E420 woes...

[benzadryl]

Hello all, I recently acquired a 1994 Mercedes E420, with ASR, for 750$.
It was running when I bought it. However, it still has odd running issues.
From a cold start, it will run strong and chirp the tires on acceleration, and run WOT all the way up to 6k rpm.
Once warm, after about 10 minutes of driving, it will perform fine under normal traffic conditions, but when I try to wring it out up to high rpms, it Lurches - the revs will climb, suddenly stop, and climb again, and repeat that until I let off the throttle. This is above say, 3000 rpm.
It idles a bit rough, it used to sputter out and surge, but after the ETA it kind of just revs and drops down again very quickly at idle once hot, very choppy like it has a cam.
Maintenance done (some by me, some by P.O.)
rebuilt ETA
rebuilt MAF
upper+lower harness 2003 and 2016
fuel filters, pumps (I checked fuel pressure, about 47 psi on idle.
engine management temperature sensor
caps, rotors, wires, F8DC4 plugs
shifter bushing- transmission was acting weird before but it seems to have gone away.

It didn't throw a CEL for a while but after the distributors it gave 6 blinks at the led indicator by the ecu.
Really all I can think of now at this point is the 02 sensor, cats, brake switch, NSS. or maybe some weird transmission lockup thing, or an ASR issue.

I'm a bit lost at this point, any helpful advice is appreciated.

-Laz

 

[emerydc8]

Have you checked the diagnostic codes--other than just what the built-in pushbutton tester displays? It might help to narrow down the problem.

 

[gsxr]

Start with diagnostic codes as emerydc8 mentioned above, you need a hand-held blink code reader (see the De-Coding subforum stickies).

However, what you describe sounds a LOT like secondary ignition problems related to either moisture in the caps, or liquid on the back side of the insulators, or oil leaks from the exhaust cam seals / cam advance solenoids.

What happens if you drive at light throttle for say 30-60 mins... will it then pull to redline smoothly? Or does it NEVER run properly, no matter how long it's been running, after reaching operating temp?

Also - what brand caps, rotors, and wires were installed? Did you remove the rotor bracket to inspect the cam seals and look for liquid on the back of the insulators?

O2 sensor, brake switch, or NSS should not cause what you describe. Plugged catalysts, maybe.

 

[benzadryl]

gsxr,
I am running beru ignition equipment AFAIK...
PO did the caps and rotors before I bought the car, but it sat for a while.
pulled off the cap, cleaned up the contacts with a rotary tool, reassembled. same issue
Went to the dealership today, got original cam seals for 11 bucks a pop, went home and installed.
Starts up and idles fine at temp, a lot smoother than before. not choppy.
I had a seperate issue that prevented me from driving it today.
tommorow I will wind it up to redline and take it on an extended tour.
Thanks for your insight.

 

[nocfn]

If you can run for 2-3 miles in 3rd gear to get the cats really hot that will help. (may help)

Curious if you saw oil behind those insulators removed or freckles like one might find on toad.

 

[benzadryl]

Well, sorry for the late response as I was working on various troubleshooting.
I pulled off the BERU caps/rotors/isolator and replaced the seals with Mercedes parts, using a little bolt-washer-cone jig to press them in evenly.
The engine runs great, cleaned up all the oil and resealed the insulators with clear-coat paint.
it seems that the problem of the engine "loping" like it has a cam is only in the reverse and drive gears.
since the car has 180k miles, it's probably a trans issue.
car has telltale slow reverse engagement. what is the best course of action?
-flush with dex 3, doing pan gasket and filter
-remove and replace
-remove and rebuild (I have some experience with such, but never a 722.3)
I know the answer may seem obvious but I wanted to consult you all.
Thanks,
-Laz

 

[gsxr]

Fluid & filter won't help a slow reverse engagement. When the delay becomes longer than ~2 seconds to engage reverse, get it fixed sooner rather than later.

