Priming engine when changing oil--Dummy oil didn't shutoff
 

In all of my cars I've always primed the engine once I fill it up by pulling the fuel pump fuse out and cranking it for a few seconds. I also fill up the filter with oil to aid in faster priming.

However, on this car i just changed the oil and went to crank it and after 15 seconds, the dummy oil light wouldn't go out. So I tried it again, for about 15 seconds more to no avail. The oil light still on. So I went at it a third time for like 10 seconds and nothing, oil light on.

So, oh well I pulled the fuse back in and cranked it to start it and of course I heard that dry start-up take place. The oil light did go off after 1 second.

Does anybody prime their engines when doing oil engines? If so have you experienced the oil light not going off when cranking without fuel pump fuse?

Is cranking RPM not fast enough to spin oil pump fast enough after an oil change? I did put 4 quarts in the crankcase and also filled the filter with oil.
Conditions outside were about 15F and i'm also using a Nissan Filter with 10-30 viscocity Full Synthetic.

I've never tried this. Every time I change my oil I just change the filter and pour the new oil in. Start it up after that, never had a problem.

I've always primed the filter, when the vehicle has a vertically mounted filter, but never pulled the fuse.

same here, i just put some oil around the seal for better seal but thats about it

Yea, I do this too, forgot to mention it.

I never heard of having to do that after an oil change or the need to do it at all. If there is such a need, then we would have to "prime" our engines everytime we start the car after it has been sitting for more than a couple of hours or overnight. (???).

I tried something like this to prevent the timing chain rattling at start-up (just keeping the accelerator floored to avoid the engine to start). Spun the starter around 7-10 sec, didn't work. Seems RPM is too slow to push the oil up

:sprint: and i lube the oil filter ring.. thats about the it.. never heard of your procedure.. what is the purpose of priming the engine?

The big difference here is that while your car sits overnight, the oil filter has an anti-drain valve that prevents the oil from draining out of the filter. You are talking about give or take a quarter of a quart that stays in the filter.

When you do an oil change, provided that you do change the oil filter :)
you obviously remove the filter and put a new one. While you crank to start the engine, the oil pump now has to fill up the filter with oil, in the meantime , the engine components, specially the top run a bit dry.

I've done this for over 13 years on all my cars as someone mechanic told me as a trick to priming engines to alleviate the dry start as a result of an empty oil filter.

And boris this is a bit perplexing to me, maybe RPM is too low for pump to scoop the oil

I mean, RPM the starter can give out.

Why would you need to prime your motor? The VQ is a whine up toy compare to the motors that would require you to prime them.

S

To minimize even more of a dry start-up as a result of empty oil filter

Isn't possible to fill the filter before putting it in? I always did it on my older cars, however don't know about Max, since don't do it myself.

So basically 15 seconds dry cranking trying to prime versus just starting it and it running 2-3 seconds dry?

First off, i'm not the engineer or the mechanic that came up with this.
this could very well turn into a debate and that's fine. I'd like to see what other's think.

In my head, it defenitely makes more sense 15 seconds of slower rpm cranking speed at let's say 300rpm's over 1200 rpm's of dry start-up.
You incur more wear at higher rpm's and not having enough oil in the bearings for 1200 rpm's. Cranking at 300rpm's while you build oil pressure may be better and sufficient for the oil that's left in the bearings while oil pressure gets built up.

After changing the oil, assuming it's done after warming up the engine, there is more oil residue on the engine components from the used oil that has just been drained than on an engine that has been sitting overnight. Plus, there is some oil from the fresh one that has been just poured in. I still don't see the logic of this "priming". Just my thoughts. I might be overlooking some engineering factors here.

+1.

Assuming you warmed the engine before draining the oil, you've got enough of a film on the bearings that starting the engine and running for a few seconds while the pump is churning will not hurt the engine.

Now for those people that let the engine sit for an hour and dribble the last half oz of oil onto the ground, then you're asking for trouble. just drain the damn oil and refill when it stops pouring out. put the filter back on, refill, and start the thing up.

You are forgetting that it takes about 12 psi to put out the LOP light. With our horizontally mounted filter you can't presoak/prefill it more than somewhat less than half full (without making a mess) and at a cranking speed of maybe 300 RPM the pump still has to fill the remaining volume of the filter before the oil gets pushed into the main oil gallery and then gets fed to the top of the engine and the bottom end etc, (and the VQ35 has the piston squirters as well) before it can build up pressure anyway, and at cranking speed the pump's output (volume) is a lot less than at idle. So it may not be able to develop enough pressure to put out the LOP light by cranking it over with the starter, but the oil is still "filling" the system which will shorten the time required to build up oil pressure on the first start. It also depends on the actual viscosity of the oil and the condition of the engine and other variables that will affect this as well. I have been able to put the LOP light out by cranking the engine over with the starter after an oil change with other cars that I have owned, but I haven't tried it with the Maxi, but I do presoak/prefill the filter. The LOP light goes out pretty damn quickly so I haven't had a second thought about it. It certainly isn't going to hurt anything by doing what you are doing, but it really isn't necessary if you presoak/prefill the filter. As mentioned above just use the starting WOT fuel cut procedure......it will save you pulling the FP fuse. Direct acting DOHC engines like ours ARE especially prone to damage caused by lack of lubrication of the cams and cam followers, so having the engine oil pump develop oil pressure as quickly as possible is a good idea. Some piston engines used in other applications are not even cranked over or started without having an external pressure system apply oil pressure to the system first. I sure wish though that Nissan would mount their damn oil filters vertical (threads up) like my Focus. Just behind the rad. and you can completely prefill it.

