47 Dodge Oil breather cap smoking

[Built in America]

Oil breather cap smoking.

 

Thank you again for everyone that has  helped to give us tips to get our 47 Dodge 2 ton beast on the road running and stopping.

 

Keeping her strong we noticed smoke starting to slightly come out of the oil breather cap either after about 30 minutes of running, or on days that are hotter than 80°.

 

Should we be concerned or is this part of the design and purpose of the oil breather?

 

We do not smell burning oil, engine block is tight, oil pressure is ideal, all audio lines through oil filter canister are clean and running, oil pump seems to be operating correctly, etc.  In-line six runs at about 115° to 120° on Hot days. Runs below 115° that on days that or less than 80° outside.

 

Oil may need to be changed. Changed about eight months ago, and topped off last month.  Only reason I haven’t changed in 8 months is because once we changing the oil we ran the 47  maybe 20 miles over the period of time of getting her up and running.

 

Thoughts?

[Ivan_B]

I think this was recently discussed in another thread, and the general consensus was that a little smoke/steam is normal. I only found the other thread myself, because my cap was smoking also and had me worried

Is that a DIY coolant expansion tank? ?

[D35 Torpedo]

1 hour ago, Built in America said:

runs at about 115° to 120° on Hot days. Runs below 115° that on days that or less than 80° outside.

 

 

 

Thoughts?

 Are you saying it's running at 120F or 120C? If it is Celcius, you have a problem. If it is Fahrenheit, you have another problem.

[Built in America]

10 hours ago, Ivan_B said:

I think this was recently discussed in another thread, and the general consensus was that a little smoke/steam is normal. I only found the other thread myself, because my cap was smoking also and had me worried

Is that a DIY coolant expansion tank? ?

Thank you!

 

I had a feeling but wanted to double check. I’ll definitely change out the oil knowing that it’s likely lost its intention.

 

Oh yes, that actually was what apparently the old farmer did for the overflow. When we found it we figured we will leave it as is give me love the history as well as the Classic field.

 

Old fan belt and a mason jar!

[Ivan_B]

Found the threads I was talking about, turns out they are not so recent after all ?

Feel free to read through those for more information. As for the overflow tank, I do not believe it is necessary with the OEM radiator with huge top reservoir, but if it's a period-correct quality job, keep it :)

 

What about the engine temps? @D35 Torpedo is correct, you are either running very hot or cold... Are these off the dash gauge? You might want to check that with an IR thermometer.

 

[soth122003]

You usually see the steam/smoke in humid environments. These engines are not sealed so moisture can accumulate in the oil pan area and turn to steam when the engine reaches operating temp.

 

Joe Lee

[Built in America]

12 hours ago, D35 Torpedo said:

 Are you saying it's running at 120F or 120C? If it is Celcius, you have a problem. If it is Fahrenheit, you have another problem.

Good question.

 

120°F (where in the US / California)

I noticed our water temperature gauge was staying at zero for quite a while just up until the beginning of July. That was after about two months of running it on the road frequently.

 

Currently it takes about 20 to 30 minutes to reach 115°. it’s about 120° if we’re running it for longer distances and it’s a hotter day.

 

We did put a different exhaust on it. Wonder if that is not allowing the proper resistance in the exhaust manifold thus letting out too much pressure/Heat too fast.?

[Built in America]

1 hour ago, Ivan_B said:

Found the threads I was talking about, turns out they are not so recent after all ?

Feel free to read through those for more information. As for the overflow tank, I do not believe it is necessary with the OEM radiator with huge top reservoir, but if it's a period-correct quality job, keep it :)

 

What about the engine temps? @D35 Torpedo is correct, you are either running very hot or cold... Are these off the dash gauge? You might want to check that with an IR thermometer.

 

Thanks again!

 

The gauge is an aftermarket that we temporarily have mounted below the dash until we have the original gauges restored.  Thermostat runs directly into the side of the block where the original was.

Strange that the gauge didn’t read anything up until about a month ago when we started running it during hotter temperatures outside.

 

I didn’t notice that the intake tube running into the head of the block from the water pump is equally as hot as the exit line that runs from the top of the block into the top of the radiator = tells me the radiator is not cooling the coolant.  Going to clean out the radiator fins (The original ) and possibly give the radiator a flush to see if maybe there are cloggs.

 

Hopefully the water pump has not gone bad. Seems like it’s working. When we come to an idle and I press on the Excelerator the temperature drops slowly by 3 to 5° = assuming this is indicating that the water pump indeed is working and pushing more coolant back into the block when I idle up.

 

Thoughts?

[Built in America]

51 minutes ago, soth122003 said:

You usually see the steam/smoke in humid environments. These engines are not sealed so moisture can accumulate in the oil pan area and turn to steam when the engine reaches operating temp.

