Smoking on startup

[jakebson]

1985 Nissan 720

138,100 miles

 

Just to get all the details, picked up the truck in November after it had been sitting for 10 years. Sorted out the fuel issues and have been driving it most days since the middle of November. It has always had some white smoke which seemed to be mainly condensation on startup. It had no real odor and would go away after a minute or two. I have been keeping an eye on the coolant level closely and it is not going down. I had changed the oil right when I got it running, unfortunately the odometer stopped working so I wasn't sure how many miles I had put on it after the oil change, but my guess would be less than 500. I used Castrol 10w30 Synthetic. After reading about older engines (on here) doing better on conventional oil I drained the Castrol and put Rotella T4 10w30 in on Saturday. After I went for a short drive (15min) and checked the dip stick after it was high. I checked the jug and realized I had over filled it by about a 1/2 quart. I drained it out before driving it again.

 

Now the last 2 days after starting it the smoke is thicker and a bit blueish at times, and it last a little longer before it stops smoking 4 to 5 minutes. After that it does stop and doesn't smoke anymore even while idling. I was in full stop and go traffic for a bout 10 minutes today and there was no smoke or condensation coming out of the tailpipe at all. My tail pipe comes out right behind the drive side rear wheel so I have a good view of it from the side view mirror. The smoke does not have much odor, but it definitely has a blueish tint at times that wasn't there before.

 

Is this just symptom of overfilling the oil? How long before that would clear up? Or something more serious like the signs of worn valve seals? That task definitely intimidates me, and I am not sure I could do it. Something else altogether? Should I not drive it anymore until this is resolved? I did put a new PCV valve in this morning. The old one was still moving, but was pretty dirty with oil on it. Figured that wouldn't hurt. Besides the smoking after startup, it is driving and idling well. Maybe some slight fuel efficiency issues, but I am not certain since I have only had the odometer working again since early last week. I filled up for the first time since fixing it yesterday so I should be able to calculate that soon.

 

Not sure if it is related, but the truck is also dieseling a bit, and today it was the worst it has done that after a 30 minute drive.

 

And yes, it is the coldest it has been since I have had the truck. In the teens and low 20s today. I realize that will make more condensation from the exhaust.

Edited January 6 by jakebson

[datzenmike]

1/2 a liter over won't hurt anything. There's lots of room for it just don't go off roading.

 

The Z24 is known for blowing it's head gasket. The preventative measure is to re-torque your head bolts once a year. I would make this priority one. All you need do is borrow a torque wrench and 10mm? socket. (check size) After sitting overnight so it's cold, loosen just one bolt and immediately torque to 60 Ft. Lbs. Now move to the next bolt and do the same for all the rest. You can do in any order you like. 

 

Smoke after starting is likely the valve seals. They are only a couple of bucks each and easy enough to change. If this does not change anything it's not the end of the world.

 

There are two rocker arm shafts, one each for the intake and exhaust side. Loosen each of the 5 bolts slightly in turn till the valves are all closed. Don't loosen the bolts all at once. Lift the rocker arm shafts away and keep in order. Remove the exhaust side spark plugs. Get about 3 feet of 1/4" yellow nylon rope, tie a big knot in one end and push about 2 feet into the #1 cylinder. Turn the engine forward with a wrench till it won't move any further and the rope is compressed into the combustion chamber and tight against the closed valves. DO NOT use the starter for this. The two valves are now held in place and can't move. Compress the valve spring, remove the keepers and lift away. Pry the old oil seal up and off. Press the new oil seal down the valve stem and into place. Install the valve spring. Do the same to the other valve. When done back the engine up slightly to release the rope and move to the next cylinder.

 

At some time take for a good long drive. Over half an hour. Remove all spark plugs and keep in order. How do they look. The spark plug condition is a look inside the engine and can indicate it's wear. They ideally should be a pale tan or creamy color. Take pictures of them 

 

 

 

[ElliotV]

31 minutes ago, datzenmike said:

1/2 a liter over won't hurt anything. There's lots of room for it just don't go off roading.

 

The Z24 is known for blowing it's head gasket. The preventative measure is to re-torque your head bolts once a year. I would make this priority one. All you need do is borrow a torque wrench and 10mm? socket. (check size) After sitting overnight so it's cold, loosen just one bolt and immediately torque to 60 Ft. Lbs. Now move to the next bolt and do the same for all the rest. You can do in any order you like. 

 

Smoke after starting is likely the valve seals. They are only a couple of bucks each and easy enough to change. If this does not change anything it's not the end of the world.

