305 serious sludge

[YakkoWarner]

Don't know how relevant this is because it comes to me very much second hand, but my father used to always go on about how he killed a 1956 Chevy by cleaning up the whole top side of the engine - he claims the dirt and sludge were the only thing helping it maintain oil pressure and once it was all cleaned up it shortly failed due to oil starving.

This was way before I was even born so I have zero firsthand info, but it sounds plausible as does the secondary theory that in the process of cleaning it up he got residue down in the pan and blocked the oil pump pickup which would have had the same result.

Either way I'd be wary of anything that "breaks up" the sludge in large chunks - if you run some sort of cleaning stuff with the oil, be prepared to change the oil and filter often since all that "stuff" has to go somewhere...

 

[TotalyHucked]

I agree with most of the advice in here, run a synthetic oil and change the filter religiously for a while. Then pop the VC's off in 6mo-a year and see what it did. Synthetics have alot more detergents in them than dinosaur oil does. I *might* consider even adding like a small pour of ATF at the end of each oil change for the last 50-100mi or so. But I definitely wouldn't do anything to try to majorly break it all up quickly. That'll spell disaster.

Yakko, I say the same thing as your dad about automatic transmissions. If you don't know their history, if it's high mileage or if it just hasn't had religious flushes, DO NOT FLUSH an auto trans. It WILL fail shortly after. All I ever do is drop the pan, fresh filter and top it up. Every. Single. Person. I've ever known that had a trans flush done was rebuilding/replacing the trans within 6mo

 

[rich weyand]

I'll second Mobil 1.

The other thing that leads to engine gunk is no PCV valve or a broken PCV valve. Make sure you have a functional PCV valve on the engine. Just get a new one to be sure; they're cheap. If the PCV valve's been removed, put it back.

Blow-by of the exhaust gases past the rings is a thing. The PCV valve makes sure those exhaust gasses are pulled out of the crankcase and recycled into the engine. Otherwise they condense into the oil and turn into gunk.

 

[Sad Sack]

I'm sorry, but I disagree on the pennzoil, saw a couple of mid/late 70s Chevy engines in for warranty and our GM rep wouldn't buy them because they were running the pennzoil.........I wouldn't put pennzoil in a fored

I was once told that since Pennzoil is a paraffin-based oil that one could see weird issues if mixed with asphalt-based oils like Valvoline as an example. True or not, who knows but an old ford I had that PO ran Pennz in sure had some goofy looking crap around engine surfaces that convinced me to stick with Valvoline and never had an issue in any car I had that ran Valvoline. Then syns and newer oils hit the market and things have gotten better.

 

[cmichels83]

Put full synthetic Walmart or Costco oil in for 1000 miles and dump it. Do it again for 2000 miles and dump it. Then put Valvoline Restore and Protect in and change every 3000 miles.

Run Seafoam in the gas tank per their instructions (only gas, not oil). That will clean the carb, valves, and top of piston.

I have done this to bring an engine with +200k miles on it back to running decent. The thing barely ran when I started the process, runs pretty good now. The oil still gets changed every 3000 miles even with the synthetic because it gets dirty pretty quickly due to the crap that built up from the prior owner's neglect.

Here is a video about the Restore and Protect.

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[hack_man]

The bigger issue......it's still a 305

 

[Mike_82_Shortbox]

Trying to scrape it out causes more issues than just letting your maintenance schedule get you back on track. The only concern I would have is the oil pump pickup screen. You don't want to scrape it because the chunks you miss can block the pickup screen and even the oil return passages.

That's exactly what happened to me on a V6 Ranger many years ago. While I was working at a commercial shop. Everybody told me not to mess with it (I was sort of new), but I was convinced that all that junk needed to be scraped out, and it was about 10 times as bad as this car. So after I did that the engine had zero oil pressure. On my dime I had to pull the oil pan, and the fastest and easiest thing to do was just replace the oil pump and pickup screen assembly. Of course I cleaned a ton of flakes and crap out of the bottom of the oil pan as well. Then I put in another new oil filter, and new oil, and everything was right with the world. The truck came in for leaking valve cover gaskets, and that's what led me to the wall-to-wall sludge inside. Everybody told me just replace the gasket and put it back together, but I didn't listen, and it cost me four book hours at $15 an hour back in 1991. Never scraped any sludge since.

