White smoke and coolant from exhaust.

[Sjoost]

Hi all,

 

Finally I got my 280z original engine to start up (project ongoing).  All seemed well, no white smoke, but I had coolant leak from the small tubes near the fuel injection rail. The tubes were totally worn out. So I fixed all 3 the tubes.

Started engine up again, and suddenly noticed white smoke from the exhaust. Also noticed the inside of exhaust was wet (looked like coolant). I also noticed the fan really blowing hard (full power) immediately. 

 

What I did before was install  new radiator. I forgot to take out the air from the water system I realize now (maybe reason?) and filled it up to just below the cap (is this too full?). 

 

Before all this, earlier I checked compression on all cylinders (with cold engine, lower side but nicely consistent on all 6, 100psi). I concluded all fine for cold block. 

 

I know, it could be a head gasket leak, but I have also seen other options. Like water Temperature Sensor failing,  or somehow coolant drawn into inlet/exhaust manifold?

 

I hope someone has some suggestions/tips before I go for the head gasket.

 

Thank you for now.

 

Joost

 

 

Edited March 30, 2020 by Sjoost

[NewZed]

Did you let it get fully warmed up?  Won't hurt to run it if it is a head gasket problem.  Make sure first.  Get it to full temperature and let it run for a while.

 

You can't overfill the cooling system.  It  will release through the radiator cap if pressure gets too high.

[Sjoost]

hi NewZed,

 

Thank you for  a fast reply. few followups

1. How long should i keep it running to warm up? 5 minutes?

2. The liquid in the exhaust suggest significant amount getting into exhaust system or not? How can that get there while car running for about 2 minutes?

3. That fan speed, is it normal that it blows full speed at idle (~1000 rpm). Temp Sensor issue?

4. I have also read that there could be some issue with inlet manifold. Could that also be the case here?

regards,

 

Joost

Edited March 30, 2020 by Sjoost

[NewZed]

It's warmed up when the temperature gauge says so.  I'm not sure how your engine has been modified.  Sounds like you have an electric fan?  Run by a thermo-switch?  A stock L28 has a fan clutch.  the fan can only go as fast as the engine does.

 

A head gasket will blow exhaust in to the cooling system when the engine is running.  Is it possible that you punched a hole in to your intake system or cracked something and your "fix" is allowing coolant in to the intake?  Is this s turbo engine?

 

Does the white smoke smell like antifreeze?  All engines have moisture from the exhaust when cold.  It's a byproduct of combustion.

 

Just need more details about your setup.  Not enough here to say what's happening.

Edited March 31, 2020 by NewZed

[Sjoost]

Hi NewZed,

 

All is stock on my engine, except for the radiator. No turbo, just L28 1975/76 model. I get your point on the fan (stock too) and looked okay.

What i did this morning:

1. Removed the radiator cap

2. Started engine (remarkably starts on the first go every time:-))

3. Kept it on for maybe 3-4 minutes. 

4. At start no smoke, after 30-40 seconds white smoke, and liquid sputter from exhaust.

5. Apparently i have some small leaks in my exhaust system, as some liquid dripped out of exhaust also. But i do feel it is a significant amount (5cm x 5cm puddle on concrete floor).

6. Smoke was gone after about 2-3 minutes. 

7. no sign of increasing temperature on the gauge (but felt the radiator and was slightly warmer (but no way heated)), or gauge, or sensor is could be broken.

8. I shut down after 4 minutes, as i was getting smoke at the connection of my down comer pipe from the exhaust manifold (which i might need to tighten further also).

 

- i figure the water pump is working, as i see flow in the radiator. I do not see any bubble in the radiator (your suggestion on exhaust gas entering water system from blown gasket)

- nu punctures found in the inlet manifold

- during idle, after some time it dropped refs further but stayed on. I figure that states the engine is running in normal idle at that moment.

 

I am a bit reluctant to keep it on longer, scared to damage something further.

 

doe this give any more clue?

 

great thx already,

 

joost

[jhm]

Hey Joost-

Sounds like the problem started after you fixed some coolant leaks in the vicinity of the fuel rail?  If so, maybe relook those repairs to ensure the repairs themselves weren't the cause of your issues?

 

Have you had to refill your coolant during these tests, or is it maintaining a constant level of fill?  

 

Liquid in your exhaust during first couple minutes of startup is not all unusual, as NewZed pointed out, and can even be caused by nothing more than atmospheric condensation (usually from the previous shutdown).  If this is what's occurring, it will be water only.  If you can detect actual coolant in the liquid in the exhaust (I don't know how one can definitely do that), then you likely have a problem.

 

A good way to monitor engine temperatures is with a simple IR thermometer, especially if you're not confident in the temp gauge readings.  You can use the IR unit to check temps at various points....radiator, coolant lines, engine block, etc.

 

Good luck with it.

[NewZed]

There are other ways for water or coolant to get in to the engine.  Have you checked you oil lately?  If water is leaking in to a cylinder some will leak past the rings.  See if your oil level has increased.  If it has there is probably water at the bottom of the oil pan, if it hasn't already blended in to the oil.

 

If the smoke is gone after 2-3 minutes, does the smoke really matter much?

 

Places for coolant to get in are cracks in the cylinder head or erosion of the cooling passages in the timing chain cover.  Also, the bolts to the thermostat housing pass in to the timing chain cover.  A crack in the cylinder head can let coolant directly in to the intake system, in to ne of the runners.  From there it might drain back to the plenum where it can get in to all of the cylinders.

 

You might pull your spark plugs and see if one is abnormally clean.  Water in the cylinders will clean them up.  Might help you narrow the focus.

 

If there's no water in the oil and the engine isn't locking, hydraulically, you won't do any damage by letting it burn off whatever gets in there.  People actually build systems to squirt water in to their engines.  Some people pour water in through the carburetors to clean carbon out.

[Sjoost]

hx jhm,

 

I just followed up advise from NewZed again, tightened downcomer. Looked up some more internet youtube's how to discover if there is a blown-out gasket.

 

I stated up, with radiator cap of. It started right up again, no smoke, and i could see a flow in the radiator. No signs of bubbles there. After about 30 seconds, white smoke again, which did disappeared after like 2 minutes. Some smoke coming from engine after some time, but felt it was some residue on the exhaust shield. So kept running. No leaks, and all smoke gone.

Figure for now, all fine. Radiator was warming up (car was on for about 15 minutes, and i drove a bit), but no change in oil temp or water temp gauges (need to check that). I did just touch the block, valve block and valve cover to see how hot they were. They were hot but i could still touch them, and good sign the radiator was getting warm. 

 

Figure, all looks fine for now. Did order gasket set, just in case

Was trying to upload some movies... but no luck.

 

What I also did, is open the oil lid, engine changed speed right away and was about to die, so put it back on, and all back again. Seems vacuum system is okay.

Edited April 6, 2020 by Sjoost