Slick 60's

Hey all. My F250 with a 300 has around 40psi oil pressure while driving...Until I make a right hand turn. Going straight, turning left, backing up, it's all good until I turn right. Sharp right turns it drops quickly, whereas with long gradual right turns it slowly drops. As soon as I staighten out it pops right back up.
It's a mechanical gauge and the sender is on the drivers side. The engine is out of an 86. Am I missing something simple here or could this be a serious problem?

any oil pressure issues are potentially serious until diagnosed

heard of this with front sump pans while climbing steep hills, and rear sump pans and severely quick stops but never while turning one way.

seems that all of the oil in the pan must be flowing to the right side on the turns, away from the pickup tube and screen.

there are a few different 300 pans, a pic of yours would be helpful.

after checking the oil level,(and insuring you do in fact have the correct dipstick for your pan) i would start by inspecting the pan for dents, getting a mechanical pressure gauge to test and observe under the same turning conditions and if all of those are fine but the issue still presents then pan removal and inspection of the tube and screen may be needed.

I am assuming you have already done a "wiggle test" to ensure this is not a wiring problem. Might try over-filling the sump a quart or so temporarily to see if there is any change if verification with another gauge still indicates a problem. With 40 psi, I would not expect a loose pickup, but as Ice stated, it definitely warrants quick investigation.
Paul

Thanks guys.

I believe that I have the rear sump pan, but I'll check when I get home tonight and get a pic of it.

I'm pretty sure I have the right dipstick. I put 6 quarts of oil in, and it's at the full line.

I have a new extra mechanical fuel gauge that I haven't used yet. I'll pop that one in and see if it does the same thing.

I also forgot to mention that when I had the engine put in I had a high volume oil pump installed. Dunno if that has any relevance to the issue.

ICEMAN6166 wrote: seems that all of the oil in the pan must be flowing to the right side on the turns, away from the pickup tube and screen.

Is the pickup tube on the passenger's side of the engine?

the tube is supposed to be set so that the screen is in the center (L to R) of the pan close to but not touching the lowest point of the pan. about 1" off the bottom i think.
if the screen and tube somehow twisted then its possible for your condition.
a high volume pump could possibly make it worse but only if the screen was twisted.

since you say you had it installed i am assuming you did not see it before the pan went on, leaving your trust in parts you did not touch and someone elses work.

Not sure what kind of gauge you are planning to use, but I would cobble in a mechanical one for diagnosis, just to eliminate the electrical possibilities.
I didn't note if this were a problem since installation or something which just showed up.
My reason for suggesting over-filing is that I would not expect a properly installed pickup to be starving with 6 quarts, so if temporary over-filling eliminates the problem, you can feel fairly certain pan removal will be required. Even a pinhole in the pickup tube can cause this problem if in a location allowing exposure to air when turning right.
I am stil leaning toward an external problem, however, especially with results dependent on the severity of the turn.
Over-filling can be equally detrimental, and you may see differing oil pressures when over-filled.

Still haven't gotten around to checkin on this yet...I was just gone for military training for two months. The truck sat in the garage the whole time and now I can't get it to stay running.

Ice - No I did not install it myself. I bought the parts myself and gave it to a garage that I regularly use and trust. But I suppose no matter how much you trust a place there's still the possibility they can mess things up.

Toyz - I do currently have a mechanical gauge installed in the truck and it has a new sending unit. Once I get the truck to stay running I'll try that overfilling test. And I wanna say it's been like this since I got it back, but can't be certain. I didn't drive the truck for a couple months after I got it home. I'd start it, let it idle, then put it back in the garage. I noticed it once I started to take it around the block.

I'll also get a pic of the sump and measure the dipstick.
Thanks again for all the help so far guys.

I went to harbor freight and bought the triple gauge set that uses a clear tube and reads pressure at the gauge. Its not expensive and comes with the adapters needed, and you can see the oil in the tube. I have used it when starting motors for the first time, or to make sure the oil pump is actually pumping oil. No wires involved and swapping back to a sending unit is a breeze. I also use it on my engine stand to monitor water temp and amps on a spare engine.

