timing gear woes
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timing gear woes
my 88 f-250 with 189k miles runs very good untill the big timing gear went bad. i replaced it and now the truck runs very rough checked the compression and now it reads 0-30 but it wont hold on the guege it just flutters guege is good timing marks are good what could cause this problem?
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Joined: May 2002
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From: Broken Arrow, OK
It sounds like the Shraeder valve in the compression gauge is stuck open or missing. On other engines it is common for valves a pistons to meet when the timing components fail, but the EFI 4.9 is nowhere close to interference. When I checked it with a piston at TDC and opened a valve to stock lift it didn't even touch the clay. What's the idle vacuum?
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timing reply
the guege is perect worked good on a good motor, engine runs rough as heck, going to tear down engine soon ,iam going to check camshaft make sure lobes are not wore down then take head off and get checked for flatness
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Joined: Sep 2003
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From: Houston TX
I doubt the head would be the problem. I've been thinking about what could cause this problem, but it's hard to pin down. The gear change is pretty cut @ dry I would think. The notches are lined up. To me, that leaves the distributor next. Are you sure it's stabbed right? Rotor pointing to #1 when #1 cylinder's piston is all the way up? I have trouble seeing the cam go flat nearly overnight unless something drastic happened when the gear went south. But I would suspect flat lobes before I would head problems. But to me, it sounds like some kind of timing or ignition problem. IE:I think it's possible to have the distributor 180 degrees off, if you stabbed it when the timing marks are on the pully mark, but 180 out from normal. You have to make sure #1 is actually all the way up. If in doubt, pull the plug and watch the piston. Also, both valves will be in the up position. I wouldn't be in a hurry to tear down the motor until you exhaust all other possibilities. MK
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Joined: Sep 2003
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From: Houston TX
Thought of something else...Make sure the timing gear lock pin is not sheared off. That could cause problems, and it could drift on you. IE: You could stab it correctly, but it could drift off without you realizing it. MK
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