Oil pressure dummy gauge drops to 0 at Idle when warm

[98EdBomber]

162K miles. Bought vehicle with 20K on it and it ran flawlessly until timing chain issues. Religiously changed oil/filters, among other maintenance (O2 sensors, etc). Currently getting 18mpg. Recently did Cam/jackshaft guides and tensioners repair which went fine. No sludge build up. I removed the oil pan and removed broken plastic pieces and the oil pick-up tube as well and made sure there were no fragments left in the pick-up tube before I reinstalled it (Which could cause low oil pressure). Engine is now smoother. Also did 00M12 kit about 10-20K miles ago. Also replaced oil with 5w-30 regular not synthetic (which shouldnt make a difference here)

Only problem now is the dummy oil gauge is dropping to zero at stop lights and at idle when in park when engine is warm. It started doing this about a week before I decided to do the guide repair. It was pure coincidence on the timing of this happening.

Heres my thoughts on a few things:

I am also getting FRONT camshaft chain chatter at idle (although minor), which i initially thought was because the hydraulic tensioner was wore out. With the oil cap removed, I noticed the camshaft guide bounces around (engine running) as if the tensioner isnt putting out enough pressure to keep the chain taught, causing chatter (presumably). Now this could be because of actual low oil pressure or just a worn out tensioner so Ive ordered a new one to make sure. Hasnt arrived yet.

About the oil dummy gauge. I thought it was the oil sending unit so i replaced it at the same time i did the guide repair but problem still exists.

When I rev the engine(warm) the symptoms go away. Quiet chain, gauges normal. Let off gas and back to idle...symptoms return.

Im scared it might be the oil pump or the crank bearings. ALSO I havent hooked up a mechanical oil gauge yet but that was my next step to see what my actual oil pressure is at idle.

What do you guys think? Can anyone help me get this sorted? Thanks!

 

[98EdBomber]

If the oil pump was going bad wouldnt I have these symptoms all the time and not just at idle? What about if the crank bearings are worn out?

Why is this only at idle that Im getting these symptoms? I dont get it.

Should i try a thicker oil and see if that helps and if so then I may need new bearings?

 

[koda2000]

162K miles. Bought vehicle with 20K on it and it ran flawlessly until timing chain issues. Religiously changed oil/filters, among other maintenance (O2 sensors, etc). Currently getting 18mpg. Recently did Cam/jackshaft guides and tensioners repair which went fine. No sludge build up. I removed the oil pan and removed broken plastic pieces and the oil pick-up tube as well and made sure there were no fragments left in the pick-up tube before I reinstalled it (Which could cause low oil pressure). Engine is now smoother. Also did 00M12 kit about 10-20K miles ago. Also replaced oil with 5w-30 regular not synthetic (which shouldnt make a difference here)

Only problem now is the dummy oil gauge is dropping to zero at stop lights and at idle when in park when engine is warm. It started doing this about a week before I decided to do the guide repair. It was pure coincidence on the timing of this happening.

Heres my thoughts on a few things:

I am also getting FRONT camshaft chain chatter at idle (although minor), which i initially thought was because the hydraulic tensioner was wore out. With the oil cap removed, I noticed the camshaft guide bounces around (engine running) as if the tensioner isnt putting out enough pressure to keep the chain taught, causing chatter (presumably). Now this could be because of actual low oil pressure or just a worn out tensioner so Ive ordered a new one to make sure. Hasnt arrived yet.

About the oil dummy gauge. I thought it was the oil sending unit so i replaced it at the same time i did the guide repair but problem still exists.

When I rev the engine(warm) the symptoms go away. Quiet chain, gauges normal. Let off gas and back to idle...symptoms return.

Im scared it might be the oil pump or the crank bearings. ALSO I havent hooked up a mechanical oil gauge yet but that was my next step to see what my actual oil pressure is at idle.
What do you guys think? Can anyone help me get this sorted? Thanks!

this. i would immediately start by getting the pressure checked with a real gauge and if it's really low, start using a heavier weight oil (straight 30 or 40) until you decide what to do about it.

 

[98EdBomber]

Oops. Brian fart. Yeah straight 30 wouldnt be a bad idea. Im going to try some 10w-40 and see what happens. Ive also ordered a new tensioner to see if that will help with the chain chatter.

 

[drdoom]

Totally different engine, but I saw a '95 Taurus the low pressure at idle right before the engine went...literally sounded like someone had a jackhammer in there when it blew.

