G with issues...
Hi Guys,
Finally got myself a 92 300 GD after admiring them for a long time, a bit of an impulsive purchase!?! It currently has the following issues I know of that need to be addressed;
- There is black engine oil in the headertank and it can't go more than about 5 miles or 15-20 minutes before the temp rises, no water in oil, when it does go up to about 110-115 the rad is hot on the right side but goes warm to cool on the left of it. Same thing happens with or without thermostat, block test shows no gases in headertank but then that does not rule out HG as it's oil in there hence a bit baffled?! Starting from cold shows deposits of black engine oil in water droplets and grey smoke, droplets clears up after a few seconds and the grey smoke calms down after a mile or so smoke smells like diesel...
- The heater does not come on at all which does not help the engine cooling side of things or bleeding air when I've flushed the system out a few times for the oil to get out but its stubborn! I can feel the hot air from the vents but when I turn the switch nothing happens, fuse under the glove is ok so I'm also really hoping its not the blower...
- Central locking does not want to lock, I turn the key all does lock and then instantly unlock themselves?
Any advice, suggestion would much welcomed many thanks
With oil in the header tank could mean and most probable a head gasket leak but do not rule out engine oil cooler leak which is housed in the radiator. This can be and needs to to be tested out.
The temperature difference of the radiator you have described indicates radiator blockage, this could be due to oil in the system restricting coolant flow or that the radiator is indeed blocked. Test this out after flushing the radiator, pour hot water into the radiator to check if even temperature is sensed if not it is a definite blocked core. Have the radiator flow tested and pressure tested of the engine and if fitted, gearbox oil coolers. You can have the radiator re-cored. If a leak in the engine oil cooler is confirmed, your head gasket may be sound but if not it is more likely the head gasket is in need of replacement.
Have a new thermostat fitted when the head gasket is renewed as a matter of course. Have the heater matrix thoroughly flushed out as well.
NOTE: it is illegal to drain any coolant with anti freeze into the drains (£2,000 fine) - collect the drainage into a vessel and have it properly disposed off, say a friendly garage taking it off your hands, they may charge for it. I do not know if council recycling sites cater for coolant disposal as they do for engine oil. And keep pets and animals from drinking this waste, it could kill them.
On some models the central locking unlocks after locking indicating one of the doors is not properly shut. Do check all doors, if the problem persists then Central locking will need checking out, most likely a fault on the driver's door solenoid as it is a master controller for all other doors or it may be you have a separate controller fitted to your vehicle.
Hi
Just a couple of Q's is it Man or Auto, AirCon and just the standard 6 cylinder OM603, not been altered?
Sounds like the Engine Oil Cooler in the Radiator has gone porous and is allowing Oil into the Water but not vice versa.
Radiator off, flush and test etc can be rebuilt
A new Radiator is £722 + vat rebuild around a third of that depending on Oil Cooler issue
You can test the Heater Fan Switch for output quite easily, switches do pack up as do the motors and resistor packs
Switch is £37.10
Fan is (Single - Early) £174
Fan is (Twin - Late) £454
Resistor £62.50 aprox (Lots types)
Sounds like the CL is feeling resistance, misaligned lock, door or actuator?
Gav
The radiator can be tested out in situ. Depends on if you have equipment to do the tests or adapt the tests for your self, otherwise it is best removed and have radiator specialist to do the testing for you. I can expand on self tests latter.
You can have a compression test done to the engine and it is worth to have a leakage test done; this will or should identify any leakage from head gasket into the coolant system.
When you lock the car do all doors actuate, if so do they all lock and then unlock? If they do then i would be looking at the drivers actuator first to see if its all hooked up right. Do none of them stay locked?
Bit of a front dash strip but if you get to the back of the heater switch then you can do a simple volt test with a multi meter through the positions to see if the switch is receiving a feed and then passing it thru to the resistor and fan in turn, unusual for the resistor to pack up completely, you usually just lose some speeds, are all not working? If all not working and the switch is providing power then suspect fan i guess. if you post or PM your chassis number i can tell which fan its got and maybe narrow down the resistor position, some are behind the dash, some under the bonnet...