Seriously, if you're that paranoid that you're doing damage to your motor, build yourself a pre-lube system like they do for marine diesels. Then you can run that for a few minutes so you're absolutely there isn't a dry spot. Seriously though, if you keep up on your maintenance, I bet your motor will outlast the time you probably would keep the car. If you keep the car until it dies, all this extra work would equal a negligible difference compared to those who keep up on oil changes, but don't prime. Also it's a very very rare occurrence to see VQ's needing a top end rebuild because of oil starvation, or at least from what I have observed.

Very good point about the LOP light taking 12psi to go off. If this is the case, then you can sit there cranking for 5 days and won't see the light go off. However, like you said, doesn't mean that you won't build less oil pressure. I'm not so concerned about the light taking 12psi to go out. But the mechanical aspect of it. Is the oil pump building at least 5psi or so at 300 RPM's? Even if you build 5psi of oil pressure cranking at 300rpm's to prime the engine, it's may be enough to fill up the oil filter before starting the engine and avoid a less of a dry startup.

As far as filling the filter completely, I defenitely can fill it to the top without making a big mess, it can be done. When I say to the top, that means to just below the opening of the center threads.

In every other car I had, the light went out in about 10 seconds of cranking.

And I agree with you, I wish Nissan would've mounted the damn filter vertically. And another thing I don't like about the setup is how the filter is sitting at the very bottom along with the oil cooler lines. I think those lines are really so close to the bottom of the car. I mean in other cars if you hit the bottom of the oil pan with something on the road, chances are it will survive. But i'm always afraid of hitting those oil cooler lines with debris from the road. Granted, there is a shield there, but it's not a steel shield, it's only plastic.

And Maximase86
Not that i'm paranoid. I'v been doing this for a long time to every car i've owned. A little more negligence could mean the difference between your engine lasting another couple of months or another year, who knows, but can't be negative negligence.

Our cars don't have engine oil coolers. The lines you see there are for power steering...and there should be lines for the tranny cooler is you're automatic.

Seriously though, I think saying not priming your engine is negligent is a bit bold. Have you destroyed an engine because of it, do you know someone that has? I'll tell you that on this board, you're more likely to destroy a motor from burning oil (VQ35), and not checking the level, then from not priming your motor. I guess I'm skeptical of priming because I've yet to see a motor fail because you didn't prime it.

Either way, this is an interesting conversation. :)

If priming the engine was important then it would be stated in the owners manual or some documentation. I have been filling my oil filter before installing it since back in the 1960's to hasten oil circulation when you start the car but I rarely did that on customer's cars. I think the main precaution is that when you start the car, don't rev the engine until the oil has a chance to build up pressure. The same thing applies when starting the car on a cold morning.

No oil cooler?? My car does sure look like it has one. the manual also states that there is one...? I could be wrong but thats what I see.

well, maybe the word negligent is a bit too strong for something that some people choose to or not to do. Not sure what that word is though.

To this day, never destroyed an engine. Wouldn't know as I've always filled my filters and primed the engine.

You will not destroy an engine in a day or 2 by not priming it. It's more of a longevity thing what I believe in.

And DennisMik, doens't mean that because it's not stated in the manual, that it won't help longevity. Sure if it will destroy the engine, chances are, that it will be in the manual, suing is not cheap either.

Any detriment to longevity is minor. I used to drive my cars on the job and would get 450k before I scrapped it and that was more because of the body rotting out from the salt on roads.

What you are saying is correct in theory. In reality, I haven't seen it.

The VQ35 has an oil cooler (coolant cooled). I agree, in the "big picture" not "priming" the system as discussed does not appear to cause any real apparent problems considering that probably 99% of cars never have it done, but I still think it's a good idea (and it takes little effort) to presoak/prefill the oil filter. And it is more professional. I think "dry cycling" the engine is unnecessary because I find with prefilling the filter the LOP light does go out almost immediately on the first start. The Maxi's oil pump is mounted right on the crankshaft and the filter is quite small so it does/should build up pressure quite quickly. Have we beat this one to death?

thought so. I haven't really taken the time the explore the engine bay in this cold weather but oil coolers can't be mistaken for power steering pumps lines :D Anyway

Defenitely agree, probably 99% of cars don't get this done and they last quite a while.

As far as the LOP light is concerned, (at least my experience with cars I worked on) that even filling the oil filter with oil, the LOP light will take another 1.5 seconds or so to go out ( even with high volume oil pumps) so add that to the typical 1 second daily and you got 2 + seconds. In all the cars I've worked, on this is my story. So I always prefill/presoak filter and prime the engine, so when the car starts the LOP light is out in 1/2 split second. Now, on my maxi, it did take over a second to go out. Yes, that's with 4 quarts in crankcase and with Nissan filter (Other local filters may be a bit longer, which takes a bit more to fill up as you crank to start) after I exhausted the cranking as the LOP light did not go out priming.

Just to clarify........those are the oil cooler "coolant supply" and "coolant return" lines (not oil) that you see running along side the oil pan. The coolant supply comes from the firewall side of the block, then through the cooler and then returns to the inlet side of the coolant pump at the thermostat housing.