4psi hot idle/35-40 over 2k rpms oil pressure, bad front cover o-ring?
08-25-09, 09:52 PM
#1
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4psi hot idle/35-40 over 2k rpms oil pressure, bad front cover o-ring?
I recently picked up an '87 RX7 TII. The car had a Mazda reman engine with about 29k on it, and had a few issues. The first issue I am in the process of fixing is the low oil pressure problem.
The gauge read 25-30psi / 60ish psi when cold, and would sometimes drop to 0 when fully hot, and get down to 30psi with rpms from 2-3k. I verified with a mechanical gauge today and found that the pressure really is around 4psi at idle and 40ish under load.
I have already shimmed the eccentric shaft thermovalve to no avail. There is oil leaking from the oil pan/front cover area. On the hierarchy of things, the next step would be to check/replace the front cover o-ring.
I own a haynes manual, but the information about the problem is not well documented. I read mazdatrix's faq on the subject and understand how to install the new o-ring.
My question is now what am I looking at in terms of:
1. Labor time
2. Parts needed other than the pan gasket, front cover gasket (or rtv), front cover o-ring, and waterpump gasket.
3. Other things I should check/replace when the cover is off
Furthermore, how much damage has been done by driving the car this way? And continuing on, what other problems could possibly cause symptoms like this.
I have used the search engine for hours, but have not found a good guide for the install process. What pitfalls should I know about so I can avoid them?
Thanks for reading this long post. I bought this car a few weeks ago and this is pretty disappointing to say the least, but hopefully she'll be back on the road in no time.
The gauge read 25-30psi / 60ish psi when cold, and would sometimes drop to 0 when fully hot, and get down to 30psi with rpms from 2-3k. I verified with a mechanical gauge today and found that the pressure really is around 4psi at idle and 40ish under load.
I have already shimmed the eccentric shaft thermovalve to no avail. There is oil leaking from the oil pan/front cover area. On the hierarchy of things, the next step would be to check/replace the front cover o-ring.
I own a haynes manual, but the information about the problem is not well documented. I read mazdatrix's faq on the subject and understand how to install the new o-ring.
My question is now what am I looking at in terms of:
1. Labor time
2. Parts needed other than the pan gasket, front cover gasket (or rtv), front cover o-ring, and waterpump gasket.
3. Other things I should check/replace when the cover is off
Furthermore, how much damage has been done by driving the car this way? And continuing on, what other problems could possibly cause symptoms like this.
I have used the search engine for hours, but have not found a good guide for the install process. What pitfalls should I know about so I can avoid them?
Thanks for reading this long post. I bought this car a few weeks ago and this is pretty disappointing to say the least, but hopefully she'll be back on the road in no time.
09-06-09, 08:55 AM
#3
What weight oil are you using?
Does the oil pressure vary with different weights, ie 20w50 vs. 10w30?
My S5 used to have very low oil pressure at idle, around 5psi when hot. This was with Castrol 20w50. ONCE for convenience I used 5w30 because I had it on hand for my wife's car and I didn't want to make a trip to the store. Idle oil pressure went to an indicated -0- psi and oil pressure at higher rpm was also considerably lower.
Recommended oil viscosity, esp. in warm seasons, is 20w50.
I have since shimmed my thermal bypass, my idling oil pressure when hot is around 25 psi. This is of course with 20w50. I would expect that the pressure would be lower with a lower viscosity oil.
Does the oil pressure vary with different weights, ie 20w50 vs. 10w30?
My S5 used to have very low oil pressure at idle, around 5psi when hot. This was with Castrol 20w50. ONCE for convenience I used 5w30 because I had it on hand for my wife's car and I didn't want to make a trip to the store. Idle oil pressure went to an indicated -0- psi and oil pressure at higher rpm was also considerably lower.
Recommended oil viscosity, esp. in warm seasons, is 20w50.
I have since shimmed my thermal bypass, my idling oil pressure when hot is around 25 psi. This is of course with 20w50. I would expect that the pressure would be lower with a lower viscosity oil.
09-06-09, 10:12 AM
#5
Give yourself lots of time to do this right. I did this with a friend and it took us a few hours. Sometimes things are difficult to reach, things are in the way, and things are dirty.
Do not rush anything.
And for the love of god, keep the clutch pedal down. Use a piece of wood or anything you can do to keep it depressed. Otherwise when you loosen that front bolt, you will drop your bearings and then you are screwed.
