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Urgent Advice Needed on '95 E420

4K views 37 replies 7 participants last post by  knapster 
#1 ·
Hi

I am a sailor and have just come back for 3 months before I ship out again.

I own a '95 E420, a car which has not been driven and/or started since md-2015. In between, the car was left without any gas in the tank for almost a year & then my wife by mistake put in 87octane gas in it to get it to the gas station. The car started fine, but it kept back firing and would not hold power. She managed to get it to the gas station, filled the tank with 93octa and put in fuel stabilizer.

Now, she says that the car still starts fine, but after 15 minutes she says that you can hear sharp rapid fire popping noises in the engine, as opposed to backfiring, and then it stalls.

I've obviously not started the car as I don't want to exacerbate the matter.

I'd have taken the car to my normal garage in Brooklyn, but for a certain reason, it's not possible. I am taking it to a local garage who knows Mercedes and I've assured him that the car comes with OBD-II connector.

Having said that, can somebody please guide me as to what needs to be checked first and fixed, apart from oil and coolant change? I seriously need the car as we're handicapped without it.

Many thanks in advance for all advice, suggestions and feedback.

Also, wishing everyone a belated Happy New Year.

Cheers
 
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#2 ·
This seems to be an electrical problem rather than a fuel issue. I'd start there by checking the spark plugs, wires, caps, rotors and ignition coils. Also verify that the engine wiring harness has been replaced. If it still has the original harness then all kinds of problems can result due to the degraded wire insulation. Sane goes for the throttle body.

The car doesn't have an OBD II diagnostic system. The mechanic will need to use the 38 pin connector to hook up to his scanner. Did the check engine light come on?
 
#3 · (Edited)
Hi knapster

Thanks for the reply.

1. The upper harness was replaced, but unsure of the lower harness.

2. The wife says that no lights came on. Having said that, when I tried to move the car some 6 months back (I, unfortunately, had a very short leave of only 15days, before I was called back), the car would backfire and stall when I tried to move it. It'd start up fine though.

3. I had bought a WOT enrichment module from a forum member, which I still have to install. He suggested that removing the distributor caps and cleaning them. Your thoughts, please !?

I'll make a list of what you suggested and have the mechanic look at those problems, first, before going for a oil and coolant change.

Thanks once again.

Cheers

PS: I am going to change the spark plugs, etc.
 
#4 ·
The caps should be checked and the suppressor plates behind the rotors. Water condensation can develop behind these plates, especially in humid climates, and can cause misfiring.

The modules should be checked too. Make sure they are all properly seated in their connectors. Check the fuses in the base module. If one of these fuses is blown, it will cause bad running condition. Check all fuses for that matter.

Also verify that the voltage regulator is good. Battery should show 13.5 to 14.5 volts when car is running.
 
#5 · (Edited)
Thanks knapster.

I am assuming that this takes care of all the electrical gremlins (unless you come up with more).

Is there anything mechanical that should be checked? I am planning to install the WOT enrichment module before having the battery reconnected and I've searched the forum threads for the installation procedure (where and how), but I could not come up with anything specific. Would you be able to guide me through it or at least point out where so I can do the same with mechanic on how to do it?

BTW, how many and what modules are you instructing to be checked?

Once again, many thanks.

Cheers
 
#6 ·
The modules just plug in. Disconnect the battery and remove the LH module and replace it with the one you have. There's no simple way to check the modules other than making sure they're plugged in securely. You will have 4 modules located in the box under the hood - passenger side in the back.

Mechanically - have him check the fuel pumps, fuel pump relay and replace the fuel filter. The pumps should put out over 50 psi with a steady needle at the gauge.
 
#7 ·
Thank You knapster.

Will do.

You've no idea how grateful I am for your advice.

We just moved from NYC to Bayonne and with all the MB expert garages away by at least 29miles + tolls, this creates a logistical challenge of getting the car to a garage + being able to get it back. I've never missed more the commuting ease & convenience that was NYC.

Will the a/c+heater still perform or just the change in filters + adding the freon will suffice? I'm aware of the PIA involvement that's the dash removal to get to that.

Cheers
 
#8 ·
One Thing At A Time

Caps and rotors would be the 1st project I'd attack. After sitting for so long I'd suspect moisture in those caps are causing these issues. Check the posts in the caps for corrosion. It could be water in the fuel lines, too. :dunno:

Look for rat/mouse damage to ALL the wiring in the vehicle. No codes, no warning lights(CEL) is a good thing.

