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M270/M274 camshaft faults

Cjay110

New Member
Joined
Aug 23, 2023
Messages
6
Location
Lincolnshire
Car
Mercedes 250
Hi everyone,

I've recently been hearing a rattle only on cold start up. Checked codes and initially had P001685 Inlet camshaft timing control value/signal outside max range.
Since that has gone and now I'm got 2 faults stored for each camshaft sensor. (Component faulty faults)

I replaced the timing chain and still have these faults although it does start better. I also carried out camshaft adaptation afterwards and failed.
Is it likely to be the adjuster at fault also? Is there any way of checking it to confirm?

Thanks in advance
 
The M274 has the Camtronic valve lift system, but from what you describe is sounds like a straightforward camshaft position sensor failure? There are two of them, aka 'magnets' or 'hall sensor'. Typically they malfunction when warm, causing intermittent non-starting when the engine is hot. Have you had the codes read with STAR?
 
On another note, when replacing the timing chain, it's a good idea to replace also the guides and the hydraulic timing chain tensioner as matter of course. The hydraulic chain tensioner can leak which causes a rattle at startup because the oil drains out of the tensioner straightaway (it's not holding the oil pressure). Normally you'll only get the rattle at cold startup, until the oil pressure builds up.
 
On another note, when replacing the timing chain, it's a good idea to replace also the guides and the hydraulic timing chain tensioner as matter of course. The hydraulic chain tensioner can leak which causes a rattle at startup because the oil drains out of the tensioner straightaway (it's not holding the oil pressure). Normally you'll only get the rattle at cold startup, until the oil pressure builds up.
Thankyou for your response.

Apologies for my lack of information, I also replaced the chain tensioner.

Guides and everything else was checked as this repair involved splitting the chain and feeding in the new one and rejoining. The new chain came already split and supplied with pins and chain plates to reassemble (Genuine Mercedes part)

The vehicle has been scanned with xentry and they advised to check the chain. The chain was very slack so I replaced.

It's possible this is a m270? The vehicle doesn't have camtronic. The cams are adjusted via cam adjuster sprockets at the chain side of the engine. The vehicle has already had the magnets and both intake and exhaust cam sensors replaced also. (Genuine parts)

I've read alot about the cam sensor reluctor wheel being pressed onto the camshaft and possibility of it spinning on the cam to throw a fault. But I checked and it all looks OK? Is it special tools to check properly or just via aligning marks?
 
On another note, when replacing the timing chain, it's a good idea to replace also the guides and the hydraulic timing chain tensioner as matter of course. The hydraulic chain tensioner can leak which causes a rattle at startup because the oil drains out of the tensioner straightaway (it's not holding the oil pressure). Normally you'll only get the rattle at cold startup, until the oil pressure builds up.
As you've said yes the rattle was only at cold start up, that's all solved, but still have long crank, EML on and P001685 Inlet camshaft timing control value/signal outside max range.
 
The M270 and M274 are identical, the only difference is that the M270 is transverse and used in FWD applications, while the M274 is longitudinal and used in RWD applications.
 
Have the camshaft position sensors been replaced?
 

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