Overheating again...300GD
Hi guys,
I know, overheating has been discussed before and very extensively indeed, however I (and service guys too) can not figure out the solution of my specific case. Here it is:
Type: 300GD 5speed manual 1990 LWB. 250 000km mileage.
I asked for an overhaul at the service concerning mainly chassis/ diffs, also same bodywork and to be on a safe side I asked for a radiator +cooling tubes cleaning too, as during summer days temp went up to 90-95. ( By the way, can anyone tell me OFFICIALLY what is the line in betwen 80 and 120? 90 or 100 Celsius?).
When I picked up my G it was running home fine - on the highway. But on the next day I used it in the city and noticed that water temp went too high, even boiling once with an outside temp +5 degrees... I have found some water underneath, and the yellow lamp went on on the dash (low water level sign).
Knowing, that it can be possible cylinderhead/gasket issue I have checked the oil- no white/yellow foam in it, also the water reservoire- no oil in it, however there was somee kind of foam- I suppose because of previous boiling. When the engins runs on idle, there are no bubbles in the water and also no white smoke fromthe exhaust .
Returned the G to the service, they have checked the thermostat/tried two of them also tried the same whitout them- result was always the same: after acouple of minutes temp goes high and stays very close to boiling. I was told,that visco is fine, works as it should.
What would you say, where should we continue the check? Radiator ? Water pump? sthing else?
Many thanks in advance (sorry for my English..)
szenaG
don't apologise for your English, its a rubbish language at best. Have you felt the radiator for cold spots ...uneven temperatures, either of which would suggest your radiator is blocked/furred up
Be a good idea to check centre of the rad when engine is warm, and engine is switched off!, and place hand on centre of rad, or if you can get hold of one, a laser temp gauge to check temps all over rad.
OK,will do and will keep you updated
Radiator can be re cored.
You say the top hose was stiff. This doesn’t sound good.
It could be that the cooling system is pressurising due to combustion gases getting in to the cooling system. A garage can check for this easily with an exhaust gas probe.
Diesels can be difficult to diagnose when it comes to head gasket failure or cracked heads. You won’t always see white exhaust or mixed oil/water.
I see...I hoped that the tube was stiff because the flow of the water inside radiator was blocked/reduced and the pump produced more pressure, than the reduced cross-section could handle. I' m not sure if my theory is correct though ...
1992 300GDS
I had heating problems when I pushed the engine the temperature went up very high above the red line!!!, and then if I took the throttle off it would drop back slowly.
Someone said that because the radiator tubes run horizontally they fill with sediment when the engine has done over 125000 miles mine had done 148000 miles and caused the engine to overheat,
I changed the radiator as it has a oil cooler in one of the tanks and I didn’t know what condition it would be in, buying a non genuine radiator that was half the price of Mercedes and everything went back to normal the temp gauge running just over the 85oc mark and it never moves above. I fitted it 3 years ago.
Some update: the radiator was completely clogged (is it the right word?) and I was told that it is not repairable. I need a new one...and it is not a cheap thing ~ 500 Euros made by Nissens.
You should be able to get your existing one rebuilt. I paid around 200 euro.
Hi
chances are that all the hoses have furred up along with the heater valve and heater matrix no point fitting a new radiator if the plumbing is contaminated as well...if you squeeze the hoses and they crunch that is sediment adhesion.if your heater failed to turn off properly the valve is furred up..if your heater never got really hot then it is clogged like the radiator....you can try an flush the entire system with brown vinegar by sealing the lower pipes and filling through the top hose.... let the vinegar stay in the plumbing for at least 24 hrs then flush with a medium pressure garden hose until all flows clean water....MB radiator is Euro 1000....very few workshops can recore because of the integral oil coolers .......
Nissens? I thought they were made by Behr, at least on petrol models...
http://www.hehlhans.de/tipp98-5.htm
Oh boy! It is beginning to sound that my "find" is less good than she looked/s - she runs hot too.
Mine is also having a new radiator fitted as we speak, It ran hot and then dumped oil and water all over the driveway ! I am hoping it is related to the radiator / Oil cooler and not a head gasket !. Currently we are trying to flush all the oil/water mix (porridge) from the water system which is not proving easy.
Once this is sorted, it will most likely need a complete exhaust system, all Oils and Filters and thats just for starters! Looking forward to getting my G on (and off) the road.
I got my radiator from a local radiator specialist in Newcastle and when I picked it up it was Behr and it had some grid marks on when I looked closer it was the Mercedes sign ground off!!
The water system on vehicles should be clean if the owner has kept 25% antifreeze in the system as this is an rust inhibitor
My G is Diesel
I got the radiator from a local specialist factor, made by Valeo. As a rule I just avoid any Chinese made items.
Hoses though I have had to get from MB.
Hi
With the radiator out close off the bottom hoses and pour large quatities of boiling water into the top hose. until full make sure the heater is selected to hot ...once full open the bottom hoses completely to allow the water to move out with force..repeat until water flows clear....there will still be some on the heater matrix so open the hose beside the battery when system is full and blocked at the bottom and this should clear after one flush....still do the vinegar treatment to remove the lime that has accumulated because of the overheating... flush with garden hose until all the sediment has cleared....
hey, next update: BEHR has been installed instead of Nissens for approx 400 Euros- pick up time tomorrow PM
you did well to buy new, a recore is cheaper but cannot be guaranteed not to leak after a while, while the new one buys you peace of mind.
Does anyone know the coolant capacity on a 617 engine. The small book I have does not state the amount. I am guessing about 10 litres? Have a new radiator to fit, and in the current weather conditions just want to make sure I have enough anti freeze.
Thanks
You are looking at 11 Litres if the engine block has been drained as well. 5 Litres of antifreeze will do the job for you.
To the 5 Litres antifreeze add 5 Litres of water, this gives you the 50:50 mixture required to give you adequate protection for a mild winter, as per normal, for the UK. To mix antifreeze for protection for even lower temperatures, read the mixing ratios on the antifreeze can and mix accordingly.
Hi Guys,
well, I promised to keep you updated, so here are the latest -sad- news: G could make couple of hundred clicks with the new Behr radiator and then.... Crack in the cylinder. S!@#$%%%%t!!!!!
As head removed it was even visible that 2 cracks were at N 5 and 6cylinders...white smoke from the exhaust, watergoing down ..all the symptoms were present.
Now a new (used) head willbe bulit in...let`s hope it will be OK
Cheers
Just to add my experience of this problem, my 463 diesel had this overheating problem, when it was driven fairly hard the gauge would keep climbing until you eased off and let it cool down. If, when hot, you stopped the engine and had a look/feel around, the centre of the rad was cold. Being mean, I took the rad off, uncrimped the ends, steam cleaned the core and rodded it with bits of welding wire, re-crimped the ends back on, and hey presto, now runs cool, and no leaks at all. I did this well over 6 months ago and all is still well. For example last Sunday I towed a trailer with a tractor on, approx 3.2 tonnes for 90+ miles without the gauge offering to move, and from the day I re-fitted the rad I've not had to put a drop of water in. Just a case of being careful when removing and re-fitting the plastic ends of the rad to avoid any leaks, I even re-used the original seals.
You are a brave man indeed, to even try this, my hat off to you.
Take care,
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Well, I could not check the surface of the radiator, but I could reach the thick tubes down and upper too and they were evenly hot. The upper thick one on the righ hand side of the radiator was very stiff. If the case is a block inside the radiator, can it be disassembled, or cleaned with some chemicals/additives?