing you can check, and a very easy check at that. A '92 180E I purchased some years ago became harder to start in the mornings as winter approached. I also noticed that the idle speed was not well controlled. Investigation revealed the fuse on the OVP was blown and the injection was working without the aid of the ECU. The blown fuse may have resulted from a jump start due to a flat battery as I noticed that a new battery had been fitted immediately prior to my purchase. With the fuse replaced it was a much happier car.

By the way, I think you will find your TE has two fuel pumps with the filter above the panel forward of the right, rear axle.

Greg

 

Greg thanks for the info. Do you know where I can obtain the CD service manuals or any haynes print manuals here in Oz. As for the OVP relay I have been avoiding that because the car is idling fine....since I changed the leads, rotor and distributor cap.

Cheers
Chris

 

Chris

The MB Club here in NSW has a library that includes factory manuals. I would be surprised if the MB Club in Victoria does not have manuals as well. I have also purchased my own. For the 300TE I have MB North America factory manuals for both M103 engine and W124 chassis & body (separate manuals), a Haynes W124 manual and a Brooklands (I think) W124 manual. I purchased all from a motoring bookshop (Motorbooks) in Sydney. They are on the web at
http://www.motorbooks.com.au/
Any large motoring bookshop should be able to get them for you. Some MB dealers and parts suppliers also carry the Haynes manuals. I believe the MBNA manuals are now only available on CDROM. You can buy them on the internet.

Re the OVP relay, it is 2 minute job to check the fuse. Well worth the time.

Greg

 

I sourced a Haynes service manual today from a Motor book shop near my house for $50Aud. I also rang around to get a price for a cold start valve and fuel pump and backflow valve and was shocked to be told by mercedes that a cold start valve was over $500Aud. The wreckers said about $77Aud for a used one. I will pick up my haynes manual tommorrow and try and do some diagnosis in the next few days. I used to work on cars a lot about 15 yrs ago when I was modifying datsuns and its amazing how you go back to your roots on working on cars so you can't be taken for a ride. Again thanks Greg and Bamberger for your thoughts. I wish I had the internet when I was modifying Datsuns...

 

Chris,

Some diagnosis as you suggest is the way to go. Throwing parts at it can get very expensive and still may not fix it. Assuming the OVP and fuse is OK and the ECU is getting power, then possibly the mixture is wrong. Without the ECU operating, mixture is determined purely by the adjustment of the mixture screw in the fuel distributor. With the ECU operating correctly, you have a closed loop (feedback) system where the oxygen (lambda) sensor tells the ECU what the mixture is like according to the exhaust gas. The ECU then controls the mixture by way of the electrohydraulic actuator (EHA) attached to the fuel distributor, overiding the fixed mixture setting. I would be looking at some diagnosis in this area. Do a search along the lines of EHA and oxygen sensor on the Tech Help forum at
http://www.mercedesshop.com/shopforum/index.php3
and you should come up with instructions on how to diagnose this system. You mention you have already done plug leads, rotor and cap. How's the air filter? How's the exhaust system for restrictions (ie. cat and mufflers)?

Interesting you mentioned modifying Datsuns. You must be from a similar era to me. Whilst I never owned one, I spent considerable time helping mates build up Datsun 1600 rally cars around 20 years ago and I also spent a lot of time in the navigator's seat in rallies. My time in my younger days under the bonnet and behind the wheel of my own cars (including competition) was with Minis. Mercs came into the picture 20 years ago when I bought the 350SLC.

Get involved with the MB club there. You may even want to consider the national rally of all the Oz MB clubs in Queensland next year. We have registered for it. Maybe we could discuss our 300TEs there.

Regards,
Greg

 

Had a quick look last night for the OVP and fuse but pulled the plastic cover off behind the battery and saw two relays behind a big connector. Where is the fuse situated behind the plastic cover because its not part of the relay. Another tip is that my wife said yesterday that she smelt a faint smell of gas and reading the post it could even be the EHA valve. I actually feel sorry for her because it was my idea to buy this car and even though she agrees it beautiful car to drive she is not very confident with it due to it not starting and spending a lot more money on thaen we intended. Also beleive my car to get around is a datsun 1200 ute which I do most of the work myself and wouldn't change it for anything...

