|08-03-2007, 06:26 AM||#11 (permalink)|
A Hydraulic lifter, also known as a hydraulic tappet or a hydraulic lash adjuster, is a device for maintaining zero valve clearance in an internal combustion engine. Conventional means of adjusting valve actuation always requires a small clearance to be left between the valve and its rocker or cam follower to allow for thermal expansion and wear. It is vital that a valve must never be prevented from closing completely; this rapidly burns it away, especially in the case of the exhaust valve. The hydraulic lifter was designed to ensure that the valve train always operates with zero clearance, leading to quieter operation and eliminating the need for periodic adjustment of valve clearance.
The hydraulic lifter consists of a hollow expanding piston situated between the camshaft and valve. It is operated either by a rocker mechanism, or in the case of dual overhead camshafts, directly by the camshaft. The lifter is filled with engine oil intermittently from an oil gallery via a small drilling. When the engine valve is closed, the lifter is free to fill with oil. When the valve is opening and the lifter is being operated on by the camshaft, the oil feed is blocked and the lifter acts just as a solid one would, oil being nearly incompressible.
The first firm to include hydraulic lifters in its design was Pierce-Arrow in the early 1930s. Hydraulic lifters were popular on automobiles designed in the 1980s, but most newer cars have reverted to bucket-and-shim mechanical lifters. Although these do not run as quietly and are not maintenance-free, they are cheaper and rarely need adjustment because the wear caused by operation is spread over a large area.
There are a number of potential problems with hydraulic lifters. Frequently, the valvetrain rattles loudly on startup due to oil draining from the lifters when the vehicle is parked. This is not considered significant provided the noise disappears within a couple of minutes, although typically it usually only lasts a second or two. A rattle that does not go away can indicate a blocked oil feed or that one or more of the lifters has "collapsed" due to wear and is no longer opening its valve fully. The affected lifter should be replaced in the latter circumstances. In extremely rare circumstances, a lifter can "pump up" and create negative valve clearance so that its valve cannot close. This is more serious as burned valves will result. In all cases it is important to follow the manufacturer's recommendations for oil viscosity and quality.
Cars with hydraulic lifters include the first generation Mazda MX-5 and most General Motors models produced in the 1980s.
Cars of today (through 2007) with Hydraulic Lifters include (Whether Roller type or Pivot type): All Ford F150s (V6 or V8), Rangers (V6), Mustangs, Aston Martin All GM/Chevy Trucks (V8), Envoys, Trailblazers (V6), Corvette etc... Toyota Tundra(V8) All Dodge trucks (V8), Jeeps (V6 & V8) and yes all of the Hemi engines Most Mercedes V6 & V8 engines Most Audi V6 & V8 engines
Keep in mind that most of these, especially the trucks, have used Hydraulic Lifters for 50+ years. The problems referred to above were mostly solved 30 years ago and today are practically non-existent.
In summary the majority of V8 and many V6 apps on todays market use Hydraulic lifters due to near zero maintenance, longevity and excellent performance. On the flip side, in 4 cyl. apps it is still preferred to use the mechanical tappet.
HERE IS HOW THAT ARTICLE RELATES;
M271 four-cylinder engines
In mid-2002, Mercedes introduced a new 4-cylinder engine family to replace the notorious existing four-cylinders. The M271 family is a clean-sheet design. It has various new features to improve efficiency and refinement. First of all, there is twin-balancer shafts to eliminate the inherent vibration of inline 4-cylinder engines. Secondly, the cylinder head now employs variable valve timing at both intake and exhaust side. Thirdly, roller cam followers and hydraulic lifters are used to reduce friction and noise. Fourthly, all M271 engines have a more efficient supercharger and intercooler than the old one. Reduced clearance between the supercharger housing and compression roller reduces gas leakage thus the small supercharger can produce higher boost pressure. Lastly, by using smaller supercharger, reduced capacity to 1.8-litres (from 2.0 or 2.3-litre) and an aluminum crank case, the engine is smaller and lighter. For example, the engine for C200 Kompressor weighs 167kg, some 18kg lighter than the old 2.0-litre unit which produced the same power.
At the moment of writing, M271 family consists of 4 engines. Surprisingly, all of them displace 1.8 litres.