I would say for best results to remove the radiator and let the professionals test it and report, not a hard job to remove at all
Radiator will have engine and gearbox coolers built in....does not sound like gearbox oil in the header if its black but will add to the cost and complications... just go very very careful when you undo all the cooler pipe off the radiator, spray them with penetrating oil many times before you try and go gently with the correct size tool!!! they strip threads for fun and they can become scrap easily...alloy thread / steel nuts ... not the best design...
Further to Gav's excellent advice. If you do decide to remove Radiator yourself, you will need some big spanners to remove Oil cooler unions, I think you can brace the union using another spanner, but most spanners this big only in hands of garages, go easy on the unions.
May be a silly point, but if the rad is heating up and you have 'cold' spots, it could caked in mud in the rad. I had all the rads removed and cleaned (Main, oil and aircon) and now everything works fine. Although I do tend to clear it down after a bit of 'Mud play' its surprising how much does collect and cake on over time.
HTH
Spider1V
Jason is right - 50% of the time you will damage the threads undoing the oil pipe nut
So - disconnect oil cooler from main rad and leave connected to pipes !
Hi
A 1992 300GD with OM603 will be a 463 series?
463 has the Engine Oil and Gearbox Oil Coolers built into the Radiator not separate like the 460 series 300GD with OM617
Even worse to remove!!!
Hi, yes I believe Gav is right it is the later model as there is no separate cooler visible, I also notice black oil gathered between the breather pipe and plastic bit on top right of RAD, after every drive? Further electrical issues discovered are that the wipers don't squirt water front and back even though power is being received from the cable to motor with no noise heared when pressed, the air recirculation button on centre dash does nothing as the flap in the air intake does not move and is in the down position, all the buttons do not light up even though obvious functions such as rear wipers work when pressed? I believe the resistor for motor is behind the dash and hence does that mean the later blower motor type with twin blade? I'm a bit reluctant to touch dash having already chipped the wood strip across the dash hence are there any other Mercs where wood trimmings can be swapped with as I can't seem to find anyone selling any trimmings in case you need it after taking dash out to replace motor or inspecting etc? Thanks
Hi, yes I believe Gav is right it is the later model as there is no separate cooler visible, I also notice black oil gathered between the breather pipe and plastic bit on top right of RAD, after every drive? Further electrical issues discovered are that the wipers don't squirt water front and back even though power is being received from the cable to motor with no noise heared when pressed, the air recirculation button on centre dash does nothing as the flap in the air intake does not move and is in the down position, all the buttons do not light up even though obvious functions such as rear wipers work when pressed? I believe the resistor for motor is behind the dash and hence does that mean the later blower motor type with twin blade? I'm a bit reluctant to touch dash having already chipped the wood strip across the dash hence are there any other Mercs where wood trimmings can be swapped with as I can't seem to find anyone selling any trimmings in case you need it after taking dash out to replace motor or inspecting etc? Thanks
Hi
Is there water in the washer bottle? 
Separate switch function to operate washers and wipers....do you have a handbook?
The washer motors like seizing up if not used, especially the rear one... depending on the type of motor they can be stripped, if its a sealed type a quick tap often frees them up, they just get silted up with lack of use, the early type can sometimes be stripped and cleaned etc.... a new one is usually the long term solution though circa £50 for front a little les for rear and head lamp from memory...
The buttons not lighting up could be bulbs, but unusual for all to be out, they should illuminate with the head lamps switched on, however there is a dimmer (potentiometer) switch on the cluster to adjust brightness of the cluster bulbs and all the dash bulbs etc. and this could be turned right down? from memory there are two knobs coming through the cluster glass, one resets the trip by pushing, the other is the dimmer by twisting...
Under Dash Resistor is probably the early type but i can tell if you PM me your chassis number
i.e. LWB would be WDB 463 328 27 07XXXX
SWB would be WDB 463 327 27 07XXXX
07XXXX being the serial number....
The wood is G specific so hard to find, German eBay is the best place as not many 463's get broken in the UK...Although sellers in other Euro countries like Belgium are good too...
