Seized Oil Pump, 302

[Swath]

Hi all,

Posted a bit of an intro in the chat section.

I have a 72 with the 302 in it. Just getting into this thing so there is a lot I don't know.

I just bought this yesterday and on the way home I noticed the oil pressure was low but I did not know if the oil pressure gauge was trusworthy or not.

About half way home the gauge dropped to zero and the motor started making noise. I checked the oil, couldn't see a level on the dipstick, put two quarts in but the noise was still the same. I went ahead and drove home, ~7 miles. Checked it out today and the oil pump is locked up.

I hope I didn't ruin the bearings but hard to imagine not causing some damage.

I am planning to pull the motor and replace the oil pump and cross my fingers that it runs well. 13,000 on the rebuild according to the PO. Recently worked on at a shop, replaced intake gasket and oil pan gasked as well as rear main seal.

When it did run it was strong, it has an aftermarket intake (edlebrock), headers and feels like a cam but that is a guess. Malory dizzy and coil.

Asking for advice about steps to take and additional things to look for.

Pull motor, drop the pan, replace oil pump. (Can't do this in the rig can I?)
Dizzy had shavings on the worm gear. Does this mean the gears on the cam are bad also?
Is it stupid to think it will still run well with just a oil pump swap?

Not the warm reception I was hoping for, time to get dirty on my new old Bronco. I was just looking forward to using it as a DD and taking my time planning it's path.

 

[Broncobowsher]

If the distributor driven gear has shavings on it, the drive gear on the distributor is probably destroyed as well.

Normally you can get the pan off and do a pump in the truck, but with what you describe the original plan of pulling the engine is a much better idea. Cam will need to come out, bearings will need to be inspected.

Sorry, it isn't going to be as easy as just putting another pump in it and be done. Metal shavings are a very bad sign. Hopefully the damage is limited.

 

[tatersalad]

tthat is how i got my new 351 efi a couple of years ago. I did pull the pan with motor still in . it fired back up after the new pump but had a nasty knock. my situation was that I hadnt driven it in a while and it was low on oil, my high volume oil pump ran her dry . good luck

 

[bmc69]

For starters, how did you determine that the oil pump is "locked up"?

 

[DJs74]

Swath,

Sorry about your situation and I don't mean to be doom & gloom but my honest opinion is that you should just plan on taking the motor out and get right into a tear down, inspection and rebuild. If you lost oil pressure, the motor started knocking and then another 7 miles was added on to that, it probably isn't going to end up being just a pump replacement.

In my experience, the moment you hear the motor knocking due to lack of oil / pressure - it's generally too late. The noise you heard was more than likely the rod bearings knocking due to oil starvation and if they were lacking oil, then all the other bearings downstream were probably starving for oil as well.

Also, if it were me and I had just laid out the bills for a Bronco and basically blew up on the way home, I think I'd be calling up the previous owner to let them know. I mean, I know you probably didn't get a warranty or anything but the Bronco shouldn't have given up on your way home. Just sayin... unless you twisted it up to 7K RPM or something crazy on your way home, it should not have let you down this early

good luck,

DJs74

 

[broncogt]

I think the only way you could seize the oil pump is if something got sucked through the screen on the pick-up.

 

[Broncobowsher]

I think the only way you could seize the oil pump is if something got sucked through the screen on the pick-up.

What came first, the chicken or the egg?
Did metal debris get into the pump and cause it to fail or did the pump fail and starve the engine for oil causing metal debris? Some pickups have more open mesh than others. Fine mesh will keep out more metal shavings but can starve the pump (thick oil or sludge), while coarse mesh could allow shavings through (that wedge in the pump) but don't starve in sludge.

Either way you need to know clearly see what damage has happened and that isn't always easy to see in the truck. There is metal in the distributor gears, the cam has to come out for inspection. The pan has to come off. At this point about the only thing left is to pull the heads, pistons/rods, and the crank. If everything is good, a gasket set isn't that expensive and it will all go back together real fast and easy. If there is damage, better to find out now instead of after doing a lot of work and throwing some money in new parts at it for a lost cause.

 

[Broncobowsher]

13k is an odd mileage for an engine to let go. Usually they die pretty quick, in the first couple thousand miles. If it makes 10k without issue, it should be a good engine.

