Thermostat change on M273 engine
02-04-2019, 05:29 PM
#1
Senior Member
Thread Starter
Thermostat change on M273 engine
on my way to work this morning my check engine light came on. the common p0128 error, indicating a failing thermostat. relatively cheap part. my question is this..i noticed on the older 550 engines, attached to the thermostat is a nice, easily movable radiator hose..attached to my m273 engine, is some stupid clunky huge metal tube, that makes any work in that area basically impossible. What purpose does it serve? can i just get rid of that and use the old style radiator hose?
02-04-2019, 06:40 PM
#2
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'15 S550, '10 E350 P1/P2, '02 ML320
I'm gonna need pictures. Both the M273 in my '08 S550 and the M272 in my wife's '10 E350 have a rubber hose with a metal end that all but disappears when it is clicked into the thermostat housing.
02-04-2019, 06:56 PM
#3
Senior Member
Thread Starter
underneath the oil filter..attached to my thermostat housing is this stupid metal pipe...upon further research it has something to do with 4matic
02-05-2019, 05:45 AM
#5
Super Member
on my way to work this morning my check engine light came on. the common p0128 error, indicating a failing thermostat. relatively cheap part. my question is this..i noticed on the older 550 engines, attached to the thermostat is a nice, easily movable radiator hose..attached to my m273 engine, is some stupid clunky huge metal tube, that makes any work in that area basically impossible. What purpose does it serve? can i just get rid of that and use the old style radiator hose?
Last edited by EasyPhil; 02-05-2019 at 09:41 AM.
02-05-2019, 06:22 AM
#6
Senior Member
Thread Starter
the sad part is that all of those parts you mentioned have been replaced within the last 2 years..the belt tensioner, both pulleys and the belt were replaced in december
02-05-2019, 09:03 AM
#7
Senior Member
That metal hose is the 4matic version of an upper radiator hose
Easy to remove, I believe there is one screw on the right side, then two hose clamps that come off. They are the clip type, not regular clamps. Pull out the clip and the hose comes off. Key to putting it back together is reinstall the clip on the hose FIRST, then push the hose on. That way you know it is on properly when it clicks. You can't put the hose on THEN the clip, because you won't be sure that it is on completely.
Once that hose is off I think there were 2 or 3 screws holding the thermostat housing, along with an electrical connector.
If you have all the tools it's less than 30 minutes work from what I recall (although I did it about 5 years ago so don't remember exactly)
I didn't drain any coolant, since the hose and thermostat are so high up they were quite empty. Make SURE you do this on a cold engine though. I believe a small amount of coolant spilled but if you have a rag or two underneath it isn't a problem. Check coolant level once the job is complete.
Easy to remove, I believe there is one screw on the right side, then two hose clamps that come off. They are the clip type, not regular clamps. Pull out the clip and the hose comes off. Key to putting it back together is reinstall the clip on the hose FIRST, then push the hose on. That way you know it is on properly when it clicks. You can't put the hose on THEN the clip, because you won't be sure that it is on completely.
Once that hose is off I think there were 2 or 3 screws holding the thermostat housing, along with an electrical connector.
If you have all the tools it's less than 30 minutes work from what I recall (although I did it about 5 years ago so don't remember exactly)
I didn't drain any coolant, since the hose and thermostat are so high up they were quite empty. Make SURE you do this on a cold engine though. I believe a small amount of coolant spilled but if you have a rag or two underneath it isn't a problem. Check coolant level once the job is complete.
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02-05-2019, 09:41 AM
#8
Super Member
Back then was the time to do that, but I get it. When I changed the gaskets on the oil cooler it made sense to change the thermostat as well.
02-05-2019, 03:54 PM
#9
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S550 w140, 07 S550
I have replaced the thermostat last year after my oil cooler gasket failed and put all the coolant into the engine and then almost overheated my car on the freeway. Oil level shot right up.
The thermostat rubber had actually gotten wrinkled because of the oil going through it, and although I was not getting any codes or issues with the heat, I went ahead and changed it.
*** Definitely make sure oil cooler gasket is replaced if you haven't already. It almost cost me the M273 engine .
The thermostat rubber had actually gotten wrinkled because of the oil going through it, and although I was not getting any codes or issues with the heat, I went ahead and changed it.
*** Definitely make sure oil cooler gasket is replaced if you haven't already. It almost cost me the M273 engine .
02-05-2019, 04:20 PM
#10
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Thread Starter
I have replaced the thermostat last year after my oil cooler gasket failed and put all the coolant into the engine and then almost overheated my car on the freeway. Oil level shot right up.
The thermostat rubber had actually gotten wrinkled because of the oil going through it, and although I was not getting any codes or issues with the heat, I went ahead and changed it.