I'd get that misfire sorted out before I did anything else. Then attack the other possible issues, oil change, filter, other fluids, plugs, wires, fuel filters, rubber bits, etc.

The heater should be fine, change the coolant and be certain that the thermostat works once you get the engine issues sorted out. I suspect you may find some flaps in the air handling system might be sticking, though.

The A/C could be an issue, but let's see what it does when the engine is sorted. There are several solutions to attempt before you rip into the dash.

Was this vehicle stored inside or outside for all that time? :confused:

Keep us posted on your progress.
 
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#9 ·
Hi knapster and LogicalPosition

Thanks for the advice.

Going through your advises, this is the list that I've made. Please point out if I've missed anything:

38pin connector and not OBD-II

1. Change caps & rotors and spark plugs - Check the posts in the caps for corrosion. It could be water in the fuel lines, too. The caps should be checked and the suppressor plates behind the rotors. Water condensation can develop behind these plates, especially in humid climates, and can cause misfiring.
2. Check fuel pump and fuel pump relay. The pumps should put out over 50 psi with a steady needle at the gauge.
3. Change oil, filter, other fluids, plugs, wires, fuel filters, rubber bits, a/c filter, etc.
4. Coolant flush
5. Check thermostat.
6. Check for rat/mouse damage to ALL the wiring in the vehicle.
7. Check Modules. Make sure they are all properly seated in their connectors. Check all fuses. Check the fuses in the base module. If one of these fuses is blown, it will cause bad running condition.
8. Check modules are plugged in. 4 modules located in the box under the hood - passenger side in the back.
9. Verify that the voltage regulator is good. Battery should show 13.5 to 14.5 volts when car is running.

I'm making a list of things that I'll need to pre-order going by the list and I'll post shortly. I tried to talk to autohausaz and they'd not assist. Guess things have changed recently, as earlier they'd help out with the technical and mechanical things.

Cheers
 
#10 ·
My E420 sat for longer than yours did and I had similar problems reviving it. No matter how you try, you do not get all of the gas out of the system. In my case, as it dried out it left a residue that later dissolved a little, perhaps in chunks too. The result was that after putting a few gallons of new, clean fuel in the tank, I had the equivalent of "old" gas. It stinks, smokes, skips, belches fire, etc. This gums up the injectors, fouls the plugs and clogs the fuel filter. My distributor caps were a little corroded too. Before it ran reliably enough for me to feel comfortable turning it over to SWMBO for her daily driver, I replaced the fuel filter twice and thoroughly fouled two sets of spark plugs. My mechanic swears by 44K Fuel System Cleaner. I used a can in the first two tanks, skipped on and then used a third can. This was ~year ago and my E420 now runs as good now as it ever did.
 
#12 ·
Hi

These are the parts that I'm buying to replace and which hopefully, gives me a baseline:

Fuel Filter with Fuel Filter Seal
Transmission Filter with Transmission Gasket Set
Cabin Air Filter
Oil Filter
Power Steering Filter
Air Filter
Spark Plugs

Is there anything that I've forgotten and should have added? Pelican Parts suggested that the caps & rotors should be first checked before being replaced, or should I just go ahead and replace them? The car has 80000miles on it.

Thanks & Cheers
 
#13 ·
Double check that you have a cabin air filter. It was optional. I would check/clean the caps and rotors first. Replace the plugs with Bosch F8DC4's only, zero exceptions. Replace all the fuses with copper ceramic types. Check the fuses in the base module inside the coffin box. Transmission fluid should be Dex III, non synthetic (8.5 qts) drain the torque converter as well as the pan. Buy a genuine MB branded trans filter.

I would do a brake fluid flush, flush the radiator and replace the reservoir cap (MB branded) refill with a correct mix of Zerex G 05 and distilled water. Also use distilled water in your wiper reservoir.

Good luck

Jayare
 
#14 ·
Thanks Jayare and I was hoping that you'd weigh in with your advice. You did not disappoint :)

I have ordered OEM cabin air filters from Pelican Parts.

I went ahead and ordered Bosch distributor caps and spark plug wires as the car was misfiring, stalling and the engine was shaking. Not to mention the popping noises.

The ceramic copper plugs were replaced by me when I bought the car @ 72000miles, but will re-check them.

For spark plugs, I'm using Mercedes# A0031590503 made by Bosch in Germany. I had used them in the earlier W126 300SE too. Will that work as I already have them?

I do have the Zerex G05 coolant with me. Thanks for the tip on the transmission fluid.

