You may remember my earlier posts where my MK2 was fouling plugs within minutes and had no power. I have found the problem - borh the cams are ADVANCED by 20 or 30 degrees i.e. the bottom timing chain has gone backwards by a couple of teeth. Short of running the car down a hill backwards in a forward gear how could this happen? It symptoms started as we were driving sedately along at 25mph in a suburban street. The chain on the left side is quite loose suggesting the tensioner is not working. What is the simplest way of removing the timing case cover. It appears that I need to drop the sump and even remove the head. Is this true?
When timing chains "jump" it most commonly occours when you shut down the engine, however in your case it happened during a slow cruise. With enough slack the chain will actually start to "ride"/ramp up the teeth and eventually hop on the gear. Had this happened to my old Alfa I would be replacing valves or much worse.
You can remove the timing cover without head removal, but the front edge of the pan/sump should be slightly loosened/lowered. In this method great care must be taken to not damage the Head gasket upon reassembly and sealant should be used as the gaskets have already been compressed and might leak.
I was taught my mechanic ethics at a young age by an old salty English mechanic to be very fastidious; he would actually grab a torque screwdriver and check the tension of my hose clamps!!! I hated his methods then, but now I really appreciate his mentoring for it contributed to my low re-work percentage.
I would say that if you engine is fairly fresh (under 160,000 km) then pulling only the timing cover alone is ok. But if your engine is over that mileage I would pull the head, have a valve-grind performed, and replace the sump gasket. The chains and sprockets are very reasonable so perhaps you might consider replacing these along with a new tensioner assembly. (Depending again on milage)
Thanks, Blake. I've since dropped the sump pan and found the chain tensioner lying in the bottom. The pan looked pretty clean, certainly no gritty bits which is encouraging. It appears that the chain has stretched just that bit past where the tensioner could cope and it has simply fallen out. I'll be replacing the chain, all the chain guides and the tensioner. I hadn't thought of the sprockets. Good point. I have been itching to replace the sump gasket because of the oil leaks from that area and I'll fix a few other leaks at the same time. I have no idea of the car's history so I don't know haw many miles it has done (20,000 on the clock now for the third time, at least) since its last overhaul which was "in the 80's" according to the guy I bought the car from. Then again, this was the guy that also said the car was free of rust and apart from both sills, floor pans, firewall and valance, he was pretty right. Until this problem I had heaps of power, a smooth and quiet engine and I was getting 24 mpg (imp. gallons) so it can't be all that bad. More on the saga later.
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