I'm trying to figure out how. (f/u with mechanic questions)
SCOUT5
Member Posts: 16,181 ✭✭✭✭
......... cleaning the mass air flow sensor on a 2001 Mercedes makes the air conditioner compressor clutch lock up. There has to be a correlation but I can't figure it out. I cleaned the MAS, started the engine to see if it helped the low end idle issue it was having. The engine bogged down to barely running, the alternator warning came on and smoke started rolling up. I shut it off and as the smoke cleared I watched as the serpentine belt parted and went slack. The air conditioner compressor will not turn.
I heard a noise the other day that made me think :what's that". The next day I raised the hood. started the engine, didn't hear it and after failing to find the issue decided it must have been road noise or a piece of debris hung on the car and had fell off. Though I knew it didn't really sound like that. But what ever it was it had quit making noise. Seems it was the compressor. What a PIA.
Comments
It's the screwdriver you used to loose the hose clamps holding the MAS in place. It fell between the compressor pulley and the block.
I wish,
There may be two components to the clutch. The actual clutch and the bearing. Sounds like the bearing siezed. See if the pulley will turn. If it won't your belt will be burnt and need replaced also. You may be able to replace the bearing and the clutch while you're at it without replacing the compressor. You may even be able to do it without taking the compressor out. But it takes a bunch of patience.
If you take it apart, beware of hidden snap rings.😲
Mercedes = high dollar maintenance
It won't turn and the belt is already burned through. Be nice if I only have to replace the clutch.
Call me stupid, but can the compressor on that thing REALLY be that hard to turn, that it can burn the belt? It makes me think the compressor failed internally and locked in place. Then if the clutch seized it would burn the belt.
But I've been called a lot worse than "stupid".
The pulley is directly connected to the bearing. The pulley turns when the engine is running. It isn't until the clutch is actuated the compressor turns. So if the clutch isn't actuated and the pulley won't turn, the bearing is siezed. to re-phrase, the pulley and compressor are only connected when the engine is running and the a/c is on. I'm referring to the pulley bearing here. There are other bearings in the compressor itself. So Nanuq, I don't and would never consider you stupid. Like most, I got my experience from bad experience and a 35 mile ride in a tow truck.
What model? I've been working on Benz's for 20+ years.
The comps fail pretty regularly on all models.
2001 E 320, It has 202000 miles on it. The auto-climate control was on but the AC shouldn't have kicked on as it was cool out.
If set on "auto" mode the compressor will cycle on and off unless the EC button on the bottom row if your control panel is pushed. I doubt there is a connection between cleaning the MAS and the comp failure.
000 230 70 11 is the MB part number for the comp. I like Nissens and Denso's. Really should replace the condenser at a minimum, I would also replace the drier and expansion valve.
What was your initial idle issue and what codes were there?
I know there is no connection. The idle issue was slow rough idle that would correct after a minute by idling up, happened when I stopped for a light or something. When cold if I put it in gear as soon as it started It would go. If I waited, I had to wait for it to warm all the way up before it would stay running when I put it in gear. When running rough if I tried to take off it would be slow to accelerate as the engine had to gain rpms to level out. I figured it was an air issue, thus cleaning the MAS, filter is clean. I was going to look for vacuum leaks too. I have a diagnostic tool but hadn't hooked it up yet. Engine runs good other than this, has power, accelerates well, firing in all cylinders.
Here are the codes it is throwing.
P0410- Secondary Air injection system malfunction
P0170 Fuel trim bank 1
P0173 Fuel trim bank 2
P0170 Throttle pedal position sensor
I installed a serpentine belt that bypassed the air conditioner, that's working fine and lets me fix the A/C later.
Idle and cold start issue remains.
My plan for now is clean the throttle body sensor, inspect for damage, test the voltage (I've never check one but I guess I'll figure it out.
Since bank 1 and bank 2 are faulted I'm thinking the MAS may be faulty. I cleaned it but it didn't really look dirty and cleaning it made no difference.
I pulled up an article on the P0410 code and it tells me that can be a fuse, a relay, the air pump or some blockage. I'll look it over better in a couple of days. If this pump is bad that's a pricey replacement so I'm hoping not.
Any suggestions?
I'll just go way out there and say, torque converter. If you're using a $5,000 scanner, go get the $10,000 model. You did say it was a MB. You could just surrender and take it to a dealership. I think you're going to end up there anyway. Whatever you do, don't go scrubbing and spraying in the throttle body. I did . $1,300. New throttle body. Not even a MB. Bad experience.
Just start replacing parts: sooner or later you'll either find the correct part or you'll have a lot more experience and it still won't run right.