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+--- Thread: 85 w123 overheating issues (/showthread.php?tid=2703)
85 w123 overheating issues - 98taco3 - 06-12-2011
Well the 300D has been up and running great for a few months now and im back to the overheating issues again. Its running around 100 degrees Celsius and has started to climb with long jaunts on the highway. Also seems to fluctuate quite a bit. Head is rebuilt, new head gasket, new water pump, new tstat, new radiator, new hoses, new monovalve, timing checked and set, valve adjustment done. Oh and a new expansion tank and cap. Only thing i havent checked yet is the sending unit. Only other symptom ive noticed is when the heat is going i seem to only get heat at slower speeds. Above 50 and its cold. Im stumped at this point, there is nothing left to check/replace at this point. I have checked it with an infrared thermometer as well. Have re pressure tested the cooling system and have no leaks. Also sprayed out the radiator. The cooling system was in sad shape when i bought the car and needed repair. I broke the rad tank and had to replace it. Everything else was replaced because it was apart and i was there. Possibly a defective water pump? Any ideas?
RE: 85 w123 overheating issues - totaldisaster - 06-12-2011
blocked passages due to rust and contamination in the block is a possibility.
did you install the t-stat with the spring side to the block?
RE: 85 w123 overheating issues - 98taco3 - 06-12-2011
(06-12-2011, 11:01 AM)totaldisaster blocked passages due to rust and contamination in the block is a possibility.
did you install the t-stat with the spring side to the block?
Block has been flushed and the thermostat was installed spring side to the block...
RE: 85 w123 overheating issues - willbhere4u - 06-12-2011
check that the little line bolted to the front of the cylinder head to the water pump is not plug full of rust
RE: 85 w123 overheating issues - 98taco3 - 06-12-2011
(06-12-2011, 06:14 PM)willbhere4u check that the little line bolted to the front of the cylinder head to the water pump is not plug full of rust
Car doesnt have the little line. any other ideas?
RE: 85 w123 overheating issues - totaldisaster - 06-12-2011
You said you had an IR sensor... how did that go? have you checked the head temp when your gauge said "hot"?
RE: 85 w123 overheating issues - Hercules - 06-12-2011
Heating only below 50mph suggests air flow problem, (fan clutch )or partly restricted radiator(water flow).
RE: 85 w123 overheating issues - yankneck696 - 06-13-2011
One time I came across a similar situation. The tubes in the radiator had expanded & blocked the airflow... Just a thought...
Ed
RE: 85 w123 overheating issues - 98taco3 - 06-14-2011
(06-12-2011, 10:55 PM)totaldisaster You said you had an IR sensor... how did that go? have you checked the head temp when your gauge said "hot"?
Checked it with the thermometer and was getting readings close to what the gauge was indicating. was around 200-205 F when the gauge was reading around 100C. Took it to run some errands today and it was heating up over 50mph. It also seems to fluctuate fairly often and quickly. Whether or not this is an electric issue or not has yet to be figured out. Just seems to me something is up. The car was hard to start this morning and bleched grey smoke. Ran fine and started fine after that.
RE: 85 w123 overheating issues - DeliveryValve - 06-14-2011
Pull your thermostat out. Then test it in the pot of boiling water and thermometer to see what temperature it opens up.
There have been a run of faulty thermostats, including Behr and Wahler brands.
.
RE: 85 w123 overheating issues - winmutt - 06-14-2011
Have you turn off the engine and verified the fan stops moving with it?
RE: 85 w123 overheating issues - 98taco3 - 06-19-2011
Fan clutch seems to be fine. Im going to replace the t stat with a factory part and see what happens. Also gonna replace the sending unit and eliminate that. Ive been driving it and have had no other symptoms at all. Seems to run fine, doesnt boil over, but is running a bit hot.