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Discussion Starter · #1 ·
I had an accident the end of January on the passenger side (US). The radiator was pushed back some inches. That hose is behind that radiator and was effected. Since the accident the car overheats after a while. Sometimes it appears that it is not going to overheat then eventually (standing still) it overheats. When I first thought it was fixed I drove it about 60 miles and then it overheated again like the day of the accident that I drove it for a while and it overheated. It first overheated the day of the accident. I have checked for leaks. None that I have found. It has been purged for air in system.

My question: with the car running I have felt those hoses (front clip is off and radiator frame, 2nd time I took it apart) by inserting my arm behind the radiator. The 2 top hoses of the connection get warm fast but the bottom that goes to the bottom radiator port stays cool. Playing with it and squeezing (it makes a bubble in the tank) it gets warm but not as warm as the other 2. Actual question: does anyone know anything about that 3-hose (factory connected 3 hoses) behind the radiator? Does one of the hoses have a one-way valve? How can 1 hose connected of the 3 have a different temperature? (it's like a 'T') My suspicion is that this (since it was hit in the accident but surely flexed) may have something to do with the overheating. (radiator changed) It only overheated after that accident. It was not a hard-hitting accident but enough (being Jan 30 and the plastic was brittle) to need a right fender - new frame - new front - new headlamp assembly.
 

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My first question is, was the cooling system ever drained, even partly, and if so, was the air bleed out? There's a small hose that connects to the head between the head and transmission.
Here is a post of mine where I found a (low quality) image online of where that hose is.


The hoses go from there to the engine, passing in just above the forward engine mount and over the De Dion tube; heater and coolant.
 

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Discussion Starter · #5 ·
My first question is, was the cooling system ever drained, even partly, and if so, was the air bleed out? There's a small hose that connects to the head between the head and transmission.
Here is a post of mine where I found a (low quality) image online of where that hose is.


The hoses go from there to the engine, passing in just above the forward engine mount and over the De Dion tube; heater and coolant.
I took that small rubber tube off and bleed the system a few times. Water comes out then one puts the hose back on. I did order a new radiator hose (that T-set - 3 hoses connected) As I said, if this T has all 3 connections, all three hoses should be the same temperature. The side with this T took the direct hit with the accident, like I said. I will look to see if something got crimped. (perhaps not likely) The lower hose to radiator is much colder. I will examine the new one and see how it is designed. The temperature rises running the engine with the car at a standstill. The oil is not murky. I will eventually do the engine-gas test in the coolant tank. The heater blows hot and the tank is hot showing the water pump is working. When the temperature starts to get too high there seems to be no heat with the heater it blows colder It is always intermittent sometimes I try it and it appears and runs quite a while without an issue The front is off it can't be driven-tested yet.
 

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I took that small rubber tube off and bleed the system a few times. Water comes out then one puts the hose back on. I did order a new radiator hose (that T-set - 3 hoses connected) As I said, if this T has all 3 connections, all three hoses should be the same temperature. The side with this T took the direct hit with the accident, like I said. I will look to see if something got crimped. (perhaps not likely) The lower hose to radiator is much colder. I will examine the new one and see how it is designed. The temperature rises running the engine with the car at a standstill. The oil is not murky. I will eventually do the engine-gas test in the coolant tank. The heater blows hot and the tank is hot showing the water pump is working. When the temperature starts to get too high there seems to be no heat with the heater it blows colder It is always intermittent sometimes I try it and it appears and runs quite a while without an issue The front is off it can't be driven-tested yet.
When the heat has been blowing on max for a time, is the cooler hose hot then?
That the heat stops when it starts overheating makes me think you might have air in the system yet.
 

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Discussion Starter · #7 ·
When the heat has been blowing on max for a time, is the cooler hose hot then?
That the heat stops when it starts overheating makes me think you might have air in the system yet.
Yeap. It had a radiator change so everything (coolant) was out. I ordered last night a vacuum device to vacuum the cooling system then with the vacuum held, one puts the coolant in and it fills (supposedly) the whole system including the heater core. This will also tell me if there is a leak by seeing how long the vacuum holds. Evilution shows a self-made version of this tool also where I first saw it. (I will order some lowering pins soon because if one really wants to work deeply on a high-mileage Smart there will be a time to do major replacements and even potentially an engine swap - I did order once a die and some rods but I used the rods on something else - I think once a self-mechanic is familiar with lowering the engine, everything (other than electrical issues) is elementary - though this may not have anything to do with the cooling problem right now at this time)
 

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I just came across this diagram (based on the 451)... does it help?
The 453 version of this diagram really emphasizes the fact that the Cooling System is U-Shaped (with hoses running under the bottom of the car, front to back), it also specifically says, "The cooling system must be filled and bled only when the engine is cold." Which supports the air in the system concerns.