 

[98EdBomber]

Totally different engine, but I saw a '95 Taurus the low pressure at idle right before the engine went...literally sounded like someone had a jackhammer in there when it blew.

Well the only thing that gets me is that its fine on the road. No chain rattling, or check gauge lights and the dummy gauge goes back to normal. I will see what happens when I put this thicker "high mileage" oil in along with a new filter. And I have a new tensioner on the way. These SOHC engines are strong engines once you get the timing chain issues fixed. I already changed the sending unit and that wasnt the problem so Im guessing its the lighter weight oil and the high mileage and the hot temps today. I will check back here to update. Thanks though...for giving me even more anxiety now.

 

[SoNic67]

On road you have higher rpm's so the volume of pumped oil is larger, enough to maintain the pressure when passing trough the enlarged gaps in the worn camshaft bearings.
I had the same thing happen, and now I am on borrowed time running Mobile 1 5W50 (in winter 5W40 was enough).

 

[98EdBomber]

On road you have higher rpm's so the volume of pumped oil is larger, enough to maintain the pressure when passing trough the enlarged gaps in the worn camshaft bearings.
I had the same thing happen, and now I am on borrowed time running Mobile 1 5W50 (in winter 5W40 was enough).

How big of a job is it to replace the camshaft bearings or is it worth it? Ive done all the work myself but maybe this would be a tougher job? I guess youd need feeler gauges find out if it even is the cam bearings.

The chain noise today at the car wash kind of scared me. It got pretty loud. Right after I put everything back together and ran the engine for leaks it wasnt as loud. Seems to be getting louder but its a little hotter today so I dont know if its the oil or the tensioner failing to keep adequate spring pressure on the chain. but it does make sense that the chain noise is louder and the oil gauge is at 0 that it would mean there is something causing a lack of pressure, most likely being the bearings i suppose. Im checking the oil pressure today with a tester but i bet its going to be low just by the sound of it.

Also, wont i get a different pressure reading with lighter weight oil or does it not matter?

 

[R1dd1cK]

I had this same problem on the Thunderbird. It just ended up being that a small piece of something got into the sensor. I replaced the sensor and never had a problem with it again.

 

[koda2000]

Oops. Brian fart. Yeah straight 30 wouldnt be a bad idea. Im going to try some 10w-40 and see what happens. Ive also ordered a new tensioner to see if that will help with the chain chatter.

you're better off with a straight weight oil, 30 or 40 weight (40 might be better as it's getting warmer out now. while 10w30 is supposed to be 30 weight when hot, it always seems to be a thin as milk when you drain in hot.

the reason it does it only at idle is that that's when the oil pump is spinning the slowest and making the least pressure. you should have about 10 psi for every 1000 rpm up to about 40-45psi when hot, on a standard oil pump. if you're only making 3 psi at idle, it'll make the gauge bounce because it's almost below the operating range of the oil pressure sending unit.

it could be a worn out oil pump, a clogged pickup screen or wiped bearings. if the bearings are still serviceable, they wouldn't be for long unless you can get the pressure up. you'll have to drop the pan in any event, so all 3 can be checked at the same time.

i wouldn't worry about the tensioner until you get the oil pressure thing sorted out. it might be a waste of money. good luck, i hope it's just the pump or screen. if the chain is only rattling at idle, you might not even need to replace the tensioner, as it may just not be getting enough oil pressure to make it work.

 

[98EdBomber]

I had this same problem on the Thunderbird. It just ended up being that a small piece of something got into the sensor. I replaced the sensor and never had a problem with it again.

Lucky you. I replaced the oil pressure switch too and nothing changed. Still low idle chain rattle and gauge lights up.

 

[98EdBomber]

you're better off with a straight weight oil, 30 or 40 weight (40 might be better as it's getting warmer out now. while 10w30 is supposed to be 30 weight when hot, it always seems to be a thin as milk when you drain in hot.

the reason it does it only at idle is that that's when the oil pump is spinning the slowest and making the least pressure. you should have about 10 psi for every 1000 rpm up to about 40-45psi when hot, on a standard oil pump. if you're only making 3 psi at idle, it'll make the gauge bounce because it's almost below the operating range of the oil pressure sending unit.

it could be a worn out oil pump, a clogged pickup screen or wiped bearings. if the bearings are still serviceable, they wouldn't be for long unless you can get the pressure up. you'll have to drop the pan in any event, so all 3 can be checked at the same time.

i wouldn't worry about the tensioner until you get the oil pressure thing sorted out. it might be a waste of money. good luck, i hope it's just the pump or screen. if the chain is only rattling at idle, you might not even need to replace the tensioner, as it may just not be getting enough oil pressure to make it work.

