crankshaft sensor??????

turbopete

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ok for the benefit of Malcolm who was away when i had the original post, my car is reluctant or fails to start when the temp guage reads above 80 degrees. this happened again today. opened the bonnet and the pipe going into the pre filter was empty. is there any way i can set up the car so that i can test the sensor without having to crawl under the car, allowing it to cool to a point that it may start again?
 

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ok for the benefit of Malcolm who was away when i had the original post, my car is reluctant or fails to start when the temp guage reads above 80 degrees. this happened again today. opened the bonnet and the pipe going into the pre filter was empty. is there any way i can set up the car so that i can test the sensor without having to crawl under the car, allowing it to cool to a point that it may start again?

if the pipe was emtpy of fuel Pete, then you have a air leak into the pipe, only ever changed one crank sensor on a 300 in my life!!
 
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i already knew about the air leak. its never a problem cold though. someone suggested it could be the crank sensor breaking down and not sending pulses to the cut off valve or wherever it goes to tell the car to turn the fuel on. when engine is cold, pipe is always half full. this is the problem ive been trying to solve from day1 with the car! got a good 2nd hand fuel heater to fit next. im also going to replace most of the feed side rubber hoses and check the metal pipes are clear with an airline next time im at my parents! all usual, and some not so usual suspects have been replaced. im also thinking of fitting non return valves and maybe even a hand primer somewhere in the system. any thoughts?
 

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But these things never stop when hot for this,,has he got 2 faults, and the fuel has run back as it has not been used
 

Cole@MBS

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But these things never stop when hot for this,,has he got 2 faults, and the fuel has run back as it has not been used

No Malc, they were worse when hot, once cold they used to seal again, when hot, they let air run into the system, done shed loads of these!
 
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There,s a "o" ring on the side of the pump which is prone to leaking air in on the 300, probley that spilt Pete!!

side of which pump? shut off valve and o ring replaced, all plastic pipes around filter, including o rings, pre filter and main filter replaced, tank strainer replaced, var never misses a beat when running. switched it off, left it 10 mins, wouldnt start. do that at a lower engine temp, not a problem!
 

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Ok Pete, if you have no fuel in the clear pipes after turning of, you have a air leak, theres nothing other it can be, you stated the facts, no fuel in the pipes, hence, air leaking back into the system!!
 
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ok then youre right. i was told i may not be but hey ho!!!! question is, where is it coming in from, seeing as ive changed evert o ring that im aware of beween the injector pump and the fuel heater? if i hold revs at about 1500-1800 rpm, i see air bubbles in 1st clear pipe as it exits the fuel heater, so it surely must be tank side of that is it?

on tank side ive replaced tank strainer, so looking 4 options now if poss! help!!!!!
 
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also when the pipe was empty and the car failed to start, i waited about 30mins for a jump start. by this point the pipe was half full (as it always is) again. this is whats puzzling me and the reason why i think the crank sensor was suggested. can anyone shed any light on this? i seem to be going around in circles!
 

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Buy a crankshaft sensor and try it. Or even better get someone who knows mercedes cars very well to look at it. Your problem would be solved by now.
Thats the beauty of forums, you may be misdescribing something, and someone may be giving you answers which over an internet connection are merely educated guesses based on experience., guesses which may be right to your description, but if your description is incorrect, the wrong advice.
The amount of customers i have who try to explain a fault and when i look at their description was not remotely close.
 
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turbopete

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any idea where the o ring is that sam unit was talking about?
 
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turbopete

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Buy a crankshaft sensor and try it. Or even better get someone who knows mercedes cars very well to look at it. Your problem would be solved by now.
Thats the beauty of forums, you may be misdescribing something, and someone may be giving you answers which over an internet connection are merely educated guesses based on experience., guesses which may be right to your description, but if your description is incorrect, the wrong advice.
The amount of customers i have who try to explain a fault and when i look at their description was not remotely close.

that would be a great idea except for 2 things.

1. my financial situation wont allow me to spend £68 per half hour (i was quoted when i thought i needed star for bas light) at dealers and indie are about £80+ per hour im told.

2. the indies are ex staff of the dealers, the dealer will talk to me which the indies wont, and this particular problem has never been come across before in their experience by the dealers and the indies seem to do very few mercs now compared to volvo bmw saab etc that they also "specialise" in! plus the car is needed every day, hence why im trying to sort it myself. its just knowing which seals etc people are talking about as i seem to have replaced all of them that im aware of!

for the record im ex trade myself. just never come across so many pointless seals etc that could be done without if they had thought the design through a little better! i also seem to have replaced almost everything so im probably going to finish the job off now! replacement fuel heater sourced from broken car that ran and started perfectly, so i can buy some fuel hose and jubilee clips and replace the rubber parts, and then theres nothing else i can think of!

i may include some non return valves and possibly even a hand primer installation (in line) during this work. i would appreciate any feedback anyone may have about doing this.
 
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