Tappet clearances?
Discussion
Just bought my first Cerbera, a 1999 4.2. It's fantastic 
I've heard that the tappet clearances need checking every 12000 miles, is this true?
If so, what are the clearances, and does the engine use commonly available shims?
Also, I guess the cams have to come off, are there any timing marks on the gears?
Thanks for any help.
I've heard that the tappet clearances need checking every 12000 miles, is this true?
If so, what are the clearances, and does the engine use commonly available shims?
Also, I guess the cams have to come off, are there any timing marks on the gears?
Thanks for any help.
yes the clearances do tend to need checking / adjusting every 12K, its 8-10 thou on the inlet and 10-12 thou on the exhaust, however I'm reliably informed that the exhausts don't tend to move and the inlets tend to get smaller so potentially you jus tkeep grinding down the shims you have.
There are no timing marks on the cams you have to scribe /mark stuff to recover teh cam timing after taking the cam out.
I've got the procedure at home I'll post it up later
Matt
There are no timing marks on the cams you have to scribe /mark stuff to recover teh cam timing after taking the cam out.
I've got the procedure at home I'll post it up later
Matt
Procedure as extracted from the cerbera workshop manual
If adjustment is required proceed as follows turn the front pulley until, the front 2 cam followers are on the overlap (inlet just opening, exhaust just closing) remove the uppermost cam sprocket bolts. Turn the front pulley clockwise until the back 2 cam followers are level, and then carefully turn the crank clockwise slightly more until the inlet cam follower is exactly 1.5mm lower than the exhaust
DO NOT TURN ENGINE BACKWARDS DURING THIS OPERATION
Now scribe the camshaft and camshaft sprocket with a line exactly level the top of the cylinder head, a carbide tipped scribe may be required.
Now remove the remaining cam sprocket bolts and fit the cam sprocket retaining tool ( a bar with a spigot on it to keep the sprocket in place which bolts to the cylinder head)
Now turn the crankshaft anti-clockwise until the camshaft has moved 1 & ½ teeth if working on the odd cylinder bank, or clockwise if working on the even cylinder bank.
This puts the engine in a safe position so no valves are bent when removing the camshaft. Slacken the timing chain tensioner but do not remove it then slide the cam sprocket off the cam and onto the spigot of the retaining tool.
The cam caps bolts cam then be slackened evenly and then removed the cam can then be removed, remove any of the tappets which required adjustment and remove the ‘top-hat’ shim underneath. Measure the shim with a micrometer and replace with one of the appropriate thickness to provide the correct clearance ( 0.010” on the exhaust and 0.008” on the inlet)
The camshaft can now be replaced and use plenty of engine oil to lubricate all parts during reassembly, while the crankshaft is in the ‘safe’ position the cam can be rotated safely to check all clearances, repeat adjustments if required.
When complete torque all cam caps to 17ft/lb and turn the cam until the scribe marks match on the head and pulley at this point the cam bolts can be de-greased with solvent, apply loctite thread locking compound to their threads and refit, torquing to 20 ft/lb, retighten cam tensioner and secure with lockwire.
Turn the crankshaft 1 revolution and refit the other 2 camshaft pulley bolts loctiting as before
If adjustment is required proceed as follows turn the front pulley until, the front 2 cam followers are on the overlap (inlet just opening, exhaust just closing) remove the uppermost cam sprocket bolts. Turn the front pulley clockwise until the back 2 cam followers are level, and then carefully turn the crank clockwise slightly more until the inlet cam follower is exactly 1.5mm lower than the exhaust
DO NOT TURN ENGINE BACKWARDS DURING THIS OPERATION
Now scribe the camshaft and camshaft sprocket with a line exactly level the top of the cylinder head, a carbide tipped scribe may be required.
Now remove the remaining cam sprocket bolts and fit the cam sprocket retaining tool ( a bar with a spigot on it to keep the sprocket in place which bolts to the cylinder head)
Now turn the crankshaft anti-clockwise until the camshaft has moved 1 & ½ teeth if working on the odd cylinder bank, or clockwise if working on the even cylinder bank.
This puts the engine in a safe position so no valves are bent when removing the camshaft. Slacken the timing chain tensioner but do not remove it then slide the cam sprocket off the cam and onto the spigot of the retaining tool.
The cam caps bolts cam then be slackened evenly and then removed the cam can then be removed, remove any of the tappets which required adjustment and remove the ‘top-hat’ shim underneath. Measure the shim with a micrometer and replace with one of the appropriate thickness to provide the correct clearance ( 0.010” on the exhaust and 0.008” on the inlet)
The camshaft can now be replaced and use plenty of engine oil to lubricate all parts during reassembly, while the crankshaft is in the ‘safe’ position the cam can be rotated safely to check all clearances, repeat adjustments if required.
When complete torque all cam caps to 17ft/lb and turn the cam until the scribe marks match on the head and pulley at this point the cam bolts can be de-greased with solvent, apply loctite thread locking compound to their threads and refit, torquing to 20 ft/lb, retighten cam tensioner and secure with lockwire.
Turn the crankshaft 1 revolution and refit the other 2 camshaft pulley bolts loctiting as before
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