 

Joe Lee

Thanks Joe,

 

Hopefully that’s the case. I’m going to drain out the old oil, and replace regardless.

[TodFitch]

57 minutes ago, soth122003 said:

You usually see the steam/smoke in humid environments. These engines are not sealed so moisture can accumulate in the oil pan area and turn to steam when the engine reaches operating temp.

 

Joe Lee

Not quite. And it does not have to be a humid environment.

 

tl;dr The crankcase ventilation system on these cars only works when the car is moving. When stopped the combustion by products, which include water vapor and unburned hydrocarbons and some acid forming stuff, will escape the block the easiest way they can which is usually the oil filler cap.

 

The crankcase ventilation system consists of the road draft tube at the passenger rear of the engine and the oil filler cap. The road draft tube should extend into the airflow under the car. When the car is moving that tube will experience a slight vacuum due to venturi effect which will create a vacuum in the crank case to pull out the combustion products that make it past the piston rings and clean air to come in through the oil filler cap. To keep dirt from getting into the crankcase, there is a wire mesh air filter inside the filler cap which should be cleaned and oiled periodically to have it actually filter the incoming air.

 

In any case, this crankcase ventilation system only works when the car is moving at a reasonable speed. If the car is not moving then the combustion byproducts (water vapor, unburned hydrocarbons, etc.) that make it past the rings will accumulate in the crankcase and slightly pressurize it. Those vapors will then come out, some through the road draft tube but a lot also through the oil filler cap.

 

So it is not unusual to see some vapor or smoke coming out of the oil filler cap when the car is stopped. This will be more noticeable on engines that have more blow by (worn rings or cylinders) but will happen even on engines in very good condition.

 

If this bothers you, then you can retrofit a positive crankcase ventilation (PCV) system. The military used it way back when on their engines because they did not want a road draft tube that could let water into the crankcase when fording rivers and those PCV parts are available from the people who cater to the Dodge military trucks. Or you can rig your own. It has been a while but someplace on the in this forum there were posts and threads on how to make your own.

[Los_Control]

I would question the accuracy of the gauge.  Simply because it did not work & then it just started working is enough for me to not trust anything it says.

 

I had a aftermarket gauge installed, it seemed to work really well & I believe it was accurate .... it was old and fell apart needed to replace it.

 

The new gauge I bought from ebay & installed it, it reads 150F while I'm sure it is truly running at 180F .... From my past experience with my old gauge.

Just saying my new gauge needs replaced it is wrong ..... same time it seems to function as it should .... At idle it will creep upwards towards 160F then the T-stat opens and drops back to 150.

It has a 180 T-stat, with the old gauge it would creep up towards 190F then drop back to 180F when T-stat opens.

 

So I can use my gauge or get by with it for awhile, as long as I know 150 is really 180 .... still needs replaced though.

[Ivan_B]

When the engine reaches the operating temperature (thermostat open, cooling through the radiator), I do not believe that you'll be able to tell the temperature difference between top and bottom with your hand. Or maybe I am just a not very sensitive person

120F for a fully warmed-up engine is very cold. Check the temperature around the head with an external thermometer, etc. Could be that either your gauge or the sensor is not accurate. You should be around 190. In fact, that's when standard thermostats open-up.

[soth122003]

Hey Los, you should be able to adjust the gage so long as the difference is not more than 30 degrees. Just bent the link that connects the pointer to the tube.

 

Joe Lee

Edited August 4, 2023 by soth122003

[soth122003]

120 is low. Might be crud built up around the sensor area acting like a thermal barrier. Try a vinager flush of the cooling system to clean out the limescale and calcium in there.

 

Joew Lee

[Los_Control]

I agree with everything you say @soth122003 I'm thinking that 120F is impossible unless the car was specifically designed to run there.

Our old flatheds are going to go 2 ways, runs at 160 cool & normal & adjusted by the T-stat installed. or it overheats. .....  120F is not even a realistic number once the engine is warmed up. ..... Heck I live in Texas, there are days that 120F might be close to the outside temperature.

 

I did use the vinegar flush on mine. I think I bought 6 gallons the first time, then 4 gallons the next time. Then over a couple years I constantly flushed my engine out.

Letting the vinegar go through several heat cycles & changing every few weeks or months. Just not convinced that is @Built in America issue.

They have a crap gauge that does not read properly.

 

30 minutes ago, soth122003 said:

Hey Los, you should be able to adjust the gage

Thats true. Let me first say I chose the gauge simply for it's old school looks. ..... Not because it had a great reputation.

Simply because it was black faced with white lettering. .... Looked like old stewart warner stuff.

After I ordered it I realized the seller was in India .... it was shipped snail mail to the USA & was about 3 months for delivery. ..... Just saying.

