How Quickly Should I have Oil Pressure after Replacing Oil Pump?

[javelinmania]

I replaced the rear main seal, oil pump and of course the oil plan gasket and cleaned everything up. I started the truck and ran 2-3 minutes but had no oil pressure. The truck has under the dash oil pressure gauge, so I am not relying on an idiot light. The gauge didn't move. How long does it take for the pump to begin pumping again or do I need to tear it apart (I hope not).

[67ChevyRedneck]

Seconds...

The pump works immediately, but sometimes it takes a couple seconds for the pressure to get to the gauge.

Are you sure the gauge works? 3 minutes of no oil pressure and you would have been hearing all sorts of bad noises.

Are you sure the oil pump shaft was engaged with the distributor?

[MARKDTN]

Did you prime it? You must prime it before you install it.

[davepl]

Definitely should be primed if possible. I don't think you could install it without engaging the distributor if the connector is integral to the distributor shaft on aftermarket ones, but:

Are you sure you didn't perhaps forget the plastic collar that joins the distrubutor shaft to the oil pump driveshaft?

In some cases if you've failed to prime it and are willing to risk the engine you can just blip the throttle and the RPM will prime it. I've done that after an oil change on my winter beater, but it's not the right way.

If you had 2-3 minutes of no oil pressure, and this motor matters to you, you might want to get an oil sample analyzed to see how much bearing material is in it.

[javelinmania]

The gauge worked before, so I don't think I was getting a false reading. In the end, I was replacing the gauges anyway- so I now have a new oil pressure gauge - but haven't tried it out. No, I didn't prime it - didn't know I needed to - now I know. Heard no noises. The oil pump driveshaft was in place to the distributor and I had the plastic collar in place. So I believe I put it together properly. What's the proper way to prime it?

[67ChevyRedneck]

You remove the distributor and use either a priming tool or some people cut up old distributors and use that (you install it on a drill)

http://www.ebay.com/itm/Oil-Pump-Pri...700d4c&vxp=mtr

When I did the pump on my 65 mustang 289 recently I unhooked the distributor power so it couldn't fire and turned it over until I had pressure, which was only a few seconds.

[bonnieclyde100]

did you set your oil pump pickup correctly so it is down in the bottom of the oil pan?

[Fitz]

Originally Posted by javelinmania

I replaced the rear main seal, oil pump and of course the oil plan gasket and cleaned everything up. I started the truck and ran 2-3 minutes but had no oil pressure. The truck has under the dash oil pressure gauge, so I am not relying on an idiot light. The gauge didn't move. How long does it take for the pump to begin pumping again or do I need to tear it apart (I hope not).

The oil pump is a positive displacement pump. It delivers pressure the moment the engine begins to turn. If you do not see pressure when the starter begins to turn the motor over there is something very wrong.

[mechanicalman]

Originally Posted by javelinmania

I replaced the rear main seal, oil pump and of course the oil plan gasket and cleaned everything up. I started the truck and ran 2-3 minutes but had no oil pressure. The truck has under the dash oil pressure gauge, so I am not relying on an idiot light. The gauge didn't move. How long does it take for the pump to begin pumping again or do I need to tear it apart (I hope not).

Before you start taking your engine apart, get a towel and a couple small wrenches and bleed the air out of your oil line going to the gauge under the dash.

[mechanicalman]

Originally Posted by javelinmania

The gauge worked before, so I don't think I was getting a false reading. In the end, I was replacing the gauges anyway- so I now have a new oil pressure gauge - but haven't tried it out. No, I didn't prime it - didn't know I needed to - now I know. Heard no noises. The oil pump driveshaft was in place to the distributor and I had the plastic collar in place. So I believe I put it together properly. What's the proper way to prime it?

For rear main seal replacement, you don't need to prime the oil pump. You DO need to take the oil pump apart and grease the gears so that it pumps immediately. I've done hundreds of them maybe a thousand in my career. Even not greased yours should be pumping now and if the lifters are not ticking you probably just have air in the gauge line.

[Wrenchbender Ret]

You can usually tell if oil is circulating by looking at the dipstick. If it has oil all over it, then the engine is getting oil. If it checks like the engine is turned off then it isn't.

[70blackfish]

did your new oil pump have a pick up tube on it? if the pump was installed dry you might have a problem, don't start it again until you know you have oil pressure, get a trimming rod and cordless drill is your friend

[javelinmania]

The truck is now sitting. I should have a priming tool Monday or so. Then I will know for sure. There are so many other things that needs to be done that this is only a minor inconvenience. Since I was replacing the rear main seals, I decided to go ahead and replace the oil pump with the round plastic piece and the drive rod. The drive rod that I received was not the correct drive rod. I think I could have made it work as there was a small pin that held an additional width piece - I'll include a picture - as it is better than I can explain. I ended up using the original drive rod. Once I get the priming tool, if it doesn't show oil pressure, I'll put the original pump back in. This is a 1978 engine (or so I'm told).

[Sammy]

I think autozone n o riellys have primers as a loan tool. Like said above n old junk distributor shaft works.

