Hi blow by

General discussion about our beloved Tercel 4WD cars
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Petros
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My tercel:: '84 Tercel4wd w/extensive mods
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Hi blow by

Post by Petros »

I have had this happen once before with my former 3ac, now it appears to have happened again on my 4ac build. It was a fresh rebuild about 5 years ago, I think it has .040" over pistons and rings, has been fairly reliable and powerful. Last summer it started using small amounts of coolant, than a bit more each time. looked like head gasket was giving up, even thought I did not overheat it. Rather than do a head gasket job (no time) I put in the head gasket sealant (allowed it to cure overnight), and coolant consumption stopped. looked like I dodged that head gasket job for a while any way.

Than just last January I noticed getting sudden puffs of blue smoke out the back, and it used 2 quarts of motor oil in only about 100 miles. Still seemed to run okay. Next day I did a compression check, found one and four good, number 2 and 3 low (it was like 160, 80, 80, 155 PSI). the air filter assembly was full of motor oil, which means high blow by or somehow engine compression was pressurizing the crank case.

I decided it was likely the head gasket since I knew it was already compromised, and although the sealing worked, it would only affect the coolant side, and not the several places the oil drains through to the crank case, these drains pass through the headgasket. the return vent is right next to the #2 and 3 cylinder, so it seemed the obvious problem. a crack could cause that too, but usually you have other problems (leaks), and I have never seen a cracked toyota head or block. It could also be failed rings, but it would be very odd to have two adjoining rings fail at the same time. Gasket seemed the only cause.

I replaced the head gasket yesterday, the cylinders and piston tops all looked good, no obvious problems. But the problem is not fixed. I was disappointed to find I still have a lot of pressure in the crank case, blowing oil out the breather tube. I rigged an oil recovery jug so I am not blowing oil into the carb, but it is obvious the crank case has way too much pressure. Ir does seem to run okay, but it clearly does not have as much power as it did before this happened, and it has the tell tale uneven cranking speed as it cycle though high compression cylinders and than the low compression cylinders.

Now my back up car is not working either (Civic that I think needs a fuel pump, it gets no fuel to the fuel rail), and I am wondering if I should plan on replacing the whole engine, or if it just needs a set of rings. I had carefully inspected the cylinder walls and all of them looked perfect.

simultaneous piston skirt failure? simultaneous oil ring failure? what else would cause this?

Could it be possible the after market rings are junk? The same thing happened my 3ac, number 3 cylinder was low compression, and it pressurized the crank case to blow oil into the airfilter. but I never tore it apart to find the problem. I sold it to another forum member as a core to rebuild (it had been balanced, and head porterd, so was worth rebuilding but I gave up on the 3ac at that point). He had told me later he did not find anything wrong when he rebuilt it, he just installed new rings as I recall. I was thinking the piston skirt failed/cracked and caused ring failure, and all of the oil burning/blow by. but piston was not found damaged.

I can rebuilt my current engine over the weekend, to have my car running on monday. but I will need to have all of the parts I will need ready and on hand. If I pull it apart and find I have something broken that needs to be replaced (piston for example, or something else?), it will likely take days to replace it.

I have thought about just finding a engine in the wrecking yard to swap out, but I run the risk of it being bad until I can drive it. I do not think I want to spend that much work rebuilding it, swaping in a temp engine so I can take my time rebuilding my good "built" engine. I could find another 4ac and rebuild it, and swap it out over the weekend. but that iwll likely take several weeks to find, and get everything I need to overhaul it, and than another weekend to swap it out. Hopefully my engine will hold up that long, but if I loose compression in one more cylinder, it will be done. that could happen any time now.

my life would be easier if I did not need to own two spar cars.

Any thoughts, any observations? Blame after market communist made rings?
'87 Tercel 4wd SR5 (current engine swap project)
'84 Tercel 4wd (daily driver, with on going mods)
'92 Mazda MPV 4wd (wife's daily driver)
'85 Tercel 4wd DLX auto(daughter's daily driver)
'01 Honda Civic (other daughter's daily driver)
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LowBuckCanuck
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My tercel:: 1986 DLX 4wd Wagon "Jenny"

Re: Hi blow by

Post by LowBuckCanuck »

Apparently Toyota's 2az-fe engine has had problems where the piston rings manage to rotate enough that the split in all the rings line up. (read about it in lemon-aid) I don't know if this could have happened in your engine, but it could explain why the 3a-c you sold had nothing apparently wrong with it. I'm hardly a mechanic, but I hope this helps.

