Last owner apparently not a big fan of changing the oil

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73-Duster

73-Duster

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I recently bought a 1973 Duster with a /6 I eventually want to swap the engine but for now the current engine will have to do. I took off the valve cover and a good amount of the gasket was missing. And there is quite a bit of sludge. Baisically I have two questions. 1 whenever I would accelerate there was a sucking sound. Could this have been caused by the parts of the gasket missing? And 2 because of the sludge would you guys just suggest cleaning the cover,rockers, push rods ect. Or should I further tear down the engine? If so how much? Proboally some stupod questions but im still rather new to engine work. Thanks for any help!
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Actually it doesn't look all that bad - for 30 years ago before the prevalence of modern oils. But now with modern oils, you're right, it should look cleaner inside. If it is running half way decent, I wouldn't tear into any more than I needed to. Try some detergent oil additive that you add to your oil to help dissolve the crud. You add it to your oil, run the engine to warm it up, then drain the oil and crud out. Afterwards, just use some high quality oil and it will probably be fine.

The valve cover gasket isn't the source of the "sucking" sound, a major oil leak yes, but not a "sucking" sound. Depending on the type of air cleaner sitting on top of the carb, it could just be the un-silenced noise of the air being drawn into the carburetor. If it is not that, it has to be a vacuum leak in the induction system and if that leak is so big that it is making a "sucking" sound, the engine is probably running like crap.
 
Yea. that's how they look. It looks normal in there. Install a new gasket and you should be fine
 
2 ways to go about this:

1) Clean out the valve cover, loosen up the valves and take the rail assembly off and clean it out..with upper looking cruddy, makes me wonder what the inside cavity of the oil rail looks like.... clean the upper and drain the oil...put the plug back in the pan and then flush the system again with a mild solvent...let it sit for a moment.. drain again. Put fresh oil and a good filter on it with something like MM oil added in...Readjust valves and drive... Change the filter every 1500 miles...Repeat every oil change until flush out isn't chunky/black tar-ish anymore.

2) Just clean out the valve cover, change the oil + add something like MM oil and change the filter every 1500...Should eventually get clean.
 
Buy some Motor Flush (I forget who makes it) and follow the directions.
Change the oil with a cheap dino oil and new filter and add a quart of Marvel Mystery oil
Run it for 1k miles or so and change it to your preferred oil and filter, because at that point it will be nice and clean
 
RzeroB said:
-- The valve cover gasket isn't the source of the "sucking" sound, _ _ _ a "sucking" sound, could just be the un-silenced noise of the air being drawn into the carburetor. If it is not that, it has to be a vacuum leak in the induction system --
Click to expand...
-- Yep !! - Also check to see if the carb, and intake are tight.
 
I had an old girlfriend that had a Malibu. Like 1979 or 80... Anyhow I did her family a favor once & changed the oil in the little 267 V8 that it had (2bbl). The valve cover gaskets were leaking onto the exhaust manifold so I bought some FelPro's and went to replace those too... As I removed the valve cover I see a hardened shell of oil & gunk formed to the shape of the inside of the valve cover that REMAINED IN PLACE when I took the cover off. It looked like it still had valve covers on it. No joke. THAT was the worst I had ever seen.

That engine lasted about six more months. I swapped in a junk yard 350 (kept the 2bbl on there) as a favor later too. Girlfriend had a fast tire spinning Malibu after that. :)
 
I bought a 68 Valiant parts car once and the owner had bragged how he never ever changed fluids in any of his cars. That's not something you tell someone who your trying to sell a car to.
 
IMO, that is not bad at all. You have no idea the kind of crap that actually takes place. The stories above are true since I have experienced similar and exactly the same things.

What you have is nice.

IMO, just change the oil and filters as normal. A step in the right direction that would also be good is to remove and clean. Also inside the shafts.
 
That sucking sound is coming from your wallet. Welcome to the world of Mopars.
 
If you were to run the engine with the cover off, you would see how the oil flows in there and how the high spots and lower areas catch only little splash droplets that just sit there and age. A flush product wont get to the high spots to wash it. The more you disturb that stuff the more will fall in and go to your oil pick up screen. Might be best to just close it up. Or pull the oil pan and clean it all including the pickup screen. Me, I think I would wait until it needs a timing chain.
And about a fuel flush i.e. diesel or kerosene, not on a high millage engine. That'll flush out a well worn bearings. The bottom end will come apart. Seen this too many times where a fuel pump failed and filled the crankcase with gasoline.
 
Last edited:
Oh! How nice! Excellent shot TMan!
Now here is a .…… neglected engine

I also never use a flush cleaning agent.
 
You've had it running, I'm sure.
Warm it up and Here is what I'd do.
Step 1. Drain the oil but leave the filter on it with the oil that's in the filter.
Step 2. Pour 1 gallon of diesel fuel in it.
Step 3. Start it and let it idle for 20 seconds.
Step 4. Drain it. Let it drain till the drips quite. Put a new filter and oil in it. Change the oil/filter within 200 miles. Good to go :)
 
I had a 300-6 in a Ford pick up that the oil pressure light would come on at idle when warmed up. After removing the valve cover all the oil was setting on top of the head. I pulled the drain plug and scraped and flushed with clean parts solvent. I removed the lifter cover too. Fresh oil and a new filter and started it for a few minutes. I drained the oil, changed the filter and did it again running it for 10 min. or so. Changed the oil and filter again. Finally I took it for a drive and did the oil/filter change again. That took care of the issue. Worked great. I worked at a dealership so filters and oil were cheap. But it did work well.
 
Be careful what you knock around that may go down the drain holes. Adding any cleaner will take all the loose stuff in the pan possibly plugging the oil pickup screen. Seen it go bad like that and wipe out a crank.
 
3 quarts of oil with 1 quart trans fluid will clean that up with normal driving.
Then use a detergent oil like Castrol GTX and they stay nice and clean inside.
 
Leave it alone. Check the valve lash, put a new gasket on it and change the oil if it's due.
There's nothing to gain by cleaning any of that, in fact loosening up that little bit of build up by running solvents through the oil will most likely wipe out the bearings.
Button it up and keep on truckin'
 
daliant said:
Leave it alone. Check the valve lash, put a new gasket on it and change the oil if it's due.
There's nothing to gain by cleaning any of that, in fact loosening up that little bit of build up by running solvents through the oil will most likely wipe out the bearings.
Button it up and keep on truckin'
Click to expand...

Totally possible.
 
I'd just put some deisel oil in it as the normaly oil you run. In time it will clean a lot of that up. Also beat on it on occasionIt will loosen up curd and get more oil up top.
For the sucking sound - look at the carburetor bolts (famous for loosening on slantys) and any vacuum hoses. If your car has AC or power brakes check those parts too.
 
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