One thing that can cause a bit of a rattle is if the rear camshaft bearing shell has worn axially allowing the camshaft to slide forwards and backwards and go plink when it finally hits the end. Because its driven by a quieter helical cut gear it moves as the engine accelerates and slows down at idle. Pulling the oil pump and checking the cam shaft end float is possible. Can be caused by rough finish on a new camshaft chewing the faces of the bearing shell or simple wear. Post a video. I think my engine does it. Next time its out I will measure it. But in the meanwhile I will try for a video of mine to compare.
thanks for the reply. I am interested in the oil pump and end float check, how can I do that? I am a little behind media wise and don't have the kit to take the video, upload to youtube and post on here. I could get my son or grandson to do it, but would take time.
My engine did exactly that but the thrust face failed and took some of the case web off and it was a new case and a rebuild....
I am persevering. Stopped raining today, so out there. Engine started on the button, all cylinders firing, checked with timing gun and all as it should be. The old popping on the 1 and 2 side is still there and regular. squirted the boots on both sides, carb throttle bushes, carb base, with carb cleaner, no change to engine. Suspect an air leak at the manifold boot but cannot try to tighten the clips as the po put the screws on the engine side so not easy. I am fortunate to have the removable engine hatch so can look down on the engine. Popping is definitely on the 1,2 side. I can hear a dull knocking which sounds to me coming from the fan housing area, I checked the dynamo bearings and fixings and all are tight. I grabbed hold of the fan and all seems tight, but clearance to the housing is very small and moving the housing very slightly causes a nice grinder noise. Anyone know the size of the fan nut.
36mm and swearing. It should be done up to quite a high torque. Certainly enough to make it difficult without a rattle gun acting against the inertia of the fan, with fanhousing renoved from the bus, as trying to get a grip on the alternator pulley may cause you to damage it or the Woodruff key locking its rotation. Then you will not drop the washers and shims fitted with the fan into the fanhousing. When I tried a socket spanner with fan in bus, I ended up in a complete mess as the half a washer substituted by a PO for a proper Woodruff key sheared and then allowed the pulley to rotate and jam on the alternator. New alternator pulley time.. I vote for the engine out for sanity. Getting at the screws on the manifold boot may not be necessary if you use a hose as a stethoscope and listen for hissing.... Its amazing how loud a proper vacuum leak is against even the clatter of the engine. Then if it is the boot just buy new clamps and a boot. Its nothing compared with the cost of an engine. Some engines may have a vacuum takeoff over on no/2 intake manifold which may have become unblocked.
ok thanks, tomorrow its the hosepipe test. re vacuum takeoffs, there are two in the inlet manifold below the carb. one is plugged with a piece of hose and bolt, the other is the vacuum hose for the brake servo. This vacuum hose I note has a join in the engine bay to a different size hose going through to the servo. If there was a leak on these hoses would that cause the regular popping. I have noticed if I press the brake pedal when the engine is running, the revs change, is that normal?
The revs may alter momentarily as the servo reduces the manifold vacuum as the diaphragm moves in the servo, but the revs should return to normal if you hold the pedal down. You can always disconnect and block the servo vacuum takeoff at the engine end to see if that is where air leaks in .. The other vacuum takeoff should go up to thr air cleaner to operate the hot air flap. My AFR meter can show very lean from a flooded condition as most oxygen in the intake appears in the exhaust. (It measures oxygen percentage remaining assuming it is being used in combustion) In that case the engine will fail to start and then produce a big backfire when all the unburnt fuel in the exhaust goes off.
I have another issue then, no hot air flap in my old style oil bath air cleaner. That's why the second vacuum takeoff is plugged presumably.