[Bigdav160]

You should be able to gain oil pressure by just cranking the engine.

You think the OEM's prime their engines before start up?

The pump is submersed in oil. No need to pack it with grease.

That oil pump drive shaft looks like a nice one and correct for a Chevrolet V8

[bigmac73]

Originally Posted by Sammy

I think autozone n o riellys have primers as a loan tool. Like said above n old junk distributor shaft works.

Sammy, I would not be so sure about that, I went to Autozone and asked to rent a oil primer for SBC, the guy just looked at me like I was crazy and told me he never heard of one, I then did a quick about face and hauled ass out of that store with no comment at all

[Kennuck]

While packing the oil pump is an accepted method to prime the pump do not use grease to pack the oil pump. Grease is not compatible with the engine oil. If you going to do this you must use petroleum jelly (vaseline).

Also I don't believe the oil pump is submersed in the oil. the oil pickup is submersed. In any case the pump should self prime in a few seconds.

Are you sure the pickup is not bottomed out on the pan? This could starve the oil pump.

[425HP409]

Even though the oil pump is submerged in oil, they sometimes will not pick up oil if the gears are dry. I have experienced this once (I removed the distributor and primed the oil pump with a high speed drill, which fixed it) so now always pre lube the pump with engine oil, and haven't had a problem since.

[Steeveedee]

I always prime Chevies by pouring oil in the sump screen and spining by hand before installation. I usually prime with the tool mentioned, using a drill. If your gauge doesn't read, you do not have oil pressure. I suspect that the engine is not damaged, as long as it didn't get too hot. You'd be amazed how much punishment I've seen engines take and live.

Buicks, on the other hand, do require priming of the oil pump, since it is external. I've used everything from petrolatum (fancy name for Vaseline) to white grease. All it takes is some lube to help pull the oil in. Buicks can also be primed like a Chevy with the same priming tool.

[MARKDTN]

I have burned up the bearings in a fresh engine not priming the pump. I usually take a new pump, (set the depth) install the pickup, JB weld it on, and submerse it in fresh oil and turn it until it pumps out the top then install both on the engine. As far as the factory not doing that-I do not believe that to be true.

The pump is not covered in oil, just the pickup. Another reason that the engine can starve for oil if the pickup falls off and why many builders weld the pickup to the pump.

[mechanicalman]

Originally Posted by Kennuck

While packing the oil pump is an accepted method to prime the pump do not use grease to pack the oil pump. Grease is not compatible with the engine oil. If you going to do this you must use petroleum jelly (vaseline).

Also I don't believe the oil pump is submersed in the oil. the oil pickup is submersed. In any case the pump should self prime in a few seconds.

Are you sure the pickup is not bottomed out on the pan? This could starve the oil pump.

I must have done about a thousand of them wrong! LOL Well I must be the luckiest man on earth because I've never ever had a problem using grease on the pump gears and I'm also 100% sure I nor anyone else ever will.

[70blackfish]

could over fill the oil pan so the oil pump is submerged. ad 4 more quarts let it sit.

[Turbo1dr]

An oil pump that sits on the inside of the engine and below the surface of the oil should prime up quickly. After all, it IS below the oils surface. I haven't had one not to prime if that's the case. Now, if it is any external oil pump like the ones in the timing cover, then, it should be packed with light weight grease or very thick oil like STP oil treatment or even *trans-gel*. You should not pack it with high temperature grease that will not melt easily like wheel bearing grease. That type of grease will clog the oil filter before it melts due to the high melting point. Think about it, you don't want wheel bearing grease to to turn to liquid in a rotor but you do want the grease to melt if you use it in an engine.

[mechanicalman]

Originally Posted by Turbo1dr

An oil pump that sits on the inside of the engine and below the surface of the oil should prime up quickly. After all, it IS below the oils surface. I haven't had one not to prime if that's the case. Now, if it is any external oil pump like the ones in the timing cover, then, it should be packed with light weight grease or very thick oil like STP oil treatment or even *trans-gel*. You should not pack it with high temperature grease that will not melt easily like wheel bearing grease. That type of grease will clog the oil filter before it melts due to the high melting point. Think about it, you don't want wheel bearing grease to to turn to liquid in a rotor but you do want the grease to melt if you use it in an engine.

I've used every kind of grease including wheel bearing grease and even Nazi grease and never had a clogged filter ever I'm talking hundreds of times. You put a little on the gears, turn them to squish out the excess, put it back together. Always works, every time, never has and never will clog a filter.

[Turbo1dr]

Originally Posted by mechanicalman

I've used every kind of grease including wheel bearing grease and even Nazi grease and never had a clogged filter ever I'm talking hundreds of times. You put a little on the gears, turn them to squish out the excess, put it back together. Always works, every time, never has and never will clog a filter.

I agree with you about putting *a little* grease on the gears and squishing it out. It's the novice engine builders that you need to be very specific about telling them about how to do things. Even though you know how much to apply to be safe, they will probably just fill it full of grease and let it ride. You're not teaching just a couple of kids on your block...this forum reaches out to the World with thousands of readers that are just learning.