66841
 

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Discussion Starter · #9 · (Edited)
I just came across this diagram (based on the 451)... does it help?
The 453 version of this diagram really emphasizes the fact that the Cooling System is U-Shaped (with hoses running under the bottom of the car, front to back), it also specifically says, "The cooling system must be filled and bled only when the engine is cold." Which supports the air in the system concerns.

View attachment 66841
Thats a nice diagram thanks. I went out and bought also today a Maddox combustion leak detector (the product, mostly 5 star rated with a few 4 stars nothing below that, from a known-to-have-cheap-tools retailer (not spamming the group with store name) with a 20 percent coupon cost 19.99 (around $50 on eBay) plus the test fluid 9.99). Later today (its nice now with the daylight so long to get tasks done) I will test to see if I get CO2 gases in the coolant tank.

Update: 7;30 PM I ran the car again and tried to test for CO2. I was able to squeeze the tester for about 30 seconds (supposed to be for a minute) then the coolant rose (the cap is off when testing) I got a negative for CO2. Tested again later for about another 30 seconds before the coolant rose in the tank and contaminated the testing liquid again. No color change again. The temperature did rise again and actually blew off the bottom radiator clamp that was not a really perfect clamp but surprised it did not hold. (screw type) I changed that clamp. When the cap is off the coolant level in the tank rises until it comes out the top. Turn the engine off it goes backs down (and then some). I am waiting to receive a vacuum/refill kit I bought that is used with a compressor to refill the coolant also. That 'T' hose will be replaced

Added 6/21: What really happened is I had an accident (as I said) to the right front that was damaged, light broken, frame broken and right side pushed back. I was far from home doing something related to work. I continued to use the car with no problem that day and drove maybe 40 miles. Suddenly, the red heat light came on. I did not continue running it. An amazing thing happened that still amazes me. I had a miracle happen. Yes, you won't believe it. It was Jan 30. I was in the middle of nowhere with my heat light that was on. I pulled with the light off from cooling a bit into an old Dunkin Donuts in the middle of nowhere. I backed up in the parking lot to the grass wondering, "do I have a few bottles of water it might take me a few miles." I backed up on the parking lot to the grass. Got out of my car to look for a couple of bottles thinking, "I need a gallon!!". At the rear of the car in the grass about 2 feet back in the middle of the rear of the car was a 1 gallon, sealed, retail bottle of water with local food-chain label. I used that without the light on to get home. This still blows me away and what I said is totally un-exaggerated. Now lets move up a couple of months: I repair the car. Take it out and drive for about 50 miles or so. When I was almost home the red light came on again. I replaced the radiator that was very slightly bent after I took the front off again. It seems to be inconsistent. Sometimes it goes longer without getting hot. The next thing I do is to run a vacuum when I get the tool that is being shipped. I tend to think it is possible that this is not a head-leak. It ran perfect until that accident (about 5 to 10 miles an hour)

6/26: I bought a Gate radiator hose that is crimped to a T that's suppose to fit the Smart (I believe this has nothing now to do with my problem I will be pulling a vacuum soon) Had to send back. The Gates is crimped in the wrong places and the T was reversed. Ordered a genuine Smart hose from local Mercedes dealer on line for $22.99. The diagram of that looked correct and exactly like the old one (obviously) (I looked at the Gates hose on Rock Auto and that looked incorrect also.)
 

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Discussion Starter · #10 · (Edited)
Appears working perfect now. Update to my issues. I have been away from the car being busy. Today it seems its working. This time I purged the rear rubber hose 3 or 4 times instead of once. I purged it, let it run from a few minutes (not long enough for it to get so hot that I could not get my hand in there. I left the spring clamp off since I would be running the car and turning off before there was much pressure. I purged it a 3rd time maybe a 4th Then I tightened a quarter turn the water heat brass sensor I made (in an aluminum short connector) to control the fan I put in front of the condenser. It has been running over an hour and no overheating even with air on. (the stock fan works with the AC so two fans are on with the air on) NOW, the lower radiator hose that was cool before is very hot. I also did notice that it would go up to 190 degrees with the software scanner then go down to 185 then go back up to 190 so the thermostat was definitely kicking in. I was concerned because after sitting for about a month I got some white smoke for a minute out the exhaust. Checking the oil it looked pristine. SO, it looks fixed. I will mention that in my case using a vacuum tool to put coolant in, the multiple purging of the rubber hose worked better. It overheated when I just used the vacuum tool
 
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