Two questions:

1. What do you mean by "reservoir cap (MB brand)" and why do I have to replace it?
2. Should I be also changing the differential oil?

Thanks once again.

Cheers
 
#15 ·
I'm not familiar with the MB spark plug number, but I'll look into it. Do the plugs have flat seats or beveled? By reservoir cap, I mean the cap on your radiator overflow tank. It is a very important part of the cooling system. With the car not being used for long periods, things dry out like rubber seals..Having a new cap is just plain ol cheap insurance IMO. It falls into the consumables arena.
 
#16 ·
Hi

Looks flat to me, but I'm no expert. Damn! I had just bought a new one from clark before I left in 2015. I guess, I'll get a new one.

How do I check whether the car has cabin air filters? Will Pelican Parts be able to confirm if I give them the VIN #?

Thanks much and Cheers :)
 
#22 ·
Will do :)

So, that covers everything?

Changing all this should not be a problem for a decent mechanic. All I'm hoping is to get the car running in a good condition by saving money on parts and then drive over to a good MB mechanic for fine tuning. The ones I know won't accept the parts that I bring in and I don't want to pay double the price that I get them for. So far, I am around $900 with the big ticket items being the Bosch distributor caps and spark plug wires.
 
#23 ·
This reminds me that every time I think about doing a little work on the car, a little turns into ~$1K. And it reminds me how fortunate I am to have an excellent mechanic that makes house calls. But mostly, it reminds me of the smile on my face when I get to give it a workout even now after twenty years. What a car, eh?
 
#24 · (Edited)
Somewhere the ETA dropped out of this discussion.

Could cause running issues all by itself.

There is a label on it. Check the date.

I live in bone dry LA and still my caps got moisture every 6-12 months with regular driving. It would start running like crap and I'd have a look and they'd be full of drops.

But I never got it running right until upper harnness and ETA (throttle body wiring, whatever you want to call it) got post '97 build dates.
 
#26 ·
Hi SoCal

Thanks.

The upper wiring harness is post-98. It's the lower wiring harness that I'm worried about. I tried doing a forum search for the part number and could not find it. Would anybody have the part# for the lower wiring harness?

Cheers
 
#30 ·
Hello 93SoCal400E

Thanks & regret the delay in getting back.

It's post 98, that much I know 'coz I had it checked out before buying the car. Unfortunately, I don't remember the date.

The parts that I mentioned above are coming around Jan 9th and the garage that I am taking the car to is busy. I got the date of Jan 16th to bring the car in.

I'll keep all posted :)

Cheers
 
#31 ·
Update 1

Finally got to the car, took off the tarp to move to the mechanic and see what was the damage done to the exterior since mid-2015. The only rust that I saw was some light rust on the exhaust which I can sand paper it away and light salt encrusted which could be brushed away.

The photos:
 

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#33 ·
Coils

Hey mate, I just wanted to add, not sure if included elsewhere in this thread, to check the coils. I've experienced similar problems with a bad coil pack. They are very cheap, and they are super easy to fix. It's maybe 5-10 minutes top even if you've never done it before, and are taking your sweet time doing it. They generally recommend replacing all of them at once, but I'm cheap... I just replace the bad one. I figure if the others go bad I can spend another 5 min replacing that one later. A pretty easy way to find the bad coil is to just swap them one at a time until the car runs smoothly. There are only 4 of them on a 8-cylinder & 3 on a 6-cylinder. I could be wrong, but I almost think that diagnostics will tell you which coils is bad? I think I remember my mechanic telling me that a while ago, when I still used a mechanic, but I could be wrong. A really cheap and easy diagnostic tester can be made with 3 test wires and an LED bulb. Bobterry99 on here has some really great threads on building a test light. You can go as simple as the 3 wires & bulb, or he will help you build a digital system that will tell you all of the codes at once...which is pretty awesome. You just need to have a chip programmed by him. Anyways, you can also use a 12V test light and 2 alligator clip wires (test wires) if you don't have an LED or can't pull one from a toy or something like that.
 
#34 · (Edited)
Update -2

Thanks Fallinggator.

Got the car back today & it cost me $4000 incl taxes.

One of the MAF sensor had gone bad and there was a rat nest, with the entire injector wiring being eaten up and had to be redone. Other than that, the tyres had to be replaced as they were developing cracks, even though they still had 60% life in them, with rotors rusted and the brake pads needing replaced too.

Fuel pressure, spark plugs, fuses and all modules were working fine.