 

There are two rocker arm shafts, one each for the intake and exhaust side. Loosen each of the 5 bolts slightly in turn till the valves are all closed. Don't loosen the bolts all at once. Lift the rocker arm shafts away and keep in order. Remove the exhaust side spark plugs. Get about 3 feet of 1/4" yellow nylon rope, tie a big knot in one end and push about 2 feet into the #1 cylinder. Turn the engine forward with a wrench till it won't move any further and the rope is compressed into the combustion chamber and tight against the closed valves. DO NOT use the starter for this. The two valves are now held in place and can't move. Compress the valve spring, remove the keepers and lift away. Pry the old oil seal up and off. Press the new oil seal down the valve stem and into place. Install the valve spring. Do the same to the other valve. When done back the engine up slightly to release the rope and move to the next cylinder.

 

At some time take for a good long drive. Over half an hour. Remove all spark plugs and keep in order. How do they look. The spark plug condition is a look inside the engine and can indicate it's wear. They ideally should be a pale tan or creamy color. Take pictures of them 

 

 

 

the head bolts are a 14mm socket in case you need to borrow sockets. I use a 14mm deep and a 3in extension to get my wrench above everything and take it easy and smooth as possible when torqing and try to get the last bit in one motion. Ditto on the valve seals but also just watch the oil and see if the level changes. For some reason even though my truck is really solid and has no blow by it will still lose the slightest bit of oil if I start driving 70-75mph which is above 3k rpm for extended periods of time but I don't think you have that issue. If you haven't spark plugs wouldn't hurt since you will be taking half of them out anyways if you do the valve seals. The diesling could be the cause of the color coming into the smoke if there is maybe a little extra fuel coming into the exhaust that is sort of steaming away the next time you run it(bit of a long shot but sometimes stuff corelates). Do you still have the original hitachi carb or is it a aftermarket carb? 

[jakebson]

Thanks Mike. I have torque wrenches, I can re-torque the head bolts tomorrow before I drive it any.

 

I'll get some seals so that I will have them on hand and take care of that real soon. I am intimidated by anything involving the engine itself. Thanks for the detailed directions on how to do it, always extremely helpful. Do I need anything special to compress the valve springs to remove the keepers?

 

 

[jakebson]

1 minute ago, ElliotV said:

the head bolts are a 14mm socket in case you need to borrow sockets. I use a 14mm deep and a 3in extension to get my wrench above everything and take it easy and smooth as possible when torqing and try to get the last bit in one motion. Ditto on the valve seals but also just watch the oil and see if the level changes. For some reason even though my truck is really solid and has no blow by it will still lose the slightest bit of oil if I start driving 70-75mph which is above 3k rpm for extended periods of time but I don't think you have that issue. If you haven't spark plugs wouldn't hurt since you will be taking half of them out anyways if you do the valve seals. The diesling could be the cause of the color coming into the smoke if there is maybe a little extra fuel coming into the exhaust that is sort of steaming away the next time you run it(bit of a long shot but sometimes stuff corelates). Do you still have the original hitachi carb or is it a aftermarket carb? 

 

The spark plugs and wires are new. Still running the original Hitachi ECC feedback carb. It has a very small amount of weeping around one of the gaskets of the carb. The carb seems to be functioning ok after I worked out my fuel delivery issues and that the float wasn't letting enough gas into the bowl. I adjusted that a few times and it is sitting right on the dot with fuel consistently now.

 

I have deep sockets and an extension. I was going to adjust the valve lashes while I have the cover off, but I need to do that hot, correct ? Anything else while I'm in there?

[datzenmike]

There are small valve spring compressors. You'll need this style with the head on the engine.

 

 

Would like to see pictures of the plugs anyway. If new then this will show it they are burning oil. Plugs are self cleaning given enough time. 

 

Valve lash is best set with hot engine. Manual says 0.014" for both.

1720103.avif

[Draker]

You have a few options when dealing with valves on the car. Either fill the

combustion chamber with compressed air and leave the hose attached throughout  the process or fish a length of rope into the chamber on the compression stroke enough to compress against the valve to keep it up while working on the seal. Don’t smash it tight, just enough to keep it up and safe. Either will work. Pop the valve springs off and get the new seal on. 

[datzenmike]

Doesn't have to be the compression stroke. The rocker shafts have to come off anyway so the valves will all be closed.

 

The L series would be different. Only way to remove the rockers is at TDC when the lobes are out of the way.

