/6 rebuild advice

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SoCal mopar

SoCal mopar

Mopar Dude
Joined
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Simi Valley
I just purchased for relatively cheap, a 2 door, 72 Dart /6 255, automatic 3. Car had been sitting for years before I got to it, supposedly :BangHead: oil looks good, brakes work good, no ticking, dies at a stop sign (what ever), points not electric, and is a vacuum nightmare, front end needs everything of coarse ......all things I can do....

Looks like the rear main seal is leaking which I am hearing is a small project.... easier to remove the engine to fix...... and taking the car for the longest drive I've done yet, it over heated....... cooled off fast, and while topping it off with water to get home I noticed it had a milky, foamy, substance ? in the radiator neck .....

I have a 318 sitting in my garage.... but.... knowing swaps aren't always/ever direct swaps/easy, would it be CHEAPER/easier to rebuild the 6 or put the 318 engine in, in its place?

My first /6 car..... I only want a reliable fun driver, nothing hot......

Thanks in advance.

Any solid or recommended mechanics in the Thousand Oaks / Camarillo areas in SoCal would be nice.
 
Change the oil/ replace the thermostat, make sure it holds water/antifreeze. Drive it again. Check for vacuum hose leaks or might need a carb rebuild. Sit for 3 years causes problems. The oil leak may slow or stop. Make minor repairs and re evaluate.
 
GRAB the carburetor by the very top of it and twist it back and forth. Pay close attention if it moves either on the manifold, OR if it moves independently of the base plate, just look for any movement at all. It's very common for the gaskets to shrink over time and this will loosen the fasteners that hold the carburetor on the intake as well as the screws that hold the carburetor together. Lots of times you can tighten everything up and it will make a world of difference.
 
i agree with giving it another go thru before deciding that it's rebuild time. sitting dries up and shrinks gaskets, allowing fluids to get where they're not supposed to be. get it all up and running again and sometimes those intermingled need time to burn off, gaskets swell back up (or blow out completely).

the milkshake in the radiator is indicative of water in the oil. which could be any host of things from simply condensation from sitting for years to a seal/gasket failure to a compromised (cracked) engine component. but it's entirely dependent on how much milkshake you have going on, and then how far you want to chase a repair.

with the price of parts and machine work costs these days, there's no real savings between rebuilding a /6 or a standard production V8. however, the real expense in upgrading to a V8 is all the peripheral things and stuffs: bigger radiator, transmission, swap/conversion motor mounts, exhaust, and a whole laundry list of ticky-tacky items like belts & hoses, ground cables, trans cooler lines, fittings, fuel line, minor electrical, etx.

anyway, i'm over the hill from you the other way in the SFV. give a shout if you need anything, i'm happy to help with whatever from parts to dropping in a V8.
 
I appreciate it guys.

The coolant is flashing off somewhere as the oil reservoir at this point still shows good oil / high level but clean so far. The milky film is interesting / thick enough to block out the green coolant, but thin layer. No froth on the valve train / rockers, in sump.... I will look more.

I've got a thermostat in my box of replacement parts.

I am going to take off most of the Emissions equipment and eliminate hoses that aren't needed. Clean up the vacuum hoses. I will check the carburetor bolts.

The rear main leak isn't bad. But if I do price out the parts and its ***$, when is it worth it for a rebuild / replace? I've had my 73 charger 318 for decades. It leaks. As long as its a slow leak I'm good.

I actually bought the car in van nuys / North Hollywood
 
Ron Sanders said:
I appreciate it guys.

The coolant is flashing off somewhere as the oil reservoir at this point still shows good oil / high level but clean so far. The milky film is interesting / thick enough to block out the green coolant, but thin layer. No froth on the valve train / rockers, in sump.... I will look more.

I've got a thermostat in my box of replacement parts.

I am going to take off most of the Emissions equipment and eliminate hoses that aren't needed. Clean up the vacuum hoses. I will check the carburetor bolts.

The rear main leak isn't bad. But if I do price out the parts and its ***$, when is it worth it for a rebuild / replace? I've had my 73 charger 318 for decades. It leaks. As long as its a slow leak I'm good.

I actually bought the car in van nuys / North Hollywood
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Well, unless you're a glutton for punishment, the engine needs to come out for a rear main seal. lol So do the math I reckon. If you pull it, that's a lot of work for replacing a seal and putting it back with a lot of unknowns.
 
I completely agree and that is mainly the question. IF i have to go down that path given the challenges I'm facing, it might be worth it to just bite the bullet and upgrade with rebuild or swap..... Small blocks I know, /6 I'm learning.... Parts are getting harder to find and more expensive to buy.

Appreciate it guys.
 
Ron Sanders said:
I completely agree and that is mainly the question. IF i have to go down that path given the challenges I'm facing, it might be worth it to just bite the bullet and upgrade with rebuild or swap..... Small blocks I know, /6 I'm learning.... Parts are getting harder to find and more expensive to buy.

Appreciate it guys.
Click to expand...
The only thing about the slant 6 is, it will never be a V8. You can turbo it, blow it, nitrous it, but it will never be a V8. That said, there are some record breakers out there, but they are some NASTY little engines and not "real" streetable. Slant 6 guys build them for the love of the engine and to be different. I can tell you FIRST HAND who gets the most looks at our local cruise ins. I do. I kinda like it. When they hear us pull in the parking lot, they caint believe it's a six when they see under the hood. Here's mine.
 
