And no noticeable change in engine operating temp, even on the trail under load................I do have a minor valve cover leak, but I don't drive this thing more than once a week. Any ideas if something else might be leaking?

I'm 90% sure that 3-4 quarts of oil IS NOT in my cooling system, this I know because by now, the freakin engine would've severly overheated and taken a crap on me (aka, not a headgasket.)

 

bump, any ideas?

I don't think the valve cover can leak that much over a month, or maybe it can just on the hardcore driving when the yota is cranked and trailing.

 

you are 3 to 4 quarts low after an oil change in 4 weeks, are you smoking at all? Have you over heated?

 

no smoke, definitely no overheating. Which is why I question the valve cover leak. Maybe rear main seal leak or something? I dunno. I know the rear of the driver's valve cover leaks.

 

the mystery of dissapearing oil. I know what you mean. My 95 was always low on oil. No leaks no smoke but always low.

 

My valve covers where slowy leaking. I took care of that when I had the HG replaced though, 3 to 4 quarts is alot in 4 weeks. No puddles under the truck? I'm sure someone is going to say degrease and then follow the drips. Either way you will need to try and take care of that soon. Where ever it is leaking from.

Question: When it is the valve cover leaking, does it normally smoke? maybe once up to temp and driving you just can't see the smoke? I'm sure someone will chime in shortly. Until then carry some oil with you

 

Now that I think about it I would lose about a quart every six weaks or so. Do you have any visable sludge build up?

Edit: this was before the HG replacement.

 

there are drips on the parking spot but no puddles, nothign to indicate the sheer volume of oil lost.

Of course when I say low, I have no idea how much oil was actually in there. It was just a tad below the L on the dipstick when hot, when I checked and saw it was low.

Also, i'm sure the stock oil pressure gauge is inaccurate, but the pressure seems to be on the low side unless I'm really getting on it. and it gets good and low on idle.

 

Use a dye in your oil to find exactlywhere the leak is coming from and you know that is recent, because it will be dyed. I would degrease (hopefully in some environmentally safe manner) the entire undercarriage first to help with the search. I would definitely check the "oil cooler" bolt and o-ring, because I thought I had a valve cover leak, turned out I just needed to torque down that bolt.

Good Luck.

 

When you said that you still see some oil on the dipstick, then that is more like you have lost about a quart of oil - not 3-4qts.

 

Thats what im thinking, It wouldnt even make it on the dipstick if it was that low.

 

well the reason it all came up is a check engine light came on......

So are you saying that between the full and low area is just a mere quart of oil? And that within 1cm of the low line is still no more than a quart or so? I just have trouble believing that lol

 

What type of oil are you using? Synthetic will blow by the rings with no noticable smoke.

 

it's synthetic, but I don't care what oil it is. I've got plenty of experience with burning dino oil and synthetic oil, you're going to have that bluish white smoke no matter what.

and since I added 2.5 quarts of dino yesterday and trailed hard, I had no smoke either.

 

My left valve cover also leaks, and from the looks of the under-carriage, that's where it accumulates. I've tried tightening the valve cover bolts, but I think the dealership stripped them when they did the valve job. Also, my oil pressure was pretty low before I replaced the HG, maybe yours are starting to go?

 

I agree. I had the same leak as Rhew. It really only leaked while it was running, since the oil is pumped into the cooler only when running. I took it off & replaced all the o-rings (there are 3). The outermost ring (about 3" diameter) was completely plasticised. It's easy to spot if you degrease & then fire the beast up. Take your skidplate off first. The oil cooler sits on the driver's side of the block, near the bottom. If you take the rubber skirt off the inside of your driver's side wheel well you can look right at it. I'd definitely check that, assuming you have a cooler. Some 3vz's only have a bolt & cover there, but a '94 should have one. It looks like a 3.5" diameter cylinder about 2" tall. Again, it mounts to the side of the block.

 

Mine was pretty low last time I had it changed (below L). The oil pressure being low happens on mine too. I'm about 1000 out from an oil change, gonna dump some seafoam in the crankcase and see if it's sludge.

 

seafoam is prolly a good idea. Seems that the oil level is now a bit above the full line, and I only added 2.5 quarts of oil yesterday. I bet that's why my check engine light is on, for oil pressure.

Anyone know EXACTLY how much oil is in the system when the oil level is at the L line on the dipstick?

 

I don't think the check engine light has any idea about oil pressure or oil level.

It cares mostly about the emmision systems not the health of the engine.

It's probably on for another reason.

 

OBD I computers like these definitely were tied in to sensors like the oil pressure sensor. And come to think of it, OBD I ecu's are so rudimentary, it'd take a near catastrophic o2 sensor failure to trip an CEL.

OBD II is an entirely different b*tc* all together, haha