550 OVERHEATS

I HAVE A 2000 550. THE TEMP.SENSOR RUNS VERY HIGH AT IDLE. DEALER HAS LOOKED AT CAR MANY TIMES AND FOUND NO PROBLEM. BLAMES IT ON THE WAY THE RADIATOR SLOPES. ANY CURES OUT THERE.

 

Where do you drive the car? In stop and go, the temp can go up if you just sit for a long time. Did dealer check thermostat?

 

I had/have a problem where the ECU is waiting until it is too hot before turning on trhe fans, which are supposed to kick in a 85 or 90C, mine is waiting until the ECU override senses the car is too hot and starts the fans. The cure is to change the sensors under the manifold, but meantime we have just wired the fans thorugh a relay to run all the time until we get around to pulling the inlet manifold off.

 

marcm - you might want to fill out some info in your profile - for example, where you are (Cairo vs. Anchorage AK might be material here!).

the only (only) time i ever had an overheating problem in my 550 was once when the oil level got low. otherwise the temp did fluctuate a lot, but never got to levels of any real concern.

doody.

 

I had a similar issue on my 550 last year.

I thought possibly it was because it was a "northern car" transplanted to South Texas.

Anyway, the cure was a new thermostat. Since the change--not expensive by the way--the temp has stayed well within range.

 

Try bleeding the cooling system. You will want to bleed the air out with the heater set to the hottest setting, and on.

If after you bleed the system you are still over heating check the condition of the thermostat.

Also are your fans coming on when the temp goes up?

 

I seem to be having the same problem now with my 2000 550. I just put a posting under engine slowdown, but that seems to be resolved but was what
I firsst noticed with the same problem I think you are having.
I am noticing large fluctuations in the water and oil temp from when in traffic to on the road. Difference from 120 to 190 in water and 140 to 190 in oil.
I am in florida and it is 75 now.
I plan on sending the car in for tires soon and figure it is time to flush the cooland and checkl the thermostats and fans. I have to heard my fan going on at all.
I have noticed two times though that after long drives and then parking in the garaged I have come out to a small puddle of antifreeze (blue/green) the size of a cigarrete pack located just behind the engine. I figured it musts be coolant overflow but my overflow tank still measures full.
Are your temp problems similar to mine?
Why would a fan stop working?

 

The fans would stop working if the temp sending units went out.

Make sure that you have the air completely bled out of the cooling system. If you get an air pocket in the water pump it will cause the car to get hot.

If you are seeing a puddle you may want check the condition of your radiator cap. You can also get a cap with a higher pressure rating to help with the cooling.

Others have added Red Line Water Wetter to their cooling systems with good results.

But first things first, make sure the system is properly bled.

 

Don't you love it when a guy with no profile info comes in here, asks a tech question, gets several answers and disappears for a week?

Niiiiiiiiiiiiiiiiiice!

 

No kinding.

 

Hey Gary
The 550 does have big water temp swings. Very different from other cars.
On mine - and all coolng system was checked and re-checked - it is normal to vae wter temp arund 90 c (needle vertical) in traffic. When running the needle would come back down to 65 c (around 10 o'clock).
Oil is about the same however the needle does not go vertical.

Fans on the water rad kick in at 90c and needle should not go significantly pas vertical.

If your car does the ssame, do not worry all normal.

However, it's good practive to flush coolant every two years at least

cheers

 

Thanks Thibaut:
I will be sending it in to the dealer in a few weeks to change all the fluids and will also do that and check out the entire cooling system. it is good to know that other cars are similar. I just don't recall it running that hot, but there is a lot more traffic down here now that it is winter.
I figure I may have everything cehcked out since it goes off a factory warranty in July.
Gary

 

Wierd, never experienced any of this on either car. Maybe my guages aren't working right?

--Dan

 

Make sure the radiator is clean... take the front grille out and gently soak and rinse all the bugs and leaves etc away.

Dont use a high pressure cleaner though, or you'll flatten the fins and make it worse.

The AC condensor is in front of the radiator, but this needs to be clean for air to get through it.

550 do tend to run on the hot side in traffic, and over cool on a cool run.

Rad cap cannot be changed for a higher one very easily. It's a specific Ferrari/Alfa style cap with screw thread.

The caps do fail, and also the radiator can get damaged easily, and leak a little. Later radiators have a better placed drain plug, which was a problem for early cars getting knocked off.

A heavy grounding of the front, can distort the oil cooler too.

I'm sure hot running could be imrpoved with a louvred bonnet. The hot air cannot get out very easily.

 

This week, on a scorching hot day, I collected a 550. I had to jump start it due to a flat battery.... DEAD flat.

Anyway, I was worried it was going to stall if the electrics got overloaded like when the fans came on... it was a 40 deg day... centigrade. So, to avoid it stalling, I heeled and toed in traffic to keep the idle above 1500rpm at all times, and I had the AC off, to save electrical load, so it's fan control was also not working..... potentially making in run hotter

Amazingly, the temperature never reached anything like what it usually does in traffic....

So basically, the coolant circulation is too slow at idle...

i'd like to know if it cavitates at high rpm, that way a fix would be to change pump pulley size, or possibly, a different water pump impellor may be needed.....