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+--- Thread: Overheating Questions (/showthread.php?tid=3518)
Overheating Questions - 87Bielenberg - 04-08-2012
Whats up guys. I just bought an 87 300TD Turbodiesel Estate with only 150k and 3 owners the second of whom was a Benz mechanic. Beautiful car and it gets me around town without any major issues. It does have a few glitches though which I want to resolve the most major of which is overheating because I want to take it on road trips and use it as a travel car. I am not very knowledgeable about these cars but I really want to learn and get it up to spec. Any advice would be greatly appreciated. Thanks.
PROBLEMS:
1. Overheats when climbing hills on the highway. Driving in town the temp will stay at 90 C and it will usually stay at 90 C even going fast on the highway. When climbing hills going fast on the highway though the temp starts to slowly climb. If I turn the heater blower on full blast this usually drops it down and helps it stay at 90-100 for a while. Eventually though the temp gauge starts climbing again and I have to pull over. The coolant reservoir will be pressed full and boiling and it will usually be leaking out behind the front passenger side wheel which is where the overflow tank drain is I guess. And this happens even when I am not going very fast and in very cold weather. It has a bastard Nissan radiator fan and apparently the original Merc fan works better, but this can’t be the only issue.
2. Rough Startup and starting idle. Revs high and sputters for a few minutes. Valves too tight? Needs valve adjustment? This is during cold temp in Montana winter.
3. Delayed/Hard shift from 1st to 2nd. Jerks. All other gears are fine. Surges at low speed or idle. In 1st gear or reverse rolling slowly or at a stop the engine will rev up to 10 rpm if it is just idling at 5. Might kick up twice while sitting at a red light. Going slowly in reverse this happens a lot.
4. When slowing to a stop the ABS comes on, you can feel it in the brake pedal and it makes its noise
RE: Overheating Questions - aaa - 04-08-2012
Does it go over 100?
Clean the bugs and debri from the radiator and condensor. And make sure your fan clutch works. After that consider a new radiator. I prefer Nissens actually.
2 - glow plugs. There are no valves to adjust.
3 - the engine rpm goes up randomly???
5 - abs speed sensors probably
RE: Overheating Questions - 87Bielenberg - 04-09-2012
Yeah the gauge maxes out at 120 C and the needle goes a few notches higher than that, so it gets hot! It will dance around 100 when Im climbing up mountain passes and eventually it will start gettin hotter quickly and thats when I will pull over. By this point the reservoir will be boiling and pressed full and it will be a good ten minutes before I can even think about slowly taking the cap off. A good little bit of coolant will have already blown out the overflow drain behind the right front wheel and I will usually have to add more and wait about 30 minutes before I press on.
The Engine kicks up in little spurts when idling or slowing to idle. Like my foot will be on the brake at a red light and I will feel and hear the car surge and strain at the brakes like it cant wait to go. Transmission? Throttle assembly???
RE: Overheating Questions - 87Bielenberg - 04-09-2012
Also the fan clutch engages the auxillary fan when at low speeds or idling correct? This car is fine for city driving, it only overheats when going up grade over long distances, like on the highway.
RE: Overheating Questions - 87Bielenberg - 04-09-2012
(04-08-2012, 08:58 AM)aaa Does it go over 100?
Clean the bugs and debri from the radiator and condensor. And make sure your fan clutch works. After that consider a new radiator. I prefer Nissens actually.
2 - glow plugs. There are no valves to adjust.
3 - the engine rpm goes up randomly???
5 - abs speed sensors probably
Glow plugs are brand new. It starts fine, 1 or 2 cranks, but its rough during the first few 10 minutes especially in cold weather but really even when the block heater is plugged in. No valves? how so?
RE: Overheating Questions - sassparilla_kid - 04-09-2012
Maybe you have too much water in the coolant and not enough antifreeze. I'm having overheating problems also right now, and I think that's my problem because the car was running fine about 85*C (just flushed coolant about a month or so ago) until I had a major leak, and then refilled with water afterwards. After refilling with just water the car runs 5-10*C hotter than usual, and even more sometimes
RE: Overheating Questions - willbhere4u - 04-09-2012
It could be a cracked cylinder head! The earlier om603 with the #14 heads are Notorious for that
If the cooling system stays pressurized over night that's a sign of a cracked head! Check in the morning befor you start the car! If the cooling system is still pressurized by squishing the upper radiator hose! My car has a cracked head and on occasion gets warm after it pushes enough coolant out of the bottle! I usually top it back off and it goes for another month or so with out issue!
RE: Overheating Questions - yankneck696 - 04-09-2012
straight water is a better heat transfer medium than water/antifreeze.
Ed
RE: Overheating Questions - aaa - 04-09-2012
(04-09-2012, 08:51 AM)87Bielenberg No valves? how so?No adjustable valves. It has hydraulic lifters.
Quote:Also the fan clutch engages the auxillary fan when at low speeds or idling correct? This car is fine for city driving, it only overheats when going up grade over long distances, like on the highway.The fan clutch is on the hub of the mechanical fan and is solely temperature based. It would indeed have limited effect at high speeds though.
Main reason to not use water is corrosion. It does work better at cooling though, although it'll boil a little earlier.
RE: Overheating Questions - sassparilla_kid - 04-09-2012
I thought since antifreeze boiled at higher temperatures it was better for cooling
? I will have to discuss this with the automotive professor at school, although I doubt he'll have any answers. He doesn't even know how to drive a stick 
RE: Overheating Questions - JustPassinThru - 04-10-2012
(04-09-2012, 11:41 PM)sassparilla_kid I thought since antifreeze boiled at higher temperatures it was better for cooling
Specific heat of water: 4.184 joules per gram per degree Centigrade.
Of ethylene glycol: 2.200 joules per gram per degree Centigrade.
Source:
http://www2.ucdsb.on.ca/tiss/stretton/database/Specific_Heat_Capacity_Table.html
Therefore, water is almost twice as good as ethylene glycol, as a heat absorber.
Unfortunately, water at two atmospheres (the pressure, roughly, of an automotive cooling system) boils at 120 C (source: http://chemed.chem.purdue.edu/genchem/topicreview/bp/ch14/property.php), and its freezing point is still around 0 C (source: http://www.physicsforums.com/showthread.php?t=129053) and cars require a wider range of temperature at which the coolant remains liquid.
There are additional factors, such as the effects of particularly hot spots in the engine on antifreeze/coolant, and the unacceptably high corrosive properties of pure water. See http://www.evanscooling.com/how-it-works/frequently-asked-questions/ for a brief discussion.
So, all in all, a 50-50 mix of ethylene glycol and pure water, plus the corrosion inhibitors which are included in anti-freeze, works best. Some say you should use only Zerex G-05 or Mercedes Benz's own antifreeze. And there may be truth to this. I've been using Prestone for the past year, but on hot days on long uphill stretches my temp gauge does climb to 100 or even 110. Probably should take my radiator out and blow the bugs out from between the fins, and start using genuine MB antifreeze. It isn't expensive, at the dealership.
RE: Overheating Questions - sassparilla_kid - 04-10-2012
I was thinking, maybe getting the radiator rodded out might help. I bet mine has some pretty good build up in it by now