Anyhow, my vote is that the communists put out a bad batch of rings that day.
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Petros
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Re: Hi blow by

Post by Petros »

I have always wondered about the gaps lining up. Interesting thought, but a properly fit ring should have the gap close to next to nother once at operating temperature (that is why checking the ring gap is so critical). I can not see that much blow by getting past a tiny ring gap.

seems a very unlikely sources, even on the newer cars. Might be BS excuse from the factory to prevent warranty claims (I have seen it before). but newer cars have a much lower emissions threshold, perhaps the gaps lining up is enough to fail emissions. I would not think the driver could feel it.
'87 Tercel 4wd SR5 (current engine swap project)
'84 Tercel 4wd (daily driver, with on going mods)
'92 Mazda MPV 4wd (wife's daily driver)
'85 Tercel 4wd DLX auto(daughter's daily driver)
'01 Honda Civic (other daughter's daily driver)
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splatterdog
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Re: Hi blow by

Post by splatterdog »

Some fairly new Honda/acura v6's have a problem with consumption due to ring gaps being lined up. They must always be offset from each other. Another problem is low tension rings to reduce drag. Very little room to lose tension with those.

Next step woud be a leakdown test. A leakdown tester is ideal, but if you can utilize you compression tester hose on an air compressor that should suffice. Just take out the schraeder valve. With the piston at compression TDC and air being forced in, listen at the oil cap, carb, tail pipe, and in your case also the neighboring cylinder.

Bummer.
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Petros
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Re: Hi blow by

Post by Petros »

I did a leak down test, results: no air out the exhaust, none out the intake, none out the radiator. I get a gurgling sound out the oil filler opening. I already know by virtue of the blow by the problem is either in the pistons, or rings. what else does it tell you?

since two adjoining cylinders had the problem I suspected the head gasket because it was also next to the gas retrun vent column that runs up the side of the block from the crank case to the valve cover. A crack in the head or block does not make sense, no crack could make its way to the crankcase from the combustion chamber without going through a water jacket, but the cooling system is operating normal, no coolant loss.

The only thing I can come up with is either rings or pistons, in two adjoining cyclers, failed at the same time. Either the rings lost the outward tension (I have seen this on badly overheated engines, they loose thier heat treat and than loose their outward spring or tension), but my engine was never overheated. I have also seen broken rings, you would not know it until you pulled out the piston. Usually this happens if you have a lot of ping or pre-ignition, which I did get occasionally, but not a regular occurrence, I always use premium or mid grade higher octane fuel to avoid that kind of damage. could be poor quality control on these rings, no telling where they were actually made, even if I bought them from a US supplier. Same is true with the pistons, a crack at the ring land would have this effect.

In both instances however, I find it extremely rare occurrence to have two fail at the same time. only bad quality control would account for that, where basically half of the new parts are junk. With todays integrated world market for car parts you just do not know what you are getting no matter the label on the out side of the box.
'87 Tercel 4wd SR5 (current engine swap project)
'84 Tercel 4wd (daily driver, with on going mods)
'92 Mazda MPV 4wd (wife's daily driver)
'85 Tercel 4wd DLX auto(daughter's daily driver)
'01 Honda Civic (other daughter's daily driver)
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splatterdog
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Re: Hi blow by

Post by splatterdog »

You have the worst luck with 3A's. Sounds like at least a head gasket because of the matching low compression on 2-3. Hopefully that's the cause of the crankcase pressure too. Did the leakdown test blow between 2-3?

Teardown time..
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rer233
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Re: Hi blow by

Post by rer233 »

After reading this, I sure am glad ALL my Tercel engines have OE rings (installed in Japan.) Got two spare engines that do too. Nothin' like being a hoarder!
if it aint there, there's a good chance it won't break!
83 SR5 Silver/Blue (Snowmobile/work beater)-totaled but drivable
85 SR5 Blue
88 SR5 White (the 'good' one)-not anymore-totaled
87 fwd silver wagon a/t
87 4wd dx Cream (a/t- not anymore- now m/t)
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Petros
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Re: Hi blow by

Post by Petros »

splatterdog wrote: Thu Feb 22, 2018 7:18 pm You have the worst luck with 3A's. Sounds like at least a head gasket because of the matching low compression on 2-3. Hopefully that's the cause of the crankcase pressure too. Did the leakdown test blow between 2-3?
what do you mean by "blow between 2-3"? volume of air? I just pluged my air compressor into the stem of my compression tester fitting. It held the pressure, with just a tiny amount of leakage, no flow meter was used. I could only here gurgling from the oil filler in the valve cover oil filler, not a steady hiss, just sounds of air leaking as a gurgle.

this engine is actually a near stock 4a, I had had it with the 3a a long time ago. It has actually one of my more reliable builds, it is balanced and has a lightened flywheel, cleaned up ports and the Delta cam street grind. Stock induction and exhaust manifold. but compared to what I have done in the past, this is a mild build.

My thoughts have also been head gasket, but I spent last Monday afternoon replacing it with a new quality head gasket, and it still has the blow by problem. So, it was not the head gasket.

When I tear it down, and presuming the pistons are good, I will go with the best quality rings I can find, saving a few $ is not worth this trouble. I tend to buy only name brand engine parts, but as one local parts store has told me they have had recent trouble with long time good brands switching to off shore production in China, than suddenly they get a lot of returns on their parts. So you never know what you are getting these days, it is hit and miss. I have come to view the "oem quality" with great suspicion, marketing BS rather than actual fact. I need to look for the same brand that the factory uses, with an honest claim that it is the official supplier for the factory and their dealers.