I dropped the lower pan to clean it all out. Took the pickup tube off and cleaned all the **** out of it. Just a bunch of plastic pieces. I dont think its clogged but i will check it again as my oil pan gasket is leaking just a tad because i decided on not using rtv on a used gasket. gonna seal it up nice and tight this time and recheck that tube.

I guess if the pump was failing It wouldnt be noticeable at highway speed huh? No lights or knocking? Because it doesnt do that. Its a fairly quiet ride on the highway. I dont know the actual pressure yet.

I know that the new tensioner may not work too but oh well, already bought it. I hate part chasing, so later today i will pick up a real gauge and see what i got. I hope its just a pump and not the bearings, I really thought id get more out of her than 160K before i had to do a major rebuild. Just my luck...

 

[©H®I$]

Hmm I was going to suggest changing the dummy sensor but I guess you already did that. When I made the switch to synthetic, my dummy sensor went dead and would take a while to shoot up to normal. Fix that problem after I changed the sensor.

 

[koda2000]

I dropped the lower pan to clean it all out. Took the pickup tube off and cleaned all the **** out of it. Just a bunch of plastic pieces. I dont think its clogged but i will check it again as my oil pan gasket is leaking just a tad because i decided on not using rtv on a used gasket. gonna seal it up nice and tight this time and recheck that tube.

I guess if the pump was failing It wouldnt be noticeable at highway speed huh? No lights or knocking? Because it doesnt do that. Its a fairly quiet ride on the highway. I dont know the actual pressure yet.

I know that the new tensioner may not work too but oh well, already bought it. I hate part chasing, so later today i will pick up a real gauge and see what i got. I hope its just a pump and not the bearings, I really thought id get more out of her than 160K before i had to do a major rebuild. Just my luck...

aren't you concerned that you found "a bunch of plastic pieces" in your oil pan/pickup? this is telling you something.

 

[Runnin'OnEmpty]

.......along with a new filter.......

I've seen oil filters collapse and cause all sorts of
trouble. Hard to diagnose too, especially if it's
been installed recently. I'd change the filter
and eliminate that as a possibility...

 

[©H®I$]

aren't you concerned that you found "a bunch of plastic pieces" in your oil pan/pickup? this is telling you something.

I remember reading somewhere that the timing chain on the SOHC would go out and some people found pieces of metal in their oil pan

 

[98EdBomber]

Went back to normal after a long drive

aren't you concerned that you found "a bunch of plastic pieces" in your oil pan/pickup? this is telling you something.

Yes. I arranged the pieces together found in the oil pan and pcikup tube and concluded it was fragments from the jackshaft tensioner and the cam shaft guide. The cam shaft guide was not totally shredded, just cracked and only a few little pieces broke off. The jackshaft tensioner was pretty much shredded. I inspected the chains very closely and I did not notice any damage to any of the chains/sprockets.

But guess what?!?!?

I just got back from a long drive across town on the highway and on some side streets and for some reason everything seemed to be OK. I even idled for 5 minutes in a parking lot and it stabilized. No check gauge light and the needle was in the middle. It was 102 degrees today btw.

I will see what happens in the morning. Now Im stumped.

 

[98EdBomber]

I've seen oil filters collapse and cause all sorts of
trouble. Hard to diagnose too, especially if it's
been installed recently. I'd change the filter
and eliminate that as a possibility...

Yep I agree, in fact, I picked up a Motorcraft one today. I debated on whether to get the K&N filter. I hear good things about them, although they are 3x the cost. Have you had any experience with the K&N filters?

 

[CDW6212R]

Stick with an Motorcraft filter, and a good oil. A thicker oil is a decent idea, if you know that the passages are really worn and bigger. On colder start ups a much thicker oil would not be good, but most quality oils flow well in most conditions.

You do need to know what the oil pressure is given the gauge readings and minor noise.

 

[98EdBomber]

Im on the West Coast in the desert and its 102 out today, so I dont think Im too worried about cold mornings for now at least. Im getting that pressure checked tonight when I have time. Thanks again!

Cheers