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Car Forum / Mercedes-Benz Cars / January 2008rough running 1987 560SL
I have just purchased a 1987 560SL with 94k original miles on it. It clearly has an engine problem & I would like some advice on how to diagnose it. The car, apparently, was running fine until one day, the previous owner started it up & it had a tapping sound & was running very roughly. This problem has nothing to do with the timing chain, rails, etc. as they were just recently replaced (about 2 years & 10k miles ago) Could this be a camshaft or rocker problem or ? Thanks in advance for any suggestions on how to proceed with this. Brian > I have just purchased a 1987 560SL with 94k original miles on it. It > clearly has an engine problem & I would like some advice on how to [quoted text clipped - 9 lines] > > Thanks in advance for any suggestions on how to proceed with this. Engines often run rough if fuel/air is poor. Change fuel filter, check fuel pump, relais, pressure and injectors, cold start regulation, vacuum regulation lines and engine housing vacuum.  SignatureRoland Franzius > > I have just purchased a 1987 560SL with 94k original miles on it. It > > clearly has an engine problem & I would like some advice on how to [quoted text clipped - 17 lines] > > Roland Franzius I'd also be suspicious that this car has way more than the 94K miles on it. It would be very unusual for the timing chain to need replacement at 84K miles. Agreed on timing chain... No way on such a low mileage. Going from good running car to crappy the next is most likely timing chain... probably due to the fact that the tensioner probably never changed. Maybe the PO had the chain and guides changed as maintaince before it had time to cause a problem. > Agreed on timing chain... No way on such a low mileage. Going from good > running car to crappy the next is most likely timing chain... probably due > to the fact that the tensioner probably never changed. > Maybe the PO had the chain and guides changed as maintaince before it had > time to cause a problem. Yes, that is exactly what happened....apparently, those plastic guides go bad & become brittle with age, not just miles...and when they go bad, a piece can break off & wedge itself in the timing gear & cause the chain to skip a cog. I have viewed the receipts and the prev. owner did have the tensioner & the tensioner guide replaced as well along with the timing chain and guide. I removed the spark plugs & checked compression. Even though the compression is good, I noticed that one spark plug (#4 cylinder) was black & fouled.....I am wondering if this is oil fouled or carbon fouled...there is no oil on the spark plug, there is a bunch of bubbly flat-black stuff on it. Any ideas ? I am told that sometimes the rockers &/or cam lobe can go do to lack of lubrication. Any ideas or suggestions would be great ! Thanks, Brian >>Agreed on timing chain... No way on such a low mileage. Going from good >>running car to crappy the next is most likely timing chain... probably due >>to the fact that the tensioner probably never changed. One plug fouled... check the resistance of the spark plug wire... should be anywhere between 1000 and 1300 ohm. If it is higher, then it is bad. I hopes this is the case. Otherwise, it woud be the fuel distributor. On a 560 engine, the wire resistance should be zero ohms. The resistance is built into the screw-on end. Read the numbers stamped into it: should be 1K or 5K. The end is replaceable seperately. > One plug fouled... check the resistance of the spark plug wire... should be > anywhere between 1000 and 1300 ohm. If it is higher, then it is bad. I hopes > this is the case. > > Otherwise, it woud be the fuel distributor. > Agreed on timing chain... No way on such a low mileage. Going from good > running car to crappy the next is most likely timing chain... probably due > to the fact that the tensioner probably never changed. Try turning off the ESP To quote you: camshaft or rocker problem (that wasn't fixed after the chain broke). Signature© 2007 T.G.Lambach. Publication in any form requires prior written permission. |
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