Different combinations of output and fuel consumption are implemented by different tuning, e.g., different supercharging pressure and compression ratio. The only exception is the CGI engine (CGI - Stratified Charge Gasoline Injection), which employs direct fuel injection. As usual, direct injection not only saves fuel, but also increases power by allowing higher compression ratio. The 4 engines are:
Model Eng capacity Compression ratio Power Torque
180 Kompressor 1796 cc 10.0 : 1 143hp @ 5200rpm 162 lbft @ 2500rpm
200 Kompressor 1796 cc 9.3 : 1 163hp @ 5500rpm 177 lbft @ 3000rpm
200 CGI 1796 cc 10.3 : 1 170hp @ 5300rpm 184 lbft @ 3000rpm
230 Kompressor 1796 cc 8.5 : 1 192hp @ 5800rpm 192 lbft @ 3500-4000rpm
TM & C reprective owners...
|08-10-2007, 10:57 PM||#12 (permalink)|
BenzWorld Junior Member
Date registered: Feb 2007
Well guys just got my car back today. The car is running like new. The write-ups/findings were 2 pages long, massive failure due to no oil pressure. Long story short $8700 in parts(entire engine) plus aprox. $3000 for 25+ labor hours. I just couldn't imagine paying out of pocket for this. Luckily I'll be covered with my extended warranty for a few more years to come. Maybe food for thought for those planning to hold on to their cars for a while. Thanks, and you guys have a good one.
|08-11-2007, 05:14 PM||#14 (permalink)|
BenzWorld Junior Member
Date registered: Feb 2007
Here's the tech write-up:
"Check engine light is on. Connect SDS and check for fault codes. Code 2054-002 (exhaust cam adjuster fault) is present. Perform cam tests and notice that at high RPMs the engine is making loud chattering noises. Remember from Oct 2005 shop foremans conf call this code. This is due to lack of oil pressure. Call TAC to confirm and support. TAC suggests to remove oil filter housing and check for end being damaged (case #636965). Removed oil filter housing, checked ok. Install oil pressure gauge and let engine oil reach 90 deg, perform oil pressure tests. At idle engine has .25 bar of pressure (should be about .5 bar). At 2000 RPMs the oil pressure rises shorttly and then drops to 0 bar. Call TAC for next step. Inpect oil filter and found full of metal. Remove oil pan and check oil pump. Found pump has large amount of metal in screen. Get EDAC authorization for engine. Replaced M271. Transfer over P/S pump, A/C compressor, Altenator, Kompressor, Intake and exhaust manifolds and airbox. Mounted engine into chasis. Clear codes, fill oil, coolant, P/S fluid and test drive. During test notice that the kompressor does not charge up. Connect SDS again and check for fault codes. Code 2006-0001 is current and stored. Code for knock sensor. Perform actual values test-does not pass. Remove air box, intake manifold and kompressor. Perform electrical test on sensor-sensor is okay. Found pins on wiring harness not making good contact with sensor. Tighten pins. Reintall kompressor, intake manifold, and air box. test drive again. Car runs fine."
That's all of it minus about half of page of parts.
|08-11-2007, 06:50 PM||#15 (permalink)|
Date registered: Apr 2005
Vehicle: 2002 CLK430
Location: Southern California
Sounds like you had a crank bearing come apart. Since you didn't hear hellacious knocking, I'll guess it was a main versus a rod.
It's doubtful we'll know what MB USA found, but I can guarantee you a factory tech (not a dealer employee) is going to find out why the engine came apart. He'll run a brush through every oil passage in the engine and figure out where and what the blockage was.
It's just a guess, but it's "possible" the fleece filter came apart. If that happend and a chunk blocked an oil passage that feeds a main, that main bearing would come apart. When that happens there will be shavings everywhere. Unless I'm mistaken, once installed in a car, a fleece filter has a 12 months lifespan - regardless of mileage.
|08-11-2007, 09:07 PM||#16 (permalink)|
Date registered: Nov 2006
Vehicle: Oo == oO 98 E320
Location: Nashville, TN
Am sure you're underwhelmed by having to have this procedure done but it sounds like your dealer got this taken care of quickly. If the mechanic was as competent as his report reads you're well set.
This does happen every once in a blue moon: a good friend recently had engine failure on his '03 Passat W8 with about 18k miles. The dealer rebuilt the engine & it wouldn't start. A new engine was brought from Germany & the car is fine. Bill to VW? Over 20k.
'87 300E: sold after 11years @ 230k & still on the road somewhere in rural Tennessee.
'94 C220 with 93k totalled 10/06 by hit & run broadsiding monster truck: not a scratch or bruise for me
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