7AFE oil-burning knowledge pool

[Piloter]

Right, so I think we all know that the 7A-FE engine has an oil-burning problem, consuming a quart every 600-700-1000 miles for most people who have a problem with it. This is common across the Celica ST, 93-97 Corolla DX, 93-97 Prizm, and probably the Geo Storm as well. The problem is largely stable if oil is regularly supplied and there have been reports of people running their cars for years and years just adding quarts routinely and not bothering to do more.

We also know that it seems to be caused primarily by sticking oil control rings, with the valve seals being a potential additional culprit.

Furthermore, we know that re-ringing and rehoning an engine can (as expected) fix the issue.

What have people tried to fix it, short of a rebuild, and what have been results? I'll start. In my case, I have both bad seals (smokes after letting sit for a while) and stuck rings (smokes on high RPMs and pretty much a little bit all the time).

Tried:
Synthetic oil switchover at ~150,000 miles to Mobil One 5-30.
Results: Decreased initial consumption for ~10K miles, then back to usual levels.
Notes: Once the first couple oil changes at 3K clean out the crud, 5K OCIs result in oil still looking quite clean. After all, with a quart every 600, you've put in 8.3 quarts in 5K miles, or right around two complete changes. *Headdesk* May as well go 7K or 10K, if you're using the OEM Toyota filter.


Tried: Seafoam, extensively.
Results: No improvement to oil consumption.
Notes: This is fun to do in parking lots...it's also a product which can be used to do a piston soak with. This is something I've not yet tried.

Tried:
Restore Engine Restore.
Results: No improvement.
Notes: Auto-RX supposedly works along similar lines, but it's not available in stores that I know of.

Tried: Piston soak with B-12. (2.5 oz per cylinder had leaked past pistons in less than 8 hours...)
Results: Discernably decreased smoke on high RPM acceleration. Evaluation still in progress.
Notes: Starting may take a terrifying amount of time. It took me about 3 minutes to get her fired up again. This is not for those with weak batteries.

Tried: Piston steam cleaning (tangentially related) w. half-gallon distilled water, sucked through the manifold until the exhaust smoke was pure white.
Results: AWESOME smokescreen. Spouse dyno reports increased acceleration and smoother idle.
Notes: This also got me a CEL. I haven't pulled the code, but I suspect it's from a fouled front O2 sensor...a sensor that to my knowledge may well be the factory original. Oh well, it had to go sometime. This is not something you want to do on a windless day with people or police/fire departments around.

Sometime this week, I'll probably do another soak with Marvel Mystery Oil, just to see if I can get the stuff to stay in the cylinders for longer and also to take the chance to peek down into the cylinders and see if the steam-clean blasted enough carbon off the pistons that I can see bare metal yet.

I'll be making long highway trips again down from Vancouver, WA to the Reno, NV area soon enough, so that should prove an excellent opportunity to evaluate the soaking/cleaning efficacy long-term.

Chip in, folks, let's try to save the n00bs some hassles and figure out what does and doesn't work...

[Flashmn]

Really wasting time and money on these magic fixes is dumb, just re-ring and re-hone the engine. might aswell change the valveseals while you're at it.

Only guy that can do magic tricks with success is david copperfield, if theres a mechanical failure, pouring whatever into the engine most likely wont fix it. Its like medicine, you cant cure a disease that needs antibiotics with vitamins.
I'd say the smallest hassle is just doing the mechanical work.

Funny thing tho, its not just the 7a-fe thats part of this problem, at one point in time, toyota used some crappy OEM parts. I've heard of a 2E engine that had broken oil rings from the factory. They replaced them at the stealership as warranty.

[darcsyde]

i've tried that Engine Restore before it's worked for me a felt a small difference in my other car

[Piloter]

Originally Posted by Flashmn

Really wasting time and money on these magic fixes is dumb, just re-ring and re-hone the engine. might aswell change the valveseals while you're at it.

Well, with the 7AGE going in in the next month or two, I have an engine to experiment with. If I fix the problem, we learn something and I can sell it as good, if I don't fix the problem, we still learn something and I can sell it as scrap. Besides, my mechanical skills aren't enough to have an engine apart and back together and running reliably, but they are enough to pour stuff in. =)

[94_Rolla_Guy]

Ok i need to chime in on this...... don't feel like typing so im gonna cut and paste all my "input" from all the other posts i can find that i wrote...


i wanna add something here, with the 93-95 1.8L oil burning (7A-FE) your not alone i think every single 93-95 1.8L burns oil, i replaced my engine with a low KM engine and its right back to its old tricks burning 1L every 750 - 1000 Km's

If i were you i would do 1 of 2 things:

1. Buy a used engine from a 96 or 97 they are better and seem to have fewer problems..but you will have to transfer all sensors & distributor from the old engine over and remove the EGR valve and block the ports. The problem is it could still burn the later engines are better but not exempt from bad rings

2. Haul the engine out of there and have the bottom end rebuilt with oversized pistons, new rings, bearings the whole bit. you can probably just reuse the head without any work being done. (to me this is the better bet the engine will be like new and last a good life)

BTW if you buy an engine with problems there gonna wanna see it running with the problems then expect the engine returned for a exchange. I personally went through this and got fucked so bad my ass still hurts...
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well im looking at around 1200 CDN for just the rebuild (parts, machine work, labour) for you it would cost a little more for removal and re-installation. Go find a few engine re-builders in your area and see what they say price wise...

