1995 Corolla 7A-FE Valve Seal and Piston Ring Replacement project w/pics

[schn0354]

Hello fellow Toyota owners,

I am fairly new to the forum and trying to get advice from others who have also replaced valve stem seals and piston rings. Owners of 1993 - 1997 Corolla's with the 7A-FE that have oil consumption problems are also welcome to add input. Please list some specs about your Corolla such as year, odometer reading, oil consumption rate, and repairs that have helped reduce oil consumption, etc. Some of the following information was posted on a different thread, but I was getting off topic and wanted to reorganize and condense. Your comments and knowledge are highly appreciated and I will continue to post quality pictures of this extensive DIY project online via this website: http://picasaweb.google.com/reedmsch...otaCorolla7AFE



I purchased a 1995 Toyota Corolla DX, 5spd, with 138,000 miles back in April of this year. It now has 144,00 miles and is running rough when cold and burning about 1 qt. of oil every 750-1000 miles depending on city/highway miles and ambient temperature. Normal consumption is about 1 qt. every 3,000 miles for this mileage. Perhaps that is why the original owner sold it. Unfortunately, I did not notice this from a test drive and vehicle inspection prior to purchase. The problem has worsened in the last 6,000 miles. Maintenance and inspection that I have recently done which could help solve this problem includes the following:

29-33 mpg gas usage
Compression test dry: CYL 1=210/CYL 2=200 CYL 3=205 CYL 4=205
Compression test wet: CYL 1=190/CYL 2=190 CYL 3=195 CYL 4=190
Tuneup: Denso double platinum plugs, Denso first time fit wires, OEM Denso rotor, OEM distributor cap, NPN air filter
PCV valve, vacuum hoses, belts, engine mounts OK
Timing chain replaced at 77K mi.
All fluids flushed and replaced
No oil leaks

There was a noticeable improvement after the tune-up, but the main problem still existed. Blue exhaust is only visible under start-up after the car has been sitting for awhile. A compression test by the Toyota dealer revealed good results on all cylinders for a dry and wet test. I talked to a number of mechanics and did some research to conclude that the oil burning is most likely related to leaky valve stem seals and piston rings (even with good compression numbers, oil control rings can be worn and/or seized up with carbon).

Before engaging in this project, I obtained an official Toyota service manual (downloaded from http://techinfo.toyota.com/public/main/main.html), which is much more helpful than a Haynes Manual. I do not have any formal technical training and have never taken an engine apart so beware that the following information may not be correct and is not written as a guide. Many specialty tools were needed and loaned out. Everything is being meticulously labeled and many pictures have been taken so I can remember how to put everything back together!

First, I pulled the cylinder head to replace the valve stem seals and check overall engine condition. There was extensive carbon build-up in the intake air plenum and intake manifold. The intake manifold was almost completely blocked on a few small but important passages leading to the EGR valve. The EGR valve was completely blocked as well! I was told that this blockage may be a contributing factor for the carbon build-up, rough idle when cold (when warm the engine still runs great though), and even oil consumption. I cleaned the throttle body and squirted throttle body cleaner through all the vacuum hoses and emissions sensors. Hopefully, my EGR system will now function correctly. EGR problems are difficult to diagnose, so I may need to vacuum test it when it is all put back together. The camshafts were in near perfect condition, with no visible wear! There was normal carbon buildup on the valves. A machine shop cleaned the intake manifold and EGR valve, inspected the head, installed the valve stem seals, removed carbon from valves, and milled the surface .002 inch. Machine shop work was $158. This is on the low side but the head was in almost perfect condition. Full valve job is more like $400-500 and very rarely needed on a Corolla. An engine is usually not worth putting money into by that point.

Hopefully, replacing piston rings will also help reduce oil consumption and bring compression up. It is not much more work and money to do this at this stage as long as everything else is in good condition. A Toyota technician viewed pictures I took of the pistons and could tell from the carbon wear pattern where oil was "leaking through" and preventing carbon buildup. A piston ring set from the dealer (cast iron, molybdenum coat compression ring) was about $100. Physical inspection of the cylinder bore and pistons was revealing. I did not professionally measure the cylinder with a bore dial gauge (could get feeler gauge and check ring gap in bore at different rotations if necessary). However it is in excellent condition judging by a small glazed surface area at thrust points, visible original cross hatch, and minor ridge. The pistons pushed through the top of the block with finger tip pressure from below. I was advised by an engine re-builder to not use a ridge reamer as it would essentially bore out the wall in my case. I was able to borrow a precision dial caliper and measure the bore diameter 1/2 inch inset from the top of bore and compare it with spec. to the 1/1000 inch. Fortunately, it is still within spec. and none of the bores are out of round (at least at the top). Most wear is in the middle though along the thrust axis. Measurements were 3.190 +/- .0005 at the 8 points measured. Living next door to a machinist and mechanic has been very helpful. Pistons and rings appeared in good condition except for the oil control ring, which showed wear, had little spring, partially seized with carbon, and all of the holes along the grooves were plugged with carbon. The pistons were very difficult to clean.

