OM603 diesel questions (300GD too lazy)
My 300 GD is lazy!
So I started looking into what could be wrong, and a couple of questions surfaced. I hope that I can get some answers here!
My car has 45000miles, so it should be in optimum condition. But maybe driving very little or standing still for long periods didn't help it? It's completely factory original with 255/75/15 tyres (also original size)
Question one: How fast should it be?
I looked into the original MB workshop manual, and the G with auto and my axles should go 141km/h @ 4650 rpm. It should reach 100km/h in 22 seconds. Mine struggles to reach a genuine gps speed of 130km/h on flat terrain and 0 to 100 also takes a few seconds more.
But I was wondering if they mean actual speed or speedometer readings in the manual as they didn't have gps in 1990?
So do you have an lwb auto 300gd, please tell me your top speed, please
(russ, pok?)
Question two: If it is too slow what could be the cause? I already changed fuel filter & air filter. So I presume it's in the dieselpump? How to test?
Can i give it some more diesel by turning a certain bolt? just to check?
Can any bosh center check/adjust the pump?
If anybody has any ideas why my car is slower than it should, please comment!
(I drove Pok's car, so I'm not imagining)
thanks
G
i can go onto die Autobahn later today and let you know what the top speed & acceleration rate are this evening. You can download Dynolicious for your iphone and test your G out... it's pretty accurate i think.
Hi G 45.000 miles and 1993 build.....any history of injectors change / service? did you change the inline diesel filter as well as the main diesel filter. did you check that the throttle pedal linkeage is set up properly in order to open the injector pump rack to the stop? the 463 300GD is not known for sparkling perfomance so if the settings / fuel flow are not correct it will be slower still to respond to the right foot.. just an afterthought.... what revs do you get when you kickdown from 70MPH?
Hi G kickdown is small black button switch under the accelerator pedal keep the carpet out of the way...that switch is fused to other features. look in the handbook for fuse allocation details.....
The kickdown on mine will not activate above 60 odd MPH, I think that is correct. 60 mph in third gear is already doing 4500 rpm. When you get to 4800 the govener starts to cut in. 5000 is redline.
Your performance sounds ok to me. Winter slows it down too. Mine always likes a hour on the road to fully warm up the oils.
This is life with a 300 diesel. There is no magic screw to turn. The only way to improve performance is a turbo conversion...then you would be better to buy the factory 300GDT
Hi G the Kickdown operation can be obtained by applying firm pressure to the top of the accelerator pedal at speeds up to 60mph or slightly more with gear selector in normal drive mode. if pedal is stiff to bottom out onto the kickdown switch check the throttle linkeage for correct setting.....and the rpm during kickdown operation....70mph with no gradient should be achieved at around 3800 rpm
I honestly wouldn’t like to state what my 0 – 100kmph time is or what my top speed is and unless we do back to back testing with some fancy electronics any acceleration figures I quote will be pretty useless.
It cruises nicely at 120 – 130kmph, anything more and it’s starting to get a little frantic due to the rev’s. GPS figures by the way.
As long as you keep the rev’s over 3k and keep the momentum going it’s actually OK.
Try some of this maybe
http://dieselgiant.com/injectorcleaning.htm
It improved the running if not the actual power output on mine.
Basically they are slow but steady. BTW mine is not and auto. The torque convertor will sap some power, but off the line acceleration won’t be much different due to the sluggish manual box in MB’s.
Russ
Just come back from the Autobahn, 136km/h is a max on flat road (GPS/Sat Nav)... acceleration rate from 0-100 were 23.2 sec and 22.6 sec (iPhone Dynolicious). Pretty close to the factory figures.
oo! by the way... my G has 258315km on the odometer, engine replacement at 170xxx km from MB back in 1997.
Just come back from the Autobahn, 136km/h is a max on flat road (GPS/Sat Nav)... acceleration rate from 0-100 were 23.2 sec and 22.6 sec (iPhone Dynolicious). Pretty close to the factory figures.
Impressively close to factory figures :)
Given your engine replacement not that many km’s ago I would suggest that it should be running at pretty much optimum output
My G300D is SWB and manual. It had a factory replacement engine some 40.000 Kms ago and I removed the first silencer box of the exhaust but other than that it's totally standard and it really feels fast, though it takes some time to get there due to the higher than standard 235/85R16s tyres.
what kind of inline bosh dieselpump is in my car?
thx
G
Hi The Bosch "M" series pump is common to the OM 603 engine..a Bosch pump overhaul shop can change the setup to give you more fuel per stroke ( a reason the engine under performs) as any "tweaking" of the pump is outside the MB service directives you have no comeback if the engine fails for any reason...the injector metering can bere jigged as well....
thank you fixwin...