Gav
Te heater fan can be checked for operation at the ballast resister which is mounted on the cabin air duct on the bulkhead directly behind te engine. I'll dig up the wiring diagram. It's easy to check rather than going in behind the centre console. Do the dash lights work?. The centre console switch lights are in parallel with them
Hi Roly, a diagram would be very helpful as I could not see anything obvious in the engine bay next to air intake hence assumed only way to access resistor was behind centre dash, the centre dash controls do not light up, only the middle diff lock button lights when pressed. Gav, I will try to on the chassis number to you mate, can I confirm that the rad can be pressure tested in situ to confirm blockage and is there any point in trying unblock or as after multiple flush, twice with detergent, it's no made difference when touched or in minimising overheating.
The ballast resistor is inside the cabin air intake box. On the outside you should see an electrical connector which can be unplugged. The resister stays insitu for testing.
You can test the output from the fan and you can connect 12v directly to the fan through the resistors to check each speed.
The centre console switch lights are not repairable, well you can but you need to be v careful. And you only need them at night so buy a touch :)
Circuit diag attached
The yellow and red diff lock lights (forget the night illumination) is important and the only way to fix them is to remove the centre console
Many thanks Roly, really appreciated! Is the air intake box the bit in the middle where the re-circulation flap opens and closes? If so the flap is stuck open with nothing happening when button is pressed and looking inside it shows nothing and trying to feel behind the flap does not leave me to believe there is anything directly behind it however I can feel a small round fan at the bottom. Outside of that box on the left hand side there is a Bosch device that has wires going in and out of it which is then only thing attached I can see lose enough to it. With regards to the oil in coolant can I confirm that the only way to completely rule in or out head gasket is to change the radiator to know for sure? Many thanks again!
Is there an easy way to rule out the water pump as its not leaking? The engine bay is a little noisy when it first starts up but I think that calms down when at running temp or my ears probably get use it, is the om603 an engine with any unique characteristics such engine noise etc as I'm not use to diesel cars.
this g sounds like a nightmare, how did you come to find it? and who did you buy it from ? did you have it inspected?
regarding the oil cooler , i would link the hoses to bypass the oil cooler it will not harm the motor short term and then flush the cooling system , a hydraulics company should have a (or be able to get ) a joiner to link the pipes , sadly the emulsified oil will be coating all the internals of the cooling system / heater rad /cylinder head and block passages.
Hi Axel, apart from the issues mentioned it is a lovely smooth drive and I may well be scrutinising everything a little excessively but it's my first G and a first diesel hence wanted to clarify what I should expect in terms of characteristics as well as ruling out the water pump regarding the symptom mentioned but it's not the usual rust bucket I've usually seen in my time and really is lovely both in and out, just not been used as much as it should have been hence the desire to deal with the obvious niggles and hopefully give it the run it deserves etc. :)
glad to hear you are prepared to 'go the distance' to solve the problems / these diesels do 'cackle' when cold so not to worry about the noise / the serious problem ref . your heater motor being u/s and your oil in the water however will hurt to sort out , hence my questions of how you were offered the vehicle and by who as there have been 'concerns' and 'issues' with traders contacting individuals via pm or e mail to offer g wagens to those who are looking .
there is a lengthy warning on the site relating to such matters , it would be good news for all of us if you bought the vehicle without this kind of thing happening , hence my questions as this kind of thing just doesn't happen overnight the seller would of been aware , be aware this problem will cost thousands to fix unless you can do the labour yourself .
Thanks, I appreciate the heads up mate, I actually got it off a lovely chap in a private sale due to lack of use and he was up front with the issues hence was able to get it at a good price hoping to rectify it as a side project when I have time/funds otherwise passing it on to another enthusiast who could as it definitely deserves to be appreciated for the classic it is. I'm in London so grateful if anyone can suggest a trusty mechanic in the area that's experienced in G's as I'd rather not try things myself if I can help it :)
Funnily enough, I ha exactly the same problem with my last land rover Td5 that I built.
I knew that the engine had "issues", but my heater never got more than mildly luke warm, and if it booted it, the coolant would overflow and a horrible messy grey sludge would come out (oil).
