Diesel engine surging on E300D

[biggles_8]

Hi all
I have a problem with my E300D. The engine surges between 2,000 & 3,000 rpm whilst driving in traffic it feels like a solenoid switching on and off it is not there in acceleration nor deceleration just cruising disconnecting the vacuum pipe to the unit connected to the s/steel flexi pipe and it stops the surging.

 

[bolide]

I'd disconnect the vacuum pipe to the EGR exactly as you said and leave it. Surging like this is an E300 Diesel speciality and as the EGR is, at best, a mixed benefit I'd leave it disconnected

Nick Froome
www.w124.co.uk

 

[Parrot of Doom]

Are you sure its not the gearbox changing gear?

Check the ATF level (you'll need the dipstick for it).

Mine used to do it when cold, a combination of ATF change, cleaning the MAF, and cleaning the EGR got rid of it.

 

[bolide]

I've seen this on a couple of Multivalves. I've seen it at 2200 rpm and at 3200 rpm. It's an off-throttle cycling of revs and you can see the EGR pull in and out at the same time

It's obviously a vacuum system fault but as disconnecting the EGR seems to have no downside - and it prevents the inlet manifold from being filled with oily black carbon gunge - I think I might recommend it

Nick Froome
www.w124.co.uk

 

[biggles_8]

well Nick the garage that i use said take the vac pipe off he's an x merc mechanic so i think i will do just that. thank you for your input Parrot but you lost me with the abreviations but it only surges when hot and it is not the gearbox how ever i do think the the fault is in the vac system for sure but as there is lots of bits to check pulling the pipe is the easy way thank you all. Biggles

 

[slamspider]

diesel engine surging and smoking

hello, i have a similar problem on my E300 diesel(1995) which i have recently bought. its the first merc car i've had so am feeling my way round it until a manual arrives through the post. could someone tell me what EGR stands for and exactly which pipe i need to disconnect to stop the surging.i had thought initially it was an auto g/box problem but have little experience of them (i worked/drove merc trucks for a while). i notice this most cruising at ~55mph and she's very smokey at this speed in particular as well as in general. i've had the injectors out and overhauled so will see if that helps. she's done 190k but i have no service history. can anyone give the torque for the injectors too please. would be very grateful for any help or suggestions. sam

 

[recycled]

exhaust gas recirculation

 

[Parrot of Doom]

Best thing is to clean the EGR system, on yours I believe its 2 vacuum actuated flaps on the right side of the engine, underneath the 2 pipes that cross the top of the engine. It'll be full of black oily gunk. A good alcohol based cleaner and an old toothbrush/bottle brush will get shut of it.

http://www.detali.ru/cat/oem_mb2.as...GM=717.446&CT=M&cat=19T&SID=14&SGR=030&SGN=02

See that page, I think its the 2 'resonance valves' that are the problem.

If its smoking lots have you tried changing the air filter?

 

[slamspider]

have fitted the serviced injectors but the smoke hasn't really lessened unfortunately. will try a new air filter. seems to be fairly smoke free when gunning it but on throttling back/ cruising it plumes out white/greyish smoke.also a light haze of smoke at idle. read somewhere that an overdue oil change or poor quality oil may cause this? so will do oil and filter. i think 5w/40 synthetic diesel specific oil is recommended?
the breather under the engine cover showed no signs of blowing oil under load- is this the only breather? and there seemed to be no pressure build up on the dip stick pipe either.
will also check header tank for bubbles on revving and air bubbles in clear fuel lines around the pump/filter.
any other suggestions?
also seems to be a rattle/clatter from the front pulleys somewhere especially noticable at idle. would the tensioner be the most likely culprit?
thanks.

 

[Parrot of Doom]

Use fully synthetic, I put Mobil 1 0W-40 in mine. Very cheap at Costco if you have an account there.

If the breather is leaking you tend to find oily fluids in the injector well at the back of the engine.

The only smoke I ever see on mine is on a cold morning, only 5 out of 6 GPs work (can't repair one of them, long story), so I get blue/gray smoke out of it for 10 seconds or so until that cylinder starts firing. The other smoke is black soot when you floor it, but only when you floor it, never at any other time.

 

[slamspider]

thanks for that. whats the best workshop manual for these merc diesels? have just flicked through a brooklands w124 manual and there's nothing on diesels! haynes doesn't do E300 1995 i believe. any suggestions?

 

[Parrot of Doom]

The best manual is forums like this