The timing sprockets may need replacing as well if they are worn.Ī typical symptom of a stretched timing chain is chain rattle that lasts a couple of seconds after a cold start. The replacement chain should be good for another 100k miles.īuy the car, and plan to get the timing chain replaced at some point. Get one that already had the chain and chain tensioner replaced. In my opinion, you should treat the chain as a 100k miles service item if you want to be really safe. It’s difficult to estimate precisely how long the chain will last. There have been cases of chain failures at 80k miles, and there are cars that go far past 100k without any problems. If it starts showing any symptoms of stretch, it should be replaced. The timing chain should be watched in the M271. When the chain skips, major engine damage can occur if the valve timing goes out of sync far enough for the valves to hit the pistons.įor some reason, Mercedes-Benz decided to use a single row timing chain in the M271 engine while its predecessors, the M111 and the even older M102, had double row timing chains, which were very reliable. I believe this is why most of the M271 failures occur during engine start up. What happens is that when the chain is stretched too much, the spring alone cannot apply enough tension, and it becomes possible for the loose chain to jump some teeth on the timing gears. There is also a spring that applies some tensions when the engine is off and there is no oil pressure. The tensioner uses oil pressure to apply tension to the chain when the car is running. As the chain stretches, at some point it will reach the limit of what the chain tensioner can compensate for. There have been cases of premature chain stretch in these engines. Leaving it for this long in the M271 engine is very risky, in my opinion. Generally, when a timing chain is used, the intention is for it to last the “lifetime” of the engine (very roughly 200k miles). Some of these cars are getting old and sometimes the roof can be a bit fussy (usually small issues though). Also, you can buy just the seals and replace them yourself (advanced DIY).Īlong with the hydraulic system, there is plenty of electronics to manage the roof on the R171. The OEM rams are expensive but there are companies that sell reconditioned units. When it does, the headliner may get soaked in hydraulic oil. The roof lock cylinder is usually the first one to fail. The hydraulic rams last only so long before the seals deteriorate and start leaking (15 years reliably at most as I see it). If the car participated in a large crash, the roof may be out of alignment, which can be a nightmare to waterproof if the chassis of the car isn’t “straight” anymore. Take the car to a high pressure (touchless) car wash and see if any water gets inside the cabin or the boot.Īccident-free history is very important for any hardtop convertible. Listen for rattling noises while driving with the roof closed. Get the car up to 60 mph with the roof closed and listen for excessive wind noise. Look for hydraulic fluid leaks – in the boot, on the headliner and around the hydraulic rams. If it isn’t, then the car may have been neglected or there is a leak somewhere. Ideally, they should be lubricated regularly – ask the previous owner about it.Ĭheck if the level of hydraulic fluid is correct. If it takes much longer than that, the pump may be on its way out.Ĭheck the condition of the roof seals. The roof should take approximately 22 seconds to open or close. Open and close the roof a couple times to make sure that it works. Also, check in the boot underneath the spare wheel. Things to check regarding the Vario roof:Ĭheck for any dampness in the footwells and carpets. Your two biggest concerns are hydraulic system issues (mainly leaks) and weather intrusion (fancy name for a leaking roof). The hardtop “Vario” roof is operated by five hydraulic actuators, powered by a hydraulic pump. Few companies succeeded in making a reliable hardtop convertible that doesn’t leak and isn’t as complicated as an open heart surgery. The hardtop roof on the R171 is actually pretty good.
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