7MGE oil pressure problems

I h8 Hondas · 07-07-2010, 01:02 AM

I have a 1986.5 Supra with about 158,000 miles. I was on my way home the other night and I noticed the oil pressure was slowly decreasing. No big deal. It wasn't dropping like a rock. I could have made it home if it hadn't started really falling when I slowed down to go through a little town. It had been running up around 3-4 kg/cm but when I slowed down it dropped below 2 kg/cm. Living in the U.S. I don't know how much a kg/cm is so I stopped and called someone to pick me up. Next day we took it to a shop which was only a couple hundred yards from where I lost oil pressure. A mechanic hooked it up to a pressure gauge that measured in psi. When it first started up it was running at about 70psi. Then it dropped down to 15. After that, as it kept warming up it dropped to 10 psi, which seems pretty low to me. But when you rev it up the pressure goes right back up to 70 and then back to 10. I've read some horror stories about these engines losing oil pressure and then ruining bottom rod bearings and/or crankshafts. So should I be concerned about this or is it going to be fine? It hasn't started knocking or anything yet.

Btw: As I was leaving the town I was visiting I had to pull out onto a busy highway and while looking carefully side-to-side I absentmindedly put it into third gear instead of first and somehow managed to not stall it. The bottom end didn't like this. I'm wondering if this mistake could have done my engine in.

907mge · 07-07-2010, 01:42 AM

It will go up with rpm since the pump is pumping more. Here is what toyota says:

http://www.cygnusx1.net/Supra/Librar....aspx?S=LU&P=4

And from what I've heard the gauge is rather off.

cre · 07-07-2010, 01:50 AM

Quote:

Originally Posted by I h8 Hondas

Btw: As I was leaving the town I was visiting I had to pull out onto a busy highway and while looking carefully side-to-side I absentmindedly put it into third gear instead of first and somehow managed to not stall it. The bottom end didn't like this. I'm wondering if this mistake could have done my engine in.

Unlikely.... and if it did then whatever broke was a day away from the grave anyway.

Your pressure is fine, but the range is a bit wider than common... what weight oil are you running?

I h8 Hondas · 07-07-2010, 02:40 AM

Not sure what weight oil it has in it. I just got it a few weeks ago and the oil was near the full mark and looked pretty new when I pulled the dipstick so I didn't think anything of it until now. It's been on jackstands most of the time I've had it. It needed shocks, ball joints, front brake pads, and rotors and since I live on a farm I didn't have much time to work on it til this last weekend. The mechanic said he wasn't going to start it up again until it had new oil. We are planning to put Valvoline 10w-30 in it unless somebody tells me different by tomorrow morning.

Looking at that link the pressure seemed to be within spec. Any ideas as to why the pressure would just start dropping other than just rpm's decreasing? Speed limit was 35 where it started dropping so the revs were down but it never dropped that low at that speed before and I was going about the same speed in the same gear as before. It had been leaking a little bit out of the valve cover before but when we opened the hood but it didn't seem to have gotten any worse, and the oil was still well above the add mark.

cre · 07-07-2010, 02:56 AM

I'd go 0W-30 or if you can't find it go 5W-30. Knowing where you're located would help, but in 90% of the US that's the weight I'd run.

I h8 Hondas · 07-07-2010, 03:32 AM

I live in northeast Missouri but I'll be going to college down at Rolla.

batmmannn · 07-07-2010, 07:08 PM

The Supra uses a low pressure high volume system and I also have read many places that the oil pressure guage is unpredictable and unreliable. I have read that using a Toyota brand oil filter instead of an after market filter can remedy this but I can't understand why. Many people hook in a better after market guage. I have heard of an oil filter blockage causing a drop in pressure. Mine dropped like yours and I was 3 quarts low and nearly disregarded the guage because of what I had read. I am monitoring my oil loss closely now. I have a Bosch filter on mine. After I added oil my pressure came back but it is very erratic at the guage, mine will start up and run at 40 then drop to 20, it's all over the place and makes little sense.

If it drops to Zero though you better stop and pull the dip stick.

