Hey guys I flushed my 86 bronco 300 engine with an engine flush additive and ran it for 5 minutes. Changed filter and added a quart of Lucas and 10w-30. Now oil pressure is low and goes up a bit intermittently. I hope I broke the sensors or something because it’s old and the wires all corroded. There’s also a ticking noise. We just installed new lifters and rockers to fix an intermittent lifter tick but now the noise is consistent. I’m at a lose here’s hope I didn’t hurt anything with the engine flush.

 

If your engine was really dirty inside, the engine flush could have knocked a lot of sludge loose inside. This can fall in the pan and get sucked into the oil pump pickup screen, blocking it. You could drain the oil again being careful to save it, and see how dirty it looks and if any chunks come out.

 

You only added "one" quart of oil ? That's not right. You need to drain all the flush out of there and put in fresh oil.

You can run this new oil and new filter for say 500 miles and then repeat the oil change. Depending on if the oil gets dirtier faster, you could change it sooner.

 

That is why I dont like them oil flush products and I had a motor do the same thing.
I was not using the car much and got rid of it shortly after.

1 qt of ATF just before a oil change is what I use now.
I add it and let it idle to warm up as I get the oil change tools together.
I may bring the RPM a little only to move it to where the oil gets changed from its parking spot.

It cleans but is not "gain busters" like the flush is.
Also my motor was not that bad inside when I replaced the oil pan, side cover and valve cover gaskets when rebuilding the truck
I also cleaned them parts in a parts washer before they went back on.

I dont know at this point if I would trust the factory gauge (with out numbers) and install an after market one for testing to see just what you have.
Maybe crud in blocking the factory sender and making it read low?
Dave ----

 

Dave, if your engine is cleaner inside, I would not use the ATF every time. There was a time when I would use Gunk, before the oil change. But I stopped doing that about 13 years ago. Have never used it in my truck.

If you drive the vehicle for long distance, so the oil gets "good and hot", IMO, the flushing is not needed. My cars always get driven for 80+% long distance, say at least 10 miles. Highway in most cases.

My F150 which has had 45,000 miles since 1991, has clean oil when I change it every two years after about 800 miles or so.

Here's my oil pressure after about 6 miles of driving. At speed, the pressure raises up to about the first part of the M.

 

I may do that after the next oil change that it is due for, as it is a lot cleaner than when I first got the truck.
If I take the truck to work like I did yesterday that was just under 80 miles, 400 miles in a week if I use it.
Other wise a few miles weekly for the trash, under 10 as a guess and then if there is a show / cars & coffee would be more than 10+ miles for that.

At one point I was getting "milk shake" on the dip stick and under the oil fill cap and could not figure out why?
I was driving it to work a lot more then, highway 95% of the drive to / from. and run a 195 stat that works.
The PCV was also working so I was
Then about a year ago it stopped and I dont know why?
But I will take it as the shake did not look good
My oil gauge runs in about the same place but the temp gauge had always read low, sits between the line and the N in normal but the heat will cook you out and you cant touch the hoses so it is hot. I have also checked the connection and even swapped the sender with no change.
Only time I have seen it go up to the middle is what it was 95* out and I had the AC going sitting idle waiting for a buddy to get gas and a coffee before a show.
But as soon as I started to move it came right back down.
Being the oil and fuel gauges read right its not the IVR
Dave ----

 

If it's driven in cold weather, the milky color under the oil fill cap is not an issue. My 05 Legacy GT wagon with an Aluminum air/oil separator would have that in winter time. It was driven for long distances. It was just the cold air hitting that area where it sat. It had 306,000 miles when I sold it last Oct.



Here's where it was in the car, engine tuned at 21psi boost. It was fun to drive...for a wagon, had a 5 speed tranny.

 

I do drive it when cold out but this was in the summer too so???
Last I checked I did not have it so we will keep and eye on it.
Dave ----

 

Good luck, there Dave

 

Hey fellas so we replaced the oil pressure sensor now it’s reading as high pressure with some big fluctuations while driving. Considering dropping the oil pan to see if the filter is clogged and to replace the gasket but my mechanic buddy says it’s not necessary. Is everything fine or should I be concerned. This pressure issue pronounced itself to me after we flushed the engine and replaced lifters and some rockers. We re added 15w30 and a quart of Lucas. Could it simply be the thick oil. Thanks again.

 

So this oil PSI reading moving all over is this at a steady RPM or RPM also up & down?
If you have after market gauge it will go up & down with RPM, cold or hot.
I dont remember if it was said or not but rule is for oil PSI 10 PSI for every 1000 of RPM.
So 10 PSI at idle (650 rpm?) hot is good and at 3000 RPM would be 30 PSI.
Dave ----

 

Don't try to troubleshoot the engine with the factory gauges. I would get a aftermarket gauge and hook it up and see what it says. You should have at least 10 psi per 1000 rpm.

 

Earlier you said the oil pressure was changing, intermittently...? The needle will rise and fall, depending on engine rpm.

 

My experience when my oil pressure was showing very low on the factory gauge...

The factory sender was close to failure. I added an aftermarket and it was very consistent in 50-55 psi range at all revs and atmospherics. The few times it drops below 50 is at idle on 100 degree days after the engine has been flogged for 30 minutes or so. Then it drops to about 35-40 until revs pick up, or a few minutes of cool down.

After replacing the factory sender, I noticed it was pretty temp sensitive. When cold, 55 psi showed about 2/3 of the way up into the normal range. On a hot day under average loading, the same 55 psi would indicate as low as 1/4 of the way up in the normal range.

I like having both the factory and the aftermarket. The factory is easy to scan while driving and good enough to tell me when I need to check the aftermarket in abnormal situations.

 

After changing the sensor it still fluctuates but no mostly sits at max pressure on the factory gauge.