Excessive Oil Consumption — Rebuild or Rering engine?

[djshimon]

I'm trying to decide whether to rebuild or re-ring this engine-
It is a Used engine with lots of power-I overheated it last summer for a few minutes then poured water in it while it was steaming-probably a bad Idea. Supposedly it has around 130,000 mileage-which I agree because the exhaust manifold is still intact and they crack around 150K I've heard. I never checked the compression after I over-heated it but it drove strong, besides loosing coolant out the overflow.
Took the head to the machinist and he said it had a blown Headgasket(on the #4 cylinder), was cracked beyond repair and that my oil consumption(going through a quart at LEAST every thousand miles) was probably a stuck ring in the #4 cylinder-what Tim said from looking at my pictures. I brought him another head that needed to be rebuilt completely.
The machinist said I should just re-ring the engine and put it back together and call it good.
I asked if I should bring him the block to check if it's warped or cracked and check if it's within spec and he said it's fine, just re-ring it, they don't warp easily.
This guy works on high horsepower Supra engines and he seems to know his Toyota's and has worked on the 4y before.
I'm inclined to do what he says-mainly because I don't have a bunch of micrometers and calipers and have never rebuilt an engine-even though Timsrv's blog makes it look so easy-although I know otherwise.

Ill probably just re-ring it, and change the main and rod bearings and check the bores and deck.
From what I've read on internet forums of all different cars, If you're going to re-ring an engine, you may as well have it rebuilt, bore cylinders, new everything, etc.

Anyone have any insights?
thanks,
aaron.

[timsrv]

These Toyota blocks are tough. I've seen original cross hatching still visible on cylinders with over 250k miles them. Unless something unusual happens these blocks typically don't need to be bored. The cranks & rods also fall into this "last forever" category. The parts that typically need replacing are timing sets, water pumps, valve guides, gaskets & seals. If the engine hasn't been overheated and ignition timing hasn't been advanced too much pistons can also last a long, long time. Overheating and pinging can damage pistons so if either of these has occurred they'd need to be checked over very carefully before re-ringing. Other parts like camshafts, valves, & lifters can wear or fail anytime after 100k miles but can also last well beyond 500k miles. Oil pumps can last forever but considering their importance I always replace regardless.

In my mind, the question of rebuild vs overhaul (re-ring) depends on pistons. The EM section of the service manual gives specs & detailed instructions on how to measure pistons. If the cylinder bores look good and the pistons measure within limits then an overhaul is worth consideration. If the pistons need to be replaced theoretically you could replace with new standard size pistons. The reason nobody does this is bores are cut to match the pistons. If the bore starts out being too big then there's nothing you can do. If you're spending the money on pistons then go with oversize (then there's plenty of material available to achieve a perfect fit). FWIW, the 4y pistons are available in standard & .50mm (about .020") oversize.

Of course this all depends on how much money you have and how long you need it to last. I've overhauled engines that were worn well beyond specs & had pretty good results. Performance can only increase regardless of what you do. Back when I was younger my time wasn't as valuable & I was always broke (so overhauls often made sense). At this point in my life time is more valuable so if it's worth an overhaul then it's worth a rebuild. It all boils down to a personal choice. How long do you want to keep it and how much is your time worth? If you do your own labor a bare-bones overhaul can be done for as little as $500. With machine work & parts a complete rebuild can easily exceed $1,500. Based on my experience I wouldn't trust a rebuilt engine from one of those "rebuild factories". Quality parts and quality labor cost money & IMO there's no way they can do a quality job using quality parts for any less than $3k (and that doesn't include installation). Good luck & please post pics/details regardless of what you decide. Tim

[djshimon]

Thanks Tim for your knowledge on this one where you say, "In my mind, the question of rebuild vs overhaul (re-ring) depends on pistons." I was stuck in the middle but I now think I'll check the pistons thoroughly and maybe just re-ring them if they are within the limits. I don't have a ton of time or money on my hands right now but I would like this engine to last another 100,000 miles.
I guess if the pistons are good then the bores should be good too?
And what about the main and rod bearings? probably should check them too huh?
I'll post back once I've put some more labor in.

[timsrv]

Bores aren't automatically good. They are more likely to survive abuse than the pistons, but they can become scored and worn just like anything else. You should still see evidence of the hatch marks from the original machining. If there are places where this is missing, then this is an indication of wear. Most bore wear typically occurs near the top & on the thrust surfaces. Scoring is the presence of vertical scratches. Scoring is usually caused by stuck or broken rings. Depth & width of such scratches will determine if the original bores are salvageable. In order to break-in your new rings you will want to purchase a finishing hone. These sell for $20-$50 and come in specific diameters and grits. Get the grit recommended by the piston ring manufacturer for the type of rings you purchase. Finishing hones come in ranges (like 3.5" -4") so get the one that falls in the correct range (FYI the bore diameter on a std 4y is 3 9/16" or 91mm). I'd say get a ridge reamer too, but if there's a ridge there big enough to require reaming, then overhauling the engine probably isn't the greatest idea.

