When you click on links to various merchants on this site and make a purchase, this can result in this site earning a commission. Affiliate programs and affiliations include, but are not limited to, the eBay Partner Network.
My truck has oil pressure at start up then after I drive it the pressure goes down. I was told that the oil pick up screen is clogged. Can I remove the oil pan with only the engine raised up?. I was told I may have to remove the transmission to get the oil pan off. This is my question, does the transmission have to be removed to do this? 302 with an automatic transmission.
SGHD (Stock Gauge Hatin' Dave) should be along soon to tell you there's no way you should trust that numberless gauge when making such a big decision. As much as it pains me to admit, I almost kinda sorta agree with him. It's a LOT of work to replace the oil pan pickup in situ. For now, we don't even know if the pickup screen is at fault, as there are other possibilities, too.
If you have to change the pickup screen, here's my experience with a 351W, which should be similar to your 302. I was replacing the oil pan gasket, but the pickup screen has to be removed as part of the process:
If (big if) the screen is clogged, I recommend replacement versus cleaning. The design is such that cleaning is difficult.
How bad is the drop in pressure? It's normal for pressure to be high when the oil is cold, and then gradually decrease somewhat as the oil heats up and thins out. What viscosity oil are you using? That will affect the amount of decrease, too.
Are you hearing any clatter from the lifters, or other noises? Obviously don't keep driving it like that if actual oil pressure is an unknown. I'd still be inclined to rule out an indication problem first.
Tap into the oil pressure sender port with a real mechanical oil pressure gauge.
If you really had zero oil pressure your lifters would be clacking and ticking. If run long that way you'd develop a rod knock or a seized rod which could break and window the block.
So see what the pressure really is before taking on a messy and unpleasant task like pulling the pan with the engine in place.
Ooh, I hate to be the bearer of bad news. In my over-inflated opinion, low oil pressure after warm-up is typically caused by one or more of the following three likely culprits, in no particular order:
1) Excessive clearance at the rod and main bearings due to normal wear and tear.
2) Excessive clearance at the rod and main bearings due to normal wear and tear.
3) Excessive clearance at the rod and main bearings due to normal wear and tear.
Most likely a new oil pickup screen is not going to fix the issue. If clogged, it would also affect oil pressure when cold, too. Sadly, I’ve seen lots of guys try a new oil pump, thinking that must be the problem, but it was no help. I do not care to discuss how I learned this, but at least my experience was on an engine where the pump was a piece of cake to replace.
But from what I’ve seen (and experienced firsthand with other engines), it’s one of the three possibilities listed above. Please don’t shoot the messenger.
Ooh, I hate to be the bearer of bad news. In my over-inflated opinion, low oil pressure after warm-up is typically caused by one or more of the following three likely culprits, in no particular order:
1) Excessive clearance at the rod and main bearings due to normal wear and tear.
2) Excessive clearance at the rod and main bearings due to normal wear and tear.
3) Excessive clearance at the rod and main bearings due to normal wear and tear.
Most likely a new oil pickup screen is not going to fix the issue. If clogged, it would also affect oil pressure when cold, too. Sadly, I’ve seen lots of guys try a new oil pump, thinking that must be the problem, but it was no help. I do not care to discuss how I learned this, but at least my experience was on an engine where the pump was a piece of cake to replace.
But from what I’ve seen (and experienced firsthand with other engines), it’s one of the three possibilities listed above. Please don’t shoot the messenger.
Karl is right if after startup and normal heat / temp and the oil PSI is 0 and the lifters / rockers are talking, not is a good way, then the bearings have too clearance.
Also think of this if the oil pick up was plugged then why dose it have oil PSI when first started but not after up to temp?
If something is plugged it stays plugged from start to finish.
Why you have oil PSI then none is when cold the bearing clearance is tighter then when it heats up the bearing clearance opens and now the oil just leaks out wherever it wants.
How many miles on the motor, was the oil changed say every 3000 miles or was it like every 5 years?
You might be able to throw in a new set of main & rod bearings and get the oil PSI back up but if the crank has marks they will not last long.
Can they be done with motor in the truck? Anything can be done but I would pull it if I was doing bearings.
Dave ----
Thinking outside the box, is it possible to blow compressed air into where the oil filter mounts and maybe blow the crap off the pick up screen, it might buy you some time...
FWIW, back in 1991, we had a ford crate motor installed when the truck had 96,000 in its 302, because of rod knock.
I would encourage testing with an external gauge at the engine BUT I had this same issue pulled the pan down found suction strainer partially clogged.
i replaced the suction strainer installed a high volume pump and drove it for another 7 years.
You stated oil pressure went to zero. What is your pressure at cold start up? Are you using the stock guage or a mechanical guage?
Plugged oil pick up screen can be exasperated by doing cold oil changes. Always drop your oil hot. That removes more sludge than a cold change.
Also keep in mind that the stock oil pressure guage has a reputation of reading low at hot oil temperatures. Swapping out the sender may be helpful.
If you do have worn bearings as Karl mentioned (3 times for emphasis...) you can improve oil pressure by adding an oil conditioner like Lucas offers. This raises the viscosity and helps fill those wear gaps.
So here's where mine set when fully warmed up, I can get it to stay a little higher if I wiggle the wire on the sending unit. Here's cold after idle settles out.
Pictures were taken on different day's, notice the fuel gauge. BTW, that's where the fuel gauge normally sits, I don't drive it much. No sense in keeping fuel in it.
I've run both 5w-30 and 10w-30, The gauge reads the same. In fact, it was only a few years back that I realized it took 6qt's of oil. Been putting 5 qt's of 5w-30 in from late 1991 till a few years back. The engine now has 42,000 miles. Since that date.
This Hennessey Takes the Expedition Tremor's Off-Roading Capability to the Next Level
Slideshow: The VelociRaptor Expedition gains a lift, upgraded suspension, Brembo brakes, and trail-ready equipment while retaining the stock 440-horsepower EcoBoost V6.
Rezvani's Latest Post-Apocalyptic Monster Is a Ford F-150 Raptor Underneath
Slideshow: Called the Fortress, the 850-horsepower pickup combines Raptor underpinnings with military-inspired features, survival equipment, and a starting price of $285,000.