Ron Sanders said:
I appreciate it guys.

The coolant is flashing off somewhere as the oil reservoir at this point still shows good oil / high level but clean so far. The milky film is interesting / thick enough to block out the green coolant, but thin layer. No froth on the valve train / rockers, in sump.... I will look more.

I've got a thermostat in my box of replacement parts.

I am going to take off most of the Emissions equipment and eliminate hoses that aren't needed. Clean up the vacuum hoses. I will check the carburetor bolts.

The rear main leak isn't bad. But if I do price out the parts and its ***$, when is it worth it for a rebuild / replace? I've had my 73 charger 318 for decades. It leaks. As long as its a slow leak I'm good.

I actually bought the car in van nuys / North Hollywood
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you stay outta my hood homie!

i'd tackle the running/over heating first before the leak as long as it's not too egregious.

yank that t-stat, run some motor purr drive & flush thru there (per the directions on the bottle), slam in a new t-stat and see where you're at.

sounds like a solid plan on the carb. prob put in a order for a carb kit and give that the ol' run around and make a plan of action from there.
 
Unless you do good finding a whole car for the extras you need that don't interchange from /6 to a v8, you're better off rebuilding the/6. Trans radiator, mounts, exhaust, for starters, are different between/6 and v8
 
The milky foam has kinda got me in awe. I've had rusty jackets which were a done deal. I'm used to looking for oil in the pan not in the radiator. I know its possible but didn't expect it. I have a thermostat and will pull the water pump as well.
 
Ron Sanders said:
The milky foam has kinda got me in awe. I've had rusty jackets which were a done deal. I'm used to looking for oil in the pan not in the radiator. I know its possible but didn't expect it. I have a thermostat and will pull the water pump as well.
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I say run it. See it if boils out of the oil. Give it a chance. It may take a while. When they sit up, moisture collects from condensation that forms inside the engine and falls into the pan and other areas, contaminating the oil. I wouldn't condemn it until you run it a good bit. Don't change the oil right away, because you won't get it all out if you do. Give it time to evaporate most of it out. You'll see it clear up slowly if it's going to.
 
^^ i concur.

run it and see what transpires.

i had a motor that just got a top end and it had very thin band of milkshake on dipstick every morning for a good while till it eventually boiled out all the funk and everything sealed tight.
 
Just to clarify guys, the coolant has a layer of milky froth on top of it. The oil in the sump is perfect. . .

Checked the radiator tonight and the froth is gone/coolant color back to bright green......

I am going to do a compression / leak down test to rule out head gasket.

Fingers crossed....
 
Ron Sanders said:
Just to clarify guys, the coolant has a layer of milky froth on top of it. The oil in the sump is perfect. . .

Checked the radiator tonight and the froth is gone/coolant color back to bright green......

I am going to do a compression / leak down test to rule out head gasket.

Fingers crossed....
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I don't think you have a have gasket issue. Sounds like condensation to me, especially if it's gone now.
 
Ron Sanders said:
Just to clarify guys, the coolant has a layer of milky froth on top of it. The oil in the sump is perfect. . .

Checked the radiator tonight and the froth is gone/coolant color back to bright green......

I am going to do a compression / leak down test to rule out head gasket.

Fingers crossed....
Click to expand...
both great tests for overall condition of the motor, but add in a combustion leak detector and you'll have the whole story.

you can rent the tool from vato zone or amazon/harbor freight sells 'em cheap too.
 
if it has stood for a long time, id expect all kinds of crap in the coolant
i'd also expect mayonnaise in the oil filler cap caused by condensation in the block dripping in the oil, for years.....

dump both oil and coolant flush cooling system
whack in some K seal and plain water for 100 miles nice hot miles

dump that do not leave it sitting in there

Replace with proper coolant

enjoy, anything needing doing will now be apparent over your known good baseline

Dave
 
Skip the k seal... You won't need anything like that
 
That sounds nice! The cam definitely elevates the /6's game.
RustyRatRod said:
The only thing about the slant 6 is, it will never be a V8. You can turbo it, blow it, nitrous it, but it will never be a V8. That said, there are some record breakers out there, but they are some NASTY little engines and not "real" streetable. Slant 6 guys build them for the love of the engine and to be different. I can tell you FIRST HAND who gets the most looks at our local cruise ins. I do. I kinda like it. When they hear us pull in the parking lot, they caint believe it's a six when they see under the hood. Here's mine.
Click to expand...
 
Compression was great - 145 / 145 /145 /145 / 140 / 150
Hopefully leak test and thermostat tomorrow.....

I think I killed my starter but after many rotations, with breaks, it rose to these levels.
 
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Decided to do an exhaust gas test on the coolant. Noticed with a warm engine and with the cap off, I got a couple good bubbles that burped out the radiator neck. Expansion / contraction without an overflow bottle - maybe

Blue stayed blue so no exhaust present in the radiator…. I think the coolant is flashing somewhere though….

…… I thought the smog pump was an AC component. Glad I looked that number up. ️TRASH!

So far cylinders and head gasket appear
In good shape.

Thermostat next….
 
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