BTW the engines will run forever evem burning like 1quart every 500-600 miles. The reason im even gonna bother is because where i live we have Emmission testing and mines not gonna pass this time around..
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not an uncommon issue at all i bet your going through about a litre every 1000Km?? maybe a little less... any ways i wont get into it to deeply, id put my money on the oil control rings being worn/stuck in there grooves... basically your looking at a short block engine rebuild... the good news is even though its burning, it will last a good long time, LONG AS you keep the oil no more than 1/2 a litre (or half the fill portion on the dipstick) down as lower can cause momentary loss of oil pressure causing bearing damage....

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its not so much a wear problem with the rings they sludge up get stuck and the drain holes in the ring grove plug, and the oil cant be controlled by the rings (stuck) and has no where to go thus it blows by the compression rings.

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with your oil burning the dealer is right i would bet $1000 its the piston rings, specifically the oil control rings stuck in there grooves. If you search on here you will find many 93-97 owners and 98-02 members with similar problems...

I have some expirience from my 94 and its consumption issues i will sum it up

- Castrol GTX seems to have the least burn off
- you can use 10W-40 but i would NOT use anything heavier IE 20W-50
- Flushes or cleaning products don't seem to do anything some make the consumption worse
- The engine will last quite a while burning oil, provided you keep oil in it
- Keep the oil level no lower than halfway down between the Low and High marks, lower and you can get drops in oil pressure that can damage the bearings
- Do the oil changes consistantly don't neglect oil changes or your oil consumtion will most likely get worse
- The compression results will be high like you said, a leak down won't find anything either..

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Hello, Im in the same boat almost identical to schn0354, started doing it when i bought it at 125k replaced the engine with a low km used one at 214 KM ,same bullshit all over started at 1L every 3000 now at 246 KM its at 1L every 1000 KM using 15w-40 diesel oil.

Im getting ready to do something, haven't decided if im gonna go 4A-GE or rebuilt the smoke factory.


I have gone into it a little more, its all the oil control rings, nothing more, on my old original engine upon removal the rings were hopelessly stuck in there grooves, nothing i found would un-stick them. after removing the scraper rings they have no spring, but still maintain the proper end gap suggesting they haven't worn at all.

I have the same bald spot on the thrust side of the bore but unfortunately my engine is about .0005" over tolerance before honing so like .0010" after, besides that the piston skirts have moderate scoring so it doesn't make sense to reuse the pistons. The crankshaft has scouring because of oil starvation because of low oil...


Gotta start a 7A-FE Oil burning fan club..... theres alot of people out there!

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the compression will most likely come out perfect even above perfect my 202km engine was doing 215psi but after taken apart and looked at the compression rings were completely free and minimally worn BUT the oil rings were hopelessly stuck level with the skirt but surpriseingly not badly worn. i put the pistons in varsol, acetone, clean oil and it took weeks for anything to happen. that motor was hopeless burning 1liter every 250-500km now my supposed "low miler" is burning 1Liter every 1250-2000k so i have been messing around trying to desludge it before im replacing bits.

From being around the corolla's a bit ive seen alot of the 93-95's (7A-FE) that burn oil but i do know and see a few people with the 4A-FE and oil issues later in 95-97 OBD2 and some minor changes seem to address and correct the issues a bit?!?!?! as the problems seem to be less.

If you want somemore reading try www.bobistheoilguy.com and check out the forum

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Hello welcome to the oil burning family, less common on the 1ZZ-FE but still a problem, the majority of the problems reside on the 7A-FE (93-97 corolla 1.8L) just search "7A-FE oil burning" or similar stuff

Over the two different engines i have had in my car both have burned oil.. I have played around and found that some oils burn less (castrol GTX 10W-40) and castrol products in general seem to work well. i have tried a few different flushes and treatments with next to no luck most of the time the treatments increase the consuption.

My advice is let it warm up a little like until the temp gauge reads something, run it gently until up to temp, keep the oil no more than 1/2 a quart down, more can cause unstable oil pressure hence engine damage.

do this and you should see the consumption go down and become a little more manageable

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The high HC's are caused by excess fuel or incomplete burn... if by chance the engines burning oil thats most likely the cause. If it hasn't had plugs in a while thats not a bad thing to do also clean the throttle body and tune-up stuff, now ive never heard of xylene, but i have heard of the methyl hydrate or gas line antifreeze aproach, also if its high on HC and you don't care about whats causing it try advancing the timming like 2 deg, that will lean out the engine, just be careful in doing so...not to lean it out too much keep an ear out for pinging...also to much lean out and it will fail on NoX

[94_Rolla_Guy]

OH yeah someone Sticky This and delete THIS post

[rice]

when i had my timming belt done, my mechanic (which is my uncle) also changed the valve seals, and the oil burning had drastically reduced!

oh yeah, and Ren, stickied FTW, y0!

