YACT: oil burning

[jagec]

I have a 1984 Toyota van (LE version). It's a 4-banger, stick shift, and runs pretty well, but it burns some oil. I've been trying to figure out why this is. The exhaust is clear at idle, but turns to blue smoke if you rev it. Since it will do this even when started cold, at first I thought it might be coming in through the valves. But today I was changing my belts, and pulled the plugs to inspect them while I had the engine cover off. For the most part they looked as if they were running OK, if a bit hot...but the #3 plug was fouled with oil. I'm thinking this means the oil I'm burning isn't general valve or ring wear...but does that mean the headgasket is partly blown? There's no oil in my coolant or coolant in my oil, so it can't be too bad...

I guess my REAL question is whether this is something one of those cheap "gasket sealer" things would fix. I'd never use one of them on a car that wasn't a beater, but...it is.

What do you think?

 

[Demo24]

or rings

 

[jagec]

Originally posted by: DEMO24
or rings

on only one cylinder? Wouldn't they wear more-or-less evenly?

 

[Analog]

burning oil doesn't mean it won't pass emissions. My brother had an old Mitsubishi that had a constant blue exhaust, passed emissions like a champ. Although it was a few years back. Most emissions tests want to see if the cat and the egr system is working, which reduces NOx emissions, which cause smog. May have changed in the past few years, so I could be wrong on this.

 

[deadlyapp]

valve stem seals? Rings? If there is oil blow by it is gonna be the rings.

 

[Zenmervolt]

Originally posted by: yellowfiero
burning oil doesn't mean it won't pass emissions. My brother had an old Mitsubishi that had a constant blue exhaust, passed emissions like a champ. Although it was a few years back. Most emissions tests want to see if the cat and the egr system is working, which reduces NOx emissions, which cause smog. May have changed in the past few years, so I could be wrong on this.

Most emissions tests now include a measurement of unburned hydrocarbons. Burning oil will throw the HC level above the maximum limit for most places.

Generally burning oil like that is bad rings, and no, they wouldn't necessarily all wear the same.

ZV

 

[Demo24]

Originally posted by: jagec

Originally posted by: DEMO24
or rings

on only one cylinder? Wouldn't they wear more-or-less evenly?

different compression in each cylinder. not majorly different but its slightly different.


its an 84 with what i assume is a lot of miles, its expected

 

[jagec]

Originally posted by: yellowfiero
burning oil doesn't mean it won't pass emissions. My brother had an old Mitsubishi that had a constant blue exhaust, passed emissions like a champ. Although it was a few years back. Most emissions tests want to see if the cat and the egr system is working, which reduces NOx emissions, which cause smog. May have changed in the past few years, so I could be wrong on this.

It's already failed....that was right after I bought it. I'm trying to get it to pass.

Originally posted by: deadlyapp
valve stem seals? Rings? If there is oil blow by it is gonna be the rings.

Rings, valves, or problems with the crankcase ventilation system are the most common causes of oil burning...but since only one plug is fouled, that leads me to believe that only that cylinder is burning oil. That probably wouldn't happen with the most common causes, so it might be something else...like a leak in the head gasket. I suppose it's POSSIBLE that the rings are bad on only one cylinder, but unlikely.

 

[natto fire]

Originally posted by: jagec

Originally posted by: yellowfiero
burning oil doesn't mean it won't pass emissions. My brother had an old Mitsubishi that had a constant blue exhaust, passed emissions like a champ. Although it was a few years back. Most emissions tests want to see if the cat and the egr system is working, which reduces NOx emissions, which cause smog. May have changed in the past few years, so I could be wrong on this.

It's already failed....that was right after I bought it. I'm trying to get it to pass.

Originally posted by: deadlyapp
valve stem seals? Rings? If there is oil blow by it is gonna be the rings.

Rings, valves, or problems with the crankcase ventilation system are the most common causes of oil burning...but since only one plug is fouled, that leads me to believe that only that cylinder is burning oil. That probably wouldn't happen with the most common causes, so it might be something else...like a leak in the head gasket. I suppose it's POSSIBLE that the rings are bad on only one cylinder, but unlikely.

Have you done a compression test yet? Keep in mind the oil control ring can wear differently in each cylinder quite easily. The compression rings should theoretically wear together, but even those could vary. I would do the compression check to see if you are getting weak compression in cylinders next to each other to check the headgasket. That has an iron block, aluminum head correct? Maybe do a leakdown test too, if you have the tools or know someone that will do it cheap.

