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Bouncing oil pressure and drop at higher rpms

zrxsix3rz

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alright i just experienced this tonight while i was at work and in I dire need of some help!!!

i was driving along at about 20 mph and i saw my gauge light come on and the oil pressure gauge was bouncing from normal to nothing, so i turned back around and let it set...later i went back out after reading some possible causes, i needed to try something so this is what i got for sure...
at idle it will show i have pressure but if i get the rpm any higher the gauge flops to nothing...this test was also in park!
i also have a very rough idle and a noise coming from the front of the engine, just recently replaced the front timing chain tensioner and using the ol screwdriver as a stethoscope it can really hear it in the power steering pump? tell me if any one else has had a ticking in the pump, also i know that i have not replaced the rear chain tensioner yet but i have the part

also after letting off the gas i can hear a slapping sound...i am dreading that its the deadly chain slap

i have done my best searching this forum for the best possible thread i can find and spent a few hours reading i cant seem to find one that fits my situation, which i usually find what i am looking for. im praying that its not this but could a chain guide break and still cause a chain slap with a new tensioner? could this slack in the chain cause the rough idle too and if there is a guide that broke, the oil pump is picking up broken guide pieces when accelerating in rpm

i do not have another person to help with these tests so i dont know if the slap is coming from the front or the back...i will continue to try test to figure this out, i dont want to sell or get rid of this truck and any help will be appreciated! THANKS
 


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jremington59

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If the slapping is there all the time chances are your problem is a faulty oil pressure sensor. You still have pressure but the gauge does wacky things. You'll know very quickly if you are running with zero oil pressure.
 




SoNic67

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I doubt is the pressure sensor, it would not act up on higher rpm's.
You might have clogged return oil passages. At higher rpm, all the oil is pushed "up" by the pump, and empties the oil pan starving the oil pump. At that point, the chain tensioner loses the pressure and starts slapping.
Something like this:

5270228002_250f737a97.jpg

5270225228_e4bed2a195.jpg
 




zrxsix3rz

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Yeah well I read up on the pressure sender but its making a top end noise now and im not getting the slapping that I thought I was hearing, people are saying anything from a spun bearing to paper from the oil filter clogging it up, I changed the oil every 3 thousand, except the last oil change I did I ran Castrol high mileage - synthetic blend... but I doubt the oil will cause this problem

Yet again Thanks for the input, any advice helps a lot!
 




Bobmbx

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YOu could have something clogging your oil pump.

A small piece of plastic, maybe? From the timing chain tensioner? Thats what killed my Sport Trac.
 




jremington59

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I doubt is the pressure sensor, it would not act up on higher rpm's.
You might have clogged return oil passages. At higher rpm, all the oil is pushed "up" by the pump, and empties the oil pan starving the oil pump. At that point, the chain tensioner loses the pressure and starts slapping.
Something like this:

5270228002_250f737a97.jpg

5270225228_e4bed2a195.jpg

My 2000 does it whenever it feels like it. High RPM,s or low, warm or cold it doesn't matter.

What I'm telling him is if the engine drops to zero oil pressure, the rapping in that engine will be almost immediate.
 




zrxsix3rz

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My 2000 does it whenever it feels like it. High RPM,s or low, warm or cold it doesn't matter.

What I'm telling him is if the engine drops to zero oil pressure, the rapping in that engine will be almost immediate.

I will start off by hooking it up to a gauge first and start from there! I bought a new oil filter and 5 quarts of oil today and I will break open the old filter to see if there are any contaminates in the filter, if nothing there I will take off the valve covers to check for clogging of the passages...if nothing there i will pull the oil pan and check the screen of the oil pump or if tjere is anything at the bottom of the pan...i hope i dont have to pull the pan but i need and love this truck

Btw this truck has 204000 miles
 




jremington59

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I will start off by hooking it up to a gauge first and start from there! I bought a new oil filter and 5 quarts of oil today and I will break open the old filter to see if there are any contaminates in the filter, if nothing there I will take off the valve covers to check for clogging of the passages...if nothing there i will pull the oil pan and check the screen of the oil pump or if tjere is anything at the bottom of the pan...i hope i dont have to pull the pan but i need and love this truck

Btw this truck has 204000 miles

When the oil pressure drops to zero does the engine start slapping? There's no mistaking the sound of an engine with no oil pressure.
 




zrxsix3rz

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When the oil pressure drops to zero does the engine start slapping? There's no mistaking the sound of an engine with no oil pressure.

i only heard the slapping sound once and it was after deceleration of the engine, after that i have not heard the slapping afterwards. i may have ran it a little longer when the slapping occurred. i have not ran it much after this came up! im trying to prevent flattening the cams if all possible. i didnt really hear a slapping noise when i drove it home, which is 5 minutes away from the house. i read around in 5 minutes the truck will come up to a complete stop from the engine locking up, which it didnt do!
where is a good place to hook up a pressure gauge? can i take out the oil pressure sender and use the gauge there?

once i get a reading i will post and replace the sender while im at it, it wont hurt to get a new one after i read they were kinda junk of a design

Thanks again for the reply, much appreciated :thumbsup: :)
 




bill06447

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I'd start simple...replace the $10 sender and see if the problem goes away. As previously mentioned, zero oil pressure results in immediate characteristic noises.

Bill
 




jremington59

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When I bought my 2000, a day or so later the warning light went on and I looked and the oil pressure gauge said no pressure. I pulled over and shut it off. I started it again waiting for the noise to start and then I remembered the term "dummy gauge". After letting it idle for a minute I realized the engine would sound like a bunch of skeletons having sex on a tin roof by then and figured the gauge was bad. I never changed it and just ignore it.
 




zrxsix3rz

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i am going to replace the sensor some time this week, if it isnt that i got another explorer about the same year as a donor the has 70,000 less mile but the trans just wont down shift and the one i have now has a brand new trans so ill be swapping transmissions to the new one

i let the truck warm up and the noise that the engine was making calmed down and we found that the belt tensioner up front was shot, she was bouncing all over the place! surprised i haven't spat the belt out driving down the road hahahaha :D
 




zrxsix3rz

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Changed the oil pressure sender and it wasn't the problem, its something else
 




SoNic67

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Of course it couldn't be - like I said, a bad sensor would NOT stop working at higher rpm's.
It's what I said above - you are pushing all the oil on top of the engine and the return is restricted.
At high rpm's your oil pan becomes emptier, suffering from starvation at pump's pick up screen - probably clogged up too.

Try using an engine oil flush product before oil change (on a warmed up engine). Use synthetic oil from now on - it has better cleaning action.
Note that the Pump pick up screen will not be cleaned by any oil flush product. It needs to be physically removed and cleaned/replaced.
 




explorers n guns

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sounds like the same problem I had with my 91 your oil pump is do dude
 




zrxsix3rz

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Well weird thing happened, I haven't done anything with my x for a couple days just letting it sit, started it up today to see what it would do, the pressure took a bit to shot up to normal. Went ahead and changed the oil, catching what I could to see if it was contaminated and pulled out the filter and there was nothing there... so went ahead and put the new oil in and started it back up!

Everything was normal and while still in park I revved it to 3k rpm and the pressure didnt drop like it was, took it for a drive just to see if it would drop again and we went about 5 miles through town and highway driving. It stayed right where its suppose to be! Will be taking it easy on it tho just to see if it wasn't a fluke lol still gettin the other explorer to fix and flip or use as parts if the problem comes back up

Thanks alot for the advice guys, much appreciated
 




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