*** Definitely make sure oil cooler gasket is replaced if you haven't already. It almost cost me the M273 engine .
The thermostat rubber had actually gotten wrinkled because of the oil going through it, and although I was not getting any codes or issues with the heat, I went ahead and changed it.
*** Definitely make sure oil cooler gasket is replaced if you haven't already. It almost cost me the M273 engine .
02-05-2019, 04:46 PM
#11
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S550 w140, 07 S550
My car started overheating and fans were blowing at full speed. The temp started going up close to the red dot.
I immediately pulled over on the side of the freeway. Fans were still at full speed which means:
1) either there is no coolant in the radiator and the fans can't cool off anything, or
2) the water pump has failed to circulate the coolant from the radiator to the engine causing the coolant in the engine to get hotter than operating temperature which triggers the fans to work at full speed by default.
(Either way I had to pull over )
Pulled the dipstick out, saw the oil level was way over the high mark ; by 2 inches.
Got a rag and laid it over the coolant reservoir and loosened the cap enough where just a bit of air was releasing. Once the air was out the cooling system, pulled the cap out and sure enough there was no coolant in the reservoir.
I was 10 min away from home so I added some more water and would turn the engine off at every stop. Had to pull the start button out and put the key in the ignition. Using the key, I could turn off the car and let it roll into a light or traffic and turn it back on without having to use the brake pedal if I was still rolling.
It was a messed up situation but when I got home and did some troubleshooting I realized; Coolant was in the oil, but the coolant tank also had oil marks in it.
Verdict:
1) when the coolant would get to normal temperature, the water cooling system would create enough pressure and start sipping through the gasket (that connects the oil cooler to the engine block) and leak into the hole next to it which was the oil passthrough hole.
2) If I started the engine when cold (when the cooling system had no pressure), the oil (which had a higher pressure) would sip through the same gasket and put the oil into the coolant port; so I never noticed my cooler tank ever empty when I would check it in the morning at random intervals.
For a $25 gasket, M273 almost overheated. I am sure if my mother or gf were driving it..I would be looking for an engine now.
02-05-2019, 06:12 PM
#12
Senior Member
Thread Starter
I replaced it myself. I never let the dealer do any work in my car unless they have to do an online programming module or wheel alignment.
My car started overheating and fans were blowing at full speed. The temp started going up close to the red dot.
I immediately pulled over on the side of the freeway. Fans were still at full speed which means:
1) either there is no coolant in the radiator and the fans can't cool off anything, or
2) the water pump has failed to circulate the coolant from the radiator to the engine causing the coolant in the engine to get hotter than operating temperature which triggers the fans to work at full speed by default.
(Either way I had to pull over )
Pulled the dipstick out, saw the oil level was way over the high mark ; by 2 inches.
Got a rag and laid it over the coolant reservoir and loosened the cap enough where just a bit of air was releasing. Once the air was out the cooling system, pulled the cap out and sure enough there was no coolant in the reservoir.
I was 10 min away from home so I added some more water and would turn the engine off at every stop. Had to pull the start button out and put the key in the ignition. Using the key, I could turn off the car and let it roll into a light or traffic and turn it back on without having to use the brake pedal if I was still rolling.
It was a messed up situation but when I got home and did some troubleshooting I realized; Coolant was in the oil, but the coolant tank also had oil marks in it.
Verdict:
1) when the coolant would get to normal temperature, the water cooling system would create enough pressure and start sipping through the gasket (that connects the oil cooler to the engine block) and leak into the hole next to it which was the oil passthrough hole.
2) If I started the engine when cold (when the cooling system had no pressure), the oil (which had a higher pressure) would sip through the same gasket and put the oil into the coolant port; so I never noticed my cooler tank ever empty when I would check it in the morning at random intervals.
For a $25 gasket, M273 almost overheated. I am sure if my mother or gf were driving it..I would be looking for an engine now.
My car started overheating and fans were blowing at full speed. The temp started going up close to the red dot.
I immediately pulled over on the side of the freeway. Fans were still at full speed which means:
1) either there is no coolant in the radiator and the fans can't cool off anything, or
2) the water pump has failed to circulate the coolant from the radiator to the engine causing the coolant in the engine to get hotter than operating temperature which triggers the fans to work at full speed by default.
(Either way I had to pull over )
Pulled the dipstick out, saw the oil level was way over the high mark ; by 2 inches.
Got a rag and laid it over the coolant reservoir and loosened the cap enough where just a bit of air was releasing. Once the air was out the cooling system, pulled the cap out and sure enough there was no coolant in the reservoir.
I was 10 min away from home so I added some more water and would turn the engine off at every stop. Had to pull the start button out and put the key in the ignition. Using the key, I could turn off the car and let it roll into a light or traffic and turn it back on without having to use the brake pedal if I was still rolling.
