M111.955 pinging after gasket job
05-08-2019, 08:57 AM
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W203 C200 Kompressor 2002 (M111k)
M111.955 pinging after gasket job
Hello forum members,
I'm obviously new to this amazing forum. I came across a 6-year-old post discussing a problem that I've been suffering from for almost a year! So I decided I should be part of such knowledge base.
This has started happening after a head gasket job. I have been studying the design of this engine carefully. A possible cause would be that whoever installed the timing chain back didn't ensure that the intake cam adjuster was at the fully retarded position. This would cause the intake cam to be always more advanced than it should, which would in turn increase overlap, and increase dynamic compression ratio.
Increasing overlap between intake and exhaust valve opening events would cause an increase in fuel consumption, a louder (and better) sounding exhaust, and with high octane fuel can cause an increase in low end torque. Increasing dynamic compression ratio would cause this pinging sound when the engine is under load at low rpm when the cam adjuster is signaled by the ECU to advance intake cam timing. The pinging sound disappears at higher rpm when the cam adjuster is commanded back to the retarded position.
I hope my explanation was clear enough. Let me know if you have any conclusions.
I am glad to be part of this forum.
I'm obviously new to this amazing forum. I came across a 6-year-old post discussing a problem that I've been suffering from for almost a year! So I decided I should be part of such knowledge base.
This has started happening after a head gasket job. I have been studying the design of this engine carefully. A possible cause would be that whoever installed the timing chain back didn't ensure that the intake cam adjuster was at the fully retarded position. This would cause the intake cam to be always more advanced than it should, which would in turn increase overlap, and increase dynamic compression ratio.
Increasing overlap between intake and exhaust valve opening events would cause an increase in fuel consumption, a louder (and better) sounding exhaust, and with high octane fuel can cause an increase in low end torque. Increasing dynamic compression ratio would cause this pinging sound when the engine is under load at low rpm when the cam adjuster is signaled by the ECU to advance intake cam timing. The pinging sound disappears at higher rpm when the cam adjuster is commanded back to the retarded position.
I hope my explanation was clear enough. Let me know if you have any conclusions.
I am glad to be part of this forum.
05-08-2019, 10:37 AM
#2
Member
Your theory kind of makes sense but I don’t think the M111 engines had variable valve timing. What year is your car? Early w203s used the m111 but starting with the 2003 model year (US) they switched to m271 engines with vvt.
i replaced a HG on an m111.955 in a w202. I don’t recall doing anything special to the cam gears when I timed the valves. I used pins to lock the cams, lined up the crank, and bolted the gears back on using the procedure described in Alldata.
It started on first crank and ran fine (minus a few coolant and oil leaks I had to hunt down!). In my case, the head wasn’t warped so the machine shop removed the minimum amount when they skimmed the head.
Have you also checked the knock sensor and wiring? Are you using the recommended octane fuel? Have you tried an octane booster— perhaps a booster might help if you had to machine more than minimums off the head and raised the compression too much.
5by5
i replaced a HG on an m111.955 in a w202. I don’t recall doing anything special to the cam gears when I timed the valves. I used pins to lock the cams, lined up the crank, and bolted the gears back on using the procedure described in Alldata.
It started on first crank and ran fine (minus a few coolant and oil leaks I had to hunt down!). In my case, the head wasn’t warped so the machine shop removed the minimum amount when they skimmed the head.
Have you also checked the knock sensor and wiring? Are you using the recommended octane fuel? Have you tried an octane booster— perhaps a booster might help if you had to machine more than minimums off the head and raised the compression too much.
5by5
05-08-2019, 10:52 AM
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W203 C200 Kompressor 2002 (M111k)
Hello 5by5,
Yes, the m111.955 has variable cam timing on the intake side only. The procedure you described should result in a perfectly running engine, but that is IF it was followed. I bought the car after the HG job, and given my experience with mechanics here in Egypt, I assume he hadn't used a cam locking tool, but rather just marked the chain links with their corresponding cam gear teeth, and reassembled accordingly.
At first, I suspected the same, that the machinest took more than needed from the head, which increased static compression, so I tried premium (which is RON 95 here) and added an STP octane booster. However, as I said, the sound is only there when the came adjuster is activated. If I removed the adjuster magnet connector, the car sounds perfectly normal, which made me believe that the problem is with dynamic compression, not static.
Yes, the m111.955 has variable cam timing on the intake side only. The procedure you described should result in a perfectly running engine, but that is IF it was followed. I bought the car after the HG job, and given my experience with mechanics here in Egypt, I assume he hadn't used a cam locking tool, but rather just marked the chain links with their corresponding cam gear teeth, and reassembled accordingly.
At first, I suspected the same, that the machinest took more than needed from the head, which increased static compression, so I tried premium (which is RON 95 here) and added an STP octane booster. However, as I said, the sound is only there when the came adjuster is activated. If I removed the adjuster magnet connector, the car sounds perfectly normal, which made me believe that the problem is with dynamic compression, not static.
Your theory kind of makes sense but I don’t think the M111 engines had variable valve timing. What year is your car? Early w203s used the m111 but starting with the 2003 model year (US) they switched to m271 engines with vvt.
i replaced a HG on an m111.955 in a w202. I don’t recall doing anything special to the cam gears when I timed the valves. I used pins to lock the cams, lined up the crank, and bolted the gears back on using the procedure described in Alldata.
It started on first crank and ran fine (minus a few coolant and oil leaks I had to hunt down!). In my case, the head wasn’t warped so the machine shop removed the minimum amount when they skimmed the head.
Have you also checked the knock sensor and wiring? Are you using the recommended octane fuel? Have you tried an octane booster— perhaps a booster might help if you had to machine more than minimums off the head and raised the compression too much.
5by5
i replaced a HG on an m111.955 in a w202. I don’t recall doing anything special to the cam gears when I timed the valves. I used pins to lock the cams, lined up the crank, and bolted the gears back on using the procedure described in Alldata.
It started on first crank and ran fine (minus a few coolant and oil leaks I had to hunt down!). In my case, the head wasn’t warped so the machine shop removed the minimum amount when they skimmed the head.
Have you also checked the knock sensor and wiring? Are you using the recommended octane fuel? Have you tried an octane booster— perhaps a booster might help if you had to machine more than minimums off the head and raised the compression too much.
5by5
05-08-2019, 03:42 PM
#4
Member
Sounds like you need to open it up and retime the valves then. BTW, I didn’t have the camshaft locking tool—I just inserted pins through the cams which indexed to matching holes in the head.
5by5
5by5
05-09-2019, 05:59 AM
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W203 C200 Kompressor 2002 (M111k)