Alright so I measured my dipstick and just the flat part is 1 foot 1 1/2 inches and the entire thing from handle to tip is 1 foot 5 inches.
It also has the front sump pan. I looked around it and aside from being grimey theres no noticeable dents or damage to it.



UnibodyMadness - Thanks for the heads up. I've been looking for a cheap gauge cluster to mount on my dash. I'm definitely going to pick one up here soon and test it out to see if my gauge is finicky.

For now it looks like my carb has developed some leaky issues, so i'll be yanking that this week and starting my education on carburetors

Well, carb is rebuilt and put back on. Of course more issues started to snow ball, and after 6 new plugs, coil, and too much time messing with my timing, the engine is back to life. Still needs some more tuning because it idles at a different rpm every time I start it, but it runs well enough. Now I can get back to figuring out the oil issue...

Dealing with similar issues. Assuming you rebuilt the carb correctly, try spraying some starter fluid around the carb and manifold. If the idle picks up or you hear whistle before you try, you may have a vacuum leak.

Thanks for the tip, I'll definitely try that. I'm also thinking the spring that pulls the throttle back to idle (hope I described that correctly) might be worn out. Sometimes my gas pedal doesn't return all the way "up."

I agree about putting an extra quart of oil in the engine. Then try driving it and see if it still does the same thing. If the problem stops, you will have an indication the problem is inside the pan, or something is wring with the dipstick in your motor . As to running the motor overfull of oil, if it doesn't foam the oil, then most likely won't hurt anything. As to momentary oil pressure loss. Doesn't do the engine any good, but most likely hasn't done much in the way of damage yet. Do the lifters start making noise when the loss happens?

Rich

Yea, when it looses pressure it chatters.

Update on the issue....
Well the snowball of problems keeps getting bigger. Long story short the autolite carb was trash and I swapped it out for a carter YF. Now I'm working on getting the truck running.

Since the engine is out of an '86 I perused through some of those forums and it seems like some of the 300's took 6 quarts. Hopefully my oil issue is because it's a quart low. So once I get this running I'll be adding a quart and testing the gauge.
Thanks for a the help so far everyone.

Since you get lifter chatter when the pressure drops, I think it is a real pressure drop - not a gauge or electrical issue. Check your oil level before starting and after warm-up. Its possible that you could have sludge build-up that slows the return of oil to the pan, artificially lowering your oil level.

bruceandersson wrote:Since you get lifter chatter when the pressure drops, I think it is a real pressure drop - not a gauge or electrical issue. Check your oil level before starting and after warm-up. Its possible that you could have sludge build-up that slows the return of oil to the pan, artificially lowering your oil level.

i had that issue once
oil drainback holes plugged so the pressure went down as the rpms went up

took a drill motor and a piece of choke cable housing and roto-rootered the holes, problem solved

Well now that the truck is operational again I got back to work on this problem. I added a quart of oil and the problem got better. The pressure will drop on right hand turns, but I won't completely loose it.

I read that on some of the HD300 they would take 7 quarts. My engine came out of an Air Force truck that was an F250. I suppose it is possible they could have ordered a HD300 in the truck? I guess it couldn't hurt to add another quart and check lol.

bruceandersson wrote:Since you get lifter chatter when the pressure drops, I think it is a real pressure drop - not a gauge or electrical issue. Check your oil level before starting and after warm-up. Its possible that you could have sludge build-up that slows the return of oil to the pan, artificially lowering your oil level.

If I check the oil level immediately after shut down it is a little low. If I wait a bit it's at the full line. Looks like I could have some sludge.

By the way, that is not a front sump oil pan, but a center sump.
Found in a lot of vans, if I remember correctly.

Well it's looking like it's either sludged up or I'll have to drop the pan. I put another quart in on the off chance I had somehow gotten some sort of 7 quart pan, but the issue is still there. Thanks for all the input everyone.