Rebuilt engine idle problems, running rich

[siteunseen]

35 miles on a rebuild and it smokes that bad but has good compression?  Sounds like valve stem seals may have dried out out and cracked if the motor sat for a while? 

If your Dad said it had a hotter cam you may need to adjust the valves to the cams specs? or the cam could be smashing down on the seals. 

There may be a reason you bought a fresh rebuild for a good price? I certainty hope nothing is too serious. 

[MrChefur]

Didn't get to check it out today, work was longer than expected. 

On 8/10/2017 at 8:36 PM, Zed Head said:

There doesn't seem to be any smoke in your two videos on Page 1.  Is the smoke a new thing?  Smoke that doesn't smell strongly is usually coolant.  Oil and gasoline smoke both smell like either oil or gasoline.  Are you a smoker?  Maybe get a fresh nose on it, I know smokers can't smell well sometimes.  No offense.

Check your head bolt torques.  Maybe they've loosened or were never properly torqued.

I'm unsure if smoke is a new thing. I didn't rev the engine too high when it was sitting in my yard, and when I'm driving I can't see it much haha. Not a smoker, for what it's worth. I'll get back soon with what the exhaust is like.

13 hours ago, rcb280z said:

I didn't see any either. Must be something new going on that's why I suggested new videos and or pics.

I'm having a hard time with the "they didn't pass me because of visible smoke". Really need to see some video, not saying it isn't happening, just need to see it.

The smoke mostly occurs during deceleration, the videos were really only idling. I'll get another one tomorrow if I can't figure it out.

9 hours ago, siteunseen said:

35 miles on a rebuild and it smokes that bad but has good compression?  Sounds like valve stem seals may have dried out out and cracked if the motor sat for a while? 

If your Dad said it had a hotter cam you may need to adjust the valves to the cams specs? or the cam could be smashing down on the seals. 

There may be a reason you bought a fresh rebuild for a good price? I certainty hope nothing is too serious. 

How would I determine if it has a performance cam? When I took off the valve cover, the cam had the standard Nissan markings on it, although I suppose it could be reground?

To be more specific, my dad says he misspoke and thinks it's a performance crank. Is it possible to determine if that's true without tearing down the engine? I don't particularly care as long as I can get the car running well.

[sweatybetty]

your vacuum is highest under deceleration. it sounds like oil getting past the valve seals

[MrChefur]

1 hour ago, sweatybetty said:

your vacuum is highest under deceleration. it sounds like oil getting past the valve seals

I got off my butt and took it to the Z specialist today. Super nice guys over at McKinney Motorsport in Temecula. Anyways, they said it's almost certainly valve stem seals and that the smoke was definitely burning oil.

[siteunseen]

That's not too big of a job. They can use rope stuffed in the plug holes to hold the valves up or compressed air. Remove the springs and stem retainers and slide the new ones on.

I don't have a clue what a shop would charge though, seals are $20 but the labor? $200? 

Glad it's not serious.

Edited August 12, 2017 by siteunseen

[MrChefur]

23 hours ago, siteunseen said:

That's not too big of a job. They can use rope stuffed in the plug holes to hold the valves up or compressed air. Remove the springs and stem retainers and slide the new ones on.

I don't have a clue what a shop would charge though, seals are $20 but the labor? $200? 

Glad it's not serious.

I'm gonna DIY it. I've got a spark plug compressor fitting from my compression testing kit around here and just picked up the seals today.

I was reading that a bad PCV can suck oil from the crank case ventilator, so I changed that out and now I've got a new issue (yet again )

The smoke changed from a white to a dark grey/black. That means it's running super rich right? How do I even adjust that?

By the way, I wanted to say thanks a ton to everyone that's helped me so far. I couldn't have done it without all you and the countless awesome posts on here.

Edited August 13, 2017 by MrChefur

[siteunseen]

I fixed my lean problem with a potentiometer.  Pretty much a volume knob from radio shack that added more fuel. Google "Blue's Tech Tips fuel tweaker". Cost $5 bucks and runs great. 