The distributor gear shavings have me thinking, did this engine get a new distributor recently? Maybe an EFI upgrade that needed a new distributor? Maybe an electronic ignition conversion? HEI? Something in the past couple thousand miles? Maybe the wrong distributor gear was installed at that time?

More thoughts, the engine is with a new owner and being driving differently then it has ever been driven before. Maybe there was a build issue but the previous owner never drove it in such a way that is was a problem. New owner found that weak spot without anyone knowing it. It is really hard to say.

 

[jckkys]

I've had an oil pump seize and the engine died immediately because the role pin through the gear and shaft sheared so the spark went away too. If it hadn't done that the pump drive shaft would have broken. Something has to give. What broke when your pump seized?

 

[broncnaz]

Well lack of oil tells us there was some issue with the rebuild or break in. Not only that a recent visit to a shop to replace a intake gasket, oil pan gasket and rear main seal?? Did they put oil back in the engine? Did it use all that oil in a short time? Id question if the engine was actually rebuilt.

While the oil pump could be replaced with the engine in the frame. Im with the others pull the engine and check it out real good. Find out what you really have for a engine. Never know what was stuck in for a rebuilt engine.
Definetly want to check the rod and main bearings there fairly cheap anyhow. Worst case would be crank damage that will show up again soon if no checked and corrected.

 

[Swath]

For starters, how did you determine that the oil pump is "locked up"?

I dropped it off at my local garage for a diagnosis. I can turn a wrench ok but I like to get a good diagnosis from a pro, usually saves me time and money.

They pulled the distributor, tried the prime oil thing and couldn't get it to spin.

That is also when they noticed the distributor was messed up. I will get a close look myself tomorrow morning.

 

[Swath]

If the distributor driven gear has shavings on it, the drive gear on the distributor is probably destroyed as well.

My exact question, if the distributor gear went bad does that mean pretty much the cam gear did the same.

Normally you can get the pan off and do a pump in the truck, but with what you describe the original plan of pulling the engine is a much better idea. Cam will need to come out, bearings will need to be inspected.

Sorry, it isn't going to be as easy as just putting another pump in it and be done. Metal shavings are a very bad sign. Hopefully the damage is limited.

But if the oil pump can be changed without pulling the motor then the cost of pulling the pan, stick in a new pump, and give it a go doesn't seem like it would necessarily cost much more money in the end even worst case scenario.

What am I not considering?

I have never done a motor that far in, I have installed intakes and oil pans and oil pumps but have never gone as far as pistons, cranks, and cams much less heads. If it gets that far I may have to take it to a builder. Not that I wouldn't want to learn, I would rather have it done professionally at that point. I do want to do a complete engine one day, just a bit light on skill and confidence.

As far as pulling the pan with the engine in, do I have to unbolt motor mounts and pick it up slightly? Or drop the suspension? Or is there enough room as it sits?

I plan to go as far as I can starting Sunday. I do have a hoist and a good friend much more technically capable than myself. We could pull the pan, pull the pump, pull a few bearing caps to inspect for signs of damage.

The gear on the cam has me concerned for sure.

 

[Swath]

I think the only way you could seize the oil pump is if something got sucked through the screen on the pick-up.

Hopefully I get to the root cause.

 

[Swath]

Swath,

Sorry about your situation and I don't mean to be doom & gloom but my honest opinion is that you should just plan on taking the motor out and get right into a tear down, inspection and rebuild. If you lost oil pressure, the motor started knocking and then another 7 miles was added on to that, it probably isn't going to end up being just a pump replacement.

In my experience, the moment you hear the motor knocking due to lack of oil / pressure - it's generally too late. The noise you heard was more than likely the rod bearings knocking due to oil starvation and if they were lacking oil, then all the other bearings downstream were probably starving for oil as well.

Also, if it were me and I had just laid out the bills for a Bronco and basically blew up on the way home, I think I'd be calling up the previous owner to let them know. I mean, I know you probably didn't get a warranty or anything but the Bronco shouldn't have given up on your way home. Just sayin... unless you twisted it up to 7K RPM or something crazy on your way home, it should not have let you down this early

good luck,

DJs74

The sound is not what I would call a knock, but that is a weak thing to hang a hat on. Sounded more like noisy cam and lifters. The 8 miles I drove it was uphill all the way, not the easiest on a motor with no oil. It must have been getting lubricated to some degree.