I should be able to get it done over the weekend, presuming I have the parts,and there are no surprises, but there are a lot of other things I would rather do with my weekend. I do not think it should be that bad, I am driving it daily. I need the 4wd we have been getting a lot of snow this week. And my wife will not surrender her 4wd Lexus to me...
'87 Tercel 4wd SR5 (current engine swap project)
'84 Tercel 4wd (daily driver, with on going mods)
'92 Mazda MPV 4wd (wife's daily driver)
'85 Tercel 4wd DLX auto(daughter's daily driver)
'01 Honda Civic (other daughter's daily driver)
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Petros
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My tercel:: '84 Tercel4wd w/extensive mods
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Re: Hi blow by

Post by Petros »

Up date: since I had a heavy work schedule and a spare car to drive I have put off pulling my '84 T4wd apart. I finally got the engine out today, and pulled the pistons to see the cause of the low comprression and high blow by.

the top two rings were badly distorted because the edge of the top of the piston has started to pull away, one part of the ring groove was oversized and distorted, like the edge of the piston was starting to melt.

Other than poor quality piston material, I can not explain this kind of failure. I have seen this kind of thing happen when the engine is badly overreved, or overheated, but neither has happened to this engine. Just crap aftermarket parts I guess. I will try and get a picture to post.

Another thing that occurred to me is the current motor oil has the zinc chromate removed, and without using an additive it might lead to premature ring wear. but this was the piston failure.

I am ordering 4 new pistons and rings, the bores look fine, so I do not plan to go oversized. Looks like it will be a bit longer before I have my car back on the road.
'87 Tercel 4wd SR5 (current engine swap project)
'84 Tercel 4wd (daily driver, with on going mods)
'92 Mazda MPV 4wd (wife's daily driver)
'85 Tercel 4wd DLX auto(daughter's daily driver)
'01 Honda Civic (other daughter's daily driver)
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seantp
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My tercel:: 1983 SR5 4WD Wagon
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Re: Hi blow by

Post by seantp »

I have oil in my air filter can too. Fingers crossed that it's the PCV valve and not piston rings although I've got 220k miles.
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Petros
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Re: Hi blow by

Post by Petros »

if the PCV valve does not help, try adding "Restore" to the oil.

Last time I had this problem on another engine, I kept driving it (vented the hose to an oil recovery container) and eventually lost all compression in one cylinder.
'87 Tercel 4wd SR5 (current engine swap project)
'84 Tercel 4wd (daily driver, with on going mods)
'92 Mazda MPV 4wd (wife's daily driver)
'85 Tercel 4wd DLX auto(daughter's daily driver)
'01 Honda Civic (other daughter's daily driver)
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seantp
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My tercel:: 1983 SR5 4WD Wagon
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Re: Hi blow by

Post by seantp »

Changed PCV valve and added restore. Still an occasional popping noise from engine compartment that sounds like air escaping a gasket. Any ideas?
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Petros
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Re: Hi blow by

Post by Petros »

an exhaust leak can make popping sounds, check around the head pipe to manifold join, and also where the manifold meets the head. check your EGR valve, that can pop if leaking.

if you still have high blow by, on mine I had the dip stick popping up, burping crank case pressure and than sinking back down into place.
'87 Tercel 4wd SR5 (current engine swap project)
'84 Tercel 4wd (daily driver, with on going mods)
'92 Mazda MPV 4wd (wife's daily driver)
'85 Tercel 4wd DLX auto(daughter's daily driver)
'01 Honda Civic (other daughter's daily driver)
8ton
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Re: Hi blow by

Post by 8ton »

Do you remember what brand the pistons were? I once got a set of Rock brand 4ag pistons I returned because i was uncomfortable with how porous they looked.
Pistons could also melt from a over lean condition or even super hot coolant steam. I have a 4ac head with a 1/4" deep by 3/8" wide trench burned between two cylinders from where a HG failed.
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Petros
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Re: Hi blow by

Post by Petros »

I do not know the brand of pistions, the machine shop that did the overbore ordered them, the owner claims they are high quality. unfortunately the machine shop I took the current set to rehang the replacement pistons on the rods did not return the old pistons. wanted to take pictures of the ring land damage.

piston is cooled from the incoming fuel air mixture every fourth stroke. a little might be through the rings and skirt, but the piston top is so hot the only practical way to dump heat is into the incoming cool air charge. I have actually seen this kind of piston crown failure on another engine with likely different brand of pistons (those were Sealed Power), though that engine did suffer a lot of ping or preignision, so I ran premium fuel in it. this engine was lower compression and I ran mid grade fuel, yet I had two pistons crowns over heat and damage the rings.
'87 Tercel 4wd SR5 (current engine swap project)
'84 Tercel 4wd (daily driver, with on going mods)
'92 Mazda MPV 4wd (wife's daily driver)
'85 Tercel 4wd DLX auto(daughter's daily driver)
'01 Honda Civic (other daughter's daily driver)
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