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Wednesday, September 17, 2008

Sebring Cooling System



Sebring Engine
The first winter after we got this car I noticed the heater wasn't working, and with leather seats and a temperature South of freezing it was a bit chilly. My first suspect was the thermostat. The dealer wants $80 to replace it. $80! Shoot, I can replace a thermostat, so I go take a look under the hood. Well, there's a likely looking candidate. There is a thermostat size housing sitting on top of the engine, connected to the top radiator hose, right where you would expect the thermostat housing to be. This looks easy enough. Well, not quite. One of the screws is blocked by the plastic (!?!?) intake manifold, which means it has to come off, which means more shenanigans. Eventually I get it off, and pull off the thermostat-size housing, and look here, no thermostat. But what is even stranger is no coolant. I am sure there was a look of consternation on my face at this point.

OK, so we have learned two things. 1) $80 might be a reasonable price to pay for replacing the thermostat being as I cannot even find the durn thing, and 2) low coolant could easily explain the lack of heat, so there may be nothing wrong with the thermostat anyway. I mean the motor isn't overheating, even on longish drives. As a bonus I also learned that there are O-rings between the intake manifold and the engine, which means I did not have to go out and buy a new gasket. Sure, I should have replaced the O-rings, but this is a shade tree operation, we are not going to replace something just on some lab guys say-so.

Put the whole thing back together and now I need to refill the coolant. Problem with this car is that the thermostat-sized housing is higher than the radiator, so you need to bleed the cooling system. Further evidence of this is the bleed screw on the top of the oft-mentioned thermostat-sized housing. I experiment with various bleeding techniques, none of which work very well and at least one has the side effect of spraying me and the surrounding area with a mist of anti-freeze, but at last I am satisfied that I have gotten most of the air out of the system.

So things are working pretty well now, the car still runs and the heater works. But I come across some DIRE WARNINGS on the internet about mixing five year (orange) and three year (green) coolant and I decide the coolant should be changed. Not wanting another ethylene glycol shower, I take it to the dealer. They don't want to put green coolant in it, they want to use the high priced stuff. They have some techno-babble reason, so I relent.

That was over a year ago. But now when the car comes home after a longish drive it is spitting anti-freeze on the floor. A quick squeeze reveals that the top radiator hose is apparently empty. Come on guys, I took it the dealer, you are supposed to know that the cooling system needs bleeding. I suspect they didn't do it. We didn't discover a problem because my daughter was driving the car to school, which is only a mile away. The engine is barely going to get warm in that distance, you will never know whether the heater is working or not.

So now it's back in the shop. We shall see what they find.

Just got a call. Problem was the radiator cap had gone bad. It was only holding 4 pounds of pressure when it should have been more like 16 PSI. Only cost $45 for diagnosis, replacement and testing. So you're thinking $45 for a radiator cap? They only cost a couple of bucks at the discount auto parts store. But remember this car had been to two experts before this shop (me and the dealer) and neither one had detected the problem. I mean, when's the last time you had a radiator cap fail? I think he flushed the system to boot. Must have refilled it with the coolant that came out. I don't think you could buy the coolant for $45.

Update December 2016 replaced missing picture.

1 comment:

CA Bob said...

I had an old Mazda where the thermostat was located at the highest point in the cooling system. I had frequent overheating problems, and I always suspected it had to do the high thermostat not making contact with low coolant levels. It would seem to be better design to have the thermostat submerged in coolant as much as possible.