[Piloter]

Bump-badump. Obviously nothing is going to be a replacement for a mechanical rebuild, but I put the miles on and I've got the spare cash to try some odd stuff. (The CEL for the steam clean was a single misfire...one cylinder failed to fire in about 30 minutes of sucking down a gallon of water. I call that impressive. Upon inspection afterward, the crud coverage went from about 80% of the piston surface to about 10% of the piston surface. Bare metal!)

Further things tried that haven't worked:


Tried: MMO soak.
Results: Same as B-12 soak. (No surprise.)
Notes: Acceleration beyond 3,500 RPMs feels as if something akin to VTEC has kicked in...this may just be due to fewer piston deposits.


Tried: Switching to a straight 30-weight oil.
Results: Improvement in consumption, as usual, for the first 1,000 miles, then nothing.
Notes: N/A

Tried: Adding a quart of ATF in the crankcase.
Results: Acceleration seemed a bit slower. This may be subjective. No consumption changes.
Notes: Pouring blood-red fluid into the crankcase seems a bit like making the poor car a victim of some dark demonic ritual.

I'll be trying Auto-RX sometime in the next couple weeks.

[zythr]

Is this still a problem?

[94_Rolla_Guy]

I finally cured it after, 245,000 km's and two engines! Get rid of it and buy a different car . . . lol

Just wanted to update some old info, and bandaids i have found.

OIL: Castrol is no longer king of the castle for helping burn off, since the original article stuff we have a new oil specification API SN, its got a more robust additive package and has better cleaning properties.

- So if your using cheap old stock oil thats SM use it elsewhere and get some new SN rated oil, preferably 5w-30

-In the last year or two i screwed around with different brands and had the best results with the new SN rated Pennzoil Yellow bottle 5w-30 its cleaning properties seem to be at least maintaining the condition and keeping things cleaner, thus helping the oil rings stay loose in there grooves.

-Stop and Go, turning off a hott engine stops all oil circulation, and when that happens the oil in the ring pack gets really hott and starts breaking down, contributing to the buildup in the ring pack. If possible leave the engine running in an effort to keep cool oil circulating.

-After "spirited" driving slow down and let internal temps drop before, turning the car off and letting the oil cook on the hott bits. Even let it idle for a minute before turning the engine off.

[YOGI.CR]

All cars have issues, they are not perfect. Even worse when we talk about 15 years old cars lol.

My car is around +300 miles and fortunately has not gone any problem at at (yet lol) I did not know they have oil issues. I will keep an eye on it.

[Piloter]

Update, some years later. After going through any number of oil changes and additives and piston soaks and blah blah blah, nothing's really changed longterm, still burning a quart every 600 like clockwork.

However, and this is important, I now have a picture of how the inside of the head looks at 244K (thanks, overdue timing belt replacement and failing water pump!) after running all this Seafoam and B12 and ATF and crap through the system for so long.


From what I've been reading, the discoloration may be due to excessive heat from running low on oil so damn often, but on the whole, for 244K and that much consumption, I think it looks pretty good.

Anybody who's more experienced with the internals (which is just about everybody), feel free to chime in and correct me as needed.

Also it seems like I've been "a couple months' from putting the engine in since I got it built, so I'll just stay silent about it until/unless progress is made.

[kaitaiya]

i wanted to share my oil experience. here's pics of my head and bearings.




my 7afe developed a knock at 176K miles. it started because i made a mistake using 5w30 instead of my normal 10w40 or 20w50. i find that the thicker oil allows cushion. i don't drive easy on my car so because the thin oil(non synthetic) i think it caused the bearings to just give out. while i waited for my blacktop to come in, i had put gear oil into the crankcase to keep it alive for a little longer. once the knock started it smoked really bad but the thick gear oil got me along for another week.

as you can see in the pic, the head is REALLY clean. used only CASTROL oil in it never anything else. i got the car when it had 72k Miles and it was always on castrol till i put the 5w30 in by accident. even though the bearings were gone, the crank had no scaring.

[Bitter]

Originally Posted by Piloter

Update, some years later. After going through any number of oil changes and additives and piston soaks and blah blah blah, nothing's really changed longterm, still burning a quart every 600 like clockwork.

However, and this is important, I now have a picture of how the inside of the head looks at 244K (thanks, overdue timing belt replacement and failing water pump!) after running all this Seafoam and B12 and ATF and crap through the system for so long.


From what I've been reading, the discoloration may be due to excessive heat from running low on oil so damn often, but on the whole, for 244K and that much consumption, I think it looks pretty good.

Anybody who's more experienced with the internals (which is just about everybody), feel free to chime in and correct me as needed.

Also it seems like I've been "a couple months' from putting the engine in since I got it built, so I'll just stay silent about it until/unless progress is made.

Looks good.