 

 

I find compressed air very scary way to do this. Anything could go wrong. Power to compressor goes off, air leak from a multitude of causes. Using rope you physically cannot drop the valve into the cylinder, hell you could replace your seals on the side of the road and stop for the night and finish the next day without worry. 

[ElliotV]

30 minutes ago, datzenmike said:

Doesn't have to be the compression stroke. The rocker shafts have to come off anyway so the valves will all be closed.

 

The L series would be different. Only way to remove the rockers is at TDC when the lobes are out of the way.

 

 

I find compressed air very scary way to do this. Anything could go wrong. Power to compressor goes off, air leak from a multitude of causes. Using rope you physically cannot drop the valve into the cylinder, hell you could replace your seals on the side of the road and stop for the night and finish the next day without worry. 

Im with you on this one. Compressed air just seems too risky. What if it finishes off wore out rings or just blows past the rings and messes with other stuff and leaks compressor goes bad. I might be paranoid but its not worth the headache.

Edited January 7 by ElliotV

[EDM620]

27 minutes ago, datzenmike said:

Using rope

Just make sure it's a SOFT rope. I've used clothesline successfully. Start with piston at bottom of compression stroke & feed as much rope as you can cram into the cylinder, hand crank the engine to just before TDC on that piston. If it hasn't compressed enough, back it off to bottom of compression stroke & you'll be able to cram more rope into the cylinder. Don't use a poly rope.

[Thomas Perkins]

Bad valve seals.Is oil all over your spark plugs.

[datzenmike]

Oil can get past worn oil control rings too. Intake valves are under vacuum that can suck oil down the stem. Exhaust are under some pressure so not as bad running. When engine is shut off both can seep down past the seals and puff a big short lived cloud on start up.

[jakebson]

Tightened the head bolts today. Don't have the valve rings or tool yet, so that will have to wait. Here are some pics of the spark plugs.

[datzenmike]

BP6ES should be the intake side, BP5ES on the exhaust. I see a mismatched Iridium plug.

 

Gap should be 0.035" or 14mm. Look smaller, hard to tell.

 

Otherwise they look very good.

[jakebson]

The exhaust side plugs are BPR5EGP I can switch them out to the BP5ES soon. The gap is 0.034 my FSM gives a range of 0.031- 0.035

[datzenmike]

BPR5ES exhaust side. Your gap is fine.

[jakebson]

Started the truck this morning and there was less smoke, but it was misfiring really bad and had no power. I had taken out the plugs to check them and I wanted to make sure everything was to spec. The gap on the iridium plugs on the exhaust side was way too big so I set them to .034. Being the ignorant person I am, I didn't realize this may cause issues since the electrode is pretty fragile. They were super fouled up when I removed them and they looked all around in bad shape. Figured I needed to swap them to the BPR5ES anyways so I wasn't too concerned. Got the new plugs in and it fired right up and idled smooth.

 

Drove it for about 30 min with some around town and highway. It started running a little rougher but nothing too serious. Parked it at home and the idle was more rough than when I first fired it up after the new plugs. Let it sit for a few hours and took it out again and is still running rough. Not too bad, just not as smooth and louder than it was before I torqued the head bolts and had to swap the plugs. I double checked that I had all the spark plug wires in the right spot and that all the vacuum hoses are connected. I checked the new spark plugs and they looked good. I pulled one of the plugs on the intake side and it still looked good, I didn't check them all though. Put a plug in the coil wires and grounded them and got good spark on both. Anything else I should check? Could I have messed the timing up somehow? I haven't messed with that at all since I have had the truck.

 

 

[ElliotV]

Since you are still running the factory carb I would double check all of the vacuum lines and make sure that you didn't accidentally crack one. That truck is right at 40 years old so those hoses are likely barely hanging on. Its possible that when you were taking the plugs out you could have moved one and put it past its threshold. It wouldn't hurt to put a timing light to it if you have one. Do you have a video of it running by chance cause a video would help knowing exactly how it sounds. 

[jakebson]

6 minutes ago, ElliotV said:

Since you are still running the factory carb I would double check all of the vacuum lines and make sure that you didn't accidentally crack one. That truck is right at 40 years old so those hoses are likely barely hanging on. Its possible that when you were taking the plugs out you could have moved one and put it past its threshold. It wouldn't hurt to put a timing light to it if you have one. Do you have a video of it running by chance cause a video would help knowing exactly how it sounds. 

