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450 SLC 1975
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14 Posts
Discussion Starter · #1 ·
Hi Guys

Can anyone help i have a 75 450SLC and lately it has been using heaps of fuel (24L/100Km highway). Have been told that it could be the Intake manifold pressure sensor or air flow regulator, but the problem i have is i am not sure if the unit on the car now is the correct one as fuel consumption has always not been that good. The number on it is 02 80 100 112 does anyone know if this is right or can anyone tell me if they have a different No.
I did not know what it was at first but the unit is located on the battery side of the engine its silver with a black knob on one side and a connection on the other.

Thanks
 

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R/C107 Moderator
1986 560SL: '84 500SL: '84 280SL 5 speed: other 107s
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Fill out your profile. Location. Model and year. RHD or LHD
Picture of the part would help. I think I know what you are describing but it is not on the battery side of my LHD.
 

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500SLC #2624. Black on Black.
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5,120 Posts
Hi Guys

Can anyone help i have a 75 450SLC and lately it has been using heaps of fuel (24L/100Km highway). Have been told that it could be the Intake manifold pressure sensor or air flow regulator, but the problem i have is i am not sure if the unit on the car now is the correct one as fuel consumption has always not been that good. The number on it is 02 80 100 112 does anyone know if this is right or can anyone tell me if they have a different No.
I did not know what it was at first but the unit is located on the battery side of the engine its silver with a black knob on one side and a connection on the other.

Thanks
That is the correct part number for your car, although that is the Bosch part number, bosch part number protocal means it should actually be 0 280 100 112, doesn't make too much difference, unless you are doing an internet search.

Read this thread, it has soom good info for you: http://www.benzworld.org/forums/r-c107-sl-slc-class/1396484-whats-name-part.html

It may not be the cause of your problems though. Has the car been looked at by anyone? are there any compenents you have ruled out? Are there any other symtoms aside from high fuel usage?
 

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450 SLC 1975
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14 Posts
Discussion Starter · #4 ·
My mechanic and another guy i have spoken to seem to think thats the problem. All i cant tell you is that the injectors have been cleaned recently and also the car stalls in heavy traffic when it is hot. Is there anyting else that could be causing this as the only other cause i can think of is the IAT sensor is faulty but I am not sure if that would impact the fuel consumption but maybe its the cause of the car stalling in hot weather.
 

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R/C107 Moderator
1986 560SL: '84 500SL: '84 280SL 5 speed: other 107s
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Try pulling vacuum on the MAPS. That is an easy start. If it won't hold vacuum it is bad. If it does there may be a leak in the line.
I don' know what the IAT sensor is.
 

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500SLC #2624. Black on Black.
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Intake Air Temp sensor, the one on the air cleaner housing intake pipe.

The thing is, it could be a combination of things, and unless you test each component properly, you may end up throwing money at things that aren't the cause.

Cold start valve could be leaking, air-slide valve could be an issue, vacuum leaks (even on a D-Jet) can cause problems, any issues with ignition, that could cause misfiring can also increase fuel consumption.

I'm not trying to make it more difficult for you, just saying don't just focus on one component.

is it a mechanic that knows his way around Bosch D-Jet that is advising you on it? There are a few guys in melb with D-Jet 450's, that could loan you a MAP to test against yours, or I know a guy, John, in Horsham, who might send you a known good one to test. (although I can't guarantee that one).
 

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450 SLC 1975
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Discussion Starter · #7 ·
Is the vacuum hose on the IMP sensor because ill have to have another look, sorry i just dont know much about it?
The IAT is an intake air tempreture sensor it is that connection on the side of the air intake but i dont know if that is the cause or how to check if it is working.
 

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450 SLC 1975
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Discussion Starter · #8 ·
Is the cold start injector and the cold start valve the same thing because it seems like i may have more than one issue as sometimes on cold engine start the car will run rough. It usually would rev around 1500rpm and slowly drop as the temp increased although it should not be the case becasue it was cleaned along with the injectors not long ago.
 