Turned out I had a crack in the head, and a small hole in the oil cooler (which on a Td5 is bolted into the side of the block, sat in the water jacket)
Once you sort the problems out, a great way to remove the oil from the water system is to use washing powder (from your washing machine)
only need a small bit added to the coolant., run it for 10 or so miles, drain, do it a couple of times and it'll clean it right out.
Interesting thread. Make me feel a lot better. Thanks for posting.
Rather than take the rad out - get one of these:
http://www.amazon.co.uk/gp/product/B00AYUHSM4/ref=pd_lpo_sbs_dp_ss_2/278...
You will also be amazed at how much fun they are.
I used a similar one for my rad; temperature varies across it. G runs at 90deg most of the time, but gets very hot and bothered on long hills in the summer.
As for your electrics; I really really wish someone in GWOA could recommended somewhere to get the dreaded early 1990s 463's wiring sorted out. I seem to remember Tony saying something to the effect that he would rather bite of his left leg. I have to laugh every time I use the rear wash wipe and the windscreen cleans itself, curiously front squirt - squirts the front. Funnier than no tach, clock and ABS - I could go on.
Alan,
The common component with the tach and abs is the overvoltage relay in the electrics compartment. Have you checked that. I think that it is the only relay with a fuse built into the top. Common failure across many MBs
Check attachment for a description.of resister removal.
Yes, air intake is as you describe
Thanks Roly, I'm pretty sure it's not located there on mine, will have another look later but I'm sure it's not there mate. Any idea what the fan is that I can feel behind the air flap in the bottom, surely that not the blower motor?
That's the heater fan alright. I've never been that deep into the G but have read that it is a major dismantling exercise.
If the ballast resister is not there then you will need to remove the fan from the dash. If you are willing, you can remove the odments tray to the rhs of the radio and reach behind and manouvre the fan out. Remove the fan knob and the big nut behind to release the fan switch.
If its the fan I can feel then surely it can just be removed from the the air intake as its directly under the intake flap? I thought it was a dash out day job??
If you are unlucky you have the early type resistor for fan motor built into fan unit, meaning complete dash removal and then spltiting the heater unit in situ to remove resistor pack.
Allow a weekend .....
Worst part is disconnecting, reconnecting heater cables.
Washer motor can just be a really bad connection.
I'm having trouble taking out the radiator, the lower right nut is stuck to the radiator solid, no amount of leverage has made it budge instead its whole mounting that's attached to the radiator so the whole pipe moves now to the point it's damaged the radiator at the joint between the radiator and the mounting the nut is attached to with oil leaking out, it's always one! I've now conceded to the fact that a new rad is obviously required hence even trying to pry the pipe out from the break still does not alow the pipe and fitting to pop out from the rad?! The only option I can see now is to get a hacksaw and cut into the radiator to detach from pipe and then hope the nut will be easier to come off once a better grip is had on the metal fitting detached from the radiator.
Hi guys,
Managed to get the radiator out but the thread on one of the oil cooler pipes are stripped well the first few any way so any idea if how I can get that sorted or even get a new pipe? Is the lower engine oil cooler pipe but I assume they only sell them in pairs?...
-
Generally, repair parts are not available from either Mercedes Benz or any Radiator supplier. If you have a 'gem' of a radiator repair specialist, perhaps they can source you a replacement part.
You are looking at another radiator or you could try to cut down to the stripped threads part of the cooler and hope the attaching oil pipe nut bottoms out for a secure seal. Make sure you block the oil tube to prevent metal fillings to enter into the cooler. As you say it is the bottom cooler; this is the gearbox oil cooler.
Alternatively, fit an externally mounted oil cooler but you will need to do some research as to how much heat need to be exchanged to choose the correct size of cooler.
Oil Cooler ?
90% of the time you strip the ally threads so either plenty of ptfe tape and hylomar or
google aftermarket - I always use pattern T1 oil coolers at around £65 new [same oil cooler but detail bracket change needed]
OR find BEHR 23.227.20.001 [oe] mb 123 180 02 65 around £170 {actual G ]
This is a common oil cooler across the diesel range
[+vat]
Easy to fix properly - just needs a new fitting brazing on.