 

I have replaced nearly all the vacuum lines and I checked them all thoroughly a few times today. Vacuum leak was my first thought. I should have mentioned, I did break the Thermal Vacuum Valve when I was taking off the air filter housing. It is the one with 3 ports. I put a plug where it was and traced back the lines that went to it and capped them. I checked the diagram in the FSM to make sure everything was routed correctly. From my understanding the TVV would only have an effect until warmed up. This is occurring most when warm. I glued the TVV and will reinstall it now that the repair is dry. Unfortunately, I do not have a timing light. I can get a video and upload it tomorrow.

[ElliotV]

Im actually in the tulsa area I just noticed your location said that. I wish I had a extra tvv so you would know that you have a good one but yes from what I know of that should only affect your timing advance until the engine is warmed up after it is warm it should allow vacuum through it and many people delete/disable it whenever they do a weber swap. You might also check that your choke is actually opening as well once the truck is warmed up that could cause idle issues if it isn't opening all the way. 

[jakebson]

Started the truck this morning and it started fine, but is running really rough. Backed it out of the driveway and it has no power when trying to drive and starts, what feels like to me, misfiring. I have no clue what I could have done to cause this. Outside of the smoke, it was running well. Here is a link to a video of what it sound like idling. No one is around to give it some gas while I video. Here is the video. Let me know if it is able to be viewed, I couldn't get it to embed.

[jakebson]

Feels like it sputtering,is is the best way I can describe it. There is plenty of fuel in the bowl in the carb, so that doesn't seem to be the issue this time. When looking down the carb should I see fuel shooting when the throttle is pulled? It almost sounds like air at the top of the carb. I sprayed around it to listen for leaks with changes in the RPM with no changes. Also had a tube to my ear and went all around trying to find any vacuum leaks and I'm not finding anything.

Edited January 9 by jakebson

[datzenmike]

23 minutes ago, jakebson said:

Started the truck this morning and it started fine, but is running really rough. Backed it out of the driveway and it has no power when trying to drive and starts, what feels like to me, misfiring. I have no clue what I could have done to cause this. Outside of the smoke, it was running well. Here is a link to a video of what it sound like idling. No one is around to give it some gas while I video. Here is the video. Let me know if it is able to be viewed, I couldn't get it to embed.

 

Is it fully warmed up when you describe running rough and has no power? If not the choke should be on at this time and that should take care of the roughness and lack of power when the engine is cold. Tomorrow before starting take to top off the air filter and look. Choke should be slightly closed from previous use. By hand open the throttle slightly. What you should observe is the choke plate snap closed. Does it do this?

[jakebson]

31 minutes ago, datzenmike said:

 

Is it fully warmed up when you describe running rough and has no power? If not the choke should be on at this time and that should take care of the roughness and lack of power when the engine is cold. Tomorrow before starting take to top off the air filter and look. Choke should be slightly closed from previous use. By hand open the throttle slightly. What you should observe is the choke plate snap closed. Does it do this?

 

I had it started earlier, but it never got fully warmed up so I tried what you just said. The choke was probably half closed so I opened it, but it did not snap close. I went ahead and started it to see what it would do and it was running a little smoother. I took it around the block and was actually driving fine, but when I would coast or come to a stop it was racing at a really high RPM. I don't have a tac, but it is much higher than normal.  Maybe the fast idle was stuck. The linkages are moving freely and visually appear to be in order and nothing in their way. I will try the choke again tomorrow after it has completely cooled down. I have triple check all the ignition stuff and that appears to be in order, and I was leaning towards a carb issue already. This is the feedback carb.

[jakebson]

I took the air cleaner housing back off and sprayed carb cleaner on all the linkages and worked them for awhile. Started it up and it was running well. I think the choke was stuck in the same position. I have cleaned the linkages recently and it was running fine so I am wondering if I may have had the vacuum line that is near the back of the carb hindering the linkage. After I buttoned everything back up it drove well on the highway and around town like it was before I messed with everything.

 

The last few days I have had this thing running at idle more than normal, but the mileage on the last tank was atrocious. 13 miles per gallon. This is the first time I have been able to calculate since the odometer quit working when I replaced the charge light bulb shortly after I got it.I had a feeling it was bad since I was filling up a lot. I mainly drive city miles with quite a bit of stop and go so I wasn't expecting great efficiency, but man that is brutal.

 

I am planning to do the valve lashes and valve seals soon when I can do them in a garage at a friends house, but besides that I feel like I am catching up on the maintenance. I read about adjusting the air/fuel ratio on here and I will work on that to see if it will help also. I am sure the carb is likely in need of a rebuild though.