Engine Oil Pressure Problems

Shadowblack5.0

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Mar 11, 2016
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I've seen the other posts but I can't quite fond one with the exact same problems so here's mine. When im idling (usually does it the worst with ac on) my oil pressure drops to half then 0 on stock gauge. Goes up of course when I rev up or accelerate. It doesn't do it as often if ac is off. My idle is 1000-1100 ac off and 900 with it on. I've replaced the sending unit. My next step is to check the pump seal and get a mechanical gauge. Does anyone have any other advice?
 
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If the reading is accurate (a proper gauge is a good idea as you mention) then it's most likely worn engine bearings. You can get by for a while with thicker oil (20w50), or you could swap in a high volume oil pump to extend the engine life a little bit. But eventually she'll need to be rebuilt.

A clogged screen or dented pan can also cause similar symptoms, but you would know best how worn the engine is or how it's been maintained for the last 20+ years.
 
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Thanks I just got the mech. Gauge in and it's not dropping to 0 at idle but around 10. So that's good I guess. Would you suggest next step be to check my oil screen?


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I'm really hoping is the oil screen, month before last/early last month severalhundred miles ago I put oil detergent in with my oil change. I'm sure the car wasn't well taken care of before I bought it and now crud is just loose. I further hope/believe this because I've got no valves rattling or strange noises.


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add seafoam to the oil, take the car for a drive 50 miles or more. then change the oil when you get home. Use a heavier oil like mentioned above, or use 4 qts of 10w30 and a qt of lucas. this is a temporary fix.
 
Already use 10w40. Not needing a temp fix tho. I guess I'll go do the oil screen tomorrow afternoon and try seafoam or some engine flush.

As you've probably found by now, getting to the oil pickup / screen requires removing the pan, and to do that it's easier to just pull the engine out. If you're going to go through that trouble, then swap in a high volume pump while you're there!

If you're just trying to have a look, a borescope through the oil drain plug would be easier. It won't give you a good view but could help determine if you have a real sludge problem. One telltale sign of a possible screen issue is if you see a bunch of careless use of RTV gasket maker in other places -- globs of that like to find their way right to the pickup. If it's just sludge, Seafoam or a full flush might be a whole lot easier than taking things apart - I'd try it first for sure.

10psi at warm idle isn't so bad, as long as it's higher at higher revs (makes it up to 35-40 at some point in the RPM range) then you're probably just fine. If it's much lower than that when you rev it up, I'd personally do something about it (like pulling the pan, cleaning the pickup, and installing that high volume pump).
 
Thanks. It's definitely lower about 20-24 from 2000-2500, then about 30 above 3300. Just changed oil and filter today and put in some engine restore at the suggestion of my dad, so far its of no help. Definitely gonna just go grab a new 5 quart and another filter and run seafoam thru my heads then do some 0-60 pulls, then run it thru my oil for about 50 or so miles and change it out once more. If that fails then oil pump, if that fails then rebuild.

Am gonna try and jack my engine up and remove oil pan without pulling engine if seafoam is no help. Not sure where I could find or rent a cheap boroscope any ideas?


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Sounds like you have a good plan. Harbor Freight tools has a pretty cheap borescope at around $79. If you happen to have an Android phone, you can get one for $10-$15 on eBay. iPhone is a little more hassle / more expensive. It probably won't show you much though, and it definitely won't help you do anything about what you do see, so if you happen to know someone who has one great but I wouldn't spend a ton of cash on it just for this purpose. It's a good tool to have for a professional mechanic or a hard-core home mechanic, but not a must-have.

You can theoretically get the pan out with engine in, but it's really really tight, and you have to blindly undo the pump and pickup to do it, and to get them back in. It's also a huge mess and hard not to damage the gaskets going back in, and I'm just getting too old for that kind of stuff. :) I've found over years of toughing it out that it saves me time to make some room before I start. Of course that's a ton of work too and requires a hoist. I'm confident you'll get it done however you go about it.

As we've mentioned before, most likely you've got some engine wear, and this will be a 'temporary' fix, so picking your temporary fixes in order of ease and expense is the way to go. Flush, heavier oil, followed by high-volume pump and pickup screen replacement, followed by a rebuild. I've gotten an extra few years and tens of thousands of miles on an old engine by installing a high volume pump, so that's better than a band-aid in my book, especially if you're not burning oil and have pretty good compression. The 'right' way is to rebuild, but that's expensive and the car may or may not be worth it to you, and getting it to run good enough can buy some time. By the time it needs to be rebuilt, a lot can happen so I never look down on 'temporary' fixes. Cars are all temporary. :)
 
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