 

[jagec]

Originally posted by: Captain Howdy
Have you done a compression test yet? Keep in mind the oil control ring can wear differently in each cylinder quite easily. The compression rings should theoretically wear together, but even those could vary. I would do the compression check to see if you are getting weak compression in cylinders next to each other to check the headgasket. That has an iron block, aluminum head correct? Maybe do a leakdown test too, if you have the tools or know someone that will do it cheap.

No, haven't done the tests...so far I've just been working on work I can do with my current tools. It's the next step though...but I'll probably get a shop to do it so I get a receipt that counts towards "emissions repair" (if I spend $150 I get a waiver)

To be honest, I'm not THAT concerned with fixing the oil burning--it doesn't burn that much, and I'll only be using this vehicle to haul stuff from time to time. But it's got to pass emissions, or get the $150 waiver.

Do you suppose it's worth pulling the spark plug+injector wires for the cylinder with the fouled plug (to shut it off), and see if it still burns oil? The engine should still run, yes?

 

[Goosemaster]

dude...MY car passed emissions and safety (I HAVE NO IDEA WHY OR HOW) your will too....

 

[Iron Woode]

Originally posted by: jagec
I have a 1984 Toyota van (LE version). It's a 4-banger, stick shift, and runs pretty well, but it burns some oil. I've been trying to figure out why this is. The exhaust is clear at idle, but turns to blue smoke if you rev it. Since it will do this even when started cold, at first I thought it might be coming in through the valves. But today I was changing my belts, and pulled the plugs to inspect them while I had the engine cover off. For the most part they looked as if they were running OK, if a bit hot...but the #3 plug was fouled with oil. I'm thinking this means the oil I'm burning isn't general valve or ring wear...but does that mean the headgasket is partly blown? There's no oil in my coolant or coolant in my oil, so it can't be too bad...

I guess my REAL question is whether this is something one of those cheap "gasket sealer" things would fix. I'd never use one of them on a car that wasn't a beater, but...it is.

What do you think?

either your valve seals or valve guides or both are shot.

 

[natto fire]

Originally posted by: jagec
No, haven't done the tests...so far I've just been working on work I can do with my current tools. It's the next step though...but I'll probably get a shop to do it so I get a receipt that counts towards "emissions repair" (if I spend $150 I get a waiver)

To be honest, I'm not THAT concerned with fixing the oil burning--it doesn't burn that much, and I'll only be using this vehicle to haul stuff from time to time. But it's got to pass emissions, or get the $150 waiver.

Do you suppose it's worth pulling the spark plug+injector wires for the cylinder with the fouled plug (to shut it off), and see if it still burns oil? The engine should still run, yes?

Yes, it will still run, albeit fairly rough. Have a friend follow you and put the engine under load to see if it still burns oil. Not sure about the valve overlap on this particular model, but it should not be enough to skew the results of this test. Plus I think a lot of those older carbed toyota's had EGR anyways.

 

[RU482]

SEAFOAM to the rescue!!!

 

[jagec]

Originally posted by: Captain Howdy
Yes, it will still run, albeit fairly rough. Have a friend follow you and put the engine under load to see if it still burns oil. Not sure about the valve overlap on this particular model, but it should not be enough to skew the results of this test. Plus I think a lot of those older carbed toyota's had EGR anyways.

It's got EGR (and fuel injection).

OK, one bizarre thing I just noticed while I was working on it today: the oxygen sensor isn't plugged into ANYTHING. It runs just fine without it, but why would someone unplug that in the first place? I guess I've got work to do tomorrow...

 

[OrganizedChaos]

Originally posted by: jagec

Originally posted by: Captain Howdy
Yes, it will still run, albeit fairly rough. Have a friend follow you and put the engine under load to see if it still burns oil. Not sure about the valve overlap on this particular model, but it should not be enough to skew the results of this test. Plus I think a lot of those older carbed toyota's had EGR anyways.

It's got EGR (and fuel injection).

OK, one bizarre thing I just noticed while I was working on it today: the oxygen sensor isn't plugged into ANYTHING. It runs just fine without it, but why would someone unplug that in the first place? I guess I've got work to do tomorrow...

did it fail for blue smoke or fail for high HC? o2 sensor will cause high HC, but if it failed for smoke and you don't wanna spend the money tearing apart the engine i'd try changing the oil to something heavy like 20w50.

 

[jagec]

Originally posted by: OrganizedChaos

Originally posted by: jagec

Originally posted by: Captain Howdy
Yes, it will still run, albeit fairly rough. Have a friend follow you and put the engine under load to see if it still burns oil. Not sure about the valve overlap on this particular model, but it should not be enough to skew the results of this test. Plus I think a lot of those older carbed toyota's had EGR anyways.