 

From memory, the fuse for the OVP relay should be under a cover on top of the relay itself. The fuse is one of those coloured plastic blade types. The fuse is only one possibility. Another check that will reveal if the ECU is powered and functioning is to see if the idle control is working properly. You should be able to load the engine at idle and have the idle speed remain constant. This is easy to do in a manual by selecting 1st gear and engaging the clutch without opening the throttle. In an auto all you can do is load it up by switching on the aircon and turning the steering to full lock to load the power steering pump. If the engine idle speed remains fairly constant then the OVP and fuse is OK.

Don't give up. When you get it all sorted you will have a car you will grow to love and should be reliable. There is no way I could get my wife to part with our 300TE and we embark on long trips in it without a second thought as to its reliability. Remember that people often sell cars when something is not quite right. It is common to have to sort out a few bugs after purchase but then everything is usually OK. Many contributors to forums such as this often recommend budgeting to have to spend some extra money over your purchase price to get everything on a used car sorted properly. What is the history of your 300TE (eg. distance travelled, service history including known work done, previous owners). Tell us more about it (eg. colour, options, condition, a photo maybe).

Here's ours:

 

There's only one mod worth doing on a Datsun

 

I removed the air cleaner assembly this afternoon and located the cold start valve as per the haynes manual and bambergers advice but found you need a really long alen key to undo the two bolts. I either have to cut an end off an alen key or buy some allen key straight to use with sockets. Checked teh OVP and it seems OK. Drove the car all weekend and it drives beautifully but it is really sucking the gas so I would love to get it sorted soon. Greg the car is an early 1990 update whicjh was owned but the owner of Gabriel Motors in Rozelle Sydney. It is not a concours winner but a clean car that was not looked after mechanically as I found out. It has most options except for the airbag, leather and electric seats. Tell me a little bit about yours if you want email me direct..

 

Chris,

Your 300TE looks nice. I love the colour. I must admit to not having seen one in that colour before. As you are aware, there are not many W124 wagons around in Oz.

As you can probably see from the pic I posted (taken at last year's MBCNSW concours where we won our class), ours is arctic white with cream-beige MB tex. Options include the 3rd row seats (standard in Oz), luggage net and cover, electric front seats, orthopaedic driver's seat backrest, higher spec Becker radio-cassette and 10 disc CD changer. I have also fitted 7" x 15" Sportline alloys with 205/60R15 Michelin Pilots.

Greg

 

Greg went to the first Mercedes club meeting last night and was really impressed with there professionalism. I couldn't believe that they had over 700 members. Can't wait to get our car sorted so we can participate in some of their activities. How did you find your car and what sort of money did you pay for it back then and what sort of problems have you had. Mine hasn't got the electric seats or the cd changer which would of been very nice to have because that will be my next purchace after the mechanical repairs and I would like to fit a towbar and tint the windows because especially with that colour it gets quite hot and we don't want a couple of cooked kids in the back. Do you know how many wagons especially the updates were Australian delivered. I read that you did the head on your car a while back. Did you replace the timing chain?

 

Chris,

Pleased to hear you enjoyed the club meeting. I believe the club in Victoria is very good. I attended their concours earlier in the year and the excellent tour of three private car collections they ran on the following day.

I had always wanted a 300TE and started looking for a 300TE to replace our 1980 300TD back in 1998. I knew it could take a while to find the right car as there were not many around (as had been the case when we purchased the TD). The good ones were all expensive at the time ($50k +) and those in our price range were rough. Eventually I saw an ad for one at an authorised MB dealer right over the other side of the city that was in our range. The salesman assured me I would not be wasting my time travelling there for a look. As it turns out we purchased it that day after negotiating the price down to $42k. It was well optioned, had covered 124,000km, had a good history, the condition was good and only bad engine oil leaks gave a basis for negotiating a good price. We did not trade our (concours class winning) 300TD as the price offered was half of the $15k we ended up selling it for privately. Obviously the 300TE has dropped in value since then, but not as much as most other cars would have in the same time.

I have been happy with the 300TE. The oil leaks eventually needed attention when oil in the coolant verified a head gasket failure at 145,000km. I did not replace the timing chain (despite having purchased a new one) as there was no discernable difference between the new and old. Reading forums since has confirmed that despite being single row, chains last well in the M103. I did replace the tensioner and valve stem seals at that time.

