Hello everyone, I need to pick your brains with an issue I am having. I have a 1994 F150 Extended cab 4x4 with a 5.0 engine (approx. 135000 miles). The past few days here at Ellsworth AFB in South Dakota, we have been expiriencing negative degree weather.

At the beginning of the week there was a blizzard with horrific winds, and to make a long story short, turned my engine compartment into a big snow drift. Since that happend, my oil pressure guage was erratic. At first it wouldn't read any pressure and after about 5 minutes it would. It seemed to run fine until Tuesday when I started it and after letting it warm up for about 5 minutes, I still didn't have any oil pressure. I had to get home and hoping the pressure would return, I started driving home which is about 2 miles away. The pressure didn't increase and because it was cold I assumed the oil pressure sending unit was shorted out due to the snow drift I had in my engine compartment the day before. As I was driving home, it started to he a chattering from the engine, which would increase as the RPMs increased. When I got home, there still wasn't any pressure.

Today, we got a heatwave (20 degress F above zero and no wind chill), so I went out to start it and it still doesn't have any oil pressure. I checked the oil, it was good, and it still chattered. I am assuming it isn't the oil pressure sending unit due to the tapping noise coming from the engine.

I went to my Auto Hobby Shop on base hoping for some good news and he said the rod may have sheered. Not exactly the good news I was hoping for. I referenced my trusty Chiltons and it looks like a lot of fun to change out the oil pump. I do have some time, but is it worth it to try to change the pump with the chattering I heard? What kind of damage may I have done driving it in this condition? (I suppose this would be an excellent opportunity to swap to a 351, but I wasn't planning on doing this this soon.)

I would appreciate any advice anyone can give me or some other insights on what else cold cause me to lose my oil pressure. Thanks.

 

well hook up a mechanical gauge first. the stock gauges suck and are not true gauges.
with that gauge hooked up you can take a electric drill and turn the pump drive shaft to generate pressure if this works then you know the pump is not the problem.

what oil are you using and you might think about a block heater

 

Thanks for the quick response...How would I hook a drill up to my oil pump? I don't remember reading that in my tech manual.

And to answer the block heater question...I was going to put one and even if I did have one, I wouldn't have had a place to plug it in at work. Not unless I had a 300ft cord to meven get close to the building.

I am using Quaker State High Milage (the stuff in the red container) 10W-30. I have used this weight oil in the past and I didn't have any issues. I guess this proves that mindset wrong.

 

i would run 5w30 if its getting that cold. to get the oil pump primed you need to pull the distributor out. just mark it so you know exactly were it needs to be when you reinstall it.

 

they told me the same thing too. rods and ****. i was like BS, only thing i had was valve chatter. Chances are your oil pump is going or gone, and your pick up screen is clogged. put a mech guage on it and got from there.

 

If it is my oil pump and I go ahead and change it, what are the chances that I did extensive damage to the engine? How much should something like cost to have repaired at a local shop, if I am unable to do this myself? I am just a little apprehensive changing the pump if the damage is beyond repair.

 

It depends is the engine knocking at all or just the lifter tick. hard to say with out seeing it. I was told to replace or rebuild my engine too, but i was like no way and it was just the oil pump

 

If it was cold enough (and it sounds like it was!) and the oil too thick, the rod they are talking about that may have sheared is the oil pump driveshaft. As soon as you yank the distributor as per Kemicalburn's advice, you will know. The rod has a nifty little way of falling down into the oil pan sometimes when the dist. is pulled and if it's in two peices as I suspect it is, then there's an even better chance of one or both pieces winding up down there. Believe it or not, this isn't a big deal. They tend to lay in the bottom of the pan out of harms way till the pan is dropped sometime in the future.

When you pull the dist. one piece of the shaft may come all the way out with it. The piece that's still in the pump will be the tough one, be prepared for a fishing expedition. You'll have to find a straight piece of rubber hose that will slip down in the hole and go over the end of the shaft to gip it and pull it up. A magnet can be used sometimes, but it tends to stick to everything else on the way down.

Hardened aftermarket replacement pump shafts can be had for 15-25 bucks. I would put one of them back in rather than a stock replacement.

If all else fails and it is the pump itself that's gone south for the winter, you'll just have to drop the pan to deal with it. I hope you have access to a heated shop to work in, no matter what!

