Slow to build oil pressure after installing Wild Horses oil pan???

[Nothing Special]

After installing the Wild Horses oil pan kit (#8066) my engine is really slow to build oil pressure when first started. I'm used to it taking maybe 5 seconds to build pressure on the first start-up after an oil change, and for the gauge to start climbing pretty much immediately after starting all other times. But now it's taking maybe 15 - 20 seconds for the gauge to start moving, and then another 5-10 seconds before it gets up to the ~40 psi that it typically idles at (assuming my gauge is accurate...). Once it finally builds I'm getting the same oil pressure that I got before the pan change, but it's just taking a lot longer than I'm comfortable with for the pressure to build.

I used the new oil pickup tube that came with the kit. After removing the old pickup from the oil pump I couldn't get the remains of the old gasket off the pump, so I took the pump off to clean the gasket surfaces better. With clean surfaces and a new gasket I put it together with no gasket sealer.

I didn't have a new gasket for between the oil pump and the block, but that gasket came off clean so I just put that back together without doing anything else. If that was leaking I could see not getting full oil pressure, but I don't really see how a leak at the pump output could cause it to be slow to build pressure.

I know it says that this kit can't be used with high volume oil pumps. I honestly don't know what I have for an oil pump. I bought this rebuilt 302 from a local engine shop. I figured if I had a high volume pump that it would be pretty easy to tell if it wasn't fitting. But the oil pickup tube seemed to match up perfectly, the support tab also lined up perfectly and the pan went on fine, without seeming to hit the pick up tube before it was tight against the block.

Does anyone have any suggestions on what might be going on here?

 

[ntsqd]

I assume that this happens every time? Not just cold starts? Are you using the same oil filter brand/model as before? Same brand and viscosity oil as before?

I does sound like you have a leak, either a pressure leak or a vacuum leak. The whole pick-up tube is under a vacuum from the pump. If that is leaking somewhere it could take a while to get enough oil into the system to develop pressure.

Since you don't know what you've got in there I'd replace it with a known pump, this one: https://stores.precisionoilpumps.com/blueprinted-melling-ford-302-5-0-standard-volume-race-pump/ While you've got it all apart I'd also install this piece of insurance: https://stores.precisionoilpumps.com/sb-ford-302-5-0-billet-hd-oil-pump-driveshaft/ using these gaskets: https://www.summitracing.com/parts/fel-os13260t, https://www.summitracing.com/parts/fel-70083, & https://www.summitracing.com/parts/fel-72516

 

[Nothing Special]

I don't know if it would do the same thing if the engine was only shut down for a few seconds. But it does happen on hot restarts when the engine has been shut down for a few minutes.

Yes, same oil and filter.

It seems to me that it has to be a vacuum leak, not a pressure leak. Not that I couldn't be wrong there, but it seems like if there's a pressure leak the pump would start pumping even quicker since there's no less availability of oil at the inlet and less restriction at the pump outlet. I could see lower pressure from a pressure leak, but not slower priming. On the other hand, I could easily see a vacuum leak make it take longer to prime the pump as it can suck air through the leak.

I know the oil pump I have has been good. It's not that old, and there's really nothing that was done to it that should make it have any problems. Same with the drive shaft. So I don't feel great about just throwing probably good new parts on in place of known good old parts. Gaskets are clearly suspect, and I'll probably put sealer on at least the pump inlet gasket this time.

 

[Broncobowsher]

Sounds like a suction leak to me as well.

 

[DirtDonk]

Did the pickup tube look like the one in the picture on the site? Look at least similar in length to the one you took our?
In other words, not too short to the point that it's not near the bottom of the pan.

A high-volume pump usually has a taller body, which can interfere physically with the pan bottom. Been there, ball-peened that.

I think (but not being a pump expert, don't know for sure) that an output leak at a pump like our oil pumps would effect how efficiently it starts the sucking process.
A gasket is actually pretty important, but once properly torqued I would think that any leakage would be minimal and not enough to effect this. Unless the mating surfaces were just not quite mated up. And one would think it would be even less apparent when cold and the oil is thicker.
Then again, isn't that the whole point of multi-viscosity oils? Flow thin when cold? Hmmm...

Paul

 

[ntsqd]

A pump output leak is no different than the pressure regulator in the pump opening up and by-passing oil back into the sump. If it affected the prime, then it *might* slow building pressure, but these gerotor oil pumps don't seem to need to be full of oil in order to pump - just enough to generate a seal and they're off and running.

 

[DirtDonk]

Good to know. Thanks
But that would indicate that in NS' case, something is amiss with how it's picking up then. Correct?

Hate to say that it's time to take the pan off again, but no matter what it seems like that's the way things are headed no matter what.
If the pickup is too close, then it would have to be REALLY close I would think. In which case, fitting the pan on without the gasket would probably tell the tale.
I know you said it did not hit when you put it together, but I'm wondering if it's not just at that ragged edge. Far enough away to still pick up oil, but just too close enough to make it less efficient.

Paul

 

[ntsqd]

That is a good point, OP, got some PlayDough? Put a ring of it around the pick-up and momentarily press the pan back into place. Slice the playdough with a razor to see what the gap between the pick-up and the bottom of the pan is. When I was building oil pans & pick-ups I wanted 3/8" as ideal. In this use can probably live with 1/2", but I wouldn't want it to be less than about 5/16"

 

[Nothing Special]

I know the pan's coming off again. I'm just trying to be prepared so I know what to do and can get it put back on pretty quickly after it comes off and with a pretty good likelihood that it won't have to come off again!