Other work has only been fairly minor. Brake pads, front brake hoses, belt tensioner, tie rod, steering damper and of course fluids, filters, spark plugs, a battery and a couple of sets of tyres. Recently I also replaced the rear suspension accumulators (air cells), the tailgate struts and also had to repair a couple of broken wires in the tailgate wiring harness. I service it every 5,000km and it has now covered about 178,000km. Its condition is better now than when we bought it as a result of a thorough concours preparation every year.

You mention fitting a towbar. Ours has one and it tows very well. Just be sure that the wiring for the trailer is done correctly. There is a proper kit for this so as not to upset the operation of the lamp failure unit. The proper kit also gives a nice turn signal repeater lamp in the instrument cluster to remind you that you have a trailer attached.

I don't know how many W124 wagons came to Australia. All the early ones were 230TE with the 300TE coming here just prior to the 1989 update model. Prices got very high around 1990 which would have limited sales.

I hope you enjoy yours as we do ours. I agree with the many owners who state that whilst the W124 may not be the most reliable MB, it is possibly one of the best all-round models, and the wagon offers all the good points of the sedan with added versatility, ideal with a couple of young kids as we have. So happy are we with ours, we have no intentions of replacing it in the foreseeable future. Sort yours out, look after it, enjoy the club and hopefully we can catch up at an interstate club event some time.

Greg

 

Well I checked the cold start Valve on the weekend and sure enough it checked out ok. Had a visual look just in case there was any loose vacuum hoses but it all looked alright. The Hard starting problem is getting worse and I think it is definetely got to do with the car running way too rich. I can even smell raw fuel sometimes now after driving it. I have booked it in to a local independant mechanic who specialise in european cars next week. We'll see what he says after a couple of hundred dollars of diagnosis.

 

Well I got our 300te wagon back on Friday after being in the repair shop for 5 days. What he found was a couple of leaking injectors and the oxygen sensor. He told me that he had to replace this parts before he could go on.. The first repair shop I had taken the car to when I bought 6 weeks ago claimed that they reconditioned the injectors so thats why I kept putting them out of the equation for the high fuel consumption. Now I found out that the injectors are so cheap $38AUD that it is not worth trying to reseal or clean them. The oxygen sensor was the expensive bit at $275Aud but I trusted his advise. So far this weekend I have done 100km and the sighns look promising, the fuel consumption looks like already half compared to before. I will keep my fingers crossed.

 

Chris,

Pleased to hear that your 300TE seems to be fixed now. As I mentioned before, usually when you buy a used car there will be a few issues to sort out. Hopefully you will have a long and trouble-free time with it and will grow to enjoy it. Obviously considering its age there will be the occasional problem to solve. If you learn your way around the car you will be able to sort many things out yourself. They are not as complicated as many would think. Enjoy!

Greg

 

Chris;

Has your hard cold starting proble been fixed after all this? I'm fighting the same problem.

Thanks - Don

 

It wasn't just cold starting it was also when the engine was hot. I personally don't think it has fixed it completely but the fuel consumption has improved and it occasionally dosn't start the first go and I have to recrank it. Talking to some other mercedes owners, they tell me that it is normal for most mercedes not to start first time sometimes. My other question for anyone in Australia is what grade of fuel do you run in your mercedes. I am just putting normal Unleaded but some people are saying you should be running Premium or even Optimax which is 98 octane...
Another 300e owner told me that he noticed that it was starting a lot better with premium unleaded...

 

Chris,

Our 300TE (at almost 180,000km) usually starts first time, hot or cold without any hesitation. My 190E (with the same injection setup but almost 220,000km) is somewhat more variable. It can often fire instantly, hot or cold without hesitation, but on other occasions may hesitate momentarily on a cold start or even require a second attempt. I don't consider this normal but to be more a symptom of ageing components in the fuel injection. I am not concerned as it is not a big problem nor does it have detrimental effects on the way the car drives or its fuel consumption.

