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We’ve had an email from a 4 cylinder 23C, Engine Rebuild DVD customer who is having a few problems with the timing procedure for the engine. The DVD shows how to time the engine when it has been split from the clutch housing, but Henrik wanted to know if it were possible to determine Top Dead Centre of piston number 1 (to time the engine) without removing the engine from the clutch housing (to reveal the marks on the flywheel). Here is what Henrik asks…
I have now seen the dvd over and over again. My problem is determining how to set the timing between crank and cam. Regarding cam the man in the DVD says something about turning the cam until both valves on cyl 4 does something, but I simply cannot hear/understand the English very well. This cam position should then refer to crank TDC cyl 1, but how can this be determined if the engine is still mounted to gearbox.
As I understand the hole in the flywheel refers to 17 deg injection timing = “G” in the pump inspection plate.
I really hope you can kill my confusion.
NB! My 23C tractor is rebuilt and running, but smokes light blue (unburned diesel) so I really suspect the timing. I have not touched the chain or pump gear during the rebuild.
Henrik Thomsen, Denmark
When the pin is in the hole in the flywheel it is 16 degrees before TDC on
number 1 cylinder.
To set the timing chain, follow this procedure…
To set the camshaft, first of all, set the tappet clearance on number 8 valve (the valve at the back of the engine closest to the steering wheel) to 0.023in (when the cam and rocker is in its lowest position). Then set number 7 valve to 0.025in.
Turn the engine away from TDC. (The keyway in the front of the crankshaft [that holds on the front pulley] is at the bottom when cylinders 1 and 4 are at TDC.) Therefore position the keyway on the right looking at the front of the engine (ie. 3 O’clock position – always turn it clockwise). You do this so that the pistons do not hit the valves.
Now remove the timing chain, camshaft sprocket and the chain tensioner.
Next turn the camshaft clockwise until vavles 7 and 8 are “on the rock” (ie. exhaust just closing, inlet just opening). Now the camshaft is in the correct position for the timing procedure.
It is now safe to move the crankshaft clockwise for number 1 cylinder to be on TDC. You can determine TDC without using the flywheel marks (ie. with engine connected to transmission) by using the flywheel pin hole as a reference point. Slide in the pin to the locating hole in the flywheel and then fix a protractor to the crankshaft, and place a pointer on the engine which will give accurate readings on the protractor. Then remove the flywheel pin and turn the engine clockwise 16 degrees (as measured on the protractor), and therefore you are now on TDC for number 1 cylinder and are in the correct position to fit the timing chain, sprocket and tensioner.
Now don’t forget to re-set valves 7 and 8 to their normal running valve clearances as in the DVD (0.012in on inlet, 0.018in on outlet).
Now set the injection pump timing as per the DVD instructions.
It’s quite an involved prodecure, but this will mean you can time the engine without removing it from the transmsission.
Hope that helps, let us know how you get on.
Steve Ridsdale (VTE)