What happens to hydraulic lifters when oil pressure drops very low?

I'm disappointed for sure, but I did buy it as is. I talked to the PO but I did not request a reimbursement. I think I could throw at least $3k at it and still get my money back on the deal. But really, I'm most interested in using the heck out of this thing and maintaining it as a daily driver and light wheeler.

I'm still excited I am back into a Bronco, even though I have to go into the motor so soon.

 

[Swath]

The only stuck oil pumps I've seen have been with high pressure pumps. They usually twist the oil pump shaft. I'd pull the motor since the clean-up is going to be pretty involved. With only 13K on the motor, you may be lucky and may get away with a crank and bearings. But why did this happen at all? Probably a sloppy rebuild.

It could very well have a hi volume oil pump. Problem is, as you hinted at, a hi volume oil pump has a lot more drag. Putting in an improved gear (bronze?), a stronger oil pump drive shaft, and modifying the oil feed to the distributor should be done when using those types pumps.

 

[Swath]

The distributor gear shavings have me thinking, did this engine get a new distributor recently? Maybe an EFI upgrade that needed a new distributor? Maybe an electronic ignition conversion? HEI? Something in the past couple thousand miles? Maybe the wrong distributor gear was installed at that time?

More thoughts, the engine is with a new owner and being driving differently then it has ever been driven before. Maybe there was a build issue but the previous owner never drove it in such a way that is was a problem. New owner found that weak spot without anyone knowing it. It is really hard to say.

The PO did not do anything extra to the motor, the original builder did put a Mallory distributor in it. The PO bought it in 08 which means he really didn't drive it much in those 6 years he owned it.

 

[Swath]

I've had an oil pump seize and the engine died immediately because the role pin through the gear and shaft sheared so the spark went away too. If it hadn't done that the pump drive shaft would have broken. Something has to give. What broke when your pump seized?

Nothing "broke", I noticed the pressure drop and then the noisy motor. Shut it down, checked the oil, didn't see any oil on the dipstick, added two quarts, restarted and finished my drive home with the engine noise consistent all the way uphill into the canyon. I started it up this morning and drove it down to the mechanic for diagnosis, same noise.

 

[Swath]

Apparently the majority believe pulling the motor is the correct path. Hard to disagree with experience. It's why I love forums, lots of wisdom.

Doesn't mean I will heed good advice, I'm a bit silly that way. Still thinking if I can replace the pump without pulling the motor the only cost is oil, gasket, oil pump, fix the distributor, look at a bearing or two, and give it a go. How much worse could it get? Really, are we talking about possibly ruining the crank? If the cam gear is bad how much worse could that be? How much more could it cost me being stupid?

Thanks for all the great feedback, keep it coming and bear with my ignorance please.

I could toss in a crate motor of some sort.

When I test drove this thing the motor had plenty of power, I certainly want that back.

As much suck as this is, I'm dam glad to have a Bronco to fuss with.

 

[broncnaz]

Something broke somewhere or the pump would turn. The pump is direct drive the cam turns the dizzy the dizzy drives the pump if the pump doesnt turn something has to break.
You can try and get by with just a pump and checking out the bearings/crank maybe it lasts maybe it doesnt. but theres a reason the engine was low on oil in the first place. Id want to take a more in depth look at it vs a just trying to get by look. It sucks having to do things twice and spending more money than you had to.
Cost well that can be anything from a couple hundred now or thousands later. You have no way of knowing how long a suspect engine will last or where it will give up on you and what it may actually cost you.
As for your engine noise well it could be the lifters and camshaft no oil up there and the lifters collaspe create more valve clearance plus the cam lobes dont get any lube so they get hot and the lifters and cam lobes start wearing fast so you end up with a flat cam.
In the end its your toy and your call. We just throw ideas out there.

 

[broncosbybart]

How much worse could it get you ask? You could do that work and ruin the motor. First off, you need to find out what is wrong and why it happened. Then you need to ensure a proper fix. The only way to do it correctly is to ensure everything is still ok. Otherwise it is just a matter of time. Seems very fishy that this would happen on your way home. I'd have a hard time with that.