If you can R&R the transmission yourself and are on a budget, and all the forward shifts are good, you could just replace the reverse clutches and re-seal the transmission. However, with 180kmi and assuming it's the original gearbox, I'd seriously consider sourcing a rebuilt unit from Sun Valley in SoCal.

 

[benzadryl]

GSXR,
I really appreciate your help.
With the car up on the lift today, I discovered a vacuum leak that affected the modulator on the transmission.
I looked at the other guides for vacuum leaks and we will see what else may be wrong.
Hopefully this will address the loping idle and the transmission weirdness.
As for a rebuilt unit, remember I have an e420 not a e500 so the 2.25k for a rebuilt unit isn't in the cards
Thanks again,
-Laz

 

[Alphasud40]

GSXR,
I really appreciate your help.
With the car up on the lift today, I discovered a vacuum leak that affected the modulator on the transmission.
I looked at the other guides for vacuum leaks and we will see what else may be wrong.
Hopefully this will address the loping idle and the transmission weirdness.
As for a rebuilt unit, remember I have an e420 not a e500 so the 2.25k for a rebuilt unit isn't in the cards
Thanks again,
-Laz

These cars are worth more than you think. the value has increased in the last couple of years so if your car is in decent shape it’s worth repairing. Or your could sell it to me. I’m looking for another V8 W124.

 

[gsxr]

If the reverse delay is ignored, eventually the reverse piston will get destroyed, making the repair a lot more expensive (or, impossible, depending on the damage). Best to remedy before this happens. If you start to hear any clicking noises when reverse engages, uh-oh.

 

[Beater400E]

If the reverse delay is ignored, eventually the reverse piston will get destroyed, making the repair a lot more expensive (or, impossible, depending on the damage). Best to remedy before this happens. If you start to hear any clicking noises when reverse engages, uh-oh.

FACT
I've seen it and had to fix it.

I'll give you $750 for it so you don't have to lose money on it if you don't want to fix it.

 

[benzadryl]

Reflecting on it I'd rather have gotten a w210 e420 because I liked my last 210 for daily driving, but this car is nice as well.
I replaced PCV hose 122 (cracked) and emptied out the trans fluid and refilling with dex VI- I'm hoping it was just a little low??
After that the reverse felt the same as my '93 300e 2.8 so I'm not super worried, but I will start looking for a 722.3 at my local PnP as a core.
Got it up to 100 celcius, ran it up and down the drag by my house and it pull hard and smooth.
If the car's really worth so much maybe I'll just flip it and get the '97 e class with the same engine.
If someone has a nice m119 w210 I would consider trading+cash

 

[Alphasud40]

Did the transmission shift quality change when you serviced with Dex VI? I would have used good old Dex III non synthetic. I think Dex VI is lower in viscosity and might push the transmission into failure.

 

[benzadryl]

Shift quality got better, since it had the right amount of clean fluid, but I haven't really done the mileage yet.
As to the type,
Where are you getting Dex III nonsynthetic for a reasonable price these days?
the replacement for dex III is dex/merc and the closest I could find was dex VI.

 

[emerydc8]

Hello @benzadryl. FWIW, I have had the slow reverse and weak-when-reversing condition on my 94 E420 since 2011. At the time the transmission was leaking badly and I was able to add two quarts of Lucas stop-slip over a six-month period.

I fixed the leak long ago. Other than not being able to reverse on anything other than a flat surface or downhill, which just requires a modicum of situational awareness when parking, the transmission works perfectly. I decided not to push my luck and change fluid or filter.

When I reverse on a flat surface I feel and hear the chattering for a second or two on engagement and then it moves slowly (no gas pedal used while in reverse). I'm pretty sure what I'm hearing is metal on metal. I was expecting it to fail long ago but it hasn't, making the repair decision easy to defer for another day. I will have to check maintenance records to determine how many miles I've put on it since the reverse issue began.