It was a messed up situation but when I got home and did some troubleshooting I realized; Coolant was in the oil, but the coolant tank also had oil marks in it.
Verdict:
1) when the coolant would get to normal temperature, the water cooling system would create enough pressure and start sipping through the gasket (that connects the oil cooler to the engine block) and leak into the hole next to it which was the oil passthrough hole.
2) If I started the engine when cold (when the cooling system had no pressure), the oil (which had a higher pressure) would sip through the same gasket and put the oil into the coolant port; so I never noticed my cooler tank ever empty when I would check it in the morning at random intervals.
For a $25 gasket, M273 almost overheated. I am sure if my mother or gf were driving it..I would be looking for an engine now.
02-06-2019, 09:39 AM
#13
Super Member
One other thing you may want to take a look at is the temperature control valve at the back of the engine. It's plastic and after 10 years and over 180,000 miles the connector for the hose broke off dumping all of the coolant out of the car, good thing I had just pulled into a parking spot.
02-06-2019, 03:10 PM
#14
Senior Member
Thread Starter
One other thing you may want to take a look at is the temperature control valve at the back of the engine. It's plastic and after 10 years and over 180,000 miles the connector for the hose broke off dumping all of the coolant out of the car, good thing I had just pulled into a parking spot.
02-06-2019, 04:51 PM
#15
Super Member
02-10-2019, 06:42 PM
#16
Senior Member
Thread Starter
to build on this question, does anyone know if its possible to remove the radiator fan/shroud without having to drain the cooling system or need to remove this metal pipe? if so, please explain
02-10-2019, 06:47 PM
#17
Senior Member
If you are removing the radiator of course you need to drain the system.
If removing the the upper radiator hose with metal shield then no as long as you do it cold. It will drain about 1/4 to 1/2 quart of coolant at most and you can top up after
this hose shroud thing is easy to remove. One torx screw, one small hose clamp then remove both large hose ends. To do that you pull he retaining clip and then disconnect the hose. You’ll see what I mean when you look at it
Removing hose and shroud is a 5 min job. Entire radiator is much longer.
If removing the the upper radiator hose with metal shield then no as long as you do it cold. It will drain about 1/4 to 1/2 quart of coolant at most and you can top up after
this hose shroud thing is easy to remove. One torx screw, one small hose clamp then remove both large hose ends. To do that you pull he retaining clip and then disconnect the hose. You’ll see what I mean when you look at it
Removing hose and shroud is a 5 min job. Entire radiator is much longer.
02-10-2019, 06:50 PM
#18
Senior Member
Thread Starter
If you are removing the radiator of course you need to drain the system.
If removing the the upper radiator hose with metal shield then no as long as you do it cold. It will drain about 1/4 to 1/2 quart of coolant at most and you can top up after
this hose shroud thing is easy to remove. One torx screw, one small hose clamp then remove both large hose ends. To do that you pull he retaining clip and then disconnect the hose. You’ll see what I mean when you look at it
Removing hose and shroud is a 5 min job. Entire radiator is much longer.
If removing the the upper radiator hose with metal shield then no as long as you do it cold. It will drain about 1/4 to 1/2 quart of coolant at most and you can top up after
this hose shroud thing is easy to remove. One torx screw, one small hose clamp then remove both large hose ends. To do that you pull he retaining clip and then disconnect the hose. You’ll see what I mean when you look at it
Removing hose and shroud is a 5 min job. Entire radiator is much longer.
02-10-2019, 07:26 PM
#19
Senior Member
Oh ok. Shroud was pretty easy from what I remember. Some clamps that get pried off at the top with a screwdriver, some wiring and other clips and it lifts up and out. There are locator tabs at the bottom so make sure when you put it back, the tabs are engaged properly into the slots on the bottom.
Not it sure if you need to remove it. Look at WIS for your alternator 8nstructions and see. I thought the Alternator unbolted and was either removed from bottom or raised to remove from top.
Not it sure if you need to remove it. Look at WIS for your alternator 8nstructions and see. I thought the Alternator unbolted and was either removed from bottom or raised to remove from top.
02-10-2019, 07:32 PM
#20
Senior Member
Thread Starter
Oh ok. Shroud was pretty easy from what I remember. Some clamps that get pried off at the top with a screwdriver, some wiring and other clips and it lifts up and out. There are locator tabs at the bottom so make sure when you put it back, the tabs are engaged properly into the slots on the bottom.
Not it sure if you need to remove it. Look at WIS for your alternator 8nstructions and see. I thought the Alternator unbolted and was either removed from bottom or raised to remove from top.
Not it sure if you need to remove it. Look at WIS for your alternator 8nstructions and see. I thought the Alternator unbolted and was either removed from bottom or raised to remove from top.
