1952 Air Cleaner, Heater Duct, & Temp Gauge Questions/help

[Don Coatney]

I still do not understand the source of pressure inside the tank.

[JerseyHarold]

You mentioned that the muffler was replaced in July.  Did you notice this issue before that time?  I'm wondering if the exhaust pipe was routed too close to the fuel tank, causing the gas to vaporize and expand.

[desoto1939]

Yes and only use the green antifreeze not the extended yellow stuff.

 

Rich HArtung

[Robert Horne]

I still do not understand the source of pressure inside the tank.

Atmosphere temperature change from cool to hot can make the gas tank have more pressure if the fuel cap

 

is not vented on our old cars.

 

I had a  situation with and engine change from a diesel engine to a gas engine.      My truck sitting in the driveway

 

late one morning had gas coming out the carb, after the truck had been sitting in the morning sun.     I opened the fuel

 

cap, and the carb stopped leaking.        I had to put a small hole in the fuel cap.      The temperature rising made the fuel

 

pressure rise.....

[TodFitch]

. . . is not vented on our old cars. . . .

The gas cap on my old Plymouth is definitely vented. And it wasn't just drilled by some previous owner, it is obviously part of the design.

 

So I'm with Don C here:

 

I still do not understand the source of pressure inside the tank.

[Don Coatney]

Question for the original poster. Does this supposed pressure in the gas tank build up when the car is just sitting in the sun? Or does this supposed pressure build up after driving a few miles?

[Robert Horne]

The gas cap on my old Plymouth is definitely vented. And it wasn't just drilled by some previous owner, it is obviously part of the design.

 

So I'm with Don C here:

This is true, our old cars should have vented fuel caps.        If the cap is working properly pressure should not build

 

up.

 

My 38 has a non vented cap, fuel tank from a Datsun 1978, that has a vent hose, I ran to the air cleaner.

 

My Coupe runs on "fumes".....

[Tones52]

I'm now trying to flush the Prestone cleaner from the cooling system. I'm on my 2nd fill and drain now. At the pace which I work and interruptions (like hitting Disneyland yesterday with my daughter now that the summer block out dates ended on our annual passes), I should be done by the end of the week with this.

 

Don - I am starting to more carefully monitor when this occurs. Generally the car is parked in the garage and the pressure build up I first noticed when putting gas in the tank the first couple of times. While it did have a vented cap, I noticed the rubber seal was a bit tattered around the edges so I picked up a new vented cap earlier this week.

 

Now these past couple of mornings, I'd check to see if there's pressure in the tank and so far none. All appears normal. But yesterday in the late afternoon, I drove to Costco which is about 4 miles away. The temp outside was in the high 90's. The temp gauge needle was just a hair over midpoint (water & Prestone cleaner).  I came out of Costco some 20 minutes later and checked the gas cap and that whoosh of pressure and smell of gas came out. Now if I had been really smart, I'd have video taped it with my phone.

 

Robert's take about the impact of hot temps outside on the fuel in the tank sounds like it might be factor at play here. Compounded maybe by my not having the carb/timing dialed in like it should be.

 

Let me over the course of the week monitor/log what's happening and I'll share it out. But know how much I appreciate the answers provided so far.

 

Tony

 

 

[Don Coatney]

I dont think your new gas cap is vented. Next time after driving to Costco place a plastic bag over the gas fill tube before removing the cap and hold it tight to the fender with one hand. Then twist open the cap from the outside of the bag with your other hand and report what happens to the plastic bag. I believe you will find that it will not balloon but instead be pulled towards the tank by a slight vacuum.

[Tones52]

Well, the payback for going to Disneyland while my wife's at work is that I've been laid up a bit with a bad summer cold. So, I've taken it easy these past few days.

 

I managed to fill and flush the cooling system, draining from the block and radiator 5 times. This is the clearest I could get the water. Wish I could flush it like some of the other members recommended but water is "Blue Gold" in my area and I wasn't going to let anything go down the storm drains either so I filled with water, run it, let it cool and then drain it.

 

I returned the Walmart Super Tech coolant and filled the cooling system with near 2 gallons of the original green Zerex (thanks Rich) and 1 gallon of distilled water. I'm using the NAPA 160 degree thermostat.

 

It was hot (high 90's) and humid today. I ran a couple of local errands and all seems OK driving the car and seeing the Temp gauge not creep beyond its midpoint but the real test will come when I hit some stop and go traffic.

 

As for the fuel tank pressure issue, I did get to try Don's suggestion (thanks Don) this afternoon after the errands and leaving my Plymouth parked out in front of the house instead of the garage. The plastic bag did balloon up and there was a strong gas smell. Fuel tank is a little less than half full. (Note to self, no cell phone in hand when putting gas in this car!)

 

In the garage in the mornings, I'd twist the gas cap off and no pressure sounds whatsoever.

 

On the air filter, I'll look to see about moving the mounting location of the bracket but in the meantime, I'm using a large nut as a spacer which is keeping the air cleaner square on the carb.

 

And was mentioned previously, it's seems that my Cranbrook has the "less delux" heater/defroster (Model 101) but at least it works.