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Discussion Starter #1
A question for those of you with mechanical oil pressure guages.

Just wondering if this is normal - oil pressure lags the engine start by a full 2 seconds when cold, when warm the pressure goes up immediately. I definitely get cam chain tensioner rattling on those cold starts.

Vid 1: warm engine start (after sitting 5mins)
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Vid 2: cold engine start (after sitting overnight)

Video-0016 | Flickr - Photo Sharing!
 

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I had a steering knuckle in my shed. Really!
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Cold oil is thick, so there isn't a lot of flow. Little flow = little pressure. As soon as some oil gets pumped around, the pressure is high because the oil is so viscous.

On a warm start, the oil is already at the correct viscosity so it flows well immediately.
 

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Be sure to use a quality oil filter with an anti-drainback valve. Probably best to stick to factory filters. A cheap filter will allow the oil to seep back into the oil pan after shut off. The only time the oil will not flow at start is if is really really cold. almost solid, since the oil pump is a positive displacement pump, which means as long as the oil is liquid, it will be flowing.
 

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Discussion Starter #5
Another question:
When starting cold, I notice the needle on the mechanical gauge go up to about 75psi and occasionally it will drop sharply but very slightly (like 2-3 psi) and then return to wherever it was before (usually about 75-80psi). After 30 seconds of running the cold engine I can blip the throttle and the increase in oil pressure with RPMs will also cause this sharp quick pressure drop at around 75psi. It is subtle so you have to focus on the gauge, but it's definitely there and happens every time. Is this one of the bypass valves opening? That's the only thing I can think of causing this. But which one would it be, the oil pump bypass or the oil filter bypass?
 
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