The most frustrating part of this job was getting a good finish on the cylinder bore to seat the new rings and provide the correct amount of lubrication for long-term ring life. I was going to use a Flex-Hone to deglaze at first, but could not obtain one on the weekend. I became impatient and used a conventional 3 stone deglazing tool. Unfortunately, I did not obtain a 45 degree crosshatch. The pattern was more like a shallow inverted arc. I should have experimented more with a lighter tension setting in the beginning. Is a quick short 1” stroke moving from the top to bottom the correct technique? My stroke length was the entire bore. The stones did benefit by removing the slight ridge though. Hindsight is 20/20. Instead of experimenting more and redoing with a correct technique, I waited until I could obtain Flex-Hone. This tool worked great and was very easy to use. I just followed instructions on the manufacturer’s website: http://www.brushresearch.com/Index.c...xHoneTools.htm. It was used longer than recommended at 90-120 seconds, to try and get past some of the previous scratches made. Yet, this was difficult since the stones removed more material than the ball ends. A 45 degree crosshatch was produced with a plateau finish (hard to see in pictures), but I am worried that the previous pattern still visible will lead to excess oil consumption. Maybe I should have used it more. I am still kicking myself in the foot, because this procedure would have been effortless had I lightly used the Flex-Hone in the first place. Anyone who has done this before, please look at the pictures and comment. I have heard horror stories of rings never seating properly, lowered compression readings, and increased oil consumption. I just do not know and am in over my head on this procedure. I was hoping to bring compression up to like new levels which are something like 210-220 PSI for the 7A-FE, Does anyone think this is unrealistic, especially in this case?

Cleaning the engine block is critical. Even small bits of metal or dirt would ruin the engine. I used about 10 large buckets of hot water with laundry detergent and a nylon brush, followed with brake parts cleaner and ATF fluid, more soapy water, and a rinse. Compressed air was used to drive away moisture and the crankcase was sprayed with WD40. The bores were lightly coated with 10W30. The engine is in Saran Wrap at the moment, awaiting reassembly.

So far this is day five and I have spent an additional $130 on an Ishino head gasket set, $17 timing belt and $6 for a camshaft oil seal from an online wholesale company (http://www.the-best-source.com). About $50 more was spent on replacement fluids, cleaning supplies, miscellaneous tools. It has been hard to plan in advance since what is needed depends on the condition of the engine upon inspection and you can’t just run to the local parts for special order parts. Fortunately, I have backup transportation at the moment.

While I am assembling everything this evening, I would appreciate input to some more questions. Everything has been flawless except the critical cylinder bore finish up until this point. Do I need an inductive timing light or will timing marks be good enough? Can anyone recommend or provide a link to a good break in driving procedure? Has anyone done this kind of work before? If so, what were your results? Truth is that I will not know the benefits until 500, 5,000, or even 50,000 miles from now. Has this information been helpful?

[psychocoder]

schn0354

I am in the process of finishing a complete 7AFE rebuild in a 93 Corolla. I did more work than you; replaced pistons, rings, rods, valves, valve springs, valve guides, valve springs, thrust washers, rod bearings, main bearings, oil pump, all gaskets & seals, had the head worked and milled when they did the complete valve job (had 3 broken ones and 2 bents ones so I replaced them all).

I did the rebuild because at the end I was going through almost 5 quarts of oil a week (drive 650 miles a week for work) but was still getting over 30 MPG (cant explain that one). It started smoking only when it was first started (or after sitting for a long period of time), then proceeded to smoking profusely all the time so I knew it was time for some major work.

Granted, it would have cost less to just buy another car, but this is my wifes baby, she bought it brand new off the showroom floor and wasnt willing to part with it yet, has been the best car we ever bought. So for her I am now into this project a little over $1000 (including parts, supplies, tools and shop work). The hardest part about reassembling the engine was getting the cam timing right, what a pain! I was first informed that the 7AFE was an "interference engine" (meaning if cam timing isnt right you bend valves) but found out differently, but the cam timing was still a bitch.

I bought and used an inductive timing light simply because I didnt like the timing the way it was simply using the timing marks, runs much better now. Once I got it started I noticed oil leaking from where the head meets the block (at least everyone who has looked at it and myself say thats where its coming from) so Im awaiting a new set of head bolts (since this engine uses TTY bolts) so I can pull the head and see if something got between the head and the block (maybe under the head gasket) that is preventing a good seal. All head bolts were torqued to specs (22lb then 90 degrees then 90 degrees) so I know its not my torquing thats causing the leak.

