95 104: Viscous or T-Stat problem? - PeachParts Mercedes-Benz Forum

haasman · #1 06-26-2003, 09:38 PM

After doing a lot of searching on this site, I am still unsure which is needed-

The 95 E320 wagon temp goes above 100c and can see 110c going up a hill on the highway with an example today’s 103f outside temperature.

At one point the AC stopped working. I stopped, waited and then started up again and the AC returned.

Going down hills I see less than 100c engine temps, going up hills higher than. With the AC off it will generally display less than 100c, whether stop and go or highway.

The coolant is MBZ and it has a –10f mixture, the viscous clutch does work on the fan, I can hear the roar and with the AC on the aux fans both are running. The engine has 10w-40 oil. The car has 97k miles on it.

Is this a viscous coupling problem or a thermostat problem?

Thanks in advance,

Haasman

1991300SEL · #2 06-26-2003, 10:24 PM

Could be lack of coolant flow - plugged radiator or perhaps the t-stat.

In some MB circles it's said that pre 1997 104 motors are prone to pre-mature head gasket failure. How old is that item? If weak, the cooling system loses pressure and up goes the temp. There's leaking head gaskets and there's blown head gaskets. The former may not dump oil in the coolant and vice versa, but maybe cause a slight rise in operating temp.

I've always believed the fan clutch was more crucial at slower speeds. Highway driving by it's nature gives a strong flow of air through the a/c condensor/radiator, but it's summer and you now have 2 heat exchangers unloading vs. just the one in winter(radiator), so I suppose it's possible that a weakened viscous fan could play a part in higher temps. Your thread does indicate this parts seems to be doing it's job.

Arthur Dalton · #3 06-26-2003, 10:44 PM

Anytime you have high moving temps, [meaning you have airflow], the thermo is the first suspect and easiest route is to change it before getting into the rest of the system,,,just takes a few degrees late opening to put you in that temp range ...

MRPerformance · #4 06-27-2003, 02:34 AM

The above responses are correct-- above 20-30 mph fans are redundant (and may actually slightly impede airflow). However, if your thermostat is defective the motor would most likely overheat regardless of operating conditions.

Yours sounds more like a case of diminished cooling capacity. My first guess would be an externally clogged radiator or condenser. I just replaced the radiator in a '93 300E and I took the opportunity to clean the condenser with compressed air. You wouldn't believe the amount of bugs, dirt and leaves that came out, and this was on a well maintained 97k mile car!

It's also possible that enough deposits have formed inside the radiator to reduce cooling capacity but considering the fact that your air conditioning is also affected I'm betting on the former, especially since the cooling systems on these cars are marginal in high ambient temps.

In order to properly clean the condenser it would be necessary to remove the radiator and blow air backwards through the condenser. It's worth it though, since that's probably the least expensive option.

HTH,

///MikeR
'93 190 2.6 sportline

#5 06-27-2003, 11:05 AM

is that the car your trying to sell Haasman? Any offers yet? Believe it or not I'm considering it for more space than I have with my sedan. The hard part is dealing with the separation anxiety I feel just with the thought of parting with my pride and joy...:p

haasman · #6 06-27-2003, 11:56 AM

Dale

It is that car 95 Wagon

I ran across the old 240D a couple of days ago ... it was like seeing an old friend. Looked good and it was running great according to the owner. Each place on the car I looked brought back memories of what I had worked on and had learned. So many demarcations of memories! Gosh, what is this with our cars. What relationships and commitments!

; ; ; ... and now back the topic at hand .... I will check the radiator and condenser today for blockage. I am also considering pulling out some coolant to reduce its water to coolant ratio.

Thanks everyone for the ideas and suggestions .... let me know if anything else should be looked at.

Haasman

#7 06-27-2003, 01:33 PM

have you tried a cooler thermostat? PepBoys carries an 82' thermostat that I've been running for over a year now. Works like a charm.......I'll get you the part# this evening if you want it. I bet yours is just sticking or slow to react.

Also if your worried about losing gas mileage or bad emissions with the 82' don't. My gas mileage is still great and last November the car blew as clean as it did a year earlier with a 87' thermo in it!!

Good Luck

haasman · #8 06-27-2003, 02:06 PM

Dale

Thanks for this -

Are you saying an 82C thermostat for the engine from PepBoys?

What are you running temps at what ambient?

Yes give me the part #. Could be the solution .... and economical as well!

Haasman

#9 06-27-2003, 02:10 PM

yes 82'C. My temps run from 82' to 90' consistently. 82 while cruising on the highway and 90 when I come to a stop. I'll get the part number for you tonight and the price. I don't remember it being much cheaper than the benz unit though, maybe 20 bucks if my memory serves me correct. Anyhow I'll look tonight and e-mail you.

#10 06-27-2003, 02:13 PM

forgot to mention ambient temps. Well it's fairly toasty here in Atlanta so I would say 80F on up to mid 90's are the norm these days and that's when I see 82 to 90'C on the gauge. During the winter here it never moves from the 82'C mark. About a needle width about the 80 mark.

Mick J · #11 06-27-2003, 05:42 PM

If there is too much antifreeze in the coolant this can cause poor cooling. MB say 50% max but unless you have really cold winters you don't need it above 33-40%.