DonkRado
NAXJA Forum User
- Location
- Charlottesville, VA
Here's my disclaimer: I searched through a ton of the oil pump threads, but I haven't been able to convince myself strongly one way or the other on this.
What are the true benefits of running the high volume oil pump over the OEM replacement?
And here's my story. I just picked up a '90 XJ with a new (crate) 4.0 in it. The motor has ~36K on it. I had to drive it about 330 miles home and I found it to be about 3 quarts low when I got on the road. I noticed the oil gauge to be reading what I would consider low for most of the trip. When the engine was cold, it would start up around 40psi and run there until it got a little warmer. Once there, it would idle around 20psi, but under acceleration it would increase (all the way up to about 40-45 psi at 3K RPM's). After I made it about 200 miles, I stopped for a couple of hours and got back on the road. I noticed the oil pressure staying fairly low this time, averaging around 18-20 at idle, and maybe 30-40 under highway load. I pulled off to check oil again, and found it a couple of quarts low this time. It made the rest of the trip safely, but did continue to blow out oil.
Of course, my first step is to find the leaks and seal that block back up. I've got a little bit of oil blowing out of CCV and FAI grommets on the valve cover, not much there. No valve cover leak that I can see. Looks like I've got a leaking spot or two on the oil pan itself (actually there's one missing bolt, and it's been filled with RTV). The real suspect in all of this is the crank seal, though. I can't be 100% due to the general covering of wet oil on the bottom of the block, but I'm pretty sure that the seal behind the HD is pushing it out. It also makes sense as it could certainly be a high quantity leak site.
So, my plan is to immediately replace the upper grommets, oil pan seal and crank seal. While I'm in there, I have thought to replace that oil pump for peace of mind if nothing else. My concern is multifold.
-Do I even really need the oil pump or does my current 'new engine' oil pump sound healthy, but fighting a large leak?
-The new engine does not look to be a HO, so I'm thinking that the oil pump should be the cast iron variety, before the aluminum pumps made their way into production. Would a replacement NAPA/AZ pump from Meling be of equivalent build quality?
-I've read about those High Vol. users who ran into fitment issues and had to bang out the pan a bit and bend the pickup to make it all work. I'd be a bit worried about any oil starvation issues resulting from such a small oil pickup area after the larger screen and all are in place. Is this valid at all?
-I've also read about issues with the HV pump hitting the crank or causing other motion path issues. Is this stuff really that commonplace? It seemed like the users with the pre-HO engine ran into more problems than the latter engines.
After all of that... I'm wondering if the OEM replacement pump wouldn't be a sufficient and a less problem prone solution. And of course... that's if I even need to replace it.
Sorry for the novel, and thanks for any advice.
-Donk
What are the true benefits of running the high volume oil pump over the OEM replacement?
And here's my story. I just picked up a '90 XJ with a new (crate) 4.0 in it. The motor has ~36K on it. I had to drive it about 330 miles home and I found it to be about 3 quarts low when I got on the road. I noticed the oil gauge to be reading what I would consider low for most of the trip. When the engine was cold, it would start up around 40psi and run there until it got a little warmer. Once there, it would idle around 20psi, but under acceleration it would increase (all the way up to about 40-45 psi at 3K RPM's). After I made it about 200 miles, I stopped for a couple of hours and got back on the road. I noticed the oil pressure staying fairly low this time, averaging around 18-20 at idle, and maybe 30-40 under highway load. I pulled off to check oil again, and found it a couple of quarts low this time. It made the rest of the trip safely, but did continue to blow out oil.
Of course, my first step is to find the leaks and seal that block back up. I've got a little bit of oil blowing out of CCV and FAI grommets on the valve cover, not much there. No valve cover leak that I can see. Looks like I've got a leaking spot or two on the oil pan itself (actually there's one missing bolt, and it's been filled with RTV). The real suspect in all of this is the crank seal, though. I can't be 100% due to the general covering of wet oil on the bottom of the block, but I'm pretty sure that the seal behind the HD is pushing it out. It also makes sense as it could certainly be a high quantity leak site.
So, my plan is to immediately replace the upper grommets, oil pan seal and crank seal. While I'm in there, I have thought to replace that oil pump for peace of mind if nothing else. My concern is multifold.
-Do I even really need the oil pump or does my current 'new engine' oil pump sound healthy, but fighting a large leak?
-The new engine does not look to be a HO, so I'm thinking that the oil pump should be the cast iron variety, before the aluminum pumps made their way into production. Would a replacement NAPA/AZ pump from Meling be of equivalent build quality?
-I've read about those High Vol. users who ran into fitment issues and had to bang out the pan a bit and bend the pickup to make it all work. I'd be a bit worried about any oil starvation issues resulting from such a small oil pickup area after the larger screen and all are in place. Is this valid at all?
-I've also read about issues with the HV pump hitting the crank or causing other motion path issues. Is this stuff really that commonplace? It seemed like the users with the pre-HO engine ran into more problems than the latter engines.
After all of that... I'm wondering if the OEM replacement pump wouldn't be a sufficient and a less problem prone solution. And of course... that's if I even need to replace it.
Sorry for the novel, and thanks for any advice.
-Donk