All in all it sounds like you've done everything correctly. I wish I would have taken pics of the engine as I disassembled it to show, as it was in worse shape then ANY engine I have ever worked on (yet it was still running and getting 30MPG). Before reassembling I cleaned every part (by hand), painted the head, block, manifold, valve cover, manifold heat shield (used 1200 degree engine paint) so now its pretty as hell and cleaner than its ever beens ince it was new. Let me know how the reassembly goes.

[schn0354]

Incredible! Well, at least your wife knows you love her more than the car! My family thinks I am crazy for taking the engine apart and you certainly did a lot more work than what I am doing.

How many miles did it have? I am surprised that it did not smoke down the highway at that consumption rate. How long did it take you to rebuild the 7A-FE? Are you finished yet? How much work did you have a machine shop do? I would like to know more about getting the timing correct since I was told timing marks would be good enough. I called a dealership to see if the head bolts were TTY before parts were ordered, and was informed by the tech they were not. I do not recall the 7A-FE to be an interference engine either. Am I misinformed? What manual did you use? Yes, I will give an update late tonight as the head is being assemble today.

Originally Posted by psychocoder

schn0354

I am in the process of finishing a complete 7AFE rebuild in a 93 Corolla. I did more work than you; replaced pistons, rings, rods, valves, valve springs, valve guides, valve springs, thrust washers, rod bearings, main bearings, oil pump, all gaskets & seals, had the head worked and milled when they did the complete valve job (had 3 broken ones and 2 bents ones so I replaced them all).

I did the rebuild because at the end I was going through almost 5 quarts of oil a week (drive 650 miles a week for work) but was still getting over 30 MPG (cant explain that one). It started smoking only when it was first started (or after sitting for a long period of time), then proceeded to smoking profusely all the time so I knew it was time for some major work.

Granted, it would have cost less to just buy another car, but this is my wifes baby, she bought it brand new off the showroom floor and wasnt willing to part with it yet, has been the best car we ever bought. So for her I am now into this project a little over $1000 (including parts, supplies, tools and shop work). The hardest part about reassembling the engine was getting the cam timing right, what a pain! I was first informed that the 7AFE was an "interference engine" (meaning if cam timing isnt right you bend valves) but found out differently, but the cam timing was still a bitch.

I bought and used an inductive timing light simply because I didnt like the timing the way it was simply using the timing marks, runs much better now. Once I got it started I noticed oil leaking from where the head meets the block (at least everyone who has looked at it and myself say thats where its coming from) so Im awaiting a new set of head bolts (since this engine uses TTY bolts) so I can pull the head and see if something got between the head and the block (maybe under the head gasket) that is preventing a good seal. All head bolts were torqued to specs (22lb then 90 degrees then 90 degrees) so I know its not my torquing thats causing the leak.

All in all it sounds like you've done everything correctly. I wish I would have taken pics of the engine as I disassembled it to show, as it was in worse shape then ANY engine I have ever worked on (yet it was still running and getting 30MPG). Before reassembling I cleaned every part (by hand), painted the head, block, manifold, valve cover, manifold heat shield (used 1200 degree engine paint) so now its pretty as hell and cleaner than its ever beens ince it was new. Let me know how the reassembly goes.

[94_Rolla_Guy]

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!

[psychocoder]

schn0354,

The car had 225,000 (miles not KM) before I started the rebuild, nothing had ever been done to the engine aside from regular maintenance and replacement of the timing belt so I was pretty impressed with that. As far as smoking, at the end it was like I was fumigating misquitos everywhere I went, so yer it was smoking like a siv. RAM Engine (the machine shop I use) did the complete valve job (valves, springs, guides & seals, lifter shims), they milled the head and cleaned it to a factory shine and ground the cams back to spec, other than that I did all the work including deglazing the cylinder bores (which oddly enough didnt have a "lip").

The time it took is hard to judge since I really only get to work on it a day a week because of my job (and other obligations from my home business) but I had it out and disassembled in a weekend and if I add the time it took to reassemble (not counting the time the head was at the machine shop) about 3 Saturdays (like I said I could only work on it a day a week (work 50+ hours a week and develop websites from home)).

As far as the timing, once I got the cam timing right ;

• place exhaust cam with knock pin facing at 5 o'clock, bolt down and torque to spec (9 ft lb), then turn it so the knock pin is facing 10 o'clock
• put the intake cam in so that the installation marks line up, bolt down and torque to specs (9 ft lb)
• turn exhaust cam so that timing marks are straight with the top of the head (or until #4 is opening/closing when you rock the cams back and forth)
• put the timing belt on (make sure before you do this that #1 is TDC)
• put the valve cover on

Once that is done then it should start (if not do the process over again until you get the cam timing right), from there I used a timing light to get the ignition timing right.

