240z overheating at idle in traffic lights and intersections

[siteunseen]

I wonder if he has the cannister type oil sending unit or the smaller one for a "dummy light".  I've read people put the smaller ones on from a local parts store and not the right one just because the counter guy says it's the one the computer shows, FWIW.

In the picture he posted of his glass fuel filter, it looked brownish red to me.  I've got them on both my carbed cars and they are a yellowish green.  He may have a rusty tank?

Car plus $6,000 chasing gremlins and still not right, mecanico no es bueno.

[Zed Head]

On 12/31/2015 at 6:36 AM, jalexquijano said:

changing the fan clutch, thermostat,

wrapping heat shield cloth on the fuel lines and

replacing wáter pump.

He also changed the exhaust manifold pipe gasket. Car timing was set at 10BTDC. Car ran fine. No backfire either from intake or exhaust.

However, once i reached home while playing with the car stereo temperature started to rise until reached 3/4. RPM dropped from 1000 to 500 and then raised to 1000 again. A few seconds later it stalled and i had to crank it again. It does the same at intersections and while at idle on traffic lights.

Took out all plugs and cleaned them.

I took the basic facts I could find and broke them up.  Overall, things don't seem terrible.  But you seem to be reacting quickly and dramatically to relatively minor issues.  You've had the engine for quite a while, with its various problems, but it does start, and run, and drive.  You're probably very close to getting it running well, IF you can resist the urge to make major changes.  You're about to spend much more money and replace a bunch of parts, because, apparently, the engine stalled a few times after it warmed up.  

Your description looks like you sit watching while the engine RPM go up and down, at idle, then the engine dies.  That's not much.  You have an engine idle problem.

Did you set the timing or did the mechanic?  Do you have vacuum advance connected?  If so, is it on a parted vacuum source or direct to manifold?  Have you adjusted the carbs at all, for idle performance.

 

If I had your problem, I would get all of my diagnostic tools connected to the engine, start it up, and wait until it warmed up and things happened.  Watch the timing, fuel pressure, etc. Try to keep it running using the throttle when the idle starts to go up and down.  All you have now is "it dies while I played with the radio, it dies at a stop light, and the gauges don't work very well.  Even the new oil pressure senders have been known to give low readings at idle, so a view with the engine revving a bit would help.  Just not much quality info to worth with.

[Zed Head]

9 minutes ago, siteunseen said:

I wonder if he has the cannister type oil sending unit or the smaller one for a "dummy light".  I've read people put the smaller ones on from a local parts store and not the right one just because the counter guy says it's the one the computer shows, FWIW.

In the picture he posted of his glass fuel filter, it looked brownish red to me.  I've got them on both my carbed cars and they are a yellowish green.  He may have a rusty tank?

Car plus $6,000 chasing gremlins and still not right, mecanico no es bueno.

Did he show the filter in a different thread?  Can't see it.  But it does bring up another diagnostic - fuel pressure.  Carbs are sensitive to high pressure.  We just need more better numbers.

That's two mentions on a funky pressure sender...

[Patcon]

The color of his fuel may or may not be a problem. He is in a completely different market without all of our blends. For that matter the tanks they pump from could be rusted tinting all the gas pumped from them...

 

 

2 hours ago, Zed Head said:

I took the basic facts I could find and broke them up.  Overall, things don't seem terrible.  But you seem to be reacting quickly and dramatically to relatively minor issues.  You've had the engine for quite a while, with its various problems, but it does start, and run, and drive.  You're probably very close to getting it running well, IF you can resist the urge to make major changes.  You're about to spend much more money and replace a bunch of parts, because, apparently, the engine stalled a few times after it warmed up.  

Your description looks like you sit watching while the engine RPM go up and down, at idle, then the engine dies.  That's not much.  You have an engine idle problem.

Did you set the timing or did the mechanic?  Do you have vacuum advance connected?  If so, is it on a parted vacuum source or direct to manifold?  Have you adjusted the carbs at all, for idle performance.

 

If I had your problem, I would get all of my diagnostic tools connected to the engine, start it up, and wait until it warmed up and things happened.  Watch the timing, fuel pressure, etc. Try to keep it running using the throttle when the idle starts to go up and down.  All you have now is "it dies while I played with the radio, it dies at a stop light, and the gauges don't work very well.  Even the new oil pressure senders have been known to give low readings at idle, so a view with the engine revving a bit would help.  Just not much quality info to worth with.

Zed Head gave you good advise, take it or leave it

[jalexquijano]

Problem is not rust in tank! just replaced the fuel filter with another glass fuel filter and i see no brownish deposits. I am more inclined to the following:

Damaged Radiator or vacuum leak somewhere. However if Datsun LLC does not have  good reputation on overhauling engines properly, i might have to tear down the engine. Unfortunately mechanics in Panama only know how to tighten and untighten bolts and screws. Nothing else.

