300TE Running hot, sound like radiator?
 

So Phoenix is tipping over the 100F mark....gonna be 115F is no time and the 300TE is starting to struggle.

Normal driving in 100F is around the 100-105C mark, so its definitely running hot.
Even on the freeway it won't decline.

Coolant level is good
Reservoir cap holds pressure
Just replaced thermostat last week with 79C version (Bosch)
Water pump replaced in 2009 when I did head gasket (Graf)
Fan Clutch works.

I replaced the radiator back in 2006 with a "Metrix" brand one...it was the cheapest go figure...

Think the cheap radiator has crapped out?

I know the 103's cooling system is capable at 115F since my 260E's did perfectly fine last summer and sat around 90-95F tops. I have Nissens in her, so I'll definitely go with Nissens.

Anything else I should consider or test before replacing the radiator?

When pulling out the radiator I like to take an air nozzle and blow backwards through the condensor. The way the aux fan shroud is made a lot of debris can collect in the lower portion cutting off a fair bit of airflow through the core. If you can get in the lower part of the shroud and blow that crap out, it may be the little extra you need. Hell if you've got access to a pressure washer, I'd even consider using it though I'd use air first to get the larger leaves and crap out and then pressure wash (or even garden hose) it to get all of the trapped dust and dirt too.

Yep, on the list to do since I am seeing 300psi on the high side at idle before aux fan kicks on so condenser might be a little dirty although I don't think its bad at all.

300psi on the high side does sound like an airflow problem.

Greetings from Goodyear.
 

I had the exact same problem about a year ago with my 91 300TE.

I replaced the radiator...I now have two spares...thermostat, bought three...new hoses, replaced fan clutch...pulled the hairs out of my head!

Finally I took it to Mike Schulte's place...which is recommended in our forum and he discovered that the cooling fan switch had been plugged in bassackwards!

Now this car runs so good it's scary!

I just took it to Lake Havasu last weekend and the temp gauge did not move one bit from where its supposed to be.

Oh...I'm at 230,000 miles.

Good luck!

I have ran mine in 105 degree weather and it definitely runs hotter on the gauge but usually around 87 degrees when moving and around 90-92 degrees when sitting at the light or in traffic. Was gonna ask about your auxilary fans...are they on as well when it's running hot? If so, what else can it be beside flow or radiator? Have you replaced the water temp sensor? It's cheap. It doesn't seem like they designed these cars to run in hot climates like Phoenix...and it is SMOKING hot there in the summer!

The car should stay within reasonable operating temperatures without assistance from the aux fan, so its not the issue -- but for simplicity, it works when the temperature reaches 110C. I hear it turn on after the car has been off for a few minutes and I restart it. I should get a resistor on the sensor so it turns on at 100C instead of 110C, but like I said, its a side issue not really related.

Is there such thing to test the amount of pressure the pump is outputting? I'm curious?
What about some sort of IR Thermometer test on the radiator? Although I know it may be difficult since the car is not "technically" overheating, but just running hotter than normal.
With A/C on, its dog slowwwwww acceleration due to the engine retarding timing so much due to the increased engine temp.

Maybe that could help. You obviously know more than I. Interesting that you say that about the pump. I had replaced my waterpump with an aftermarket before the headgasket repair and was wondering if that may have caused my overheating problem with the other engine. My hoses always looked ready to "explode" from pressure. I wasn't sure if it was because they were after market hoses or because the pump wasn't able to "keep up". With the replacement engine, the waterpump attached looked original and had no play in the bearing. The hoses also looked great so I decided to have them leave it on and give me the other pump as a back up. Anyone know if aftermarket pumps could "underperform" in this area and cause problems?

...also, when it's hot (100 degrees out here), I do not notice a substantial difference in acceleration with my A/C on. I do notice it runs a little hotter when stopped with A/C on.

ps2cho, regarding radiator best to use Behr or Nissens. Stock thermostat is a Behr 87 degree C. Instead of an aftermarket water pump it's best to buy either a new or rebuilt water pump from your local MB dealer. Coolant mix should be 50/50 water and MB coolant.

I can't offer a solution but I would really like to get a handle on what part of the temperature gauge you guys use as an indicator of 100 degrees.

On Australian delivered cars, the single mark between 80 and 120 correctly indicates 90 degrees.

Purchased Nissens radiator this morning, 2 gallons Zerex G-05 undiluted, 2 gallons distilled water....

Once I get radiator in, will report back with results.

Sptt, old hoses sometimes swell with age...but a lot of pressure is a good thing-- it means the pump is outputting at a high volume. I know my MB pump in the 260E when accelerating will almost pull the main hose into itself due to such a high suction!

I know Graf is aftermarket, but they use OE bearings and seals so it should be more than adequate.

Regarding cluster temp, ours over here has no mark, but resides almost right between 80 and 120, so one can only assume it to be 100C....? With an 87C thermostat it sits right at the midway point, half way between 80C and the assumed 100C mark, so its gotta be 100C.

Check that. I'll report back what mine is doing when I get it tomorrow. Running the Zerex 50/50 through it, original radiator, what I think is the original waterpump and new OEM MB hoses.

Right up until you blow a hole in the hose (my experience yesterday...got it up to 110*C :eek:)

Benzme...where did you find out that the single hash mark between the 80 degree and 120 degree mark is a 90 degree indicator? I count the next one above 80 as 90 but can't find anything that says what the marks actually indicate...