1995 C280 - PeachParts Mercedes-Benz Forum

TOM77 · #1 12-29-2005, 12:31 AM

HI!

I have a C280 and it overheats when i drive it for a while.., it has no coolent leaks, coolent level is full, thermostate is new( and i also ran the car with out the thermostat and it still overheated), im thinking headgasket? or plugged RAD? or i hear something about a harness??? if anyone can help me out that would be great.,

thank you

86560SEL · #2 12-29-2005, 12:35 AM

Does it have the green coolant, or the genuine MB/Zerex coolant? Mine has green and I think it is now taking a toll on my radiator.

Only MB coolant or Zerex is recommended for Mercedes.

TOM77 · #3 12-29-2005, 12:47 AM

it has the green coolent.. any ideas how to test out the rad??

#4 12-29-2005, 12:58 AM

Quote:

Originally Posted by TOM77

it has the green coolent.. any ideas how to test out the rad??

what brand thermostat? running any C280 without a thermostat will cause it to run hot, it isn't a chevy.
without the thermostat inplace, most coolant bypasses the radiator completely,

TOM77 · #5 12-29-2005, 01:07 AM

a MB thermostat, so you dont think its the RAD? what about that wirring harnesst , i heard they are bad for those.. would that cause it?? if it was the head gasket it would be oil and coolant mix,/ or leaking from the gasket external or burning it, but i dont see white smoke , nore any loss of coolent. hmm maybe fan clutch???

thanx for the replies by the way

TOM77 · #6 12-29-2005, 07:25 PM

Matt L · #7 12-29-2005, 08:31 PM

The wiring harness should not cause overheating, but it may cause a false reading on the meter. If you suspect this, check temperature around the engine, and especially at the thermostat housing with a non-contact pyrometer.

Bad grounds between the engine and body can cause false meter readings. If this is the case, there may be a difference in readings when the electrical consumption changes.

However, if your radiator is original, it could very well be the problem.

86560SEL · #8 12-29-2005, 08:52 PM

I asked that because I have been warned against having green coolant in my MB. I have heard that it is corrosive and can clog the radiator coils.

Quote:

Originally Posted by TOM77

it has the green coolent.. any ideas how to test out the rad??

nikki · #9 12-29-2005, 09:25 PM

Tom, how many miles are on your C280? I have two W202, one with 171K ('95) and the other with 62K ('98). Given mine are 4 bangers, there is a difference, but with everything I have read it would lead me to believe that it is a head gasket problem. That's exactly why I stayed away from the 6 cyclinder versus. Check the underside of the oil filler cap, if it looks like 'butterscotch' or specically it does not look like oil - then it is probably the head gasket. I know you stated it has not used any coolant, but I just had our ML head gasket done and it hardly used any fluid, but the underside of the oil cap was 'butterscotch'.

KermitF · #10 12-29-2005, 10:28 PM

Tom,

1. What temp is it running when it "runs hot"?

2. Is it running hot in sustained highway driving, or in around town (stop and go) traffic?

TOM77 · #11 12-30-2005, 06:33 AM

the care has 141.xxx kms,
it dosent have that mildo(brownish milkshake) under the oil cap,
the care is runnung about 100-120 and just about to the (red),
it happens during city driving,(stop and go)
the coolant dosent boil over
where is that harness located?

thanks for the info guys

KermitF · #12 12-30-2005, 10:58 PM

Tom,

Not sure where you are located (meaning that I do not know what your local temperatures are at the moment), but if your temp is running 100-120 this time of year (winter) you do have a problem.

1. It sounds like you have opened up the system to at least replace the thermostat lately. Have you checked to make sure that all the air is out of your system (after replacing the thermostat)? Your temp sensor (on top of head toward back - and usually a high point of the system - can be unscrewed to release any air trapped in system. If coolant flows out, you are good; if not, add coolant until it does. Squeeze top radiator hose to break trapped air free ... do all this with system cool, BTW.

2. Have you checked your serpentine belt to make sure it is tight? - should be able to push down on it and move it no more than @ 1/2 inch. If more play, need to tighten - search for "belt tensioner" on this forum for adjustment instructions.

3. You say no leaking at present, but have you looked around in engine bay to make sure no residue from dried coolant (white spots/splotches w/MB anti-freeze) seen anywhere. You could have a small air leak starting, prior to leak showing up. Drive for a spell to get engine up to normal operating temp, stop, pop hood, listen for hissing/fizzling sounds; if any sounds, trace to origin. Check around and under coolant fill tank when doing this also.

4. Does your car cool back down to 85-90 when you leave traffic and get up to speed? If yes, fan clutch is a suspect and radiator a less likely culprit.

5. Have you tried turning your heater to full high with fan on full high and seen system cool down? If yes, radiator is more of a suspect - could be blocked and require either cleaning or replacement. Before doing either you would want to check for cool spots on radiator (where blockage is). There is a tool (search for "infrared" on this forum, I think) for reading temps on differnt parts of rad. Replacing rad not that bad of a chore - go with Behr if you have to go this far.

(all this from 103 engine, which I believe is plumbed pretty much same as yours.)

Possible solutions arranged from least to most expensive.

Hope this helps.

nikki · #13 12-31-2005, 10:21 AM

Specifically you should Thank Kermit for his comments, they are very detailed and consise - good job. I agree with all he said, it's just I know the head gasket is a common issue for the six.

TOM77 · #14 01-01-2006, 11:49 PM

thanx guys for all your help, i am going to try all this, and will let you guys know how it goes.

TOM77 · #15 01-28-2006, 05:56 PM

ok guys i checked out the temp , with a infrared thermometer and the temp reads very close to the gaug, so it;s not the wiring harness, i checked the temp on the RAD and it seemed the top left corner of the rad was hotter then the other parts of the rad but i think thats normal since the upper rad hose gets hooked up on that corner. the car is running hot at about 100-120c but the coolant isnt overflowing, no signs of coolant in the oil, checked the oil cap for signs none, and none in the oil. Yesterday when i turned the car on, i ran it at idle for a good 45mints and the temp went up for 100-120c then i sat in the the car and held the gas and cranked the hearter on full blast and the temp went down to 80-90c. im not sure what;s going on with this car, also the car idles up and down somtimes, i dont thinks thats related to the overheating issue.

thanx for your help guys.