 

[Alphasud40]

I buy my fluids from Napa using the store brand. Especially when they have a sale. The oil they sell comes from Valvoline. I think the last time I bought Dex III it was $5.49 a quart. For euro cars I typically use LiquiMoly in the weight specified by the manufacturer as well as making sure the oil has the manufacturer’s approval. Have you seen the new Toyota motor oil? I believe it’s 0W-8

 

[gsxr]

I will start looking for a 722.3 at my local PnP as a core.

It must be from an M119, and unless the donor is another 400E, you'll need to use your existing FGS valvebody.

If the car's really worth so much maybe I'll just flip it and get the '97 e class with the same engine.
If someone has a nice m119 w210 I would consider trading+cash

The W210 E420 was only sold in USA for one year, 1997... you might consider the W210 E430 with M113 engine if you really prefer the W210 chassis. Get the facelift version (2000-2002).

 

[benzadryl]

Is this what you had in mind? I have a bunch in storage.
I already have a clk430 and s500 w220 so I've had my taste of the m113.
I guess the range of transmission options is wider as long as I swap over the FGS valve body.

 

[gerryvz]

If you want a Dex/Merc ATF that is dino and fully Dex III compatible, there are plenty of them out there.

I have used Castrol's "Transmax" Dex/Merc for many many years with zero issues. You can get it at any McFLAPS store, Amazon, etc. Change at 25,000 miles for best results.

https://www.autozone.com/motor-oil-and-transmission-fluid/transmission-fluid/p/castrol-transmax-dex-merc-automatic-transmission-fluid-1-gallon/945221_0_0

These are also fine and meet the Dex III spec. I do NOT recommend using fully synthetic ATF in your transmission unless it is the first fluid using when rebuilding the transmission (new seals).

https://www.oreillyauto.com/detail/c/valvoline/valvoline-conventional-a-t-fluid-dexron-iii-h-mercon-1-gallon/val0/d1

Advance Auto Parts - Down for Maintenance

Amazon.com

If you were to go FULL synthetic, I would use RedLine's D4 fluid, which is also fully Dex III compatible. Note RedLine's compatibility list below.

D4 ATF

Our most versatile ATF, use where Dexron III®, Dexron II®, Mercon® and Mercon V® fluids are recommended, provides a GL-4 level of gear protection

www.redlineoil.com

I would also trust this fluid:

Buy VP Dexron 3 transmission fluid | autos & trucks | VP Racing Fuels

Premium Street Legal Multi-Purpose Dexron 3 Transmission Fluid provides long-term protection & performance of automatic transmissions in cars & trucks.

vpracingfuels.com

 

[Joncf]

GSXR,
I really appreciate your help.
With the car up on the lift today, I discovered a vacuum leak that affected the modulator on the transmission.
I looked at the other guides for vacuum leaks and we will see what else may be wrong.
Hopefully this will address the loping idle and the transmission weirdness.
As for a rebuilt unit, remember I have an e420 not a e500 so the 2.25k for a rebuilt unit isn't in the cards
Thanks again,
-Laz

Unless your car is a complete mess or very high mileage, it should, of course be worth far more than that.

 

[benzadryl]

Today I sucked all of the atf out of the pan, pulled it off and replaced the filter and gasket.
Then I rotated the engine by hand until I could reach the TC drain plug , which I drained. It sure holds a lot of fluid!
Then I filled it up with maybe 5 or 6 quarts (all it would take while running in gear) and cleaned up.
The fluid type used had a label saying Dex III and was from a 55 gallon drum. It did not say synthetic, so I assumed it was natural.
This car certainly is/(was?) a complete mess. Like I said I paid 750 for it, I bought my w124 e320 wagon for a grand and the same for my e300. I'm not a firm believer in these cars having a high value even in a decrepit state, at least for the lower trims. Non running mercedes= <1000$
That being said, the car is probably worth something now to another enthusiast.