W140 300SEL - Corps

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A 300SEL-3.2 (W140.033) M104.990 LH-SFI ownership and repair documentation thread.

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Reserved

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Reserved as well

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Again, reserved

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@Xulfiqar

Before I even preface this thread, I'm in some hot waters that I will document here. My W140 is a 300SEL-3.2, a rare stage2 mid-update LH-SFI M104.990 engine with a distributor and single coil. I have been through the ringer trying to diagnose hesitation and stuttering (heavy) under load. Without load, the car accelerates just fine with only slight sputter here and there. As soon as you gun the throttle, the entire car shakes and hesitates. Also, above 3500rpm there is no problems with WOTing, just slight flutters. Any ideas where to start? Do I have a failing EZL? I can hear some hissing (loud) that changes with the hesitation, vacuum leak a possibility?

I will add some YT videos later if it helps

[Xulfiqar]

check the cats (it should have precats too) - and also EGR. - it maybe the EGR is opening up and because the cat is partially blocked, the engine is getting blown down with exhaust.

[hash4u]

Xulfi bhai
whats the worst a choked cat can do ?
put the car on fire due to over heating ?
damage the engine ?

[Xulfiqar]

you wont be able to drive it at all.

[corps]

The Cats and pre-cats made no diff, already had them checked. It definitely has to do with fuel or ignition. These are the days when I realise the worth of my HFM M104.

[Xulfiqar]

checked how?

did you pressure test the exhaust system? - does it run better with the exhaust manifolds loose?

the other faults can be a bad ignition control unit on this engine which may give you a heart attack if you priced it out now. They were extinct years ago, the only remaining stock of them is priced as gold now.

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@xulfiqar
ctually found an EZL for 12K PKR, pretty cheap huh? That's when someone doesn't know what they are selling in a nose-cut. I disconnected the exhaust near the manifold and it made little to no difference and there wasn't much restriction as, surprise, someone already took cats out.

Next up is the EVAP coil. Just got the entire interior out. I don't think MB ever planned on replacing the EVAP unit for the W140. I would NOT do this to myself again.

Also, my steering actuator was kicking in and ABS was shot along with MPG guage and Speedo. Went into the coffin box to get that Fuse B replaced. Fixed it up in an instant. Here is a reference for anyone wanting to see (Yes, I have removed a module as I did put some dielectric and cleaned up years of dust).

[Xulfiqar]

I believe there is a cooling fan in that box too, - it usually it shot after 5 years.

anyway - I know about replacing the evap on a W140, I have done dozens of them, the W124, W201, W210 etc are the same too. worst are the W124 - the evap is the first thing that goes in.

[corps]

What was your labor rate like. I believe 24hrs is std? That equates to 2500USD.
Pics not for the faint of heart on PW, be ready for this if you own a W140

Btw @Xulfiqar, the car fixed itself after I played around with the EZL unit and CKP wiring. Now I'm surprised as it is missing the E-GAS module in the apparatus box. Can you run it without the throttle ECU without having hesitation?

Also this particular car is a 300SEL-3.2, WDB140033. There are several E-GAS unit part numbers, I'm out of clues which one to get.....

[corps]

Here's an excellent resource for anyone looking for part numbers for their MB: https://nemigaparts.com/cat_spares/epc/mercedes/1/fg/140033/19b/

Just go back and select your car.

@Xulfiqar Here's an EPC shot for E-Gas module:

[Xulfiqar]

Its not as intimidating as it looks, its like 10 kg of potatoes in a 5 kg bag, it will only go in layer by layer.

My labor rate for this was usually a fixed sum, USD 1600/- (car remains with me for 2 days). Not many people want to do this job and the newbies that do - usually do some more damage. The amount of insulation on this car is baffling and the big huge one piece dashboard is a bit challenging for the beginner.

TBH - the person who decided to allow a copper/aluminum evaporator to be passed in the design phase of this car should be kicked in the butt. - The replacement ones which are full aluminium never fail - but the only few cars that remain on the roads today are mostly garage queens - BUT, there is no mercedes that drives better than a factory spec W140.

[Xulfiqar]

you need to lookup the export model or whatever model you have, it seems like you are looking at the US market parts.

[corps]

@Xulfiqar 300SEL-3.2 .990 was never offered in US. In EPC it shows seperately as chosen above.

Yep, got an all aluminium one as a replacement part. Found some clean Cu/Au ones as well but that's just asking for trouble somewhere down the road.

Mil $ ? = Have you ever ran a dizzy M104 without E-Gas module? I'm assuming not but worth asking again.

[Xulfiqar]

dizzy m104 sans Egas module - you jest?

[hash4u]

Damn !
hard to keep item
if you dont mind
need to save this pic for people who bug me
"why cant we buy an old German car instead of a civic or corolla"

[corps]

They can. And a 'good' W140 is much more reliable. Unfortunately this car was not loved. My recent bill is in excess of 0.1million for maybe 12 days. And it doesn't stop here. It needs a specific mindset to own a badly maintained MB, some sharp diagnostic intuition and you need to treat it like a machinery/equipment not a commodity.