 

[bucket]

I've had to scrape sludge from under valve covers a number of times. When the oil can't drain back to the crankcase and oil flows out the fill cap or PCV valve, you kinda have no choice but to scrape it out. I always did it with help from a shop vac. I'd attach a plastic funnel to the suction hose, then use the narrow end of the funnel to do the actual sludge scraping. A flat blade screwdriver would help out, as needed.

It may have been risky business, but the engines all survived. For a reasonable amount of time at least. I don't recall any failures, but I'm sure some died eventually. From a continued lack of maintenance.

 

[Matt69olds]

Around here the oil to avoid was Kendall.

I think any oil is it’s neglected long enough will look like that. In this case, it appears the engine was used for short trips where it wasn’t run long enough to get hot, and extended oil change intervals.

I personally couldn’t leave that alone. I’d a the minimum vacuum out the big chunks before reassembling it. I wouldn’t attempt to clean it out any further unless you are willing to change the oil and filter far more frequently than normally would be needed. All the debris that you know k loose is going to eventually end up in the oil pan.

 

[Broken85]

I'll second Mobil 1.

The other thing that leads to engine gunk is no PCV valve or a broken PCV valve. Make sure you have a functional PCV valve on the engine. Just get a new one to be sure; they're cheap. If the PCV valve's been removed, put it back.

Blow-by of the exhaust gases past the rings is a thing. The PCV valve makes sure those exhaust gasses are pulled out of the crankcase and recycled into the engine. Otherwise they condense into the oil and turn into gunk.

……and blow main seals

 

[Hilllbilly]

Shop vac and puddy knife the chunks out . put the valve covers back on

Fresh oil with a quart of marvel mystery oil. Run some Delo or Rotella oil with the MMO

Worked for me

 

[DoubleDingo]

Howdy, I've never seen sludge like this before... '85 C10 with the 305. What would y'all recommend short of tearing it down? I'm not exactly in a position to tear it down at the moment.

Add some diesel & let it idle for a bit, then change the oil? The oil passages themselves are clear, I thought maybe get in there with a brush & run the shop vac to try and get some of the big chunks out, just curious what you guys might do.

Just got this truck, so I'm assuming either the PO did a lot of short runs, used Penzoil, or it sat for a long time.

Thanks!

If you have access to Motor Purr Tune-Up, get a couple bottles. Add one to the crankcase and let it idle for 30 minutes, change the oil and filter. Do it one more time with the second bottle, and change the oil and filter again. Then change the oil on regular intervals. I do internal engine cleaning on all of my stuff every couple of years, especially turbo engines because they get hot and the oil can coke in there and clog passages. If you don't have motor purr in your area, use marvel mystery oil but drive it easy but do two rounds of it, first being 100-200 miles of easy driving, then the second round of the same.

 

[85_squares]

If you have access to Motor Purr Tune-Up, get a couple bottles. Add one to the crankcase and let it idle for 30 minutes, change the oil and filter. Do it one more time with the second bottle, and change the oil and filter again. Then change the oil on regular intervals. I do internal engine cleaning on all of my stuff every couple of years, especially turbo engines because they get hot and the oil can coke in there and clog passages. If you don't have motor purr in your area, use marvel mystery oil but drive it easy but do two rounds of it, first being 100-200 miles of easy driving, then the second round of the same.

Thank you I put some mystery oil in before the first oil change, ran it 100 miles & changed the oil, came out very dark (to be expected). I'll keep doing changes at short intervals until it gets better.

On the plus side I've been replacing gaskets and cleared the pump screen of sludge when I dropped the pan, gave me a bump in oil pressure.

 

[DoubleDingo]

Thank you I put some mystery oil in before the first oil change, ran it 100 miles & changed the oil, came out very dark (to be expected). I'll keep doing changes at short intervals until it gets better.

On the plus side I've been replacing gaskets and cleared the pump screen of sludge when I dropped the pan, gave me a bump in oil pressure.

I think you'll be fine then. More oil pressure after what you've done is a good sign.

 

[David King]

Looks like someone ran Quaker State, aka, Quick Sludge in that engine.