289 help.. white smoke

02minstang

New Member
Oct 28, 2004
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I have a 67 coupe 289 with a 3 spd i just recently started playing with again after 8 years. The car idles fairly good but white smoke that dissipates fairly quick shoots out the exhaust. I was thinking coolant and head gaskets. So I replaced them with no change. Then, I pulled the heads and had them magna fluxed and they are in good shape according to the machine shop. The intake manifold looks good too but hasnt been professionally inspected. The bores, pistons, rings etc look great from what I can see. Do I have a cracked block? Or, the carb needs a rebuild badly. Could it be dumping un burnt fuel through the exhaust and look like white smoke? There is a very strong exhaust smell. Im basically lost as to what to do from here. Im gonna borrow a carb from a buddy and see what happens. After that i dont know. Also, the previous owner said it would overheat down the road but will idle all day.. I realized there was no thermostat but that shouldnt matter..:shrug: Sorry for the long post. Any help is appreciated.
 
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Unburnt fuel is black.

From my understanding (which could be wrong), you need the thermostat to help slow down the movement of coolant or else it moves to fast to cool the block.

Are you going through coolant? Do you have to top it off to drive down the road?
 
Unburnt fuel is black.

From my understanding (which could be wrong), you need the thermostat to help slow down the movement of coolant or else it moves to fast to cool the block.

Are you going through coolant? Do you have to top it off to drive down the road?

I pretty much thought everything you said was set in stone but I had to be sure. I dont know for sure if I am burning coolant or not. Just a guess because of the color. I havent got it back on the road yet. Also, there is no coolant in the oil. I will put the thermostat in and see what happens but it still wont solve the smoke problem. Thanks for the reply.
 
Usually, if you have coolant going into the exhaust, some compression will leak back into the radiator as well. And ditto on needing the thermostat, it definately needs one. Without it, it takes longer for the motor to warm up, but when it does, it wil usually overheat due to the coolant circulating too fast.
 
the white smoke could be normal from condensation in your exhaust. Before ripping the heads off and doing all kinds of work, you should start by checking the basics. Are you losing coolant? How do the spark plugs look? The carb sat for 8 years without use? It probably needs a rebuild. Check those things first.
 
From my understanding (which could be wrong), you need the thermostat to help slow down the movement of coolant or else it moves to fast to cool the block.
A closed thermostat restricts the flowrate of engine coolant... thereupon reducing the amount of heat dissipation via the radiator... thereupon allowing the engine block to raise it's core temperature during the "warming up" phase. At a preset temperature, the thermostat begins to open, thereupon allowing greater flowrate of engine coolant to the radiator, thereupon dissipating excess core temperature in the engine block - ideally on an "as needed" basis.

When the McLaren F1 Team won 2 championships in'98-'99 with Mika Hakkinen, one of the design breakthroughs that year was the Mercedes (Illmor) 3 litre V10 engine was made some 20% smaller, allowing it to run hotter without integrity issues, thereby producing greater horsepower. Core heat is actually a good thing in an engine - assuming your intake air charge maintains a low (as in dense) temperature prior to the combustion chamber. The maximum horsepower per gram per hour figures being produced today hover just on 39.5% of fuel burnt, and they remain F1 engines. Most road engines would be lucky to break 32% of potential to realised energy conversion. It doesn't seem much, but that extra 6% of energy liberation per gram of fuel burnt creates a great deal of difference at the back wheels.

But I digress. Back to your regular channel.
 
the white smoke could be normal from condensation in your exhaust. Before ripping the heads off and doing all kinds of work, you should start by checking the basics. Are you losing coolant? How do the spark plugs look? The carb sat for 8 years without use? It probably needs a rebuild. Check those things first.

Im not 100% if its losing coolant but it was very low. Spark plugs definitely say shes running rich. Lots of soot and buildup with minimal run time. It idles perfect and has just a bit of sluggishness when you stomp on it but quickly works past it. I know the carb needs a rebuild but probably not bad enough to be the culprit of my problem. I was thinking possible condensation in the exhaust because Ive seen that too with my 03 cobra at times but I dont think that is the case here. Usually you can blow it out with a couple hard runs but thats not the case here. Thanks for the replys guys. I just find it really hard to believe its a block. But, as stated I will go through everything once again taking my time to reassemble the top end and throw in some block sealer.
 
Well you can start now by filling up the coolant all the way and giving it some run/drive time and keep checking the coolant level. I suggest to drive it one day, then check it the next morning, drive it again, check the next morning, that way it is consistent with what temp you are checking it and so forth. Is your white smoke problem happening when the engine is at operating temp? Is it worse when it's cold?