Used Engine

Just bot another used vehicle. Have you found an oil or gas
additive that's good at flushing any accumulated sludge out of
an engine?

I've had some success using "Motor Flush" to clean out sludge from a pickup engine (Gunk might have been the brand). It was a quart of mostly light solvents. Direction were to add to a hot engine, let it idle for 5 minutes, then drain the oil.

I've put seafoam in the oil and run it for a while (it was a mower engine). What came out was gross. I think you may get the same if you put in MMO.

Any tractor or vehicle I buy used I always pull the oil pan within 100 miles of having it. It always makes me scared that I will find bearing pieces and a bunch of metal or something, but it is good to know what you are up against right from the start.

You are going to need some pretty good solvent to break up junk at the top of the engine and get it to drop down to the pan. If you think it is a mess pull off the valve cover and pan. You can't go wrong. Do the VC first, if there's nothing under it don't bother with the pan.

It would help to know what you have bought and what the intended use.

If this is a late model, emissions controlled vehicle, and it's severely sludged, as in black carbon deposits under the valve cover, that is a bad sign. Likely the compression rings are worn beyond service and an overhaul will soon be necessary. Especially if this is intended as a daily, dependable, economic driver, and must pass emissions inspection.

If it's an older vehicle, pre emissions, carburated, possibly hasn't been properly maintained, some sludge is to be expected. Unless it's severe enough to prevent oil drainback from the top end, I would leave it alone. Just do a few oil changes and see what happens. Chemically disturbing it could cause the oil pickup screen to be clogged, forcing it to bypass, sucking loose carbon and whatever might be in the oil pan to enter the pump and oil galleys.

If the sludge is milky white, that is a sign of water. Could be innocent as condensation caused from open/missing thermostat, or short trips. Or could be serious as cracked head, leaking head gasket or coolant entering the crankcase.

Care to share with us what you have and the intended use?

one old time method I have used was to drain the old oil, put in 2 qts. of new oil & 2 qts. of kerosene. Run the engine for about 30 to 45 seconds, then drain & put new oil in. But that's from back in the days when oil had a lot of paraffin in it from the "chill" method of refining. Quaker State used the chill method & was notorious for sludging up engines. Needless to say you have to be very careful about no more than 45 SECONDS or the engine will be ruined.

I've heard of people using kerosene as mentioned below. Is some stuff called Rislone that can get at pretty much any auto parts place that does that as well.

Be careful though. The oiling through engines is performed through internal channels in the block, head, crank shaft, etc. Be careful that none of the gunk clogs or blocks them, which is pretty hard to do. The result is similar in a human being when arteries, veins, vessels get blocked...heart attack or stroke. In engines...spun bearings and the sort.

Good luck.

Mark

About 30 years ago I used a commercial product (I have no memory of what it was, but I wasn't trying to save money on it---it would have been a reputable brand) to flush the engine in a '72 Datsun pickup I owned then. I followed the directions to the letter. It blew the head gasket. If I was in your situation, I'd start with the gentle suggestions you've gotten here, and edge into the more extreme measures slowly, if at all.

Stan

I'd leave it alone. I foolishly bought a truck about ten years ago that was extremely sludged. After taking the valve covers off a couple of times to unplug the drain holes in the heads and to get rid of the blue smoke on start up, I took an awl and punched a hole in the valve covers so now I can rod out the drain holes with a bare welding rod about every year and put a self threading screw in the valve cover. That's been going on for over 60,000 miles. You mileage may vary slightly. TDF

As as far as getting the gunk out of the fuel system, Tractor Supply (and others) have a product called Mechanic-In-A-Bottle and it works great.

Drive it until it is a quart low on oil Then when engine is Hot, add a quart of diesel and let it idle about 5 minutes. Then Change oil to a 5-30. Repeat this again when a quart low. Should clean up slowly and completely.

(quoted from post at 19:30:48 02/01/15) Drive it until it is a quart low on oil Then when engine is Hot, add a quart of diesel and let it idle about 5 minutes. Then Change oil to a 5-30. Repeat this again when a quart low. Should clean up slowly and completely.

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Good advice. If you use too much solvent and have hyd. lifters there is a chance you can collapse a lifter and not get it to pump up on its own. Then you got to start taking stuff apart.

it really depends on weather you have actually identified sludge in the motor or if you are just assuming from Advertizing that there has to be sludge because of age. If you know that there is sludge you need to drop the pan and clean it. If you just think that there is, just run it with a lighter than normal oil under a light load for 2-3 hours and then drain the oil. That will remove condensation and other contaminants that the filter does not remove.

Flush oil pan if you can't remove it by pressure hose with diesel and let drain. Use Valvoline high detergent racing oil about 20 weight or 15-40 and drain 500 mile, 1000 miles. Rislone 1 quart replace oil may help, used to use it in winter for tow truck and oil change had some 'mud' come out. RN