Oil Pressure Gauge Not Working

[Runnin'OnEmpty]

Sorry to hear that. That almost sounds like a mechanical
problem now, rather than a clogged pick-up screen.
Sorta like the oil pump drive shaft was rounded out
and grabbing sometimes and then spinning in the
pump as it heated up and lost pressure...?

It'll be interesting to hear what you find when you
pull the pan. Generally when an oil pump or drive
fails, the oil pressure drops to zero and dosen't come
back like your's did.

 

[ironbandit]

I got started on pulling the engine today, got all of the wires and hoses disconnected, everything up front is off, and the exhaust manifolds are loose. Next day that it is not raining, I'll remove the bolts holding the torque converter, those holding the bell housing to the back of the block and the motor mounts. We might be getting a crane and straps this weekend, and pull the engine next week.

Ah, but, before I invest in another short block, we'll see if this old block can't be rehabbed - new crank bearings, new rings, a new rear seal, and possibly get this block boiled.

 

[ironbandit]

Thank you for the kind words, ROE. I will probably have the engine out next Tuesday, and the first thing that I/we plan to do is flip the engine over on the stand, pull the oil pan, and see what the pickup, and the main bearings look like.

Moreover, I'd like to keep the block, and take it to 500K miles. Sure, it will have been rebuilt, but the block is still original... ;-D

 

[Runnin'OnEmpty]

It's all downhill after removing the exhaust manifolds.
That was a two day job for me, just getting the
rusty bolts loose when doing a headgasket.

Hopefully the block is OK. I'm real curious about
this one. Just can't figure how the oil pressure
would be good for awhile, go to zero, and then
come back again?

Maybe the pick-up tube worked loose, or cracked,
allowing the pump to lose suction...?

 

[ironbandit]

Seeing as we replaced the heads not too long ago, and replaced all of the exhaust manifold bolts with stainless steel allen bolts, I got them out yesterday. Now, we have questions about how we can remove the nuts holding the torque convertor to the flywheel, with the crankshaft unable to be moved. I also think that there are only 6 bolts holding the bell housing to the block, and 2 nuts on the motor mounts. I think the motor mounts are more easily accessed with the 2 I-beams of the front suspension at their lowest points.

Does the torque convertor slide out of the transmission? Even if it does, we're no better off. The only access is thru where the starter fits. I'm waiting to hear from a friend that has replaced the transmission in this vehicle 3 times. Albeit, the flywheel stands a bit off of the back, there might be enough room to get an open end wrench in to get at those bolts.

Oh, yeah, and we won't know if the pickup came off, or a shaft got stripped, or anything, until we have the pan off. i will be back, possibly in a new thread, about rebuilding the 4.0L OHV mill from the ground up.

 

[ironbandit]

BTW, we wasted about 2 hours today, trying to pry the bell housing from the block, and there was still one bolt them together, guess where? Just above the starter, on the driver's side. Once out, the two split up, and the TC came out of the BH, still bolted onto the immovable FW. Once out, I was able to use a 15mm standard socket with a 3/8" breaker bar to get all 4 nuts off, and the TC came right off of the FW. Tomorrow, we place the engine on a stand, and get to the bottom of the oil pressure issues...

 

[Runnin'OnEmpty]

Good work. I thought the TC would come out still
attached to the flexplate, but wasn't sure enough
to post it.

There's a few other posts about fluctuating oil
pressure on the 1st Gen forum, but no one's
posted about tearing the engine down yet.
We're anxious to find out what happened.

 

[ironbandit]

Correct links to pics

We found the problem, right away, after the oil pan was off. The oil pump pickup screen was covered with gook (see the image below), made up of bits of RTV, sludge and the like.

The crankshaft turned without any trouble after we got all of pistons out, and the rod journals are where the lockup was. Those journals were all scored, turned and even melted in one set. Both sides the oil pump drive shaft were still in very good shape, no signs of being stripped or anything else. The rod journals, and one (#2) showed the signs of overheating, excess wear and such.

Tomorrow, we will likely start the examination of the bores and main journals, the rods are a foregone conclusion that those babbits need replaced. I will try to bring some pics back of the crank, especially where the lockup is evident.

 

[ironbandit]

Also., a suggestion: if you suspect a gummed/plugged oil pickup, the pickup is located just to the left and front of the drain plug. It was suggested to use q-tips or some such, and well, that wouldn't do a thing to what I found on mine. Better to get a couple of cans of carb and brake cleaner, and a flexible flashlight to know where to aim those sprays. You need something that will cut thru whatever is in/on the pickup screen...my screen was not visible, as you can see in the picture in the previous post.