Mazda changed the front iron casting in the early years and forgot to tell anyone. Depending on the year of your car, you may not know the right gasket, o-ring and teflon ring to use until you get that cover off.
Good luck.
Do not rush anything.
And for the love of god, keep the clutch pedal down. Use a piece of wood or anything you can do to keep it depressed. Otherwise when you loosen that front bolt, you will drop your bearings and then you are screwed.
Mazda changed the front iron casting in the early years and forgot to tell anyone. Depending on the year of your car, you may not know the right gasket, o-ring and teflon ring to use until you get that cover off.
Good luck.
09-13-09, 09:22 PM
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Well it's been a crazy process, but the pressure is up!
I took off everything including the front cover and oil pan. I found that the o-ring had slipped out and was completely blown in half.
After that I cleaned up all the bolts, changed all the gaskets using the right stuff gasket maker and Mazda gaskets, and made all the sealing surfaces shine.
I installed polyurethane motor mounts from Banzai Racing at the same time, the stock were worn with 22 hard years of battling the forces of nature. I also used the opportunity to fix some loose vacuum holes and other issues.
After torquing the bolts to spec, I got it all back together. I found that the oil pressure went right to 60 psi on the factory gauge. I was then extremely disappointed when the pressure fell right back to near zero (maybe 5-10 psi on the factory gauge), and got progressively close to where it was before it undertook the surgery. I drove it around the block and then parked it back into the garage.
I let it sit for a few weeks and went home tonight to work on it. I procured a timing light to set the timing and decided to fix two more vacuum hoses and adjust the TPS, which I had previously found to be out of spec.
I started it up and, once again the oil pressure creeped near the bottom of the gauge, it was an improvement albeit a minor one.
I decided it was time for a nice rodding so I took her out and beat on her somewhat hard. The car was moving pretty good! After redlining it a few times, the gauge was way up. I couldn't believe my eyes! I kept driving it, let it idle for a min. or so and then drove it hard for a bit and it is was 45 psi at idle and 70 or maybe near 80 psi almost always over 3krpms.
I let it sit for a bit, put on my mechanical gauge to verify pressure and fired her up. The oil pressure was right around 45-50 psi at idle and near 80psi. over 3.5krpms.
I'm still in shock over the ordeal but my Step Dad and I believe that once a good seal was made between the o-ring and front cover, it started loosening up a lot of carbon in the oil passages. It sounds plausible to me?
Anyway on to putting the poly trans mounts and going through the entire intake manifold (it looks like a nightmare).
I took off everything including the front cover and oil pan. I found that the o-ring had slipped out and was completely blown in half.
After that I cleaned up all the bolts, changed all the gaskets using the right stuff gasket maker and Mazda gaskets, and made all the sealing surfaces shine.
I installed polyurethane motor mounts from Banzai Racing at the same time, the stock were worn with 22 hard years of battling the forces of nature. I also used the opportunity to fix some loose vacuum holes and other issues.
After torquing the bolts to spec, I got it all back together. I found that the oil pressure went right to 60 psi on the factory gauge. I was then extremely disappointed when the pressure fell right back to near zero (maybe 5-10 psi on the factory gauge), and got progressively close to where it was before it undertook the surgery. I drove it around the block and then parked it back into the garage.
I let it sit for a few weeks and went home tonight to work on it. I procured a timing light to set the timing and decided to fix two more vacuum hoses and adjust the TPS, which I had previously found to be out of spec.
I started it up and, once again the oil pressure creeped near the bottom of the gauge, it was an improvement albeit a minor one.
I decided it was time for a nice rodding so I took her out and beat on her somewhat hard. The car was moving pretty good! After redlining it a few times, the gauge was way up. I couldn't believe my eyes! I kept driving it, let it idle for a min. or so and then drove it hard for a bit and it is was 45 psi at idle and 70 or maybe near 80 psi almost always over 3krpms.
I let it sit for a bit, put on my mechanical gauge to verify pressure and fired her up. The oil pressure was right around 45-50 psi at idle and near 80psi. over 3.5krpms.
I'm still in shock over the ordeal but my Step Dad and I believe that once a good seal was made between the o-ring and front cover, it started loosening up a lot of carbon in the oil passages. It sounds plausible to me?
Anyway on to putting the poly trans mounts and going through the entire intake manifold (it looks like a nightmare).
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