I'm pretty sure the pickup isn't way above the bottom of the pan. I don't know how much, but yes, it looked similar to the original, so I don't see how it could be above the oil.

I'll definitely look at the pickup - pan clearance and see if it seems reasonable. I'll also look at the pickup - pump gasket and see if it looks like there could be a leak there. I'll also look at the pickup to see if it looks like it might have any cracks or leaks (doesn't seem likely, but trying to not have to do this again). And I'll get a new pump - block gasket since I re-used the one that was on it (not a practice I recommend, but it looked good and I didn't have a new one).

As to multi-weight oils flowing better when cold, something like a 10W-40 will flow better cold compared to a straight 40 weight. But it will still be a lot thicker cold than it is hot. It just doesn't thicken up as fast.

 

[Broncobowsher]

The oil pump is capable of pumping a lot of oil really fast. Gallons per minute flow rate. A little leakage between the pump and the block won't matter. That would be nothing more than a little extra flow like a worn bearing. That should not change the priming.

The pickup sucking air. Ever have a straw with a pin hole in it. When you stop sucking it looses it's prime. You have to suck a lot to get your drink. Once you suck enough to start getting your drink, you do get some. But there is a lot of delay to actually getting it. Sounds exactly like what you are having with the slow pressure rise on start. The fact you are getting to normal oil pressure tells me the pump is moving enough volume to be opening the pressure regulator inside the pump. But I bet it isn't bypassing nearly as much as it normally does. and the oil going through the engine has a lot of air mixed in.

Checking the gap to the bottom of the pan is good. But I don't think that is an issue here. That would typically show up at higher RPM as either sucking itself to the bottom or sucking the oil level down to the pickup.

The last one would be a bad pump. loose enough that it bleeds down and has a hard time priming but good enough to have pressure once filled. I doubt it.

 

[Nothing Special]

Is there anything in the oil pump that might have fallen out of position (or out of the oil pump altogether) when I had it out? I'm sort of grasping here, but like is there a check ball or something that's supposed to keep the oil from draining back out of the pump when the engine stops? While it's certainly possible that there's a leak in the pickup side (and I agree that would explain things a lot better than a leak on the pressure side), I have two clean surfaces with a new gasket there. I wouldn't expect that to be where the problem is (although it's certainly where I'll be looking once I get the pan back off)

 

[ntsqd]

The only thing that I can think of is the drive-shaft, and I'm pretty sure you'd know it was missing.

I'd be amazed if the pick-up's position is the cause too, but stranger things have happened and since you're having to open it up again.......

 

[Nothing Special]

The drive shaft stayed up in the block when I took the pump off and seemed to slide back into the pump fine. Along with the fact that it does have oil pressure (eventually...) makes me pretty sure the driveshaft is still there

 

[m_m70]

following..........I have the same issue with my stock pan. New pump didn't solve the problem. Like you, I didn't have a pickup gasket so I'm thinking that may be the issue.

 

[Nothing Special]

I do have a pickup gasket. It was new with the new pan and pickup tube. And I cleaned the mating surface on the oil pump. So I SHOULD have a good seal there, but it's seeming like I don't.

 

[pcf_mark]

Slow to build oil pressure does not sound like the behavior from the pickup is too close to the pan. Usually at startup there is plenty of oil near the pickup and volume demand is low enough so you get oil pressure right away. Rev the engine and you get fluctuations or a drop in oil pressure then you may be too close to the pan for the pickup to refill. I think an internal leak is more likely.

 

[ba123]

Yeah, sounds to me more like air coming in the pickup...just like @Broncobowsher said. Like maybe the attachment of the pickup tube to the pump and air is coming in there.

That's what I'd check first. I don't remember, is there an o-ring there? If so, I'd replace it. I don't remember what seals that connection. Or maybe your pickup needs to be lower? Is the new pan deeper, similar, or more shallow?

 

[Nothing Special]

New pan is shallower. It came with the new pickup that is supposed to work with this pan and a stock oil pump.

No O-ring between the pump and pickup tube, just a gasket, which is new (and both surfaces were clean)

 

[lars]

Quick way to spot a high volume pump: standard pump has hex head screws retaining the cover. High volume pump has countersunk screws retaining the cover. A high volume pump is taller than a standard pump but it's not obvious unless you have them side by side on a bench.

And I agree with the others. Sounds like a suction leak.

 

[ba123]

New pan is shallower. It came with the new pickup that is supposed to work with this pan and a stock oil pump.

No O-ring between the pump and pickup tube, just a gasket, which is new (and both surfaces were clean)

And you are sure you put enough oil in it right (it says 5 quarts in the pan, so a little more total)? Maybe with a more shallow pan, your dipstick is no longer accurate? Or is this the kit that came with a dipstick and you did not properly install it...or something? (just a thought) Are you supposed to cut that dipstick or does it come properly set up?

That's a tough one, but I'd prob do two things... first, take the pickup off and inspect it for defects and if none, then try to cover the pickup part and maybe try to blow or suck air though it but it would prob have to be a pretty big hole to notice, but it might be given the circumstances.

Like if it's this tube, then what about where the tube fits into the bottom round pickup part? Or maybe at the top end, where the tube is welded to the mounting plate.


My very last thought is that this pickup just does not work with whatever pump you have and you should just replace it. It does say STOCK Bronco oil pumps only and you aren't sure. Maybe the hole just doesn't line up perfectly or something.