oil pressure...

[loki2043]

so my oil pressure has been "ok" lately but now its getting pretty scary. i dont have rod knock. my oil pressure is (on the stock gauge) in the middle of 0 and the first line. and at 3000k rpm its right under the first line, but when i let off the gas at 3k the pressure rises to the first line...then hit the gas down it goes again. yes i have enough oil. engines got 140k on her. am i looking at a bad gauge? bad pump? bearings out of spec? or all 3....? thanks

 

[amd_hcds]

Maybe you have bad oil how much miles do you have on your oil?

 

[suprahero]

I'm leaning towards the bad gauge. I just put a new motor in my wifes car, with a new oil pump, and hers reads exactly like yours. Sometimes it will go up to about half way, but mostly below that. Her turbo gauge doesn't work right either so, I'm guessing the gauge cluster is screwed. You can buy another oil pressure gauge and find out for sure though. Just my two cents worth. Hope you get it figured out..........lol

 

[xarewhyayen]

im leaning towards you misreading the dipstick. Our dipstick is pretty tricky... I say add a qt of oil, or maybe 2 from the sound of how bad your pressure is, and watch it immediately rise. Im only saying so because this recently happened to me and i thought my oil level was fine. But it wasnt.

 

[johnathan1]

how did you find out your oil was low?

 

[xarewhyayen]

how did you find out your oil was low?

by adding a qt and seeing my pressure went up dramatically...
then i noticed when i checked my dipstick that when it was low and i thought it wasnt, i was seeing the oil on the edges of the dipstick rather than on the whole thing. you get it on the edges from the oil that sits in the dipstick tube area. I think thats why i misread it. I wish we could get a better/ aftermarket dipstick

 

[johnathan1]

...I wish we could get a better/ aftermarket dipstick

From what I understand a better one is available from the dealer, for like $14.99 or something...i recall hearing something like that one here a while back...never looked into it though.

 

[billspreston01]

well...the book says like 4.3 quarts of oil when you do an oil/filter change...I always end up putting about 5 1/2 quarts in to hit the full mark on my dipstick......odd isn't it

 

[Adjuster]

I ran one quart over what's reccomended on a stock motor all the time. On my non-stock stroker motor, the minimum is 10 quarts, and it can hold 12 without foaming or problems.

So, run 6 quarts of oil in your 7MGTE all the time. Also run nice and thick oil. I run Rotella T Synthtic, and I belive it's either 10/40 or 5/40 and made for long running semi trucks that put 500,000 miles on each oil change, and run the engines for millions of miles between rebuilds. (Controling the water in the oil and filtration is key to doing this. Also regular testing of the oil, or you can just change this oil two times a year, and your fine as long as you use WIX, Purolator or NAPA filters. NO FRAM filters, they are crap paper, and don't filter very well at all.)

If you can swing the money, get a remote oil filter setup from Canton racing. (They use a non-bypassing depth filter v/s cheap disposable paper filters that don't stop particles that cause wear.) Canton also sells spin on adapters so you can use depth filters in a "spin" on type housing. Figure 130.00 for this setup and some filters, but it stops particles in your oil down to 8 microns where the paper filters stop stuff in the 20 to 40 micron range. Wear is caused by anything larger than 10 microns...

 

[jetjock]

Couple of thoughts. First, I've never understood this dipstick thing. Mine has never been hard to read. It's a dipstick, you pull it out and look at the oil. I don't get it. Second, the stock oil pressure sensor is an odd beast as far as sensors of that era go. It's a pressure to frequency converter because the ecu needs a digital signal to sample oil pressure. I wouldn't trust it beyond a certain point.

Adjuster: Good post as always. I agree with most everything but differ on some. I currently run 5 quarts but for over 100k miles never ran more than full on the stick and never had a problem. Nor do I believe in the "thicker is better" mantra. In spite of the (over) hyped rod knock issue there simply isn't any reason it's needed and there are downsides to doing it. fwiw I've never run a vis greater than 30w in 19 years and over 140k miles. Never had a problem. I'm running a 0-30 right now and it performs better than anything I've previously used. The analysis is great too.

Although Rotella 5 40 "synthetic" is a fine oil it's too thick at 100C for my tastes. Good additive package though. But it's a Group III oil and therefore not a true synthetic, something I prefer to have in a turboed engine. It's a great oil though so I'm splitting hairs. I use it in my bike and one other car that needs a thicker oil.

As for the Canton, it's a good filter but I have to question any firm who claims 8 micron at those flow rates (no bypass remember) in such a small package. I also notice they offer no standardized test data to support those claims. And if it really does 8 microns without a bypass running a "thick" oil (even a 5w rated one) in a climate like Idaho could cause excessive cold start wear. Maybe not but...

A tad expensive too for "only" 8 microns assuming it even does that. I prefer true bypass depth filtration on a submicronic level (TP for example) and the elements cost pennies. If spin on is a desire something like the Trasko is a lot cheaper and offers better filtration. Plus TP based filters remove water. No water, no acid generation. All this makes the Canton a bit extravgant for what you get. And if you really want to cut wear a preoiler is the way to go. Even an Accusump used in that way is better than nothing.

Just my two cents. I couldn't agree with you more about the full flow filters. They're pretty much gravel strainers. Btw, Napa filters are made by WIX, as are CarQuest filters.

 

[IJ.]

JJ: Is there an interconnection between the Oil pressure sender and the ECU?

 

[Nick M]

I've never run a vis greater than 30w in 19 years and over 140k miles. Never had a problem

Agreed. Not about the 19 years though

Before you drive your car in anger, install a mechanical gauge where the pressure sender goes, and see what it really is. This is after you make sure you are not low.

I don't get the dipstick problem either. Never been an issue with 5 MA70's, and two Celicas. Or any I worked on at Toyota. It does take a moment to drain all the oil, so waita moment after you shut it off and check.

.

 

[jetjock]

Yes, a direct connection. I used to think it would shut the engine down because of what happened with mine when it lost the drain plug and ran completely out of oil on the highway without the engine suffering damage. (No rod knock in that case either )

It won't. Since then I've learned it's used for cold idle. I even disconnected the input on my ecu a few years back to verify it. Lol, so the ecu knows when thicker oil is being used. It's probably why it strikes back at times

 

[IJ.]

JJ: Never knew that thanks!
(there's that learning thing happening again)

 

[jetjock]

Look at your schematics and you'll see it goes to the ecu. At least it does on mine. Another tip off is that bizzare test procedure in the TSRM where you hook a light bulb to it and watch for flashing.

 

[IJ.]

LOL I suspect mine is in this pile !

 

[jetjock]

Lol! I keep forgetting you've got a FrankenCar. Who knows what evil lurks within it

 

[IJ.]

Lol! I keep forgetting you've got a FrankenCar. Who knows what evil lurks within it

LMAO I do !

 

[mkIIIman089]

jj: what difference did it make when you disconnected the oil presure sensor from the ECU?

 

[jetjock]

None that I could notice Colin. At the time I did it to see if it'd kill the engine but it didn't even after 30 minutes. I was wondering because some cars will. For example I think some GM models do it.

This was before I learned the ecu uses oil pressure for tweaking cold idle speed. Since I live in a warm climate, use "thin" oil, and had the engine hot I didn't notice any change in idle.

Had I known I would've been tempted to hook up my pulse generator and dummy in a pulse stream but disconnecting the input didn't kill the engine and at the time that was my purpose in messing with it.