 

If I am understanding this correctly, I may not have to pull the pan? If I am am able to pull the pieces out, all I have to do is drop another one in? I have a concern about shavings in the pan. Everytime I think of metal sheering, I see all kinds of metal shavings in various sizes everywhere. I know this because I have a knack of getting slivers in my fingers.

I will have to try this out and if it works, I will be very happy due the timing of my pump failing and Christmas right around the corner. I will be changing the oil quite often the make sure to get the metal shavings (if I can). Thanks and I will let you know what I find as soon as I can do it.

 

The pump shaft is hardened steel. It usually shears off cleanly without leaving shavings. If you're concerned about it, you could get a magnetic oil plug, and even get a big strong magnet and clamp it to the bottom of the pan. Any metal in there should stick to the inside of the pan where the magnet is.

 

Kudos to TigerDan! He's probably right about the shaft shearing.

I've heard stories about pulling pans and finding several oil pump shafts in the bottom.

For oil, I'd be using Mobil1 0w-30 or something similar. Use a fully synthetic oil, not Castrol. Also, add some GM EOS or STP Oil Treatment to get the ZDDP.

 

First off, if you have no oil pressure, don't run it! My first instinct would be to put a mechanical guage on it and start it just long enough to be sure you don't have pressure. Based on the noises your hearing, this may be a waste of time, so you may decide to skip it. A snapped oil pump drive shaft sounds like a likely culprit. If that shaft is broken, that could be the source of noises. The bearings, lifters, etc. may have survived, maybe. I've seen 302's go thousands of miles with less that 10psi. It's not good, but they'll make it. If you want to see if the shaft is broke, pull the distributor. Check the hex drive in the bottom of the distributor. It's probably not the culprit, but it may be stripped. Look down the hole in the block with a flashlight. You should see a small hole where the bottom of the distributor goes. In that hole, you should see a 5/16 hex on the end of the oil pump drive shaft. If it's not there, it's broken. If it is there, it may still be broken but not driving the pump. Put a 5/16 6 point deep socket on a long 1/4 drive extension. Tape the socket to the extension, you don't want any more loose parts in there . Put the extension in a drill chuck and put the socket on the end of the pump shaft. Run the drill the same direction as the distributor (check firing order section of shop manual for direction). It should spin easy for a second, then it should have a good load on it (when it starts pumping oil). If you didn't know already, this is how people prelube new engines before starting them. If it never gets a load on the drill, either the shaft or the pump is broken/stripped. FYI, it is possible (although not ideal) to put a new shaft in from the top, but you will never get the old one out that way (there is a clip on the shaft that keeps it from coming out the top). You must get the old one out, so the pan must come off. Once the pan is off, you can check the condition of the motor and decide if it's time for more cubes or a new pump & shaft.

 

first, the gauge is an idiot light. that is why it never moves. you need to check with mechanical gauge first, before you drive or start vehicle again.

second, is the weight of the oil to thick for your weather. if in doubt do an oil change and use a motorcraft filter at the same time.

third, dropping the oil pan is no fun in summer, so it will be hell to do in your below zero or up to 20 degree heatwave weather. have a shop do it if you can afford it. or try to let a garage rent you a bay. you are in the service find a retired soldier that ows a service station. he may help you out.

fourth, my oil pickup screen was so clogged it was stopping oil flow. this is a common problem in these trucks. also it may be the oil drive like your shop said.

i hope i helped give you a direction to go in.

good luck.

 

The parts stores sell sending units that do actually vary with pressure, the "gauge" version. That's what you want. They also sell the "switch" version of the sending unit which always goes to mid-range as long as the pressure is above minimum. Ford puts these in and they're virtually useless.

 

I went out to my truck this evening and took my distributor off and tried to prime the pump by hand. I was spinning it for about a minute and in both directions with chnage in tension. I am assuming the rod is broke. In a post I put in a different section of this site and they said I may be able to put the shaft out with a magnet or a piece of hose. I thought I would get clarification on this before I either get someone else to it for me, because I do not have a lot of time to the pan, or try and fish the shaft out from the top. By the way, has anybody had a shop change the pump for you? If so, how much was it so I can find a reasonable quote? Thanks for the information so far, I have learned more about oil pumps than I ever thouhgt I would.