hottemp

I have been turning wrenches for 30 years. I have worked on alot of different stuff in my years. My daughter has a 98 4 runner 2.7 L engine with 160K. All is great and runs well. Uses 1/2 quart every oil change 3.000 miles since new. The other day I took off the oil fill while is running and got a lot of blow by. I dont know how long its ben like this because it does not leak a drop and never opened the oil fill while running before. I belived the motor was going south on me. My buddy thats a toyota mechanic for years also said not to worry all 2.7L have some blow by at the fill. He said it was not bad blow by. Ok so thats my ?. This is the only 2.7L I have laid hands on. What your opinion.

xxxtreme22r

I don't know the 2.7's at all but check to make sure the pcv valve is working properly, if that's stuck shut it will create more crank case pressure then normal. That's the first place I would look on any motor.

hottemp

Thanks, Did that. Compression 175 to 185 on all cylinders, scanner shows all is well. Like I said I have done this for years, just never fooled with this engine. Will do a leak test when I get a new guage for my tester. Dropped the darn thing today while hooking it up.
I am hoping my friend is right just the nature of the engine. It runs so darn well and engine is really clean. No oil seepage at all.

scuba

Have you checked the valves lately?
They need to be adjusted every 60K miles.
If they haven't been adjusted, they could be too tight..

Just my 2 cents.

hottemp

No I dont think I have ever checked the valves. Thanks

Texas_Ace

Most likely just the rings wearing/sticking, my dads corolla 1zz engine does the same thing and it has 130k hard miles on it.

I would not worry too much about it, give it a good oil change with some mobile 1 and maybe some marvel mystery oil if you feel lucky. That will clean out the internals as good as they will get.

If the oil comes out real dirty after doing that, then run the same thing again till the oil comes out looking ok. I generally change the oil after ~1000 miles when doing this cause of all the junk it will clean out.

I have used mobile 1 to clean motors many times and love it, the mystery oil is a new addition but no complaints yet.

Also would not hurt to run some seafoam through the intake/gas (not oil, not a fan of that).

J2F42C

See what results the leak down produces. I have an exhaust valve that has a bad valve guide in my 5VZ but have been too lazy to break it down so I run a PCV catch can to capture all the blow by for the moment.

Tooner

I've got the same issue on my 2004 Tacoma Prerunner. I first noticed it after I bought it in 2005 with 16k miles. There is so much blowby that oil mist sprays out the oil filler onto the hood. I did a compression test and all was good (+/- 180 psi from all 4 cyl). I did a leak down test and it had 50% leakage, which is way above the 15-20% max it should have. From the oil filler I could hear air hissing but I couldn't hear anything from the exhaust pipe or intake manifold. So this tells me valves are good and its a ring problem (but the compression is OK so ???). I posted it on a couple of forums. Some people said "don't worry, not a problem". Others said "rings bad". I took it to the dealer just before the 60k warranty was up and told them about the problem. I also told them that it was lacking power just so they wouldn't say "it's normal". They checked it out and said everything is OK and that the blowby is normal! Well I got 80k on it now and it seems to run fine other than it doesn't have a lot of power, but it's only a 2.7 and I don't have anything to compare it to (like a 0-60 mph or a 1/4 mile time for other Prerunners, which I have only found for the v6). How much blowby does everyone else with a 2.7 have? Anyone with a 0-60 time on a Prerunner (mine is 12.5 sec)?

dannygriffith82

having the same issue

dannygriffith82

hey have a 95 taco with the 2.7 it pulls 12.5 0-60 all day

stout890

sorry to open up a old thread but this is one of the only threads online i have found with my issue and seems like alot of people have this same issue. mine is the same but with some more details

Background
so originally i bought my truck with 145K miles and the original engine eventually blew a head gasket and burned exhaust valves and had what i thought at the time was massive blow by by around 175K due to a bad IAC valve sticking and leaking coolant into the cylinders (didnt find that out till later) and possibly other lingering issues.

so i ordered a brand new engine from YOTA1 balance shaft delete and stage 1 cam.....long story short after break in i'm in about 1k miles on this new engine with Penzoil platinum 5-30 put in after break in and valves were checked by Toyota after 500 miles and were in spec with a few being at the tight side of the tolerance but still within spec.

after all that had same crappy start up issues as i had with the original engine that eventually killed it. turned out to be the IAC vale changed it out and start ups are a lot better but not perfect

Issue
with the new engine i still have massive blow by out of the oil filler cap. like so bad that the oil mist sprays all over the engine bay. also to note no oil or even air pulsing is noticed from the oil dip stick. i would expect to see some there if the crank case was being pressurized

so i do a compression test

180-190 on all cylinders... great right?

well i did a leak down test after just to get a baseline for the new engine and..

35-40% leak rate even as can be across all 4 cylinders and i can hear it through the oil filler cap hissing....

also to note while i was doing the compression testes oil sputtered out of #3 cylinder while i was cranking the engine for the compression tests on 1 and 2, than eventually stopped as if it cleared out any oil in there.

i plan next to leak down test again with a better tester and also do a wet test maybe. because i have a harbor freight tester that i think is junk.

plugs look like #3 has some ash deposits

also to note the engine was overheated during first start and warped the head and was sent back to the builder and was rebuilt again with a successful first start and break in.



So what do you guys think about this and what tester to you guys recommend for leak down?

how can i have good compression but garbage leak rate?

any other ideas of things to test or try?

Co_94_PU

iTrader: (-1)

Compression and leakage aren't mutually exclusive because the piston rings are actively oiled when you're cranking.

Pulling your valve cover during leak testing can give you a better sense of if the issue is rings or valve.

I expect you'll find #3 has a bad valve seal, or its directly inline with the PCV inlet (oil pool in the intake runner)

stout890

if i had a bad valve id think logically i would hear the air through the intake or exhaust. i used a mechanic stethoscope to listen to the header at each cylinder and intake and it was silent. the valve guide could be bad and causing the oil to be present in the cylinder but i think unrelated unless someone can say for sure im wrong.

how do you guys leak down test? i hear some tester do 100PSI for testing but the cheap harbor freight one i have has you set the leak rate gauge at a setting and it ends up being around 1 BAR which is like less than 30PSI i noticed i could fudge the leak rate to be better if i cranked the air pressure above that setting. so it has me wondering if i need a gauge designed for 100PSI?

I'm an Aircraft mechanic by trade but don't do piston engines, but during my training and reading some of the FAA materials in the AC43.13-1b today, states that a dynamic differential pressure check (leak down test) that 80PSI minimum be used because cylinder pressures help seal the rings against the wall during operation. so the 30 PSI may have been allowing the rings to falsely show a leak.

Has anyone have experience with the kind of tester i have? does it work for you?

i'm probably gonna get a aircraft grade tester possibly if there not 1,000$ ill report back the new readings when i do

in the mean time maybe some of you guys with a 2.7 pop the filer cap while running and tell me if you have any blow by or not? maybe this is normal for this engine.