[psdenno]

Why do you think there's a problem with the radiator and how could it cause a rough idle and stall?  You don't have an overheating problem.

Do you have the only Z in Panama?  My guess is that there are others.  Find out who they are and who works on their cars.

Dennis

[jalexquijano]

They dont use the car in traffic conditions. I dont have rough idle issues or stalling while running the car. it only happens when you are stuck in traffic and it starts with a drop down from 1000 RPM to 500 and raises back to 1000. After minutes from that the car idles gets more rough and unstable and suddenly it shuts down. Plugs start to get black and acceleration gets difficult. This car is supposed to be used under normal heavy traffic conditions.  

What other pictures would you like me to get for you?

Edited January 5, 2016 by jalexquijano

[jalexquijano]

20 hours ago, Zed Head said:

I took the basic facts I could find and broke them up.  Overall, things don't seem terrible.  But you seem to be reacting quickly and dramatically to relatively minor issues.  You've had the engine for quite a while, with its various problems, but it does start, and run, and drive.  You're probably very close to getting it running well, IF you can resist the urge to make major changes.  You're about to spend much more money and replace a bunch of parts, because, apparently, the engine stalled a few times after it warmed up.  

Your description looks like you sit watching while the engine RPM go up and down, at idle, then the engine dies.  That's not much.  You have an engine idle problem.

Did you set the timing or did the mechanic?  Do you have vacuum advance connected?  If so, is it on a parted vacuum source or direct to manifold?  Have you adjusted the carbs at all, for idle performance.

 

If I had your problem, I would get all of my diagnostic tools connected to the engine, start it up, and wait until it warmed up and things happened.  Watch the timing, fuel pressure, etc. Try to keep it running using the throttle when the idle starts to go up and down.  All you have now is "it dies while I played with the radio, it dies at a stop light, and the gauges don't work very well.  Even the new oil pressure senders have been known to give low readings at idle, so a view with the engine revving a bit would help.  Just not much quality info to worth with.

The timing was set in the middle at 10BTDC. I have the vaccum advance connect to a ported source in the front carb. The carbs are adjusted properly.

[Zed Head]

2 hours ago, jalexquijano said:

 I dont have rough idle issues or stalling while running the car. it only happens when you are stuck in traffic and it starts with a drop down from 1000 RPM to 500 and raises back to 1000. After minutes from that the car idles gets more rough and unstable and suddenly it shuts down. Plugs start to get black and acceleration gets difficult.

This is good information.  Another clue would be what the temperature gauge does while these things happen.  Even though they're not accurate, they're still good indicators.  Where is the needle when you're "running the car" and where is it when you're "stuck in traffic"?  If it's in the same spot, then the cooling system is working.  Engine temperature is not changing between driving and stopped.  But engine bay temperature might be. What thermostat temperature are you using? Maybe you just need to use the 160 and you have a 180.

Here's a question for the carb guys - would measuring fuel flow on the return line be worthwhile?  I don't see it in his pictures but I don't really know what I'm looking at.  Could be that his guy is running it dead-head style and the insulation is being overpowered at a stop, or he just has low flow for other reasons.  If I had carbs I'd probably use that as an overall check of the lines and fllters.  Without good fuel flow past the carbs vapor-lock could still be a problem.

 

Also - I attached a picture of what looks like a hose laying on your throttle linkage.  Could cause throttle feel issues.   

Edited January 5, 2016 by Zed Head
Hit the wrong button

[jalexquijano]

while running the car the temperature gauge needle sits in the middle. Once stuck in traffic or at a parking it starts moving to 3/4.

[Patcon]

If when sitting in traffic you rev the engine some, up to 2500 rpm's or so, does the problem go away for a minute? I believe you are running too much pressure on your fuel system and flooding the engine out...

[Zed Head]

33 minutes ago, jalexquijano said:

while running the car the temperature gauge needle sits in the middle. Once stuck in traffic or at a parking it starts moving to 3/4.

So you do have a small amount of heat buildup.  Still doesn't really explain your problem, but might be a factor.  

Here's something easy to look at that might be significant, especially since you're in Panama and probably don't use your heater - are the heater core coolant lines from the back of the head blocked off or are they looped back to the water pump, from the head?  Or are they connected properly to the heater core?  Looping the line back to the pump inlet (bypassing the heater core) can cause overheating, in a perfectly fine cooling system.

 

And, still wondering about fuel pressure, and the return lines for your fuel supply system.  Important.