rebuild engine oil pressure
10-26-04, 10:39 AM
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rebuild engine oil pressure
Hi all
I'm allittle freaked out. I'm in the process of breaking in my remanufactured engine on 87 TII. For the first 60 miles or so the oil pressure was reading close to a 90-95 range at 2.5-3K rpm. Now (I'm at 80 miles) I noticed it dropped to like 50 or 55 at 2.5-3k rpm. It idles at 30 psi just like before. Is this something I should be concerned about. What should I do ? Please help.
I'm allittle freaked out. I'm in the process of breaking in my remanufactured engine on 87 TII. For the first 60 miles or so the oil pressure was reading close to a 90-95 range at 2.5-3K rpm. Now (I'm at 80 miles) I noticed it dropped to like 50 or 55 at 2.5-3k rpm. It idles at 30 psi just like before. Is this something I should be concerned about. What should I do ? Please help.
10-26-04, 10:45 AM
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90-95 is very high, 50-70 is factory specs. Is this in an aftermarket gauge, or the factory? The factory sender has been known to stick from time to time.
Since you are still seeing 30PSI at idle, it's doubtfull that there's a problem. Keep an eye on it.
Normally, the imfamous o-ring problem will cause almost zero oil pressure at idle, and only about 30 PSI at redline.
Since you are still seeing 30PSI at idle, it's doubtfull that there's a problem. Keep an eye on it.
Normally, the imfamous o-ring problem will cause almost zero oil pressure at idle, and only about 30 PSI at redline.
10-26-04, 04:00 PM
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Originally Posted by Aaron Cake
This engine is not necessarily a Mazda reman.
Btw I believe my engine is mazda reman. I did go personally to malloy mazda to pick it up. So I doubt the o-ring could be the problem. Also I doubt the oil pump malfunctioned. I just wanted to know the factory oil pressure specs to see if I'm within limits. I'll try different oil pressure sender to see if my gauge will display anything different. I also noticed my oil pressure gauge is kinda sluggish. It seemed to jump up and down faster before. Maybe something is sticking. Thanks for input.
One more thing. I'm thinking about getting mech oil pressure reader to verify exact oil pressure I'm getting. Anyone know a particullar kind to get that works well and where to get it?
Last edited by fc3sguy; 10-26-04 at 04:05 PM.
10-26-04, 04:25 PM
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I just finished an s5 rebuild and was getting an intermittant oil pressure reading. Sometimes it would read ok but most of the time it would fall back to zero or stay at zero the whole time. I hooked up a mechanical guage and it read fine, so it was some problem with the sending unit. There's nothing like reading 0psi after a rebuild to freak you out.
10-26-04, 04:27 PM
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OK, that was not mentioned in the original post.
Oil pumps don't really malfunction. There's nothing that can go wrong, unless the sprocket is spinning on the shaft, which is very rare.
Factory specs can be found in the Factory Service Manuals, at http://www.fc3s.org . But 30 PSI at idle and 50+ PSI after 3000RPM is within factory specs.
Another gauge is important. Almost any will do. I prefer the Autometer electric gauges, so you don't have to run an oil tube into the cockpit.
Oil pumps don't really malfunction. There's nothing that can go wrong, unless the sprocket is spinning on the shaft, which is very rare.
Factory specs can be found in the Factory Service Manuals, at http://www.fc3s.org . But 30 PSI at idle and 50+ PSI after 3000RPM is within factory specs.
Another gauge is important. Almost any will do. I prefer the Autometer electric gauges, so you don't have to run an oil tube into the cockpit.
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10-26-04, 04:42 PM
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It must be something about getting air to the senders while doing a rebuild, because mine did the same thing. Replaced the sender with new, she's worked ever since...
Oil pressure before the rebuild was always 60-62 psi; pressure after the rebuild, with the bypass pellet installed, is always about 58. Weird...
Oil pressure before the rebuild was always 60-62 psi; pressure after the rebuild, with the bypass pellet installed, is always about 58. Weird...
10-26-04, 09:37 PM
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Well I ordered oil pressure tester so I'll be able to verify my oil pressure accuratelly. In the meantime I had a question about valves that control the pressure in the lubrication system. I'm suspecting either oil pressure control valve or oil pressure regulator valve. Both are shown in the link http://www.teamfc3s.org/main/factory...ION_SYSTEM.pdf
Also I'm not sure what's the role of the eccentric shaft bypass valve is. Would it play a role? Actually if someone could tell me what each one of those valves do and which one should I suspect to have some dirt trapped inside and letting oil leak out to oil pan.
Btw I switched out a oil pressure sending unit with one I had laying around and there's no changes in pressure readings.
Also I'm not sure what's the role of the eccentric shaft bypass valve is. Would it play a role? Actually if someone could tell me what each one of those valves do and which one should I suspect to have some dirt trapped inside and letting oil leak out to oil pan.
Btw I switched out a oil pressure sending unit with one I had laying around and there's no changes in pressure readings.
10-27-04, 03:39 PM
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You're within factory specs. Why are you trying to solve a non-problem? 
The main oil pressure regulator is at the rear iron. It bypasses around 50-70 PSI, depending on a number of things (temp, manufacturing tolerance of spring, etc.)
The front regulator bypasses at over 100PSI. It is probably not your problem.
The eccentric thermostat should have been replaced with a solid pellet during your rebuild, but unfortunately Mazda does not do this. If this sticks open, you will have uniformly low oil pressure accross the board. You should replace this with a pellet.
The rear regulator sticking slightly open is not going to lower oil pressure that much.
The main oil pressure regulator is at the rear iron. It bypasses around 50-70 PSI, depending on a number of things (temp, manufacturing tolerance of spring, etc.)
The front regulator bypasses at over 100PSI. It is probably not your problem.
The eccentric thermostat should have been replaced with a solid pellet during your rebuild, but unfortunately Mazda does not do this. If this sticks open, you will have uniformly low oil pressure accross the board. You should replace this with a pellet.
The rear regulator sticking slightly open is not going to lower oil pressure that much.
10-27-04, 04:50 PM
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Thanks for input Aaron Cake. I know I worry too much about my car I't my nature. However now that I dropped my idling RPM down to 700 and my oil pressure drops to 10 psi I worry even more. I know I used to get more than 50-58 at 2.5-3.5k RPM at the very beginning so I know something got clogged up or something is sticking. And unfortunatelly I'm gonna waste my free time untill I find it or give up trying :P. So how hard is it to get to oil pressure regulator valve.
Last edited by fc3sguy; 10-27-04 at 05:16 PM.
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