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Smoke on startup, occasional miss, yet smog test was perfect

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Smoke on startup, occasional miss, yet smog test was perfect

 
Old 12-07-18, 08:56 AM
  #1  
myf16
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Default Smoke on startup, occasional miss, yet smog test was perfect

My 1990 has only 145k miles. Last month's 15 mph smog test numbers vs (max allowed) were: HC 6 (71), CO .01 (.48), NO 2 (524). Close to zero emissions.

Yet when I start the car after parking overnight there's a big cloud of smoke in my rear view mirror. This was true before the smog test. Also the car has an occasional miss (noticeably momentary loss of power) while driving at 30 to 50 mph. I had a persistent coolant loss with no drips which I interpreted as a head gasket leak. I cured that with Bars Leaks rather spending an absurd amount of time and effort than taking things apart. The oil has always looked clean, and I haven't noticed any decrease in level, but I drive only 250 miles per month. So a very slow oil loss is possible.

One other clue. In order to pass the smog test I had to replace the upstream oxygen sensors. The sensor on the right bank was black and oily looking and had resistance too high to measure (rather than the normal 6 ohms). With new sensors it smogged perfectly as it has for many years.

What's your diagnosis and course of treatment? Just drive it this way?
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Old 12-07-18, 10:07 AM
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Originally Posted by myf16 View Post
My 1990 has only 145k miles. Last month's 15 mph smog test numbers vs (max allowed) were: HC 6 (71), CO .01 (.48), NO 2 (524). Close to zero emissions.

Yet when I start the car after parking overnight there's a big cloud of smoke in my rear view mirror. This was true before the smog test. Also the car has an occasional miss (noticeably momentary loss of power) while driving at 30 to 50 mph. I had a persistent coolant loss with no drips which I interpreted as a head gasket leak. I cured that with Bars Leaks rather spending an absurd amount of time and effort than taking things apart. The oil has always looked clean, and I haven't noticed any decrease in level, but I drive only 250 miles per month. So a very slow oil loss is possible.

One other clue. In order to pass the smog test I had to replace the upstream oxygen sensors. The sensor on the right bank was black and oily looking and had resistance too high to measure (rather than the normal 6 ohms). With new sensors it smogged perfectly as it has for many years.

What's your diagnosis and course of treatment? Just drive it this way?
Your big cloud of smoke on start up sounds like the ACV valve on the power steering pump. It tends to go bad with age and leak. There are two vacuum tubes that lead back to the intake and when that sensor leaks- you are pouring oil back into your intakes- hence the smoke. If you pull the tube ends off the sensor and find oil, your sensor is bad. Either buy a new sensor or pull the sensor off and plug it with a bolt. You don't really need that sensor.
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Old 12-07-18, 12:20 PM
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Thanks so much. This would explain a lot. The car DOES lose power steering fluid and it's not ending up on the garage floor.

I will report my results.
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Old 12-07-18, 05:21 PM
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Originally Posted by myf16 View Post
Thanks so much. This would explain a lot. The car DOES lose power steering fluid and it's not ending up on the garage floor.
Then it's ending up inside your alternator. Check it soon and if so you better do something about it quick before your alternator dies.
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Old 12-10-18, 09:09 AM
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well the engine burns the majority of the PS fluid through the valve hence the puff of smoke on startup, but yes some of it can also drip onto the alternator which will cause it to prematurely fail.
replace the $3 o-ring at the bottom of the PS reservoir to stop this leak (if any).
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Old 12-20-18, 06:47 PM
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[LiamNeesonVoice]This job needs a very special set of tools. Tools which make it a nightmare for people like me.[/LiamNeesonVoice]

I must have spent 2 hours trying to loosen that valve before discovering that special set of tools. Normal tools didn't work. My expensive stubby 17mm wrench didn't work. (I could not get it fully seated.)

In the end I used a Harbor Freight 17mm crowfoot wrench, a 3/8 to 1/4 inch reducer, a 1/4 inch socket wrench, and a visegrip clamped on the handle of the wrench. With the crowfoot wrench fully seated I had just enough torque to break the old part loose. I used Harbor Freight long handle right angle pliers to open the hose clamps and slide them up the hoses. With these special tools the job is pretty quick.

I suspected that a deluge of fluid would materialize as I made the last turns by hand, but I don't know how I could have avoided that outcome. Yuck. All over the alternator too. The cylindrical valve element actually fell out at this point.

Installation of the new part was a breeze. I used teflon tape on the threads.

With this much effort to R&R the part, there is no way I would recommend trying to repair the old part. A new Toyota part is about $36 on eBay, or less if you catch a 15% off general sale.

The car appears to run and steer normally. In fact, low speed steering seems to require much less effort. Not that I minded the higher effort, which reminded me somewhat of the old days of unassisted steering.

Edited to add: It's great no longer seeing a huge cloud of smoke when starting the car!\

Another addendum: I am falling in love with the LS400 all over again. It drives perfectly now that it's no longer getting indigestion from steering fluid. With the cloth seats it's the most comfortable car I own. So smooth and quiet.

I wonder whether the steering fluid was responsible for the black deposits on my passenger side (which is the intake side) oxygen sensor.

Last edited by myf16; 01-18-19 at 03:40 PM.
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