Still smokin

[Sailor Bob]

Guys, I am looking for advise. I just got the 240 running after a few changes in an attempt to get her ruuning better and cleaner - the car was running after a fashion when I got it, but nothing that would live up to the Z reputation. It had a set of very troubled looking four screw SUs that had loose throttles, dipsticks from a 260 and a sticking choke, just a good case for replacing. I got a set of Carbs from ZTherapy along with a stripped down balance tube, set them up according to the book, installed new plugs and wires (NGK) and blanked any unused hookups for pollution gear.

Pulled the choke and turned the key - it gave me a little fright, it started so aggressively, running perfect. I was sooooo pleased, however I did notice some smoke when starting, but it seemed to fade away quickly and nothing when at a steady rpm. When she was warmed up I sat in her and pumped the gas a couple of times to about 2K and noticed smoke in the garage (hose fell off the exhaust when I nailed her). Got out and nailed her a couple of more times from the engine comp while looking aft and she was belching smoke when hammered. Leaving some oily residue on plugs - but I haven't actually run the car since the changes - she is still on blocks (waiting on tie rod ends)

Car has 46K on the engine, compression check a couple of weeks ago was 165 ish all around. Seems powerful. Sounds good, maybe a little valve noise - heard worse.

What is the cause? Common? what next?

Thanks

SB

[240ZX]

Based on your explaination, I would say your valve guides may be worn enough to pass oil. Was the smoke blue or white?

Tom

[peterc]

How long has the car sat? What color is the smoke? When I started my '83 for the first time (after sitting in a farmer's field for 6 years), it blew white smoke for half an hour. Turns out it was just burning off six years of rain water in the muffler, .

Bluish smoke indicates oil. Since the compression seems fine, most likely culprit would be dried out valve stem seals. Not unusual if the car has sat for an extended period of time. Lucas makes an oil additive that will soften them up until you're ready to do a rebuild. Or you can replace them, without doing a rebuild (check forums).

cheers

p

[Sailor Bob]

Glad you guys said that - I have heard that the valve seals dry with time layed up and this girl had 15 years sitting in a garage and over the past two years has only had 200 miles of use (accordding to the PO) .

The smoke is dark - I initially thought it was rich fuel mixture. It seemed to make sense cause the carbs were in very poor condition, but now not so much.

Thanks for the tips.

[Arne]

I'm going to disagree. If the engine has been sitting, and it's passing enough oil to slick up the plugs, I doubt that it's the valve seals. Valve seals typically let the oil in on overrun. Rev it up and it runs clean, back off and while it returns to idle (high vacuum) it sucks oil down the valve stems, and then makes a big (but short duration) puff when you open the throttle back up again.

No, my guess is sticky oil control rings. Compression rings are still doing their job, but the oil rings are stuck in gunk in the grooves and aren't scraping the cylinder walls clean. Did you pour ATF in the cylinders for a few days before starting it the first time? ATF is highly detergent, and can de-gunk the oil rings if you let it sit and slowly soak down past the compression rings.

[Sailor Bob]

When I was looking at buying the car the PO told me the car had poor compression (110 all around) so befor committing to the car I started off talking to a freind who is a HD mechanic (he has great instincts for this kind of stuff) and he told me that it was likely gunky rings recommending that when I got the car to run it hard for a couple of hundred miles with deisel lube oil (heavy detergents) change oil and repeat.

That was my intent but when I checked the compression I assumed the PO had simply done the test incorrectly, because my results were very good and I switched tactics.

I don't have much background in mechanics - limited experience, talk and reading really, but I do pick up fairly quick and that makes sense that some rings would bind but not necessarily all of them. I did find that #5 and 6 seemed wetter than the rest.

Could I still use the atf ?

[Bruce Palmer]

Rick,

We are going through a deal on the engine out of my wagon. The oil rings were stuck and I mean solid. Looked like coked up oil in the divots of the expanders to the point the rings were stuck!! I'd follow your budy's suggestion and give it a "rinse cycle" with something..... Heavy duty diesel oil ya say. Does he have a specific recommendation? Would it be a good break-in oil?

[Arne]

I'd put a couple ounces of ATF into each cylinder and let it soak there for several days. Then change the oil and use the high-detergent diesel oil as step two.

[ozconnection]

I don't see why you couldn't do the ATF thing now. It might take 24-48 hours for it to work. When you do start it, expect to see huge plumes of white smoke until the oil burns off!!! You could do this twice if you like, just to be sure. Be mindful that ATF can foul up spark plugs. Ask me how I know this.

How much ATF to put in each cylinder I don't know exactly. At a guess maybe 10-20 mls. What I would do though would be to lift the passengers side of your car a bit more so that the engine block sits perpendicular to the ground. That way when you drop in the atf (via the spark plug hole of course!), the oil flows evenly around the rings to do their job.

I would change the engine oil and filter after this too, just for good measure, you don't know what crap will be in your oil and what effect the ATF will have if left in the sump.

Cheers

[Mike]

Just had to....

[moogrr]

I know this an old thread, but

i had a similar problem recently. Drove the car back from Utah (2000 mi) didn't burn a drop. No smoke. Adjusted the timing, adjusted the valves, tinkered with the carbs a bit, and changed the oil with 10w30. Blue smoke - a lot. No blow by at valve cover. Back three plugs a little wet looking. Noticed the oil was a little over the full on the dipstick. Drained a litre out. SMELLED LIKE FUEL. Don't know enough about these cars to give you a concise explanation, but changed the oil again and now I'm golden. Thought I got burned by the seller... but turns out it was my fault.

Good luck.

Ted.

[Travel'n Man]

SB-

I own a 1930 Model A Tudor and when I first got it I had a similar problem. My Model A mechanic told me to do the same as Arne had mentioned but change the oil and replace one full quart with Marvel Mystery Oil. I am still running that "oil blend" and it has cleaned and helped my challange a lot. After 500 miles (and 500 miles is a lot for a Model A) I will change it out and replace. That Marvel Mystery Oil seems to have done its job, no more smoke and the engine sounds better as well, I'm sure things were sticking in there. I don't average 500 miles per year on that car (summer driving and parades mostly).