Now for the manual, I bought a Chiltons a few years ago when I changed the timing belt sp I used that for the loosening/tightning sequences for the head bolts and cam bearing caps,the torque specs for the engine and of course for the specs as far as clearance and such, aside from that I didnt really use the manual as Ive rebuilt several engines in my life.

Unfortunately I believe your dealership has misinformed you (possibly), I know the 93 7AFE engine does in fact use TTY bolts so you may want to check into getting a set (ITM bolts from NAPA for $35 a set). Aside from that everything went pretty much according to plan, the engine is together but I have to remove the head either tonight or tomorrow to see if something is on the head gasket as I do have the small oil leak where the head meets the block.

PS: I forgot to mention that I also replaced the timing belt setup with a complete new kit

[schn0354]

Pschocoder,

After investigating further, the head bolts do appear to be TTY. They were torqued to 22 ft/lbs, additional 90 degrees, and additional 90 degrees again in a three step squence instead of just to a particular final torque spec. This is typical of a Torque to Yield bolt with an aluminum head. At the final turn I was reading 175 ft/lbs on the torque wrench, so the cylinder head is definitely on tight. Perhaps too tight? I was informed that the bolts can be reused if not visibly stretched or have damaged threads. Haver heards this advice from a number of techs now. However, I understand by definition TTY bolts stretch and should not be re-used. Well since the head bolts are already on, I am certainly not taking them off and getting another head gasket set. If they are TTY, it is odd that the Toyota manual does not mention using new head bolts. Haynes manual does not mention it either. Toyota does not stock them at the dealership. Very few sources online sell them. Confusing. A multi-layered steel head gasket was used, similar to the original. They are very durable, but require tight tolerances. If the head gasket leaks when the block and cylinder head expand, I will be very dissapointed!

Your timing advice is the same as what I have. I put a paint mark on the valve cover housing and distributor rotor before removing. I also put a scratch mark on the exhaust cam indicating the distributor position. I am hoping to not have to use a timing light. What is there to adjust anyways?

[Gerson]

wow, very good info guys. I rebuilt my cylinder head when I had 179K on my 1994 corolla w/1.6L 4A-FE because the valve seals where bad and the car smoked. I never rebuilt the block on my engine since it is in real good shape. I have 191K miles on my car and no problems at all. This is very helpful information if I want to rebuild the whole engine for performance purposes or 4A-GE 20v. Most of this work is done by me.

[Cabanon]

mine drink 1gallon every 1500kms
but still get 35-40mpg
it does drink more oil when cold & when hitting 5000rpm+
in 3rd going 110km/h + i can see it like shit in the rear mirror view
kinda funny to blue smoke like shit, but not that really funny actually.
i really think i am going to the same thing you did.
but with no experience at all in motor rebuilt, i dunno.
anyway, really really good topic!
it started drinking oil when i switched to synthetic oil at 185ks, now 196ks

[Bitter]

wow, i guess i'm better off than most. 1993 with 122K miles and i use about 1/2 qt every 3k. i add 1/2 qt atf before i change and that stops my oil burning till the next change. eventually i'd have to change the seals, but the car probably wont last that long. either get hit or rust out.

[schn0354]

Well, I removed the cylinder head and will be replacing the head bolts after all. Can anyone recommend a good source. No local retailer sells them. Dealer does not stock them. ITM, Felpro, Ajusa, Beck Arnley?

[psychocoder]

Originally Posted by schn0354

Well, I removed the cylinder head and will be replacing the head bolts after all. Can anyone recommend a good source. No local retailer sells them. Dealer does not stock them. ITM, Felpro, Ajusa, Beck Arnley?

schn0354,

You can call NAPA and they can order them for you, they run about $35 a set.

[Bitter]

the dealer should be able to order anything you need at no additional cost.

[schn0354]

Roger that. The head bolts are on order from the dealer and I will receive them in 3 days.

[tashirosgt]

schn0354,
Did the manual you downloaded show the headbolts marked with the symbol for "non reusable" or not?
Also, is that site where you downloaded the manual a free site if you register or does it charge a fee?

[emiliorescigno]

This oil burn on 7A-FEs seems pretty widespread, both my 4A-FEs never burned oil, they both died at 198k Miles and 230k Miles because of BHGs, and never had any sort of problem with valve stem seals.

Is there some difference in the 7A-FE that causes this?

edit: I forgot to mention, my Supra's 7M-GTE burns like a mother, and I think it's the stem seals. (The turbo is freshly rebuilt, and compression test was alright)