You will want to get familiar with the EM section of the service manual and info in my blogs might be useful. Bearings are probably okay, but it's just a good rule of thumb to replace them. They are cheap and you'll be removing them anyhow when you take things apart, so just replace. The cam bearings are pressed in place so just leave those & re-use. As long as the block is not being hot-tanked they will easily make it another 100k miles (most likely more). If you hot tank the block then the cam bearings and the soft plugs will need to be replaced. Tim

[djshimon]

Can you see the scoring? There is visible scoring up and down on the 4 cylinder-remember when you thought it looked like a stuck ring from the oil consumption and oily head Tim? It's not very noticeable when I run my fingernail across it. Will a hone take this out or is this in need of a bore? Also, it started rusting a bit at the top from sitting in the garage-how bad is this? -I just oiled it to stop it. The small lines in the rust going horizontal are from my fingernail.

[timsrv]

Boring & replacing pistons is always the best, but your budget will determine if that's possible. When I was younger & always broke my attitude was "anything I do makes it better than it was before, and due to money (or lack there-of) rebuilding is out of the question"..........so I would hone & re-ring. All & all I had "better than expected" results so I guess it was the right thing. The rust will clean-up with a finishing hone. If it's hard to feel the scoring with your fingernail then it will likely clean-up too. When I run finishing hones I run at low RPMs (like around 300 - 500) and vigorously move it up and down the full length of the cylinder. You want the hone scratches to be at ~45 deg angles (90 deg to each other). I would drill a small hole in the cap of an ATF (Automatic Transmission Fluid) container and hold/squirt ATF into the cylinder with one hand and run the drill/hone with the other. Don't overdo it. Your goal is to rough it up and break the glaze............nothing more. If in doubt, stop & inspect. When you can't see any of the original "shininess" on the cylinder walls then you are done.

Honing will leave grit behind so be sure to clean it good before re-assembling. If you have the block out, use a pressure washer then oil immediately after to prevent rusting. Tim

[djshimon]

Thanks Tim. I'll let you know how it works out.

[djshimon]

Well I finally got the pistons out and the fourth piston(transmission side) was marked up pretty good on two spots. This is the piston that the Head rebuilder guessed had a stuck ring due to the condition of the head. So I'm definitely taking the block in to be checked by the Machinist and most probably bored out to put in oversize pistons. Here's a picture of the piston marks on one side. The opposite side has the same marks-and the cylinder has matching marks although they don't seem too deep.

[timsrv]

Ouch. If you can afford it, I'd recommend boring the engine and replacing all the pistons.

[djshimon]

So I'm awaiting on an Overhaul Gasket Set from Tonkin Toyota. My engine came out of a 1989 van but my van is a 1987. According to the parts department the gasket set is different for 1986 to half of 1987, Then different again for 1989. There are 3 different overhaul gasket sets for the 4y. I had him order me the 1989. What would be the difference in gaskets? I understand the 1988 and 1989 have different injectors, is that the difference?

[timsrv]

As far as gaskets go, I can't think of any differences from 86-89. There's always product improvements, but that should effect all years equally. Like you said, it might be something very small like injector basket o-rings. Silly to have a completely different part numbers for something like that though. Most manufacturers will simply include all possibilities (at least on the small inexpensive items). Tim

[djshimon]

Thanks for the quick reply. Don Johnson(that's his name!) said I'm getting the last one in the U.S.! -at least through a Toyota dealership, and for the 1989 4y. I'm sure the private Toyota warehouses have them still but this is getting a little scary.

[djshimon]

First off, Happy Holidays TVT!
Now for the business end:
I now have my rebuilt engine sitting in the garage. I had the engine shop bore it with oversize pistons. They sent my crank out and it was replaced with another one from who knows where? They did something to the cam lobes, and it got new lifters(the farthest lifter was stuck and took some work to get out. I had them put on the head and oil pan too.
I have to put on the rest. A few questions:
1. Should I use FIPG and paper gasket for the coolant pipe that goes behind the intake manifold?
2. And for the oil filter holder?
- Seems like I should because if the paper gasket leaks it'll be hard to get in there to tighten those nuts/bolts.

3. And the dipstick tube(or does the dipstick tube have an o-ring?).
I was going to use FIPG with the paper gasket with the water pump too-It's how I did it last time(but with rtv) and it didn't leak.

Ok. Here's some pictures.:


I'm so excited it's getting close. I miss my van so much. All that room! Up high in the air!

[timsrv]

Gaskets alone are supposed to seal but I personally like a little extra insurance. I like to put a very thin layer of FIPG on each side of these gaskets. And when I say thin, I mean just enough to wet them. I want to see a very small amount of FIPG being displaced when the part is torqued down. Just remember you'll get about the same amount of excess oozing on the inside of the engine too, so don't overdo it. If you get big gobs on the inside they can fall off and end up in bad spots.

