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.

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.

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?

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.

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

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

Man, keep reading.... :frown:

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.

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.

i have a filter from toyota in a red box its plastic wrapped and the gasket is pre lubed, is this a new or old toyota filter?? either way im gona use it so it really doesnt matter...

Oil Filters
 

Not sure I can get those here but we do have a NAPA. Didn't make much sense that a Toyota filter would change the reading. Yes my sender is in question. Reminds me to go check my oil level. I just crossed the 100 mile mark on the tripometer.

ALL filters cause a change in pressure. Pressure == resistance to flow. ;)

There are much worse things to run than the newer Toyota filters, but they're not very good and you can get much better for close to the same price. I don't remember how to tell the difference other than taking them apart. The old style used a varied density foam-like medium and the newer are paper. They haven't been available in North America for some time so unless it had a half inch of dust on the box when you picked it up it's unlikely it one of the famous ones... it's a shame too because they were supposed to be VERY good filters.

Anyone here uses a FRAM and I'm coming to get ya! :squint:

Lol, I used Fram once, rhen it was a oain to get it off when i cahnged oil next, so now I use the K+N ones since u can get a socket on them to get them off. :dance:

I just picked it up from the mechanic this morning. I had him fix the A/C while he had it. He said the oil looked good but there was a wad of paper in it. It didn't look like paper from an oil filter either. He said to just drive it and keep an eye on the gauge. I drove down to Rolla today and it seemed to be doing fine for the whole 3 hours. I'm just hoping there's no more paper in it.

Sabotage
 

Sorry for the double post. After 350 miles. I have experienced little to no oil loss in my Supra. I guess that clenches it. Someone had to have drained it of oil without my permission or knowledge. If I have lost any it is less than a quarter quart so it is hard to measure any closer than that....Makes no sense. I guess someone hates me.

I have a fram on there now.. its the orange one not the cruddy white one.
still I went and purchased a mobil one. w/ 10w30 mobil one oil.
so im all set for my next oil change.
might do mobil 1 10w40 high mileage.

CRE, what do you use for oil filters?

Wix (NAPA Gold to be precise) right now because I got a good deal on several. I think next I'll probably try out Amsoil's EaO filters. I change my filters more often than I change oil so it makes sense to move to something with a finer medium, but I'm trying to find something that's not too expensive... Otherwise I'd go with a nice expensive Canton filter system. I'm ALWAYS learning when it comes to oil and filtration.... maybe I should go with a dual head setup. Sorry, I'm a little scattered right now.