/6 rebuild advice

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SoCal mopar said:
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.
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It might surprise you that your leaky rear main seal is actually a leaking oil pressure sending unit over by the Distributor. Leaking down to the pan seam and down like a leaky rear main.

Cheep easy fix with a new sending unit.

Good Luch with the project.


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George Jets said:
It might surprise you that your leaky rear main seal is actually a leaking oil pressure sending unit over by the Distributor. Leaking down to the pan seam and down like a leaky rear main.

Cheep easy fix with a new sending unit.
Click to expand...
always worth a look because those are a known culprit!

a miserable job (i mean, not nearly as bad as a rear main, but still) so plan on lots of brake clean and rags. it's even more fun if somebody has plumbed in the pick up for an aftermarket pressure gauge!
 
I’ll look into that for the oil leak.

160 Thermostat didn’t work. Although according to the gauge the cap popped at 180 ish….

But it didn’t overheat on the dash?

Im going back to Napa tomorrow and am going to put in a 180-195 thermostat.....

I am going to put on a 13-15 pound cap to ensure accuracy.

I am going to add a reservoir which mine is missing....

Because this is the second time it has heated up under load I am going to take it to a radiator shop and have it flushed to see what they find. In town the temp is 130ish and stable so far.

The car is a dog in the acceleration area. I am going to learn all about timing and points next....

I appreciate your guys input as so far. I agree and don't think a rebuild or head gasket is on the table yet.

For the reason of rebuild advice this thread could be closed. IF you guys want to follow my progress I will start a new thread.
 
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volaredon said:
Skip the k seal... You won't need anything like that
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True not totally necessary

but as i'm never sure what type of head gasket is used .......
a monotorque uses plastic or fibre rings around water ways and oil ways

some of the older ones use metallic rings
as the coolant PH will drift when its left for years a little dash of the magic in a bottle might help if those metallic bits have started to corrode, corrosion takes up more space than the metal that was there before but its porous

completely appreciate that putting powdery glue in, is not everyone's idea of a sensible move

but it works and you avoid the awful mess it can make of a compromised cooling system. if you take it out once you have given it a short time to do any job it might need to do.

not taking it out is the problem....

Dave
 
I changed the rear main seal in my 1964 slant when I had the oil pan off (lift engine 3" above K-frame). Not hard. The seal is in an aluminum block, separate from the main bearing blocks (unlike the V-8's). Same PN as Hemi engines. While the seal block is out, verify the tapped holes for the oil pan bolts aren't stripped (common) since a chance to fix 'er with Helicoil insert. I'd also replace rod bearings while in-there since often show dirt tracks. Pull one main bearing cap to check. If still silvery top coating, it is fine and likely the other main bearings are also. I used a silicone pan gasket from Real Gaskets of TN (also valve cover).
 
What's your thoughts on those "real" gaskets?
I have them in mine as well but haven't run my engine in quite a while so the oil sits in the sump below gasket level. I've heard nothing but bad news about their gaskets, a good idea on paper but not in practice...
I bought 2 of each when I bought them to have spares ..

Also on the talk of K seal above I've never seen anything but the metal ring type head gasket on any /6... No plastic rings
I don't think that "technology" was out yet when this engine was in production
 
I’m a sucker for slant sixes so I’d stick with it. Here’s a question: are you sure it’s ENGINE oil in the coolant? Not ATF? The internal radiator/trans cooler could have corroded through causing intermingling of coolant and ATF. Just something I thought of to check before you get too crazy into it! A new radiator would solve and may not be a bad idea anyway if it’s old and clogged.
 
volaredon said:
What's your thoughts on those "real" gaskets?
I have them in mine as well but haven't run my engine in quite a while so the oil sits in the sump below gasket level. I've heard nothing but bad news about their gaskets, a good idea on paper but not in practice...
I bought 2 of each when I bought them to have spares ..

Also on the talk of K seal above I've never seen anything but the metal ring type head gasket on any /6... No plastic rings
I don't think that "technology" was out yet when this engine was in production
Click to expand...
They are very clear on "don't overtorque". Since the torque they spec is so low, I clean the oil pan bolts and holes well and use thread-lock. That is after first bolting it up all around, then go back and threadlock each bolt w/ proper torque. I don't have a small torque wrench so use hand-feel, which is pretty close (1/4 drive ratchet handle). I suspect people who have problems are less careful. Real Gaskets began w/ aircraft engines, which are much more critical. Some of their silicone gaskets have woven fibers inside for strength. Expensive (~$35) but should last forever if you don't overtorque to cut them.