What mine really needed was a backflush, which is just about impossible to do. Perhaps, if you remove the intake manifolds, and take the rockers off, and the timing cover, you could turn the camshaft in a counter-clockwise manner, very fast, with a mineral spirits or some such solvent poured down the valley at the same time, you might very well accomplish this feat. An immediate draining of the oil pan would be in order, and what you find in what comes out should let you know if your attempt was successful. I can tell you, I dumped a half gallon of Super Clean water-based cleaner into the engine, and I had to use a screw driver to break thru the crud over the drain to make it come out.

 

[Runnin'OnEmpty]

.......I had to use a screw driver to break thru the crud over the drain to make it come out.

Wow, that's a really tough build-up. Thanks for posting
that pic, it gives an idea of what can cause oil pressure
flucuations. Your idea of spraying brake cleaner directly
on the screen is probably the only way to even have a
chance of getting one opened up.

Hope the rest of the engine is salvageable. At least
you have new heads already.

 

[ironbandit]

Not much done today, aside from taking a few pics of the crank and upper mains in the block, the conditions and schedule weren't permitting anything additional, aside from a botched cam removal. That got stopped on the upper thrust plate bolt, a Torx bolt. Couldn't get the bit seated correctly due to gunk, and rounded out the torx of the bolt. Perhaps, with a bit more time tomorrow, I can clean out the top of the bolt, and retry, or resort to a screw extractor. I'll share the pics after I get them out on Putfile, or Dropbox. Putfile went away, but Dropbox is still there.

*I am back, with the help of some friends in a chat, that helped me figger out how to post pics here without taking up local space:

Here we look at the block, the main bearings, from underneath:

Now, we look the rod journals on the crankshaft, badly scored:

And, finally, a closeup of rod journals 2 & 3:

Oh yeah, a friend contacted me last night about the crank that he pulled out of a 1996 Explorer, which I am pursuing. This old crank will need to be reground or the next set of babbits on the rods will self-destruct.

 

[ironbandit]

Today was a short one, had other vehicles to do work on, but I got the camshaft out of the block today, and found the answer to one question: there IS a roll pin in the top of the oil pump drive, where the camshaft-driven gear is anchored to the rod that the oil pump drive shaft fits in. It could sheer off, but it would take a lot of force to do so.

This was likely a remnant of a bygone era, when the block had a distributor driven off of the cam with the oil pump. If the pin DID sheer, the distributor would stop turning, and the engine would stop running. How about that for a fail-safe?

DANG, I forgot to mention, that top bolt of the cam front thrust plate? Today, I took a little more to assess, and found the proper Torx bit, a T-30. I put it in an impact tool, the kind that you smack with a hammer, and that got the bolt loose without an issue. I'll likely replace both bolts, just on principle.

 

[ironbandit]

Safety note

I'm about to go on a rant, so bear with me.

Today I went back and took my razor scraper to the mating surfaces of the block and head, block and timing cover, then proceeded on to do the same thing to each head, 3 sides scraped excepting where the rocker covers go on. After this, I wiped all of those surfaces down with paint thinner, to remove any residual bits of gasket. Then, I went and checked the fit of the oil pump driveshaft at both ends, and they both solid, with no play. That points directly at the oil pump pickup being covered with goop. Then, I took the pickup, and sprayed the screen with brake cleaner, guess what? The screen came back and was shiny again! All of the crap that was on it went back up the tube and out t'other end.

Now, for the rant. If you happen to see a low oil pressure reading, it might just be a wonky sender, or it may be a partially blocked oil pickup screen. So, drain the oil after warming the engine up, and once the drain is clear of drips, take a flexible LED, available at http://www.harborfreight.com, and see if the oil pickup is visible to the front and left of the drain hole. You may only see the pickup's metal parts, but it is only thing that should be in the pan aside from the baffle on the crank journal caps. You can try to clear the screen by dumping something like Varsol, or paint thinner, or mineral spirits, a quart or so, into the filler with the drain plug back in. Let that sit, overnight, and drain that out the next day. Reexamine that which you saw, and if it hasn't improved, then do it once more, dumping what remains of the gallon of *solvent*, not cleaner, that you got into the filler, again , drain plug back in. Let it sit overnight again, and repeat the exercise of the previous day. This time, there should be something visible, and you can use a spray like brake cleaner to break up any additional blockage on the pickup screen. Mind, be prepared to fill the crankcase with a very cheap oil, and filter, changed after you have the engine warmed up again. Tranny fluid can be used to help clean, but don't drive anywhere or put any load on the engine - idling for 15 minutes, if the oil pickup is clear, should do the trick for cleaning the engine inside.

***Make sure that you are wearing some type of eye protection, in case some of the solvent drips into your face***

Whatever you do, make gorram sure that the solvent you use is NOT water-based, or it will screw up whatever fluids that put in after it. That is where the malted-milk came from in mine. And, my machinations are likely what caused the garbage to break loose and plug up the oil pickup screen.

