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Was running fine before.... now, white smoke and stalling


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I bought my 76 280z about a month or two ago. Proceeded to replace the front calipers, change the oil and filter, and get all the pine needles out of the engine bay and interior. So, I took a few joy rides, everything ran great and I was lovin life in my Z.

 

Now, only a handful of miles later I can't even get it to run long enough to warm up. It started by staggering when I stepped on the gas moderately, bogging and a nice cloud of black smoke. Now when I start it, it seems like it is definitely missing, and the black smoke has turned to white smoke, then sputters and dies

 

I have checked each wire for spark, disconnected, lubed up and reconnected each injector, fixed holes in intake hose(with duct tape, but still), replaced spark plugs, the wires seem to already be new, tried removing cold start valve, disassembled and inspected AFM, and still... same result

 

Am I missing something obvious or am I just in denial of the fact that it's probalby a head gasket.

 

Really, I only want to be able to drive it about 10 miles to my shop where I have a ka24de dohc waiting for it, sure it's 20 less hp, but it's a 5spd (can't handle the 3spd auto much longer), it runs, and it's about 20 years newer.

 

Thanks for reading my long post, and please offer me some advice to at least limp it to the stable.

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White smoke is the biggest sign of a blown head gasket. On the L-Series engines they seem most vulnerable between 5th and 6th cylinders. Check the sparks plugs and see if they happen to have alittle rust color on them or if your running rich those two plugs will look "clean". A compression tester will work best to diagnosis this. A poor mans way to do it is also to get a pressure test done on the cooling system (the tool can be "borrowed from a local auto parts store or they can even test it for you) the drop in pressure will indicate a leak and if no spray or sound could be found then it's most likely internal. Hence, a blown head gasket. That's wear I'd start. Good luck.

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Mine was running rough but driveable then *Poof* white smoke like hell. Then the entire radiator emptied into #6. and sprayed rad fluid all over the back of my garage. How is this possible? I replaced the head gasket the head itself was flat and it didn't change a bit! In fact the old gasket showed no sign of trouble. That engine is now sitting on the garage floor of a friend's house along with the original 4 speed, he wanted it.

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Mine was running rough but driveable then *Poof* white smoke like hell. Then the entire radiator emptied into #6. and sprayed rad fluid all over the back of my garage. How is this possible? I replaced the head gasket the head itself was flat and it didn't change a bit! In fact the old gasket showed no sign of trouble. That engine is now sitting on the garage floor of a friend's house along with the original 4 speed, he wanted it.

 

When you changed the head gasket did you make sure to torque all bolts to spec? This happened to my old civic and I later realized that the only thing it could have been was improper torqueing of the bolts. Also, how long did you have the car. There could have been a time when it got overheated way too much and warped the aluminum head. This would cause a head gasket to blow no question. Things also might look straight to your eye but the only way to be sure is to drop it on a magnaflux machine.

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Thanks for the feedback, I was hoping someone has a miracle cure for a case of the white smoke, but I guess I'll be towing it to the shop. Hopefully she'll be on the road again soon, under her own power.

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Dr. J, it's great to see another s30 in Columbus. I'd have to agree that you likely have a head gasket issue. Mine did pretty much the same and the gasket was still intact. I chalk it up to the gasket simply getting old and rotten. After I replaced it and re-torqued the head it's been fine and I daily drive it now. Anyways, if you ever want any help from someone with some experience on these cars, let me know. I'm always up for wrenching on an old Z. -Mike

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When you changed the head gasket did you make sure to torque all bolts to spec? This happened to my old civic and I later realized that the only thing it could have been was improper torqueing of the bolts. Also, how long did you have the car. There could have been a time when it got overheated way too much and warped the aluminum head. This would cause a head gasket to blow no question. Things also might look straight to your eye but the only way to be sure is to drop it on a magnaflux machine.

 

I checked flatness with a stone table and feeler gage. I torques the bolts as specified 30Ft-lbs, then 45 then 60 I believe and in the proper order. Plus I used a high performance gasket which supposedly would "seal even on mildly warped heads". Anyway it might have been a crack in the head and I wouldn't be surprisd if it was warped and I didn't catch it on the table. Butr there was NO sign of damage to the old gasket.

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  • 2 weeks later...
Things also might look straight to your eye but the only way to be sure is to drop it on a magnaflux machine.
Magnaflux will show cracks but not distortion.

 

The simplest way to check for an blown gasket is to start the car with the rad. cap off and check to see if there are anny bubbles in there, if yes, compression is making it's way in the cooling system and when you turn it off the vacuum inside the cylinder sucks coolant back in thus the white smoke.

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Always replace the head bolts with new ARP bolts.

stock bolts will lossen up - stretch etc. Hondas are really notorius

for this as well. (yes I junked a honda cvcc after filling up the oil pan with water)

Recheck bolts after a few heat and cool cycles.

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