Guildford radiators (+44 1483 277713 - actually in Cranleigh, just near Guildford) completely stripped and rebuilt/ recored all of my rads (replaced main rad core with thicker higher performance version while they were there) , replaced a fitting I had snapped off (and added a couple of new fittings for temp sensors at inflow and outflow points).
Very quick, reasonably cheap (couple of hundred-ish) and high-quality work.
this is a 463 g wagen it has a plastic tanked radiator ,the alloy bosses are moulded into the end tanks and then have steel connections fixed to them this causes galvanic corrosion and then it is bye bye coupling when you undo the hose .
this is shaping up for a new radiator, 460 g wagen rads can be recored and are rebuildable ,plastic rads are a throw away item .
I should jump in with a comment about " 'plastic' and 'throw-away'.. hear that a lot in the context of 463s".. but I wouldn't want to be controversial 
I've got a 463 with seperate oil cooler behind the headlight. Mine was a 350TD. Is this normal? Does it cool well as it is enclosed behind the light. I think it should have a fan but have not checked. Is Tony reffering to a 350TD cooler? I've now got a rad from an 'ML' with combined oil cooler. Not sure if I should pipe it up and keep them seperate? Any views.
Radiator finally in now I just need to find some polish bloke in Essex who can apparently sort out the blower motor in only a few hours working from air intake....otherwise can anyone recommend a capable garage in the London area that have experience in doing this job and if so the average cost of part and labour? She really is a joy to drive although the Mrs. Wants the comfort and speed of the newer Range Rovers?!...she does not like the 'tractor' experience of the G although I try to tell her its more like driving a tank which did not go down well either...
Hi guys, is there step by step guide/process for me to follow when removing centre co sole to get to the blower motor resistor and motor? I think the thin stop going across needs to be removed in order for me to aid removal if centre piece with switches and heater knobs etc? The ride is quite firm I've realised and I hear noise from the boot area when going over bumps like I'm carried g something but I'm not, it does not sound mechanical though, any way I can soften the ride so it does not feel too sturdy over bumps? Cheers
Hi guys, is there step by step guide/process for me to follow when removing centre co sole to get to the blower motor resistor and motor?
I think you may find that there are lots of guides in the members area.
Not sure if they cover what you want, but no doubt someone who knows will be along shortly.
Hi guys, now that I've got the beast up and running, any advice on tweaks/service tips etc? I think I may need to service the injectors as I notice a slight engine shake from cold start but she travels smooth and no rough idle etc. may try some injector cleaner first, can anyone tell me if they notice the G N S gear knob vibrate when they touch it whilst the car is running? Other than that I don't notice any vibrations within the cabin. Furthermore can anyone recommend details for what I need to do a full service? I'm also looking to fix the little bits n bobs now too like the central locking which only works if I manually lock both front doors and then the boot door central locks the rear doors only any other combination results in the doors to instantly unlock itself. I also want the grease the window runners as one if them is a bit slow on the front passenger side, is it easy to remove the door car and gain access? I also want to get to the bottom of the windscreen washing motors and the air intake flap which do nothing when pressed, last but not least I will look to leave the blower motor to the professionals. I notice the ride is quite firm and sturdy hence would like to know if anything can be done to make it softer/bouncier, it's currently on the original 16" all terrain tyres hence can anyone recommend and good road tyre and size? I'm also thinking of changing the colour of it, does anyone know the average cost of re-spraying a G and any good people in the London area to do the job as well as any experience of wax oiling the underbody to prevent rust etc? Cheers :)
Glad the G is now up and running! 
From Memory (which is fast fading lol) I am sure there are some explanations in the members section, now things are going 'tickety-boo' you may have time to send Tony your membership then you can get access?
Spider1V
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Many thanks for the response, it is an Auto with no A/C and I believe the standard OM603. Can I test the switch and resistor myself, if so how would I be able to do so? All the doors have been checked to ensure the are closed but it still occurs, intially it did not work at all due to a blown fuse but one I replaced the fuse the CL worked fine but then started playing up a few days later with the fuse being fine also which is strange. Furthermore will the radiator need to be removed in order for it to be tested for blockages or can it be done whilst fitted? Lastly is there any other symptoms I need to be aware of if the head has gone apart from the already oil in the header tank? Many thanks again in advanced