AMC 360 oil pressure fluctuating

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IrishCJ6
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Joined: Sat Nov 02, 2019 9:25 am

AMC 360 oil pressure fluctuating

Post by IrishCJ6 »

Guys, I need some advice, a couple if weekends ago I was out wheeling and hit a tree stump which put a sizable dent in the oil pan. I drained the oil and using a slide hammer and a welded nut I tried to remove most of the dent. I then filled up with my normal 20w50 and some stop smoke additive (burns a little oil) and I noticed that the oil pressure would be normal at idle but when you accelerated the pressure would drop off and when the gas pedal was released the oil pressure returned to normal. My thought was the dent had damaged the intake or the dent maybe was still blocking the pickup. I thus removed the oil pan, and saw no damage to the intake pipe work and the strainer looked perfect. So I repaired the dent and reinstalled the oil pan. I've still got the same issue. Can anybody shed any light on a possible cause for this. Was thinking a oil filter issue or oil pressure release valve.


Note my oil pressure would normally be:


60 PSI cold

40 PSI hot normal running rpm

20 psi idle

letank
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Joined: Wed Oct 03, 2012 9:16 pm
Location: SF bay area

Re: AMC 360 oil pressure fluctuating

Post by letank »

very strange, at first it looks like an inverse relation between the oil pressure and rpm.

The easiest at this point is to install a mechanical gauge.

Otherwise it is probably some bad contact of the wire/or the sender when the engine is rev'ed up, hence low oil pressure. Depending on the year and model of your engine/cluster combo the resistance spread was changed after the 86 model, for the earlier year when the oil pressure wire was disconnected the pressure was at 0, infinite resistance, and a high pressure was a low resistance. Reverse for the latter years.

you can test the oil sender readout with an voltmeter on the Ohm scale, one clip to ground, one to sender tip, at idle oil cold it will be around 25 ohms is about 40 psi, and 70 ohms about 10 psi. This is the quick and dirty.

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Michel
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fulsizjeep
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Re: AMC 360 oil pressure fluctuating

Post by fulsizjeep »

The oil pick up could have been damaged if the pan was hit hard enough.
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