Cold Engine vs. Hot Engine Maintenance Ops. - FJ62

ZGMikey

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Joined
Dec 13, 2016
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67
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Boulder
I've got the car in the garage with the axles broken down and the exhaust a little cut up due to the PO pulling the cats. Tonight I thought I would check compression and set valve clearances. Checked the FSM and both processes are based on a hot engine. Has anybody performed these with a cold engine? I can kind of see the need for a hot engine to check compression, but for valve clearances? The thermal expansion coefficient for 304 stainless is such that the valve might expand another 0.0015 inch. And the valve clearance for intake is 0.008 inches. Exhaust is even higher.

So...how do you guys set valve clearances...hot or cold engine...and what results have you seen?
 
Joined
Mar 31, 2014
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Gone
Set the valve clearances cold with a loose drag of the feeler gauge (vs a firm drag). They'll be fine. Maybe one blade thicker if you want to get technical. You can always check them again some day down the line when you can warm up the engine.
 
Joined
Jul 26, 2015
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313
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Montana
I haven't tried the engine running technique, and don't plan to. Hard enough for me to feel confident with my settings with everything static. With that said I've always set #1 to TDC via the mark on the flywheel (dash not dot), pulled the air cleaner and loosened the valve cover up, idled the truck to operating temp and then shut down and tried to work through the valves while everything is still warm. Inevitably by the time I do half and then get the crank rotated for the second half the last few are probably cold but that's as good as I get. I've heard of people doing them cold and just adding .002 or so. Haven't done it myself though. Might try that next time.
 
Joined
Aug 26, 2009
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down in a hole.
I've set them both ways.

The thing about adjusting them with the engine running is that I believe you aren't intended to actually adjust them running, but to check them running with the engine at temp- this gives you a better idea of which ones need what type of adjustment. then shut engine off and adjust, fire engine back up to check, repeat as need be. as long as the valves are allowed to close all the way and have consistent lash without too much gap, you'll be ok.
 
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