You should also make sure your coolant temp sensor is nice and shiny brass, they get crusted with calcium from the radiator water. Another thing is the thermotine connections look exactly like the coolant temp sensor wires. They get crossed up a lot. One is black the other green but both are bullet connections. When you google the above it has a great picture showing this mistake. 

Hope that gives you more info to read up on. You are a mechanic. 

[rcb280z]

Lets concentrate on one thing at a time. Replace your stem seals to stop the oil burning and then we can start with the rich condition.

Because you live in CA it's going to probably be difficult to pass emissions, going by what you have described as issues so far. So I would ask the Z mechanics to put it on the sniffer and tell you how far away you are from passing smog. I have to do that with my 77 every time. Usually just a quick adjustment and I'm there. If you do that before you start cleaning connections and adjusting on stuff you'll see just how much better you will it make just by cleaning connections. Tell them to just test it for you. You don't want to be labeled a "Gross Polluter". That could happen if you're running too rich and they run it through the system.

Edited August 13, 2017 by rcb280z

[MrChefur]

3 hours ago, siteunseen said:

I fixed my lean problem with a potentiometer.  Pretty much a volume knob from radio shack that added more fuel. Google "Blue's Tech Tips fuel tweaker". Cost $5 bucks and runs great. 

You should also make sure your coolant temp sensor is nice and shiny brass, they get crusted with calcium from the radiator water. Another thing is the thermotine connections look exactly like the coolant temp sensor wires. They get crossed up a lot. One is black the other green but both are bullet connections. When you google the above it has a great picture showing this mistake. 

Hope that gives you more info to read up on. You are a mechanic. 

I've got a new coolant temp sensor on the way from Rockauto right now since it was only $8. I'm not sure if it's a 240 vs 280 thing, but my coolant and thermo time switches are both injector connectors. They are color coded, however, and both work. 

I'll look into the fuel tweaker as well, thanks.

2 hours ago, rcb280z said:

Lets concentrate on one thing at a time. Replace your stem seals to stop the oil burning and then we can start with the rich condition.

Because you live in CA it's going to probably be difficult to pass emissions, going by what you have described as issues so far. So I would ask the Z mechanics to put it on the sniffer and tell you how far away you are from passing smog. I have to do that with my 77 every time. Usually just a quick adjustment and I'm there. If you do that before you start cleaning connections and adjusting on stuff you'll see just how much better you will it make just by cleaning connections. Tell them to just test it for you. You don't want to be labeled a "Gross Polluter". That could happen if you're running too rich and they run it through the system.

Haha, I'm definitely getting ahead of myself here. My dads mechanic friend happened to pop by as well and thinks it's the stem seals as well. I'll do as you suggest and get those done before getting myself into a mess, haha.

I honestly didn't even think to ask the Z mechanics if they had a sniffer. I kinda assumed it was a smog specialty shop thing. I've got new connectors on the way from Rockauto as well,  but I'll be sure to clean everything thoroughly.

[Zed Head]

14 minutes ago, MrChefur said:

I've got a new coolant temp sensor on the way from Rockauto right now since it was only $8. I'm not sure if it's a 240 vs 280 thing, but my coolant and thermo time switches are both injector connectors.

You said that you already tested the sensor by the test in the EFI Book (assuming that you did it at the ECU connector since that's what the Book shows) and it was in spec.  No reason to replace the sensor if the resistance matches the temperature, by the chart.  

[MrChefur]

Just now, Zed Head said:

You said that you already tested the sensor by the test in the EFI Book (assuming that you did it at the ECU connector since that's what the Book shows) and it was in spec.  No reason to replace the sensor if the resistance matches the temperature, by the chart.  

That's true, but a new one was only $8 and I figured it'd be nice to have.

[sweatybetty]

rcb made an excellent suggestion. 1 thing at a time!