550 Overheating at Idle

I think that your thermostat is spoiled.

greetings, gianfilippo-italy

 

My 99 550 was great until I changed the thermostat, since then in los angeles summer, stop and go traffic it reads 210. was much cooler befor thermostat change. but no problem in winter. could be thermostat, it is $ 250. also there are posts regarding fans operate on time but the engagement is not 100%.

 

if the fans are working "well" then I would suspect the radiator. These are are about 10 years old now with coolant changes by most owners in the every 2 yr. area. There is aluminium and steel everywhere which makes for electrolysis that the coolant is supposed to help moderate. The reality is that crap builds up in the radiators and plugs them decreasing efficiency. Also fan motors increase friction and decrease efficiency with time too. It is not a bad Idea to pull radiators and back flush them. I do that when I do my major because I'm a diy'er. Old cooper radiators can be boiled out. Aluminums ones cannot. All you can do is flush them very well and replace them when bad. The best radiator techs are in bad neighborhoods like wilmington there is Dave's on anaheim street and around fig. Good neighborhoods only have radiator replacers. Pull the radiator out yourself and take it to a bad hood and they can flush it out real good for you for a few bucks. It is also cheaper to custom make a new 550 unit than buy a OEM one. You will surpised at how much junk comes out if you flush it yourself. Also, the 550 has those crappy hoses under the plenum that davehelms of scuderiaramparteinovations.com has good replacements for better than OE. Those hose act like bad arteries in your heart and the inner walls of the crap hoses comes off and plugs your radiator = heart attack= water No flow. If you turn on your heater and the temps drop at idle that would make me think fans or radiator. A marginal radiator can stil cool at 60mph because the wind is much higher than what you can do with just fans. Also check the surounds of the radiator so that forced air is not bled off around the radiator. That also reduces efficiency.

 

DW- You might try the cheap fix first and flush your radiator and then change to a modern anti-freeze and carefully bleed, or have your technician bleed, the system. I use Valvoline Zerex G-05 and have no problems with overheating, even at the 6000' or so altitude where my car lives.

Taz
Terry Phillips

 

easy solution, fan belt has stretch marks, old. change or adjust belt before you spend $$$

 

Mitch- You are correct. They should be changed at three year intervals. I assumed that had been done, which may be a bad assumption, even though the OM and WSM call for it.

None of the late model V12s, however, have a recommended coolant change interval in the OMs or WSMs, so I usually assume it has not been done recently.

Like the Porsche service manager told me: "They have permanent anti-freeze." Of course they do. And my car has permanent tires. Believable Story.

Taz
Terry Phillips