Oil pump shimming / pressure question after cam swap
09-26-2005, 11:56 PM
#1
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Oil pump shimming / pressure question after cam swap Just finished my cam swap, started her up, perfect; no leaks, idles great..
Only thing I'm mildly concerned about is the oil pressure.. I decided to shim my pump spring while I had it apart, and although the idle pressure is about what I expected, after letting it run for a bit to bleed the cooling system I revved it and it seems like the oil pressure just keeps climbing. Saw 70 psi. at around 4000 - 4500RPM.
It's quite possible there is nothing wrong; I tried Amsoil in the C5 this last oil change, but I only had 10w-40 lying around.. And I've heard Amsoil tends to thicken with age, which is the inverse of most oils..
So before I go off on some tangent about stuck relieve valves (all parts of the pump were cleaned, lubed and carefully assembled - actually I was amazed at all the crap I found floating in the pump), I'll go with the "time for oil change back to 5W-30 Mobil 1", and hope that the pressures return to "normal".
The oil was still around 185'ish when I checked it, so not fully warmed up. I went conservative on the shim size, so it's not like I over did that part. But my mind works overtime, dreaming up cocked springs or stuck valves.
What do you folks think?
Only thing I'm mildly concerned about is the oil pressure.. I decided to shim my pump spring while I had it apart, and although the idle pressure is about what I expected, after letting it run for a bit to bleed the cooling system I revved it and it seems like the oil pressure just keeps climbing. Saw 70 psi. at around 4000 - 4500RPM.
It's quite possible there is nothing wrong; I tried Amsoil in the C5 this last oil change, but I only had 10w-40 lying around.. And I've heard Amsoil tends to thicken with age, which is the inverse of most oils..
So before I go off on some tangent about stuck relieve valves (all parts of the pump were cleaned, lubed and carefully assembled - actually I was amazed at all the crap I found floating in the pump), I'll go with the "time for oil change back to 5W-30 Mobil 1", and hope that the pressures return to "normal".
The oil was still around 185'ish when I checked it, so not fully warmed up. I went conservative on the shim size, so it's not like I over did that part. But my mind works overtime, dreaming up cocked springs or stuck valves.
What do you folks think?
09-27-2005, 10:53 AM
#2
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The LS1 oil pump can be a rotten bich to center on the crank snout. I don't know if this could have anything to do with erratic oil pressure readings, but I do know that if the pump is not centered almost perfectly, it will wear unevenly.
There are two methods to align the pump:
1. use two sets of feeler gauges set at .002, and place them between the pump and crank snout 180* apart. Sweep the feeler gauges around the crank snout, keeping 'em 180* apart...this will center the pump on the crank snout.
2. GM makes a tool specifically for this...I'm sorry, but I don't have a part number...
There are two methods to align the pump:
1. use two sets of feeler gauges set at .002, and place them between the pump and crank snout 180* apart. Sweep the feeler gauges around the crank snout, keeping 'em 180* apart...this will center the pump on the crank snout.
2. GM makes a tool specifically for this...I'm sorry, but I don't have a part number...
09-27-2005, 11:01 AM
#3
Launching!
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You know, I looked at the factory manuals that I own, before installing the oil pump, and it made absolutely no mention of a tool (or procedure) for centering the oil pump. In contrast, it does show special tools and procedures to center the crank seal and cover. It also mentions that the seal will wear unevenly if not centered properly.
All that said, I did make sure the pump was centered about as well as you could make it by hand..
*UPDATE* I called 5 major engine builders (the creme of the crop) and they all say they do not use feeler gauges to center the pump on the crank. So at this point I'm not going to sweat that part of the install.
All that said, I did make sure the pump was centered about as well as you could make it by hand..
*UPDATE* I called 5 major engine builders (the creme of the crop) and they all say they do not use feeler gauges to center the pump on the crank. So at this point I'm not going to sweat that part of the install.
Last edited by Dan_the_C5_Man; 09-27-2005 at 03:52 PM.
09-27-2005, 11:09 AM
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Both LS1/LS6 reference books I have make it a point to illustrate the importance of centering the oil pump as perfectly as possible. When I get home, I'll post some of the text.
That said, you're right...this may not be the problem at all with your ride.....
That said, you're right...this may not be the problem at all with your ride.....
09-30-2005, 01:57 AM
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What is your idle pressure? I shimmed mine when I took it out. I shimmed it about 1/8 of an inch and just guess it should give me about 15lb. more. Well at idle I consistantly have over 40 and at 3,500 I am at about a bit over 60. It is kind of opposite of you I guess. May be the spring on mine was worn out and it just will not push more. Or the Mazda sending unit and gauge is wacked ( I think the later has a higher possibility). I never worked on a piston motor before but I did notice the clearance difference of how the pump is installed. I just centered it as much as I can and hope the pump gears will turn free with out any bind.
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09-30-2005, 05:33 AM
#8
Couple of thoughts here. I have the same reference books discussed in the previous posts. While I didn't shim as the books state, I did "wiggle" the pump back and forth a few times and then pick a halfway point to lock down the bolts. I followed the service manual, which doesn't mention centering the oil pump at all (at least I couldn't find it).
The Amsoil you are using is 14.0 Cst at 100 degree C. I would change to the Amsoil 5W-30 which is 10.6 Cst or the German Castrol 0W-30 which is a little higher. I am not big on the Mobil-1 viscosity values as they are close to a 20W oil when hot.
The Amsoil you are using is 14.0 Cst at 100 degree C. I would change to the Amsoil 5W-30 which is 10.6 Cst or the German Castrol 0W-30 which is a little higher. I am not big on the Mobil-1 viscosity values as they are close to a 20W oil when hot.
10-10-2005, 08:45 PM
#9
Launching!
Thread Starter
Just an update, I swapped out the oil back to Mobil 1 5w-30, and I get around 35~38 hot at idle, and I don't think it's going over 70 during redline, so it looks like I'm good to go.
I'm guessing as time goes on the new spring will relax and it may fall a few PSI. Just didn't want it over 70, that's all.
Thanks for the responses.
I'm guessing as time goes on the new spring will relax and it may fall a few PSI. Just didn't want it over 70, that's all.
Thanks for the responses.
10-10-2005, 08:51 PM
#10
Launching!
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Originally Posted by mazdized
What is your idle pressure? I shimmed mine when I took it out. I shimmed it about 1/8 of an inch and just guess it should give me about 15lb. more. Well at idle I consistantly have over 40 and at 3,500 I am at about a bit over 60. It is kind of opposite of you I guess. May be the spring on mine was worn out and it just will not push more. Or the Mazda sending unit and gauge is wacked ( I think the later has a higher possibility). I never worked on a piston motor before but I did notice the clearance difference of how the pump is installed. I just centered it as much as I can and hope the pump gears will turn free with out any bind.
FWIW, Lingenf. stated "as long as it's not over 70 PSI (continuously??), you are o.k." They said over that, you start having issues w/ seals leaking, etc.