As it is said, those that don't learn from history are condemned to repeat it. That is my story, and I'll be stickin' to it. rant off

 

[ironbandit]

Block is well within specs

Even with 345000 miles on the odometer, this block is still in very good shape. All cylinders are at less than .001" taper and the same for out of round. The ridge at the top is less than .005", and I'm not going to bother with a ridge reamer, just run the hone up and down, until the glaze is gone.

The block, oil pan, plate between the block and tranny and the oil pump will be going to the machine shop here in Waldorf, MD (Advanced Automotive Center) to be cleaned, in something akin to a large dishwasher, tomorrow morning.

I'll be getting a crank (used) from a 1996 Explorer 4.0, that was bought for the transmission in it. Hopefully, it will measure up as standard when we get it out of the engine. At that point, I can order the rebuild kit from Ebay, and start putting it all back together.

New pics showing the crud build up on the inlet screen assembly:

First, the pickup with the edge peeled back; you can the crud around the edge:

Next, the restrictive plate removed, and the screen area not cleaned with the Brake Cleaner...

The plate, removed, showing the side that was against the screen:

Finally, the plate and screen, prior to scrubbing with a wire brush:

I have a new inlet coming, but this was very educational. A debris glopped up screen can only be thoroughly cleaned by removing oil inlet, and peeling back the upper half to remove the plate and the screen.

 

[Runnin'OnEmpty]

Glad to hear the block is in such good shape, Eric.
That's amazing with the mileage on it. These engines
are indeed tough.

Hope I didn't mislead you when I recommended a
non-flammable cleaner for soaking the screen. I had
in mind one of the solvent cleaners that's used in
parts cleaner machines. They're formulated to cut
oil and grease residue. Just checked my can of CRC
brake cleaner, and it's non-flammable and would be
a good choice for spraying the screen through the
oil drain hole as you described.

If I might suggest one thing, even though the ridge
measures only .005" I'd still cut it flush with the
cylinder. There's a possibility when the engine is fired
for the first time, the top ring will contact the ridge
and break. New bearings might just tighten up the
clearances enough for that to happen.

Good luck with the rebuild and keep us posted...

 

[ironbandit]

The .005" of the ridge needs to be cut in half, as that was the difference between the diameters on and off of the ridge. So, the net height of the ridge is only .0025", and honing should make that neglible. There is too much chance that the ridge reamer will take off more and leave a taper out at the top, causing the top ring to expand and then contract as it followed the piston back down. With the ridge that shallow, the pistons had no trouble coming out, and I don't think that it is worth the risk of shaving too much off at the top.

The condition is likely due to the fact that I run AMSOIL in my engines. And I hope that a new oil pump pickup tube comes with the kit that I am going to buy for the rebuild. While I have you here, any tips on how to remove the wrist pins from the connecting rod, in order to replace the pistons?

 

[Runnin'OnEmpty]

.........any tips on how to remove the wrist pins from the connecting rod, in order to replace the pistons?

Back in the shade tree days, we'd heat the rod and use
sockets to tap the pins out, or maybe use a large vise. I've
heard of guys dropping the piston end into boiling water
to heat them up. Usually we would end up with broken
pistons and the pin still seized in the rod.

Really, the best and safest way is to take the new
pistons and rods to a machinist and let them press
the old off and the new on.

 

[ironbandit]

The block, oil pan, camshaft, oil pickup tube, and motor mounts went to a machinist here in Waldorf this morning. He should have them cleaned by the end of the week, and he suggested using the rods and pistons from the donor that the crankshaft is coming from. Old pistons usually get destroyed pressing the wrist pin out, and the pins normally come with the new pistons. Guess I'll wait and see what this donor crank looks like, and then decide whether the new pistons will be used, but most certainly, the new rings will be.

 

[ironbandit]

With this most previous entry, and the help from the fellas in the chat room, I was able to figger out how to post the photos for the work to be well documented. With this, I think I'll open a new thread to document the rebuild process. After all, it started with the oil pressure fluctuating, but that got us to the bottom of one particular issue. Many other issues can result in an engine locking up, so the rebuild process should take on a separate discussion.

I really should go back and find those photos that I had in my 4WABS retrofit from a cuppla years ago, and place them out on Dropbox, so that they won't go away like they did when Putfile disappeared. I also joined Photobucket last night, but Dropbox is a lot easier to work with, and I have a copy of the material locally in case something should occur in the "cloud".

 

[ironbandit]

Prepping for the rebuild

One more quick post, to report what is happening. I'm waiting for parts, some coming by post, others by pulling them myself. A friend has a 1996 4.0L OHV that he bought for the transmission, and we are going to get the crankshaft from that engine, if it still in good shape, and at the standard measurements on all journals. Today, I spent a couple of hours "cleaning" the crossmember and frame rails that the engine sits over. More an adventure in scraping and brushing with a wire brush, I can see the crossmember now, and the frame rails are cleaner, if not ready to be painted. Which 'minds me, Farm Implement Yellow is needed to put new paint on the damper...