I had bought the following parts from Pelican for almost $950:

1. Elring Klinger Transmission Gasket Set
2. Bosch Oil Filter Kit
3. Mann Power Steering Filter With Metal Reinforcement
4. Fischer & Plath Oil Drain Plug Seal (12 X 16 X 1.5 Mm)
5. Mercedes OEM Cabin Air Filter
6. Mercedes OEM Fuel Filter With Threaded Fittings (82 Mm Diameter)
7. Mercedes OEM Transmission Filter
8. Mercedes OEM Power Steering Fluid
9. Original Brake Fluid
10. Mann Air Filter

Bought from eBay:

1. Bosch Spark Plug Wire Set for $257.15
2. Bosch Set of 2 Distributor Caps for $ 179.10
3. Philips H3 and H4 Xtreme Power Bulbs
4. Trunk Stop Rubber Boot Set for $34.90 from Turkey

I already had OEM Coolant and Spark Plugs.
 
#36 ·
Thanks Fallinggator.

Got the car back today & it cost me $4000 incl taxes.

One of the MAF sensor had gone bad and there was a rat nest, with the entire injector wiring being eaten up and had to be redone. Other than that, the tyres had to be replaced as they were developing cracks, even though they still had 60% life in them, with rotors rusted and the brake pads needing replaced too.

Fuel pressure, spark plugs, fuses and all modules were working fine.

I had bought the following parts from Pelican:

1. Elring Klinger Transmission Gasket Set
2. Bosch Oil Filter Kit
3. Mann Power Steering Filter With Metal Reinforcement
4. Fischer & Plath Oil Drain Plug Seal (12 X 16 X 1.5 Mm)
5. Mercedes OEM Cabin Air Filter
6. Mercedes OEM Fuel Filter With Threaded Fittings (82 Mm Diameter)
7. Mercedes OEM Transmission Filter
8. Mercedes OEM Power Steering Fluid
9. Original Brake Fluid
10. Mann Air Filter

I already had OEM Coolant and Spark Plugs.

HOLY CRAP!!! $4,000 for a MAF Sensor and injector wires? The airflow sensor is about $100 for Bosch OEM. Let's call your list around $200 assuming you got some ATF as well. I'll just assume you got really nice tires, and call them $200 a corner for $800. That brings us to $1,100. The injector wiring is a little tricky, but I'll just assume the worst and call it $1,000 which brings us to $2,100. Let's say you are in a high sales tax state, and call it $170. That brings us to $2,270. They charged you $1,700 in labor to install the injector harness & O2 Sensor? I've got to just go back to how I started this comment, and say HOLY CRAP!!! I honestly think I'd just send it to the crusher or part it out if I was given the choice. If it was an 8-cylinder, then I might consider it; but...HOLY CRAP!!!

Sorry if this is adding insult to injury.... :| I'm just shocked at what these places charge for this stuff whenever I think about what I could do in a lazy weekend in my driveway. Particularly now that a lot of places will loan you specialty tools you don't have. At least now you and your wife have the car working again. That's always a plus. Although, I almost wonder if you could have put in a V-8 for that? Steal one out of a 420 SEL. Well, either way cheers mate! I sincerely hope that it lasts you a long long time now, and that it remains problem free for many years.
 
#35 · (Edited)
Update - Contd

The mechanic added the following & charged (This is where the $4000 (incl taxes), comes in):

Oil Filter, Premium Motor Oil, Trans Fluid Dex 3, Fuel Cleaner, Injector Cleaner, Gear Oil, MAS Sensor ($615), Wire Harness Kit, Freon, Gas, Brake Pads (Front & Rear), Brake Rotors (Front & Rear), Mini Bulbs (For the interior reading lights $16x2), Door Sill Double Sided Tape, Michelin Premier (205/60/R15) with nitro, mounting & 4 wheel alignment.

He did the following:

Performed diagnostics, oil change, transmission flush, with torque convertor, filter & gasket change, flushed differential fluid, removed thermostat & cooling tank. Cleaned tank and cooling system. flushed brake system. Flushed power steering system. Removed & replaced air filter & cabin dust filter. Removed old gas and blew out line, replacing filter & filled with new gas. Replaced wires, caps & spark plugs after gapping them to specs, cleaned fuel rail & injectors, greases sun roof rails & wiper joints. Cleaned throttle body & checked fan belt. Performed an ac charge & flush. Checked for moisture, vacumm lines, voltage regulator and engine mounts.

Did a few extra things too, but that I'll show in the photos after the car has been washed :)
 
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