...I don't want to "mess" with my pump...
I just want everything to work as it is supposed to.
So this is what I plan to do (in this order, so correct me if it's stupid)
1) I'm going to change screw on & inline fuel filter and air filter.
2) I'm going to look for the fueltank filter (where is it?) and clean (or replace) it.
3) I'm going to drain & clean the fuel tank.
4) I'm going to purge the fuel pump to clean the injectors (with product like in russ's link)
5) I'm going to send the car to a Bosch diesel center to have the pump checked/adjusted.
6) I'm driving to sahara with no engine worries in my head.
Somebody recommended me this scenario:
"Take a new clean 5 liter jerrycan with clean diesel, put it under the hood connect it directly to the dieselpump (bypass all filters) and test how it goes...." Doesn't sound like a stupid idea to me, but what do I know...
G
My G300D is SWB and manual. It had a factory replacement engine some 40.000 Kms ago and I removed the first silencer box of the exhaust but other than that it's totally standard and it really feels fast, though it takes some time to get there due to the higher than standard 235/85R16s tyres.
I bought my 300GD because I heard these were old school 'bulletproof' half a million miles engines...Yet there are a lot of people with 603's who had replacement engines in their car...(morty, pok etc...) How come??...
My high tech BMW performance diesel 320d did 300.000km without a hickup.
My Saab 900 2 liter petrol did 360.000km on LPG when I sold it.
Hi regular oil changes (not synthetic) and coolant inhibitor help.cylinder head gaskets are a weak feature and will let water into a cylinder which can cause conrods to bend slightly..lowering compreesion as a result...engine will run rough or off a cylinder at cold in this condition.. cranshaft rear oil seal can fail if oil changes are not regular ( every 6000 miles is ideal) from new not high mileage.....
OO! speaking of oil change, how to change the engine oil in a 603? I have only done it once on a LR disco...
I sent a mail to Mynadiesel....they are famous for tuning MB dieselpumps.
maybe very interesting for a lot of us...
this is what they answered:
Hi
No problem in adjusting the injection pump.
The cost for adjustment is 250€ and it increses the horsepower by 15-20%.
Rebuilding the pump with 7mm elements costs 950€. With this about 10% more hp over the basic adjustment can be achieved in naturally aspirated engine.
Antti Arola
Mynä-Diesel Oy
Does it mean if one goes for the €950 option could get 113x1.15x1.1 = 142PS?? Not bad at all!!!
Does it mean if one goes for the €950 option could get 113x1.15x1.1 = 142PS?? Not bad at all!!!
And that's worse case scenario!!!!
Right, I might give up the 35mm Summarit idea and go for this diesel ppump thing!
If it was as easy as turning a screw, why would MB not do it in the factory?
emissions, durability, economy....it's the same as with chiptuning today...
my bmw 320d has 163hp you can remap it to 220hp...and you don't even have to turn a screw...
All sounds too good to be true. Just adjusting the diesel pump to gain extra power can only mean one thing. More fuel. Not much of a step from that to over fueling.
Just Google diesel EGT to find out the consequences of that
On the one hand it would be nice to get more power out of the 603 but IMHO that won’t come easy or cheap. I have heard of people applying good old fashioned techniques such as gas flowing, larger valves, different cam profiles etc. but that equals major surgery.
I can honestly say that the only situation where I’ve found the lack of power irritating is cut and thrust city driving. Something I fortunately don’t have to do in the G.
As I’ve said before there’s no such thing as a fast G
Want fast, get a bike or a what ever car :) (I appreciate that isn’t what you’re trying to achieve)
MB made a OM606 non turbo. It was the same block as the 603 and had 24V and EFI. They rated it at 136hp. 23hp increase. It is possible but you need more fuel and air
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@ pok, thank you
@ fixwin,
no kickdown (doesn't work) @ 70mph (112km/h) above 60mph I have to use the lever to change down to 3rd (I do this to overtake trucks)
also when I want to use kickdown I almost have to push the pedal into the the carpet. Where can you adjust this?
G