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1999 slk 230
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160 Posts
Discussion Starter #1
Hi all, after doing good search, I got more confused about the subject I was searching, so I decided to post my problem hoping to get decent advise as usual; the car is 99 SLK 230, I do not have check engine light, so every now and then I hook up my OBD scanner to see if there is any code; well it gave me two codes P0410 and P1236, the later code most relating to K40 relay, I went there checked everything found nothing the car runs fine no lose of power or nothing I had a bit dirty air filter all the connections are fine, what else should I check? in one of the threads there was a mention of air pump, where would that be? and if there is something wrong with the air-pump wouldn't that make the car run not so good? any advise is appreciated :surrender:
 

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98 red 230 slk
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454 Posts
Check and see if your supercharger clutch is constantly engaged, even at idle. If so you may have a bad/frozen clutch or the ecu is sending a constant signal. Also your aircheck valve may be going out (p0401). Time to replace it?
 

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1999 slk 230
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160 Posts
Discussion Starter #3
Check and see if your supercharger clutch is constantly engaged, even at idle. If so you may have a bad/frozen clutch or the ecu is sending a constant signal. Also your aircheck valve may be going out (p0401). Time to replace it?
Thank you for your response, if the air check valve is going bad wouldnt it make the car run not so good? also where would the air check valve be ?
 

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98 red 230 slk
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454 Posts
I'm simply going by the info your scanner gave you. The air check valve last approx 50k miles. I've replaced two. If you're tool handy you can do it. Run a search on "secondary aircheck valve" and it will answer all questions. They do go out slowly at first and don't always throw a CEL...
 

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1999 slk 230
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Discussion Starter #5
I'm simply going by the info your scanner gave you. The air check valve last approx 50k miles. I've replaced two. If you're tool handy you can do it. Run a search on "secondary aircheck valve" and it will answer all questions. They do go out slowly at first and don't always throw a CEL...
I am very handy 95 per cent of the mechanical work I need I do myself including mt motorcycles, most treads I read P1236 was relating to K40 or SC clutch the other code I had is P0410. someone was describing a shield that gets dirty, I dont know where would that be he said somewhere by the air filter about 11.2 " can shape, I could not find that so I gues I need better direction before I start any work, stay with me Ill get to the bottom of this, thank you
 

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1999 slk 230
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160 Posts
Discussion Starter #6
clutch pully

I went to the car, ask a friend to start the car while I was watching the SC pulley, I noticed the clutch was very sluggish, I am assuming that I need a new or rebuild clutch pulley, anyone in this group knows where to buy or rebuild these pulleys?
 

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98 red 230 slk
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I'm sure someone else will chime in but until then.... If the engine is warm , the s/c clutch should only engage past 2000 rpm. If you are getting engagement at idle then your clutch is catching and may only need a good cleaning. You can also unplug the s/c and see if you get complete disengagement at idle.
 

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1999 slk 230
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Discussion Starter #8
I'm sure someone else will chime in but until then.... If the engine is warm , the s/c clutch should only engage past 2000 rpm. If you are getting engagement at idle then your clutch is catching and may only need a good cleaning. You can also unplug the s/c and see if you get complete disengagement at idle.
Hi thank you for your suggestion, how do I clean the clutch
 

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1998 SLK 230
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2,650 Posts
if the clutch is faulty it would throw a code from memory something like p0806 or p0801....

clutch is disengaged at idle, but engages at above 800rpm (or so). you will here it click and see it engage. this is if the car is in D (drive).

IF the car is in N or P it will engage at around 2000rpm.

the s/c starts to build boost at around 2000rpm you will feel it "kick in" (while driving) this is the bypass valve shutting allowing to build boost and make power.

it only turns off at idle for fuel economy, save a bit of wear and tear and for noise reasons...
 

