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986Jim · 03-14-2006, 03:43 AM

Does the sound increase and decrease with RPM? You say it's between 1000-1300rpm. If you rev from 1000 to 1300 in neutral does the ticking get faster as the rpm gets higher?

You either spun a main or rod bearing through detonation because of using the wrong gas, or low or dirty oil situation. I highly doubt it's a manual head so you won't have lifters to adjust it will most likely be a hydraulic head. If so you could be low on oil and the lifters are not getting "pumped up" enough.

Is it worse better or no change with cold or hot motor? If its just on a cold motor then Mercedes could be using large ring gaps stock for a Kompressor motor which have noise when the motor is cold. Upon piston expansion the noise goes away as the gap tightens up. I have seen factory turbo/super cars use gaps as large as .0008 before which is stupid large then run with an equally large piston/wall gap.

Other things could be heat shields etc but they wont really change with RPM so much. What you need to discover is if it's mechnically linked to RPM if so then your into the motor for sure. Low octane on a Kompressor will cause detonation and make the motor spin a bearing. For your case I hope thats not it.

Just for educational purposes for those not knowing what a spun bearing is.. Around the crank where it lays in the block there are bearings. They are not ball bearings but just aluminum pieces (two) that go around the crank with a hole in the center like half moons on each side about 3/4" wide. Oil is pumped into the surface of the bearing and the crank floats on it.

When a bearing spins, it attaches it self to the crank beause of detonation where the crank is crashing into it all the time with a lot of force or low oil causing lots of heat and it fuses to the crank and the bearing spins around with the crank. The bearing spinning is now not allowing that oil to get throug the hole in the center which is where the crazy ticking noise comes from. Eventually it lockes up all together from friction and the rod flyes through the block. I have seen it in a few different Mercedes motors before.

03-14-2006, 03:43 AM	#13
986Jim Registered User Join Date: Feb 2006 Location: Toronto Ontario Posts: 291	Does the sound increase and decrease with RPM? You say it's between 1000-1300rpm. If you rev from 1000 to 1300 in neutral does the ticking get faster as the rpm gets higher? You either spun a main or rod bearing through detonation because of using the wrong gas, or low or dirty oil situation. I highly doubt it's a manual head so you won't have lifters to adjust it will most likely be a hydraulic head. If so you could be low on oil and the lifters are not getting "pumped up" enough. Is it worse better or no change with cold or hot motor? If its just on a cold motor then Mercedes could be using large ring gaps stock for a Kompressor motor which have noise when the motor is cold. Upon piston expansion the noise goes away as the gap tightens up. I have seen factory turbo/super cars use gaps as large as .0008 before which is stupid large then run with an equally large piston/wall gap. Other things could be heat shields etc but they wont really change with RPM so much. What you need to discover is if it's mechnically linked to RPM if so then your into the motor for sure. Low octane on a Kompressor will cause detonation and make the motor spin a bearing. For your case I hope thats not it. Just for educational purposes for those not knowing what a spun bearing is.. Around the crank where it lays in the block there are bearings. They are not ball bearings but just aluminum pieces (two) that go around the crank with a hole in the center like half moons on each side about 3/4" wide. Oil is pumped into the surface of the bearing and the crank floats on it. When a bearing spins, it attaches it self to the crank beause of detonation where the crank is crashing into it all the time with a lot of force or low oil causing lots of heat and it fuses to the crank and the bearing spins around with the crank. The bearing spinning is now not allowing that oil to get throug the hole in the center which is where the crazy ticking noise comes from. Eventually it lockes up all together from friction and the rod flyes through the block. I have seen it in a few different Mercedes motors before. Last edited by 986Jim; 03-14-2006 at 03:48 AM.