Then when I do get it ......  My mistake I will replace it ...... I was just hoping I could use the fixings from the after market gauge to fix my OEM gauge .... that is different also and is not a candidate .... Junk is junk.

[TodFitch]

7 minutes ago, Los_Control said:

I agree with everything you say @soth122003 I'm thinking that 120F is impossible unless the car was specifically designed to run there.

Our old flatheds are going to go 2 ways, runs at 160 cool & normal & adjusted by the T-stat installed. or it overheats. .....  120F is not even a realistic number once the engine is warmed up. ..... Heck I live in Texas, there are days that 120F might be close to the outside temperature.

 

I did use the vinegar flush on mine. I think I bought 6 gallons the first time, then 4 gallons the next time. Then over a couple years I constantly flushed my engine out.

Letting the vinegar go through several heat cycles & changing every few weeks or months. Just not convinced that is @Built in America issue.

They have a crap gauge that does not read properly.

 

Thats true. Let me first say I chose the gauge simply for it's old school looks. ..... Not because it had a great reputation.

Simply because it was black faced with white lettering. .... Looked like old stewart warner stuff.

After I ordered it I realized the seller was in India .... it was shipped snail mail to the USA & was about 3 months for delivery. ..... Just saying.

Then when I do get it ......  My mistake I will replace it ...... I was just hoping I could use the fixings from the after market gauge to fix my OEM gauge .... that is different also and is not a candidate .... Junk is junk.

I am a little surprised that you did not check the gauge with some boiling water on the stove top before installing it. I like to check the calibration of any gauges I get before installing them.

[Los_Control]

Just now, TodFitch said:

I am a little surprised that you did not check the gauge with some boiling water on the stove top before installing it. I like to check the calibration of any gauges I get before installing them.

That is perfect advice for someone smarter then me. .... I have used that advice for many things in the past like my old T-stat or my old Aftermarket gauge.

 

My goal with the old aftermarket gauge was to use it as a donation to fix my original gauge.

It created a leak before I did the operation so I ordered a new gauge to do the replacement.

Then the new style gauge has no chance to be used as a donor to fix my old gauge .... I lost all interest in it ... I'm not testing it .... I'm replacing it.

$20 poorly spent. I'm just going to have to be more careful when choosing a donor for my old gauge .... one that actually has copper lines to be soldered together.

 

@TodFitch your advice is good .... when you order online & get a worthless product. You open the package & immediately  know you need to replace it.

No I was not going to test it. I just need to be more careful ordering a new part that will work for a donor.

[Sniper]

On 8/4/2023 at 11:19 AM, Built in America said:

Wonder if that is not allowing the proper resistance in the exhaust manifold thus letting out too much pressure/Heat too fast.?

 

This myth needs taken out, shot, hung, quartered, drawn and run thru the wood chipper.

 

Exhausts NEVER need back pressure.  If you have back pressure you are choking your engine.

 

https://www.motortrend.com/news/engine-masters-ep-9-busts-the-backpressure-myth-3-vs-2-5-inch-exhaust/

[Built in America]

On 8/4/2023 at 9:51 AM, TodFitch said:

Not quite. And it does not have to be a humid environment.

 

tl;dr The crankcase ventilation system on these cars only works when the car is moving. When stopped the combustion by products, which include water vapor and unburned hydrocarbons and some acid forming stuff, will escape the block the easiest way they can which is usually the oil filler cap.

 

The crankcase ventilation system consists of the road draft tube at the passenger rear of the engine and the oil filler cap. The road draft tube should extend into the airflow under the car. When the car is moving that tube will experience a slight vacuum due to venturi effect which will create a vacuum in the crank case to pull out the combustion products that make it past the piston rings and clean air to come in through the oil filler cap. To keep dirt from getting into the crankcase, there is a wire mesh air filter inside the filler cap which should be cleaned and oiled periodically to have it actually filter the incoming air.

 

In any case, this crankcase ventilation system only works when the car is moving at a reasonable speed. If the car is not moving then the combustion byproducts (water vapor, unburned hydrocarbons, etc.) that make it past the rings will accumulate in the crankcase and slightly pressurize it. Those vapors will then come out, some through the road draft tube but a lot also through the oil filler cap.

 

So it is not unusual to see some vapor or smoke coming out of the oil filler cap when the car is stopped. This will be more noticeable on engines that have more blow by (worn rings or cylinders) but will happen even on engines in very good condition.

 

If this bothers you, then you can retrofit a positive crankcase ventilation (PCV) system. The military used it way back when on their engines because they did not want a road draft tube that could let water into the crankcase when fording rivers and those PCV parts are available from the people who cater to the Dodge military trucks. Or you can rig your own. It has been a while but someplace on the in this forum there were posts and threads on how to make your own.

@TodFitch Brilliant.

 

Thank you for the elaborate explanation of how the components work together, their intentions, as well as what occurs when the vehicle is stopped.

