49 flathead exhaust water and smoke

[SRV49]

I'm beginning to notice a little water and smoke from the exhaust. It continues the entire time I'm driving. Any thoughts?

[Lawson Cox]

White smoke is water vapor. Could be just condensation till it warms up or if it is a lot of white smoke it could be blown head gasket.

[tubman]

What thermostats are you running (if any)? Back in the day, a lot of guys were into running low temperature (or none) thermostats to try to solve overheating problems. If you're lucky, your engine is running too cold. and some 180 degree thermostats may solve your problem. If not, a thorough cleaning of the block and radiator may help.

[Flathead Fever]

It's hard to tell sometimes when it's cold out and there is high humidity. You will get a cloud out the exhaust on those days that will look like a bad head gasket. If your running coolant and you have a head a gasket leak or a crack, the exhaust will have white smoke and smell sweet. It you have dual exhausts it will only be on one side unless something really bad happened. If it's a small leak it will smoke when you first start it and then clear out and run fine. It might have a misfire when it first strarts until the coolant is burned out of the cylinder. The sparkplug and combustion chamber in the leaking cylinder will look shiny brand new because the coolant steam cleans them. You can try to retorque the heads which if does work will probably be a temporary fix.

On vehicles that could not pass the smog test because of high NOX I would pour water down the carb while its running at a high idle rpm and the steam removed the carbon which lowers the compression ratio just enough to lower the NOX reading and pass the smog test. You can look for the presence of coolant in the oil. You check to see if the radiator is losing coolant, if not that smoke out the back is probably from condensation in the exhaust pipe.

You try to isolate the leak to one side of the engine. You remove all the plugs and pressurize the coolant system with a special tool to only 4 lbs. on a flathead or you can split the narrow solder joints on the original radiators. You let it set under pressure for a while and then crank the engine and if there is a leak it will spray coolant out of the plug hole. If it's a very small leak it will be hard to find. If one head gasket is leaking replace them both, the other one is probably ready to fail also.

I made mistake at work one day and luckily it was a phone company fleet. When you screwed up nobody cared how much it cost, we just raised your phone bill. I rarely made a mistake. This was a costly mistaje in parts and Labor. A 1991 V10 F350 aerial boom truck pulled up in front of the garage with pure white smoke billowing out the back, I could smell the coolant, Automatic head gasket diagnosis without opening the hood. I told the driver to park it on the side of the shop. About four-hours later I went to get it. The starter cranked about one revolution and just went clunk-clunk-clunk. The leak was so bad it filled the cylinder up while it was shutoff. Those little gear reduction starters are stronger than you think, it bent the connecting rod, put a curved smile in it. I ended up putting a Ford factory rebuilt short block in it. Those overhead cam V10s take a while to change over all that stuff. I would have had to pull all of that stuff to replace the head gasket but at least I wouldn't have had to pull the entire engine. I will never let a running engine with a head gasket leak shut off until it's in the stall where I'm going to work on it, I will not crank the engine until I have removed the plugs. I'm retired not and that bent rod is hanging in my garage as a reminder. Here it is, I wasn't an ASE Master Mechanic on that day.

[SRV49]

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Thanks for the input. Very helpful. I'll drive it for a bit and then see what it's doing. If it's head gaskets or more I will need to find someone local who has experience working on flatheads. I don't have the expertise, space, tools or knowledge (especially the knowledge aspect!!).