Timing chain
Thread Starter
Staging Lane
Joined: Feb 2014
Posts: 87
Likes: 0
From: Florida
Timing chain I know this is the wrong forum, but I just need a bit of advice. I have a 1986 Chevrolet c10 short wheel base that I believe has a bad timing chain. Went to crank it up this morning and all it did was make a funny sound, then white smoke came out of the carb. Sound was like a bicycle chain that goes round and round but never catches. So is there anybody that can give me a breakdown of how to replace a timing chain, this will be my first time doing it.
Teching In
Joined: Jan 2010
Posts: 34
Likes: 0
From: Tucson
Looks like no one has answered you. You may or may not have a timing chain problem. You cannot diagnose it from white smoke coming out of the carb.
Assuming this is a small block Chevy V8, pull the distributor cap and crank the engine to see if the rotor turns. If the rotor turns, your chain is still connecting the cam to the crankshaft,. However, these engines used a nylon covered cam gear and the nylon has a tendency to age and break off. This allows the timing chain to skip teeth.
If you do need to replace the timing chain, start by pulling all the spark plugs, then the radiator, then the water pump, then the crankshaft pulley, then the harmonic balancer (you will need a puller for this). Then loosen the oil pan bolts a turn or two. Now remove the timing cover. You will see the chain running from the crank to the cam and 3 bolts on the cam gear. Line up the timing marks: Cam at 6 o'clock and crank at 12 o'clock EXACTLY opposite each other. If the cam tries to turn after removing the gear, you may have to pull both valve covers and back off all the rocker arms to remove pressure from the valve springs.
Now remove the cam gear and chain. Reinstall in reverse order. Make sure you replace the cam gear and the chain and double check the timing marks.
Having said all this, it's probably a cold morning and your old truck just wanted to stay home that day.
Assuming this is a small block Chevy V8, pull the distributor cap and crank the engine to see if the rotor turns. If the rotor turns, your chain is still connecting the cam to the crankshaft,. However, these engines used a nylon covered cam gear and the nylon has a tendency to age and break off. This allows the timing chain to skip teeth.
If you do need to replace the timing chain, start by pulling all the spark plugs, then the radiator, then the water pump, then the crankshaft pulley, then the harmonic balancer (you will need a puller for this). Then loosen the oil pan bolts a turn or two. Now remove the timing cover. You will see the chain running from the crank to the cam and 3 bolts on the cam gear. Line up the timing marks: Cam at 6 o'clock and crank at 12 o'clock EXACTLY opposite each other. If the cam tries to turn after removing the gear, you may have to pull both valve covers and back off all the rocker arms to remove pressure from the valve springs.
Now remove the cam gear and chain. Reinstall in reverse order. Make sure you replace the cam gear and the chain and double check the timing marks.
Having said all this, it's probably a cold morning and your old truck just wanted to stay home that day.
If the chain has jumped a bunch of teeth, you may well have some bent valves. Be sure to verify the condition of all the valves before you go to the trouble to change the chain only. The heads will need to come off to fix the valves.
^^yeah what he said.
If the cam gear has stripped plastic teeth and the marks are off upon disassembly then the valves very well could have smacked the pistons. You could throw a timing set on it and do a compression test before fully reassembling everything. If the numbers are ok run it. If not pull the heads...
If the cam gear has stripped plastic teeth and the marks are off upon disassembly then the valves very well could have smacked the pistons. You could throw a timing set on it and do a compression test before fully reassembling everything. If the numbers are ok run it. If not pull the heads...