Some dipsticks have o-rings & some don't. I can't remember now if ours do. Look for a groove on the tube where it slides into the block. If it has a groove, then use an o-ring, if it doesn't, then maybe use a small amount of FIPG there too. There is not going to be any oil pressure in this area, just splashes and a misty vapor, so it's not an area to be too concerned about. You're on the home stretch now! If you hustle you can get it done in a day, but I'm assuming there'll be lots of other little details that take your time/attention (almost always the case with 25 year old vehicles), so give it 3 or 4 more days of attention & you'll be cruising again! Tim

[XxCisnerosxX]

My mechanic told me the reason he wanted me to switch to 20-50 oil was due to the fact that it's burning it up rather quickly. I asked why not just fix the problem of the burning up too much oil and he said that the rings on the pistons needed to be replaced. And said that on some 2001 Saturn models there was a liquid to leave on the rings overnight so that there would be no hassle removing said rings.

is there such liquid? Will replacing the piston rings help with not burning oil so much? I just had the oil pump replaced about 2 weeks ago and the van is much more noticeably quiet. Any help appreciated!

[Burntboot]

Sometimes a thicker oil will help reduce oil consumption.
It can also starve bearings of lubrication.
It's better to burn oil than trash the engine internals.

A better course of action would be to do a crankcase flush with something like "Seafoam".
If the burning condition still persists then move onto something like "restore".
If neither of those methods work, start looking for a replacement engine.

BB

[ninz30]

I think your valve stem seals are bad... I could see how worn piston rings would cause oil consumption, but worn stem seals would also and are far more common issue on these vans.

[joegri]

i,m with burntboot with this situation. however i,d go just a lil further. find a 4ye motor bolt it to an engine stand and build a top notch new rebuilt motor. but only do this if yer gonna keep it and drive it for another 5/10 or more years! seems like you cant just do some work to the top of the motor and a lil to the bottom of the motor ya gotta go all in and do the whole thing. jus my 2 cents

[ninz30]

i,m with burntboot with this situation. however i,d go just a lil further. find a 4ye motor bolt it to an engine stand and build a top notch new rebuilt motor. but only do this if yer gonna keep it and drive it for another 5/10 or more years! seems like you cant just do some work to the top of the motor and a lil to the bottom of the motor ya gotta go all in and do the whole thing. jus my 2 cents

Your .02 cents will cost this guy over 2k.... What's "burntboot" ???

[timsrv]

Sorry about being late to the party. Business is booming and my son & I have been working double shifts all week (haven't had any extra time for the forum). Here's a thread where I replaced rings and bearings in one of mine: http://www.toyotavantech.com/forum/s...ngine-Overhaul. Yes it's a big job, but if you plan on keeping the van long term it can be rewarding.

Out of curiosity, just how much oil is yours consuming? If it's less than a quart every 1,000 miles then I wouldn't worry about it (keep running 10w40 & add oil as required). As a general rule they say to replace rings when you get down to a quart every 500 miles. On mine I let it go until it needed a quart every 75 miles (and no, it didn't leak). I love that van now. Especially now that I don't need to add oil all the time. I run 10w40 and don't need to add ANY oil between changes (I change oil every 5k miles).

On the 4y I think oil rings are more likely to cause excessive oil consumption than valve seals/guides. Usually the rings don't actually go bad, they just get stuck in the piston grooves (and that's what creates the problem). When the engine is running oil is spraying and flying everywhere inside the engine. The spraying/flying oil covers the cylinder bores when the pistons are at the top of their strokes. The oil rings work like little round squeegees to scrape this oil off the bores and drag it back into the sump (where it belongs). When the rings get stuck they don't push against the bores anymore and you end up with oil in combustion areas (where it gets burned with the fuel). In theory you could disassemble the engine, free up the rings, reassemble and have good oil control again. But considering the work involved it makes more sense to just put new rings on. If there was a way to un-stick oil rings without disassembling the engine, that would be awesome. I'm not sure how much faith I'd have in "ring job in a can", but I guess it could be worth a shot. Burntboot, have you actually had luck with these products? What if you took out the spark plugs and squirted a couple teaspoons of Seafoam into each cylinder, then let it sit for a couple days?


Ninz has a point about the importance of knowing what's causing the problem. pulling the valve cover and replacing valve seals might be worth a shot, but if the guides are good the condition of valve seals isn't such a big deal. If the guides are shot, replacing seals would only be a temp fix. When it comes to knowing actual cause, disassembling the engine and checking is the only way to know for sure, but as a rule of thumb, valve guides/seals will typically only blow blue smoke out the exhaust for a few seconds after initial start (after engine has been shut-off for 1/2 hr or so). Bad (stuck) rings will usually make it smoke all the time. Tim