Rebuilt and smoking!

[That-hurt]

Hi.

The day eventually came when I could start the 240Z 74 { basic tune running SU type Carbs} I have had the engine re built with new pistons / rings/ valves the head pressure tested etc and it was all put back together by a professional engine builder. So I know { hope} there is not an issue with the actual motor. I set the static timing. Put in a millers 20-50. Filled up the cooling system. Pulled all the plugs and spun it over to get some oil round. Put a bit of fuel in the tank. Set the SU carbs as best I could. I replaced the plugs and cranked it over. It fired and ran. The engine was rebuilt back in may 2011 and has sat since then.

The engine ran. a little lumpy but it was running. I then noticed white smoke coming from the exhaust. Quite a lot of white smoke. on revving it was puffing out the back.

I checked the timing. all good. I let it warm up but still it smoked. I adjusted the carbs a little to lean the mixture as I thought it may be that, but it still smokes.

It has not been run for more that 20 minutes in total. i am wondering if it is still burning off any stuff they may have used in the engine re build. Maybe its some crud in the fuel..

I am hoping to heck that it's not a head issue! The car sounds great it revs well it idles smoothly feels right if you know what I mean. I let it run up to normal operating temp and then switched off. Seems fine...

Any suggestions?

thanks:disappoin

[SteveJ]

Were you running an ethylene glycol antifreeze in the cooling system? If so, was the smoke sweet smelling?

White smoke is frequently coolant related. A few of the causes include a block that wasn't decked properly, a warped head, an improperly torqued head, or a bad gasket. I'm not really an engine guy, so take it for what it's worth.

[beermanpete]

It is most likely oil burning off. Assembly lube, as you mentioned, is certainly present in a freshly assembled engine. Also, oil could have built up in the exhaust system from the old engine if it had bad rings.

If there are no other signs of problems run it more and drive it to give it time to fully warm up and burn off all the residue from the rebuild, old engine issues, and dirt and dust that has settled on and in the exhaust while sitting for a long time.

[That-hurt]

Many thanks.

I am going to let the engine run for a an hour or so to get really hot. See if it is engine lube burning off. I hope it is. The smell of the white smoke is not sweet as such but I will check it again later. I will get it hot and check the oil and water levels r to confirm that it is using / not using water. lets hope the smoke goes away and its not the glycol / steam burning off. I hope its not.

thanks for help...

[PastorMike]

If it is indeed steam, the water vapor will evaporate into the atmosphere and eventually disappear. If it is smoke, the cloud will dissipate, but never evaporate. Smoke will also smell like burned oil; steam will not.

[xs10shl]

I always thought it was important to put a new engine under some load to seat the rings somewhat early in the process? (i.e. not too much idling for extended periods) Could be wrong, so check with an expert.

[Phred]

Probably a bit late for this, but...

You should NEVER let a new/rebuilt engine sit and idle. The two most important issues of an engine are at stake. #1 is the cam/rockers. At Idle there is low oil pressure, with a weak stream hitting the lobes which are crying for lube during breakin. #2 the rings need to be under load to seat against the cyl wall. This is done by putting the engine under load. This will build more cyl pressure which forces the top ring against the cyl wall, encouraging the ring to seal. If this not allowed to happen, the cyl can gloss over and sometimes the the rings will never properly seal. After intial fire up, all you have to do check for leaks, set timing, and drive. During the drive, stay on unused roads that allow you to accelerate then coast down. Keep accelerating, and coastin down, not allowing the engine to stay at a constante speed. Keep the engine under load as much as possible. This is how a dyno works. The engine is put under partial load say 20% of max, for about 20 min. frequently running the throttle through a lsow/med. acceleration mode. Some engines will be ring sealed within a half hour. Depending on the ring type, and cyl. hone job ( grit of stone, cross hatch style) it may take an hour. Also, during this time, you also have max oil pressure running through the engine giving the cam it's best chance of breaking in.

Phred

[That-hurt]

The car is not ready for a run yet as I have to get the interior finished over here we need an MOT before we can get near a road. so as an alternative I have sat with the car and ran it up until its hot. I did this a simulation of a drive eg high and low revs for intermittent periods as if driving on a road.

The smoke you speak of does evaporate so I am of the mind that it is a head gasket problem. I can see seepage along the joint of the head and the block. under number 1 cylinder when i taste it it is sweet. I took the plugs out and they look wet with a mixture of oil and water looking into the bores I can see the crowns of the pistons look wet. I checked all the compressions and they are all between 160 and 172 psi the lowest being 160 on number 4.

it has used a little water by the looks of things. I have set the carbs as best as I can to try and eliminate any rich mixture.

Is it possible that these guys that re built the engine did not torque the head down properly. I was told they did do some work on the head and I am presuming they then pressure tested it.

I am as you can imagine a little angry after spending a small fortune on the engine rebuild. If it is a head issue I am a bit stuck as there are not many 240Z in the Uk to start with. I will have a look at the head bolts and check their torque settings first. if this is not the problem then I will be an angry call to the engineering company that did the work. let me know what you think as you are all helping.

Thanks for now.

[Phred]

It would probably be enlightening to give them a call, to see if they used any gasket sealing compound on the head gasket. There is a sealing ring around the cylinders, so it's not unusual to find good compression, and water leaking at the same time. The cut outs in the gasket where the water flows can only be sealed with a really good flat surface, or gasket sealer. Even with a freshly surfaced head and block, I still will use a sealer on the gasket, a little extra insurance goes a long way to keeping your sanity. So, you have nothing to loose, and everything to gain with a retorque. From experience, if you have replaced the head bolts with the stronger turbo bolts, torque them to 60 ft.lbs. If they are the old bolts torque to 55 lbs. Sometimes the bolt torque can fool you. The bolt can take a set, so one at a time working from the center out, release about 10 lbs. (slacken the torque) and then torque up with one smooth movement. Zig-zag back and forth from the center out, put it back together and give it another go. Good luck.

Phred

[PastorMike]

Find out how to perform a leak-down test, and then do the test. You will be able to detect any leaks from the cylinders into the water jacket by listening for bubbles or hissing noises. You might need to vary the coolant level to detect the noises.

[That-hurt]

thanks chaps.

just re torqued all the head bolts down. put it all back together and its exactly the same as before. i have just sent the engineer a text asking for his opinion..

I did a few more checks. no oil in water, no water in oil. plugs are black with what looks like oil and water they are all quite wet. no overheating. no bubbles in the water. really annoyed now as I have spent years restoring this car. I have used this guy before and I have had no problems with him in the past. But this time something has been missed.

I put a piece of white paper over the tailpipe and revved the car. no water, no sign of oil. its has to be a problem with the head I cannot see any other reason.

I am going to ask around to see if anyone has a spare known good head and see if this sorts it.

If anyone has any other gems of wisdom I am all ears.

Cheers.

[Lyttek]

The FIRST THING I would do at this point is take it back to the shop that did the work. If THEY put it all together, then THEY should be looking at it. Don't get another head and swap and see if that fixes it... or really do ANYTHING else... the more YOU do to it, the more likely they'll be able to say it wasn't their problem, or YOU did something to it or whatever.