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500SLC #2624. Black on Black.
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Is the cold start injector and the cold start valve the same thing because it seems like i may have more than one issue as sometimes on cold engine start the car will run rough. It usually would rev around 1500rpm and slowly drop as the temp increased although it should not be the case becasue it was cleaned along with the injectors not long ago.

Yes, they are the same thing. However, if it is leaking, cleaning won't fix it.
 

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450 SLC 1975
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Discussion Starter · #10 ·
I will have to have a look into the cold start injector. I was going to try get a new MAP sensor as its hard to know the condition of another 2nd hand one but I want to make sure that is the problem and also would like to test it with one i know is working. My mechanic had one in his shop that he was going to swap and test it with but it was a 350
 

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I will have to have a look into the cold start injector. I was going to try get a new MAP sensor as its hard to know the condition of another 2nd hand one but I want to make sure that is the problem and also would like to test it with one i know is working. My mechanic had one in his shop that he was going to swap and test it with but it was a 350
A new one will set you back AUD$3000+. No, that is not a typo.

At least that is the MB Australia list price. lfedje on here got a NOS one for his car back in March, I'm not sure how much he paid or where from.

Bosch do a 1 for 1 swap and reman on them as well.

There is some VERY good info on MPS's here: http://members.rennlist.com/pbanders/manifold_pressure_sensor.htm
 

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450 SLC 1975
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Discussion Starter · #12 ·
yeah I know because MB Melbourne were asking around that price, i don't think they want to sell it. I tried a place called imparts and they said it was around $560 still a bit of money especially since i'm not sure that it is main problem so might start investigating the other things mentioned first and see if it fixes the problem or try that bosch 1 for 1 swap is it available in Melbourne?
 

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500SLC #2624. Black on Black.
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or try that bosch 1 for 1 swap is it available in Melbourne?
I think You'd have to send it to Germany. would likely be a case of them sending you the refurbed one, and charging you a core charge, then you send them yours and they refund the core charge.
 

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'72 350SL, '85 300D, '98 E320, '19 Subaru Outback (sold '14 GLK250)
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I think You'd have to send it to Germany. would likely be a case of them sending you the refurbed one, and charging you a core charge, then you send them yours and they refund the core charge.
I wouldn't think of buying a new one without first doing the two simple tests that are in the manual - vacuum and resistance. If the old one passes those, it is more than likely good.

The 350SL one won't be much different - you won't hurt anything by trying it.
 

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1965 220SEb coupe 1988 560SEC 1993 300CE
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on second thought

I inquired about having my MAP rebuilt through the Bosch 1:1 remanufacture program. I thought I had hit pay-dirt on how to help make the old '73 run like new again, but...the cost, while not the inobtainium price of new, is rather steep as well. I was quoted 600 EUROS for a MAP rebuild. Ooofff...might as well call it an even thousand bucks when you are said and done. You can find the information on the program here:

Bosch Automotive Tradition

Regardless, it is nice to know it is an option.
 

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1976 UK Delivered 450SLC
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I to have a 1975 450SLC and was getting in excess of 25 litres per 100 when I bought it. It was not one thing causing the high fuel consumption but many. I found timing was set to TDC, 2 ignition leads were open circuit (this thing will run on 6 cylinders with no problems) fuel mixture was also HIGH which I adjusted down. Now she gets 16-18 litres around town and better than 14's on a run.
 

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'72 350SL, '85 300D, '98 E320, '19 Subaru Outback (sold '14 GLK250)
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12,289 Posts
I to have a 1975 450SLC and was getting in excess of 25 litres per 100 when I bought it. It was not one thing causing the high fuel consumption but many. I found timing was set to TDC, 2 ignition leads were open circuit (this thing will run on 6 cylinders with no problems) fuel mixture was also HIGH which I adjusted down. Now she gets 16-18 litres around town and better than 14's on a run.
With the D-Jets, you have to dod just what you did. Go through each system methodically just as outlined in the shop manual.

Only things not covered well are how to check the trigger points and the AAV. Both really important.

And then, most owners don't have access to a CO analyser (or modern equivalent) and it is the only way to set these cars up to run efficiently.

L/100km?? Only in Canada eh? Or in UK/Aus/NZ too?
 
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