I think the best pan sealing is with a cast-aluminum cover with a silicone O-ring type gasket captured in a U channel. You torque until metal-metal contact and the silicone is properly compressed. Same idea as a "face O-ring" seal. My 1996 Plymouth 2.4L valve cover is like that (DOHC w/ sunken spark plugs). The oil pan is traditional stamped-steel w/ flat hard gasket, though has never leaked. My 2002 Chrysler 3.8L valve cover is stamped steel with silicone gasket, but not captured in a channel. It has hard plastic washers at each bolt hole so you can bolt it tight without over-squashing the silicone. Better than classic Mopars, but still leaks reported by many owners, especially the rear valve cover (gets hotter) though sometimes might instead be dripping down from the PCV valve. I've had to change mine several times. Leveraging that, the Real Gaskets design might be better if it had hard plastic washers at each bolt hole to allow tightening the bolts more without over-squashing the silicone.
 
volaredon said:
What's your thoughts on those "real" gaskets?
I have them in mine as well but haven't run my engine in quite a while so the oil sits in the sump below gasket level. I've heard nothing but bad news about their gaskets, a good idea on paper but not in practice...
I bought 2 of each when I bought them to have spares ..

Also on the talk of K seal above I've never seen anything but the metal ring type head gasket on any /6... No plastic rings
I don't think that "technology" was out yet when this engine was in production
Click to expand...
I don't like them. I tried their valve cover gasket. No matter what I did it leaked like a busted dam.
 
SoCal mopar said:
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.
Click to expand...
#1 Do a compression check. All cylinders fairly even? Good. Move on to #2 If you've got a wonky pressure number, do a leak down test. Air will go one of three places: Out the exhaust, up through the carburetor or up through the rad. If it's intake or exhaust, you have a bad valve and need to pull the head. If you have bubbles in the rad, it's a head gasket and the head needs to come off.

#2. Do a pressure test on the cooling system. Hold pressure? Good. Milky oil is probably condensation. Not hold pressure? Probably a blown head gasket. Fairly easy fix. Little known fact. Chrysler was notorious for milling cylinder heads flat and not bothering to have the combustion chamber volumes in spec. Take the head in to check the valves, guides and measure the two end combustion chambers for volume. If it needs valves and/or guides, do that first, then check volumes. I pulled a stock head off of my '79 225-2V and milled .030" off it to JUST bring it into spec. Taking .100" off will get you about 9.0:1 compression.
 
SoCal mopar said:
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.
Click to expand...
My vote would be to repair the 6. You could put in a mild cam and the Super Six 2V intake. Split exhaust manifolds like Dutra. Use an X pipe to keep the noise down. Rusty would be a good one to listen on the slant.
Seeing as how the foam is gone, probably a good idea to replace the thermostat and drive it.
When doing a compression test, 4 or 5 hits on compression should do the job. The first 2 should get about 90% of the final after 5 compression strokes.
 
Last edited:
volaredon said:
What's your thoughts on those "real" gaskets?
I have them in mine as well but haven't run my engine in quite a while so the oil sits in the sump below gasket level. I've heard nothing but bad news about their gaskets, a good idea on paper but not in practice...
I bought 2 of each when I bought them to have spares ..

Also on the talk of K seal above I've never seen anything but the metal ring type head gasket on any /6... No plastic rings
I don't think that "technology" was out yet when this engine was in production
Click to expand...
I have one of those silicone valve cover gaskets. It's ok, but I don't think it is worth paying extra over cork or rubber in hindsight. Now if someone made a one piece oil pan gasket...

Also, I have swapped a slant six rear main seal without pulling the engine. Annoying but a bit less work. You will want a "Sneaky Pete" from Lisle Tools. 27000 Sneaky Pete
 
Sneaky Pete - going to have to remember that guy.

I am going to pressure wash the engine and add the black light dye to the oil. After a couple days see if it is or isn't the seal.

Fortunately the radiator was the over heating culprit and I am pretty sure I have a vacuum leak causing a loss of power. A few problems with my new car causing me to think ahead to a possible engine change.
 
Mine ran hot when I got it and had no acceleration. Poor thing couldn't get out of its own way. Found the float set wrong on the "remanufactured" carb, stuck heat riser, stuck mechanical advance, and blown a vac advance can.
 
SIX225 said:
Mine ran hot when I got it and had no acceleration. Poor thing couldn't get out of its own way. Found the float set wrong on the "remanufactured" carb, stuck heat riser, stuck mechanical advance, and blown a vac advance can.
Click to expand...
All things I’m going to have to try and figure out.
 
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