 

Definitely learned a tremendous amount about why the geniuses designed this engine in a manner that they did; as well it’s connecting the road draft tube with the oil breather cap = we had no idea.

 

I don’t mind the minimal misting. Just wanted to make sure there wasn’t something going bad inside that was causing anything to overheat, burn, etc.

[Built in America]

On 8/6/2023 at 6:22 AM, Sniper said:

 

This myth needs taken out, shot, hung, quartered, drawn and run thru the wood chipper.

 

Exhausts NEVER need back pressure.  If you have back pressure you are choking your engine.

 

https://www.motortrend.com/news/engine-masters-ep-9-busts-the-backpressure-myth-3-vs-2-5-inch-exhaust/

Thank you Sniper!

 

Very much appreciate your professional input. That was just us troubleshooting every area possible within our “YouTube university” degree lol.  Your explanation also helped us remove one other item off the list in regards to the  optimal running conditions and if the new exhaust could be hindering.

[Built in America]

On 8/4/2023 at 9:52 AM, Los_Control said:

I would question the accuracy of the gauge.  Simply because it did not work & then it just started working is enough for me to not trust anything it says.

 

I had a aftermarket gauge installed, it seemed to work really well & I believe it was accurate .... it was old and fell apart needed to replace it.

 

The new gauge I bought from ebay & installed it, it reads 150F while I'm sure it is truly running at 180F .... From my past experience with my old gauge.

Just saying my new gauge needs replaced it is wrong ..... same time it seems to function as it should .... At idle it will creep upwards towards 160F then the T-stat opens and drops back to 150.

It has a 180 T-stat, with the old gauge it would creep up towards 190F then drop back to 180F when T-stat opens.

 

So I can use my gauge or get by with it for awhile, as long as I know 150 is really 180 .... still needs replaced though.

Thank you!

 

Good point. I should’ve gone back to kindergarten mechanics before looking past the basic logic of a newer thermostat going from no reading to  115 degrees 5 months later ?.

 

Thankfully we didn’t have to remove the water pump so I’m not quite sure what degrees the T-Stat is currently. I’ll look to pick up a different gauge. Would really like to know what we’re running it. To the touch it’s not so hot that I can’t hold my hand on the top of the block for three seconds before needing to remove.

If I recall these engines were designed to run a bit cooler than most given they stand idling and running at slow speeds working farms all day long.

[Built in America]

On 8/4/2023 at 9:53 AM, Ivan_B said:

When the engine reaches the operating temperature (thermostat open, cooling through the radiator), I do not believe that you'll be able to tell the temperature difference between top and bottom with your hand. Or maybe I am just a not very sensitive person

120F for a fully warmed-up engine is very cold. Check the temperature around the head with an external thermometer, etc. Could be that either your gauge or the sensor is not accurate. You should be around 190. In fact, that's when standard thermostats open-up.

That makes sense. Thank you again for the clarification.

 

You’re right, although I’m definitely a compassionate guy, not quite sensitive enough to properly gauge the temperatures with my hand. ?. In our 41 GMC I could typically feel a significant difference between coolant  flowing out of the block and into the radiator, compared to the line of coolant flowing from the bottom of the radiator up into the water pump = seems not as significant of a difference in our 47 Dodge.

[Built in America]

On 8/4/2023 at 1:47 PM, soth122003 said:

120 is low. Might be crud built up around the sensor area acting like a thermal barrier. Try a vinager flush of the cooling system to clean out the limescale and calcium in there.

 

Joew Lee

Thank you that’s a good point as well.

I’ll double check with our team but I think when we cleaned out all fluids  in the beginning they did a vinegar soak but will confirm - they might’ve just done a flush with water.

[Built in America]

On 8/4/2023 at 4:00 PM, TodFitch said:

I am a little surprised that you did not check the gauge with some boiling water on the stove top before installing it. I like to check the calibration of any gauges I get before installing them.

That’s true - I should have.

 

It’s a shame we can’t trust where things are made nowadays. Pretty sure we made sure that the replacement was made in the US.  Regardless will give the corner flush as it likely needs it, easy enough to pull the temp gague.

[D35 Torpedo]

Back pressure typically will help low rpm and hinder high rpm power. My guess is with a smaller exhaust, the exhaust speed is greater at low rpm vs a large exhaust. The exhaust speed helps scavenge the cylinders, creating more torque. A large exhaust has sluggish exhaust speed down low, making for poor performance until engine speed comes up to where the exhaust speed takes off. At that point the engine makes great power and the exhaust flow exceeds that of a small system. So generally, depending on the engines displacement and rpm range, there is an exhaust size that isn't to small or to big. This is why guys will put exhaust cut outs on there cars for racing. So they can have the best of both worlds. Usually, factory exhaust is on the small side and increasing it will do little to no harm.