I just found this in Google It recommends 10w 40 for my NA 87 Supra though I read that Cres recommendation of 0w30 used primarily in climates -40 below will get into your bearings and tight surfaces quicker at start up and flows like water even at these arctic temperatures. I am currently running 10w 40 but will switch to 5w30 after I find out why I am losing oil and fix it.

http://www.opieoils.co.uk/performanc...mmend_oil.aspx

cre · 07-08-2010, 02:41 AM

Man, keep reading....

cre · 07-08-2010, 02:45 AM

Oh, and as for the oil gauge... there's nothing wrong with the stock oil pressure gauge. They're not renown for failure either. The SENDER however is known for being inaccurate as far as calibration goes and it is internally dampened causing a significant delay in report. If you've got bouncing readings check the wiring and connector... it's unlikely that the gauge or the sender is at fault.

If anyone ever adds an aftermarket oil gauge do keep in mind that you still need to leave the stock oil pressure sender in place and connected as the ECU does read it... you may remove the stock gauge from the cluster though.

cre · 07-08-2010, 04:22 AM

God... I can't get away from this thread... just saw the Toyota filter thing. Toyota's old filters were VERY well constructed, but today's filters are a poor comparison. Filters such as Wix (NAPA Gold), Mobile1, K&N and PureOne are much better filters.

07-07-2010, 01:02 AM	#1
I h8 Hondas Stock Join Date: Jul 2010 Location: Bethel, Missouri, U.S. Posts: 12	7MGE oil pressure problems I have a 1986.5 Supra with about 158,000 miles. I was on my way home the other night and I noticed the oil pressure was slowly decreasing. No big deal. It wasn't dropping like a rock. I could have made it home if it hadn't started really falling when I slowed down to go through a little town. It had been running up around 3-4 kg/cm but when I slowed down it dropped below 2 kg/cm. Living in the U.S. I don't know how much a kg/cm is so I stopped and called someone to pick me up. Next day we took it to a shop which was only a couple hundred yards from where I lost oil pressure. A mechanic hooked it up to a pressure gauge that measured in psi. When it first started up it was running at about 70psi. Then it dropped down to 15. After that, as it kept warming up it dropped to 10 psi, which seems pretty low to me. But when you rev it up the pressure goes right back up to 70 and then back to 10. I've read some horror stories about these engines losing oil pressure and then ruining bottom rod bearings and/or crankshafts. So should I be concerned about this or is it going to be fine? It hasn't started knocking or anything yet. Btw: As I was leaving the town I was visiting I had to pull out onto a busy highway and while looking carefully side-to-side I absentmindedly put it into third gear instead of first and somehow managed to not stall it. The bottom end didn't like this. I'm wondering if this mistake could have done my engine in.

07-07-2010, 02:40 AM	#4
I h8 Hondas Stock Join Date: Jul 2010 Location: Bethel, Missouri, U.S. Posts: 12	Not sure what weight oil it has in it. I just got it a few weeks ago and the oil was near the full mark and looked pretty new when I pulled the dipstick so I didn't think anything of it until now. It's been on jackstands most of the time I've had it. It needed shocks, ball joints, front brake pads, and rotors and since I live on a farm I didn't have much time to work on it til this last weekend. The mechanic said he wasn't going to start it up again until it had new oil. We are planning to put Valvoline 10w-30 in it unless somebody tells me different by tomorrow morning. Looking at that link the pressure seemed to be within spec. Any ideas as to why the pressure would just start dropping other than just rpm's decreasing? Speed limit was 35 where it started dropping so the revs were down but it never dropped that low at that speed before and I was going about the same speed in the same gear as before. It had been leaking a little bit out of the valve cover before but when we opened the hood but it didn't seem to have gotten any worse, and the oil was still well above the add mark. Last edited by I h8 Hondas; 07-07-2010 at 02:52 AM.