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1998 SLK 230
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2,650 Posts
not much to clean in the clutch... the gap b/w the clutch plate and pulley is about 0.9mm or less. if the gap is larger you can remove the washers inside to make the gap smaller. it will still "bite" but be noiser....

i wouldnt put any solvent or water down there as the coil can be shorted out costing you an new coil and ECU component. water or solvent also might come into the pulley bearing reducing its life
 

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1998 230 slk
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109 Posts
just changed my check valve, 135,000 miles. Completely clogged. Had the same 0410 code. Took about hour and a half. Take the air filter housing off it's easier. Also change your shut off valve while your there. Really needed a 27mm crowfoot wrench but didn't have one. A 1 1/16 open end will do also. Good luck, An indy wanted $375.00 just for labor, told him to go pound sand..................
 

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1999 slk 230
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160 Posts
Discussion Starter #12
just changed my check valve, 135,000 miles. Completely clogged. Had the same 0410 code. Took about hour and a half. Take the air filter housing off it's easier. Also change your shut off valve while your there. Really needed a 27mm crowfoot wrench but didn't have one. A 1 1/16 open end will do also. Good luck, An indy wanted $375.00 just for labor, told him to go pound sand..................
thank you for the info, If I take the parts apart can I see if it is clogged? where is a good place to buy this parts?
 

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1998 230 slk
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109 Posts
You won't be able to blow air thru the check valve if it is clogged

google part numbers

check valve 002 140 68 60
shut off valve 002 140 55 60

Both are about 60.00 bucks
 

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1999 slk 230
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160 Posts
Discussion Starter #15
just changed my check valve, 135,000 miles. Completely clogged. Had the same 0410 code. Took about hour and a half. Take the air filter housing off it's easier. Also change your shut off valve while your there. Really needed a 27mm crowfoot wrench but didn't have one. A 1 1/16 open end will do also. Good luck, An indy wanted $375.00 just for labor, told him to go pound sand..................
Ok guys, what would be the logic, 1- does these parts air check valve and the shot off valve be tested. 2 should I replace these then worry about the clutch and the pulley, which is the most expensive part $496.00.:confused:
 

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98 red 230 slk
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Well....If you would like my opinion, if it is running fine, good gpm, boost, and no CEL, then screw it.. Drive it till you get a light! No need to worry as these two things will not damage the engine if/when they fail. Oh, by the way, I have 154k miles and my slk has never been to any mechanic in the 4 1/2 years owned by me.
 

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1999 slk 230
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160 Posts
Discussion Starter #17
Well....If you would like my opinion, if it is running fine, good gpm, boost, and no CEL, then screw it.. Drive it till you get a light! No need to worry as these two things will not damage the engine if/when they fail. Oh, by the way, I have 154k miles and my slk has never been to any mechanic in the 4 1/2 years owned by me.
fact there are many
your good to listen to, in countries in the world they dont have CE light and the enjoy their cars, it is just here that re flourish the automotive industry thank you for the input

cheers
 

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1999 slk 230
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160 Posts
Discussion Starter #18
fact there are many
your good to listen to, in countries in the world they dont have CE light and the enjoy their cars, it is just here that re flourish the automotive industry thank you for the input

cheers

your good to listen to, in fact there are many countries in the world they dont have CE light and the enjoy their cars, it is just here that re flourish the automotive industry thank you for the input.
 

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1999 slk 230
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160 Posts
Discussion Starter #19
air check valve

Hi all,today I got the air check valve and replaced, a friend started the car as I watched the supercharger pulley running until around 2000 RPM, then witnessed the clutch engage, now I think that took care of the error code P0410, what about P1236, what should I do with that? or was that code related to P0410?:confused:
 

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1998 Mercedes 230 SLK
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351 Posts
P1236 probably points to a failing electrical contact, likely in the K40 relay. If you happen to know (or you are yourself) an electronics guy one could measure whether the correct voltage (12V) goes to the clutch when it should engage, and if that doesn't happen, take a look at the relay and resolder contacts. This has resolved this code issue for others, at least (see pics from the mbslk website).
 

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