Re fuel, Aussie deliveries of this era were setup to run on our regular (91-92 RON) unleaded. I have changed the value of the R16 ignition timing programming resistor on both of ours to the same setting as the euro deliveries and run premium unleaded, usually 98 RON (Shell Optimax or Mobil Synergy 8000 or similar). I posted a lengthy article re this mod that lead to much discussion both on this forum and others. The article discussed the validity of completely removing the programming resistor versus changing its value. Whether any slight performance or fuel economy gains justify the more expensive fuel is debatable. I probably feel happier using a fuel of supposedly higher quality and with added cleaning benifits. I also prefer running the ignition specs as was intended in Germany rather than the "detuned" settings for our low octane regular unleaded. If you wish to follow the discussions, look here:
http://www.mercedesshop.com/shopforu...threadid=67773
and here:
http://www.mercedesshop.com/shopforu...threadid=67772
and here:
https://mbworld.org/forums/showthrea...threadid=42715
and here:
https://mbworld.org/forums/showthrea...threadid=42714
and here:
http://www.benzworld.org/forums/mess...4&id=11&view=t
and here:
http://www.benzworld.org/forums/mess...7&id=14&view=t

 

Chris (hi from dear ol' Blighty!)

Like you I bought a 1990 300TE (my first Merc) as a family car and it's been one hell of good motor. I've owned it now for 5 years: I bought it with 97k miles on the clock and it now has 147k, so my annual mileage isn't high. Interestingly, the problems I have had over the 5 years I've owned it quite closely reflect your own experience. At 135k miles, the engine started fluffing as you pull away from standing -- the fuel distributor (GBP800 new from Merc -- I paid GBP140 for a scrapyard replacement!) was replaced which fixed it for about 3 months. Then the car cut on me completely and I ended up replacing a fuel pump and *another* fuel distribution unit (GBP500 for a recon unit). I'm still uneasy about this aspect of the fuel system. Various experts have suggested that I may have a rusty/dirty fuel tank which has allowed crud to enter the fuel system -- the only sure solution, they tell me, is to replace the whole damn fuel system -- tank, pumps, accumulator, filter, distribution unit -- which would cost more than the car is worth.

Oh Here's a tip! If ever you find that the SRS (airbag "safety restraint system") warning light on the dashboard suddenly comes on, then before you do anything else, get under the passenger seat and have a look for a thin wire pair which comes up from the floor and into a connector under the seat. If that connector has come apart, reconnect it and see if your warning light goes off. I took my 300TE to my local independent Merc specialist (who said he couldn't trace the fault because the computer fault codes gave no indication) then to Mercedes-Benz main dealership (who had the car for a day and reported that they couldn't trace the fault, but advised that after 10 years the whole airbag unit should be replaced at a cost of GBP900). I had resolved to open up the centre console to get at the SRS control unit and disconnect the warning light lead. I was hoovering out the car one day and found that my wife had pushed a large road atlas underneath the passenger seat and simply pushed the connector apart! I reconnected it and bingo.

The car is superbly built *and* excellently engineered. When I'm motorway cruising, I breeze past most traffic at 100+ mph in comfort and reasonable quiet (I think there's rather more wind noise from round the doors in recent years and I can hear the engine thrum at over 100mph -- but maybe I'm getting picky).
On sweeping, undulating A-roads (i.e. non-motorways, but fastish major routes) the car rides superbly: it doesn't wallow, pitch, or roll. Amazing for a 13-year-old estate car which weighs as much as it does and is often loaded with luggage, holiday gear, and kids. The brakes are fade-free, and utterly confidence-inspiring. (Keep changing the disks -- they are quite cheap to replace and I find the 300TE eats disks. Also always fit Merc pads. I found when I fitted OEM pads, I got a low-level rumbling/grunching noise under braking.)

Like you after the first month of ownership I thought my fuel consumption was too high -- I was getting about 24 miles per gallon. Since then I've found that even when they were brand new 300TEs would do an average 25 mpg, so you just live with it.

Like you, I got the valve stem seals replaced. The effect was very significant. Before, I used to have to top up with about a litre of oil every 500 miles; now, I probably do 2000+ miles before topping up with a litre of engine oil.

I quit my job recently to become a trainee teacher -- so our family finances are very squeezed for a year or two. The whole family loves the Merc -- air-con, full leather, electric seat controls, huge load space, elegant timeless styling. But can we afford the maintenance? I just keep my finger crossed we don't face a big repair bill in the next 2 years.