I have a similar question. I've got a 93 bronco with a 302 and almost 270k on it. Oil pressure was always excellent around the "MA" in "NORMAL" then i noticed one day it dropped to O and then N. I pulled over, checked the level and started it back up and it ran fine and pressure was around the "M". This was at about 230K miles. Now more reciently (ever since about 240k) my oil pressure is fluctuating alot. Sometime is can drive it all week and it will be around the MA and sometime it will not budge past O. Usually when cold it will be high, but if the engine is reved above 2500rpm or under a load when it hasn't been running for a while, the pressure immediately drops to O. Then the only way to get it back up is to let the engine completely warm up then get on it a little and accellerate qwuickly to about 60mph, reving it up to about 3500RPM.

I've had this problem for about 20K miles and have had a slight puff of blue smoke (very slight, most wouldn't even notice) when first starting after the truck has been sitting for several hours. I had the truck since 200K miles and back then it had, and still does, have a rear seal leak. I religiously change oil/filter myself every 3000 almost exactly (within 50 miles). I started using 10w-40 Quaker State 4x4 Synthetic Blend with about 1 1/2 quarts of Lucas oil treatment to help the rear seal leak. Then when I started having problems with oil pressure I switched between the 4x4 syn. blend and non synthetic Q.S. 10w-40 high mileage and 1 to 1 1/2 Lucas (always 6 quarts total).

Now at 270K i have a slight noise upon startup till engine gets warm, but goes away before it reaches operating temp. It sounds like a lifter on the passanger side. So now my question is about Seafoam. I would run one bottle for about the last 300 miles before my next couple oil changes. Should I be worried about plugging my oil pump / oil passages with all the sludge that is most likely in my engine?? I have heard that on real dirty engines it is recomended to remove the oil pan to physically remove all the sludge after something like this is done. Basically this is a strong runner and am looking to keep it alive. I rely on my Ford to commute back and forth from school and I also would like to see how many miles i can get out of it before it needs some major work.

I have been wanting to get, and will in the near future get a nice set of mechanical gauges for just about everything, but most importantly the oil pressure. A few more things, i did replace the oil pressure sending unit at 204k miles because it leaked, also i know that there is some blow by since the crankcase breather does have oily residue in it as well as the bottom of the air filter box where the hose goes.

Any input is greatly apreciated! thanks

 

i'll try that this weekend,

Thanks for all the info

 

I am looking at a 91 F-250 with the 460 FI and was noticing the same thing as many others. Cold it's at the N-O. Warm, it sits around the N. No smoke, no noises, idles very slightly rough at times, but runs like a banshee. The truck is in very good condition, but I don't want to buy it if this will lead to a problem down the road. I want to fix it up and use it for a couple of years, then have it as a run around truck, so I might take the chance and hope it'll last for a year or two. Any suggestions on this engine, or is the above advice par for the course? Thanks.

 

if the truck has been sitting run it with a lower grade oil for about 1,500 miles then change the oil. and put 10-40 back in it(thats what my manual says to use check yours before) after doing that my oil pressure is back up around MA in "Normal" under normal conditions

 

i have all those problems... the knocking at startup is the lack of oil pressure, i get that alot during the winter when i used sae 30..go figure. the only time i get blue smoke is when im runnin like 75 and im climbin a steep hill and it down shifts

 

oh god before you do anything like rebuild the motor CHANGE TO A GOOD OIL PRESSURE GAUGE!!!!!!!!!!!!!!!!!!!!!!!!!!!!!

the ones from ford are complete crap. i had one that started out in the middle. on my way to my parents house some 150 miles away the needle drops off and scares the **** out of me. i pulled over and bought more oil thinking i was low. the damn needle kept doing it all the way home. i ended up overfilling the oil by quite a bit by the time i got home.

i replaced with a good aftermarket gauge later and it runs steady at 50 when driving down the road and 25 when at idle.

again..........DO NOT TRUST THE IDIOT GAUGES THAT FORD HAS IN THE INSTRUMENT PANEL. THEY ARE CHEAP CRAPPY GAUGES!!!!!

 

Put in a quart of transmission fluid in the oil (drain out ! quart of oil) and run this about 500 miles will clean it out for sure. Have been doing this for about 5 years on mine, I do it about every 6 months and is clean as a pin. Pulled the valve covers about 3 weeks ago and no crude or build up. Learned this from and old mechanic about 30 years ago, works well for stuck lifters.

 

Just curious, why did u pull the valve covers off? I know a guy who would dump 1-2 quarts of ATF in his diesel tanks (50-100gal fuel) on his rig evey fill-up. Said it keeps the injectors clean because of all the detergents.