07-07-2010, 02:56 AM	#5
cre Toyota Racing Development Join Date: Apr 2007 Posts: 5,038	I'd go 0W-30 or if you can't find it go 5W-30. Knowing where you're located would help, but in 90% of the US that's the weight I'd run. __________________ If something breaks or you need to contact a member of the administration please post HERE. Unless it's a private or administration matter please post it on the forum. It benefits no one else if car related questions aren't posted for future users and takes away from the time I'm able to spend helping on the rest of the forum. If you're so inclined I'm always more than happy to accept tips via PayPal. Tip Jar --->

07-07-2010, 07:08 PM	#7
batmmannn 12psi boost Join Date: May 2010 Location: West Virginia Posts: 320	Oil Pressure The Supra uses a low pressure high volume system and I also have read many places that the oil pressure guage is unpredictable and unreliable. I have read that using a Toyota brand oil filter instead of an after market filter can remedy this but I can't understand why. Many people hook in a better after market guage. I have heard of an oil filter blockage causing a drop in pressure. Mine dropped like yours and I was 3 quarts low and nearly disregarded the guage because of what I had read. I am monitoring my oil loss closely now. I have a Bosch filter on mine. After I added oil my pressure came back but it is very erratic at the guage, mine will start up and run at 40 then drop to 20, it's all over the place and makes little sense. If it drops to Zero though you better stop and pull the dip stick. I just found this in Google It recommends 10w 40 for my NA 87 Supra though I read that Cres recommendation of 0w30 used primarily in climates -40 below will get into your bearings and tight surfaces quicker at start up and flows like water even at these arctic temperatures. I am currently running 10w 40 but will switch to 5w30 after I find out why I am losing oil and fix it. http://www.opieoils.co.uk/performanc...mmend_oil.aspx __________________ 1987 N/A 7MGE Left Hand Drive MK3 Red 5 Speed and Black Auto Supras My Next project is the Batmobile! Last edited by batmmannn; 07-07-2010 at 07:29 PM.

07-08-2010, 02:41 AM	#8
cre Toyota Racing Development Join Date: Apr 2007 Posts: 5,038	Man, keep reading.... __________________ If something breaks or you need to contact a member of the administration please post HERE. Unless it's a private or administration matter please post it on the forum. It benefits no one else if car related questions aren't posted for future users and takes away from the time I'm able to spend helping on the rest of the forum. If you're so inclined I'm always more than happy to accept tips via PayPal. Tip Jar --->

07-07-2010, 01:42 AM	#2
907mge 20psi boost Join Date: Dec 2009 Location: Harrisburg Posts: 759	It will go up with rpm since the pump is pumping more. Here is what toyota says: http://www.cygnusx1.net/Supra/Librar....aspx?S=LU&P=4 And from what I've heard the gauge is rather off.

07-07-2010, 03:32 AM	#6
I h8 Hondas Stock Join Date: Jul 2010 Location: Bethel, Missouri, U.S. Posts: 12	I live in northeast Missouri but I'll be going to college down at Rolla.

07-08-2010, 02:45 AM	#9
cre Toyota Racing Development Join Date: Apr 2007 Posts: 5,038	Oh, and as for the oil gauge... there's nothing wrong with the stock oil pressure gauge. They're not renown for failure either. The SENDER however is known for being inaccurate as far as calibration goes and it is internally dampened causing a significant delay in report. If you've got bouncing readings check the wiring and connector... it's unlikely that the gauge or the sender is at fault. If anyone ever adds an aftermarket oil gauge do keep in mind that you still need to leave the stock oil pressure sender in place and connected as the ECU does read it... you may remove the stock gauge from the cluster though. __________________ If something breaks or you need to contact a member of the administration please post HERE. Unless it's a private or administration matter please post it on the forum. It benefits no one else if car related questions aren't posted for future users and takes away from the time I'm able to spend helping on the rest of the forum. If you're so inclined I'm always more than happy to accept tips via PayPal. Tip Jar --->

07-08-2010, 04:22 AM	#10
cre Toyota Racing Development Join Date: Apr 2007 Posts: 5,038	God... I can't get away from this thread... just saw the Toyota filter thing. Toyota's old filters were VERY well constructed, but today's filters are a poor comparison. Filters such as Wix (NAPA Gold), Mobile1, K&N and PureOne are much better filters. __________________ If something breaks or you need to contact a member of the administration please post HERE. Unless it's a private or administration matter please post it on the forum. It benefits no one else if car related questions aren't posted for future users and takes away from the time I'm able to spend helping on the rest of the forum. If you're so inclined I'm always more than happy to accept tips via PayPal. Tip Jar --->

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