It's got EGR (and fuel injection).

OK, one bizarre thing I just noticed while I was working on it today: the oxygen sensor isn't plugged into ANYTHING. It runs just fine without it, but why would someone unplug that in the first place? I guess I've got work to do tomorrow...

did it fail for blue smoke or fail for high HC? o2 sensor will cause high HC, but if it failed for smoke and you don't wanna spend the money tearing apart the engine i'd try changing the oil to something heavy like 20w50.

failed for high HC. It doesn't smoke a whole lot...little enough, apparently, that the emissions folks don't give me a hard time about it. If I were to plug the O2 sensor back in (why in the world would someone unplug that?), but it was still burning oil, would that be enough to put my HC under the limit?

I'm at like 202 (150=pass) during the running test. I don't remember my idle results of the top of my head, but it failed by a similar margin. CO is okay on both counts.

 

[natto fire]

Originally posted by: jagec

Originally posted by: OrganizedChaos

Originally posted by: jagec

Originally posted by: Captain Howdy
Yes, it will still run, albeit fairly rough. Have a friend follow you and put the engine under load to see if it still burns oil. Not sure about the valve overlap on this particular model, but it should not be enough to skew the results of this test. Plus I think a lot of those older carbed toyota's had EGR anyways.

It's got EGR (and fuel injection).

OK, one bizarre thing I just noticed while I was working on it today: the oxygen sensor isn't plugged into ANYTHING. It runs just fine without it, but why would someone unplug that in the first place? I guess I've got work to do tomorrow...

did it fail for blue smoke or fail for high HC? o2 sensor will cause high HC, but if it failed for smoke and you don't wanna spend the money tearing apart the engine i'd try changing the oil to something heavy like 20w50.

failed for high HC. It doesn't smoke a whole lot...little enough, apparently, that the emissions folks don't give me a hard time about it. If I were to plug the O2 sensor back in (why in the world would someone unplug that?), but it was still burning oil, would that be enough to put my HC under the limit?

I'm at like 202 (150=pass) during the running test. I don't remember my idle results of the top of my head, but it failed by a similar margin. CO is okay on both counts.

I would guess that it would pass. It is probably running a little rich in open loop mode (to be safe). Is there no CEL on? Usually O2 sensor always throws a light, might want to check that bulb. Anyways, I would definitely try the test again with the O2 sensor, it will do better in closed loop. Remeber to clean the plug than normally fouls before you go.

 

[jagec]

Originally posted by: Captain Howdy

I would guess that it would pass. It is probably running a little rich in open loop mode (to be safe). Is there no CEL on? Usually O2 sensor always throws a light, might want to check that bulb. Anyways, I would definitely try the test again with the O2 sensor, it will do better in closed loop. Remeber to clean the plug than normally fouls before you go.

The CEL bulb is fine. And here's how I know. If I'm running the engine at a constant speed/throttle opening (like cruising on the interstate), the CEL comes on after a bit. I can make it go away just by goosing the throttle (which, in a 4-banger van in top gear, does absolutely nothing to speed or RPM...but makes the CEL go out). This is another thing I don't understand about this car. But since it doesn't seem to indicate anything actually WRONG with the engine, who knows. Maybe it doesn't "realize" the O2 sensor is disconnected while the engine speed is varying? Who knows?

 

[jagec]

I went ahead and got a waiver for the emissions testing, but it still burns oil. I was convinced it was the valve guides, so I went and pulled a head from a much lower-mileage van at the junkyard. However, I haven't gotten a chance to put it in yet, and this is kind of interesting...

A couple days ago, the van started running really rough, and lacking power. "Oho," I say, "It finally went ahead and fouled that #3 spark plug all the way." To test my theory, I pull spark plug wires one at a time, and start the engine to see how it runs. Pulling anything but the #3 wire produces a VERY rough idle, whereas pulling the #3 does nothing. Right, hypothesis confirmed. Interestingly enough, it seemed to stop burning oil...at least, not noticeably.
So today I yank the #3 spark plug. It's oil-fouled to an almost hysterical degree. The whole socket is filled with the stuff. The end of the plug is absolutely coated in thick oil. For the sake of science, I put an old (but not fouled) plug in the cylinder; lo and behold, the engine is now idling OK and running on all four.

But why would only one cylinder be burning oil? Partly blown head gasket? Any other thoughts? I guess if I change over the heads (with a new gasket of course) that takes care of both potential problems...