Yet another problem with the Dart (but I think this is a simple one). There's hardly any oil pressure in the system. The idiot light likes to flicker on and off even when at high RPMs. There's only 70K miles on the engine, and given that it's sat in a garage for the better part of 20 years, I'd say it's a safe bet that there's so much crap built up in the passageways that it's severaly limiting oil flow. I've been told that pouring a quart or diesel fuel or ATF in and running for about 15 minutes before draining the system would scour it fairly well, but I'm a bit skeptical and a little unwilling to try that on such an old and poorly maintained engine.

When I used to work at Jiffy Screw we had some stuff call Gumout (I think it was made by Pennzoil) that we'd run for about 5 minutes in gunked up engines that worked GREAT. Problem is you can't get it in normal auto stores, SOOOOOOOO........Anyone know of a good way to flush the system out next time I change the oil? If it turns out that the piston rings are good when I do a leakdown test, I'm gonna go ahead and start running full synth in there.

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'74 Duster w/ HEI ignition, beat to snot suspension, A904, 8.25" 3.55 SG rear, still being tuned up and gets 17 MPG

Know how they always build a better idiot? That's me

I flushed a 396 Chevy using diesel and straight 70W oil. Worked good and didn't hurt the engine. One gallon of #1 diesel, with one quart of 70W, and a new oil filter. Fire it up cold, let it IDLE till it starts to warm up. Shut it off, do a standard oil & filter change and run it. It'll probably clatter......well maybe not. A 396 chev had hyd. lifters, where a slant doesn't.

Roger

If it were my engine, and especially since the /6 has an external oil pump, I'd pull the pump first. Check the gears, take the pump apart and clean it out. I'm thinking perhaps it may be the pressure relief in the pump. When you reassemble, pack the pump cavity w/ Vasoline. It will prime almose instantly when you crank the engine.

My $0.02

Gilly

I've had success doing the following:
1. regular engines - the day before an oil change, I top up the oil using diesel fuel. This usually ends up being about 1 liter/quart (take your pick).
The one day of normal use (easy driving, no high reving or lugging) with the diluted lube gives the diesel time to loosen up some of those deposits and it works better if circulating while hot. Do oil change the next day as usual.

2. On severly gunked up engines, I've run the diesel for a day or too longer to give it more time to work. Then I drain half the oil but leave the dirty filter on. I top up with diesel (end up with about 50/50 oil & diesel ) and run the engine at 1000-1500 rpm for about 2 mins. Then I do the usual oil change. I'll repeat the process at the next regular oil change and then switch back to what I wrote for 'regular engines' above.

Works for me . . .

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Cheers!
Al T

Pump cavity? I assume you mean the inside of the oil pump?

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'74 Duster w/ HEI ignition, beat to snot suspension, A904, 8.25" 3.55 SG rear, still being tuned up and gets 17 MPG

Know how they always build a better idiot? That's me

Be advised. Flushing an engine can sometimes cause the pickup screen to get pluged up. ... all the crud that's broken loose is subject to get sucked up the pick-up and plug the screen.Don't get me wrong flushing a gummed up engine is probably a good Idea, but you need to be prepaired to drop the pan if it starts to loose oil pressure. I've seen it happen more than a few times over the years.

Trysix

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65 Coronet 4dr
Always being Modified

Yeah I'm counting on it. Got stuff lined up and ready to go. Figured I should pull the pump just to check the gear and make sure everything's in good shape.

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'74 Duster w/ HEI ignition, beat to snot suspension, A904, 8.25" 3.55 SG rear, still being tuned up and gets 17 MPG

Know how they always build a better idiot? That's me

If you are going to pull the oil pump and pan as part of the process, then by all means, scrape-out valve gear crud and run a solvent through the engine right before doing the pan / pump overhaul.

I have used a wet dry shop vacuum to get most of the top-side "crust" off, I have a special thin tube to get down into the pushrod pockets. (spark plug tube heads)

I would be worried about using solvent on a real dirty old SL6 if you were not going to *at least* pull the oil pump. I have had good success flushing-out the pick-up screen with-out pulling the oil pan IF you pull the oil pump and "backflush" the pick-up screen with diesel or solvent, down through the block's oil pick-up port. (use a long hose and stick it right into the threaded hole, lower, forward pocket in the pic below)

Leave the drain plug out and run a bunch of solvent through to wash stuff out. Use a stiff wire stuck through the drain plug hole to help "stir-up" the sludge and pull it out the drain hole.
Flush until the solvent comes through clean. (it take a lot of solvent and makes a big mess)

Most good running, high milage Slants I have "cleaned" and installed a rebuilt oil pump on, get the oil pressure back and run for a long time but often smoke / use some oil after doing the cleaning process.
DD

That doesn't sound pretty. Is it just for a while, or does the solvent actually damage piston rings or something else?

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'74 Duster w/ HEI ignition, beat to snot suspension, A904, 8.25" 3.55 SG rear, still being tuned up and gets 17 MPG

Know how they always build a better idiot? That's me

It's hard to say what happens, could be that the oil return rings catch some of the crud and plug-up or it could be that the rings loose some carbon / coke build-up which was helping them seal.

The biggest problem is that these are usually worn-out engines to begin with, I bet your's is already using some oil so an oil system flush will not change that.
DD

Actually it's not losing any, but there ARE drips. Kinda surprising, eh? Given its condition I'd expect it to go through a quart a day, but it holds it all pretty well, aside from the drippage.

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'74 Duster w/ HEI ignition, beat to snot suspension, A904, 8.25" 3.55 SG rear, still being tuned up and gets 17 MPG

Know how they always build a better idiot? That's me