Engine internal degreaser?

I think I bought someone's deferred maintenance.

Old motorcycle, been sitting for some time unused, and appears to have been rode hard and put away wet before that. 

Drained the oil a few days ago, STANK like nasty old varnish. Peeled the right side cover off last night to check the oil filter and was greeted by dehydrated molasses up to about two inches from the lowest point in the sump. Dry deposits, 1/8 to 1/4" thick on everything.

I scraped as much of this crud out as I could, cleaned the oil filter (centrifugal type), and sealed it back up. 

How do I get this crap cleaned out? I worry about it plugging up a passage somewhere. Tentative plan is short heat-cycle rides and an extremely short oil change interval for the first 50 miles or so. Is there a product we like for decreasing the inside of an engine? I would have used degreaser but I wasn't keen on rinsing with water.

I'd definitely give it a short run with fresh oil and then change it and clean the filter again to see how much crap breaks loose.  Beyond that, mix oil and Marvel Mystery Oil about 80/20 and run that for a bit.  It should be enough to slowly dissolve some of the crap.  You could try to break it down with heavier solvents, but I'd want to do that with it pulled apart to avoid breaking any big chunks loose and clogging stuff.  

Seafoam, it has instructions for adding to the crank case oil.

For more extreme situations I've used engine flush products from Amsoil and BG with success. 

I've always done an extra oil change shortly after using those flush products.

Last year, when I had a bunch of goop in the oil sump of my Beetle, I put kerosene in it, and let it set for a day or two, then drained it.  I think I went with two cycles of that before putting regular oil in and running the engine for a short period of time before changing the oil again.  Seems to have worked well.  No idea if that would cause a problem with the clutches in a motorcycle, though.

I can think of a couple different things you could soak the engine in that would remove the varnish; the main question is whether they'd attack the gaskets too. Given the condition of the engine, though, the varnish may be the only thing holding the oil inside the engine, so you might need to plan on taking the engine apart and replacing all the gaskets anyway. Slant Six Dan's formula seven posts down this page is one option that sounds promising.

I have heard that Marvels or ATF does a pretty good job of cleaning up those deposits. I've never had to use it though. 

The Marvel stuff is also good cutting oil for drilling metal, etc.  Mostly because it smells nice and minty.  

+1 for ATF in the first few oil fills.

See how long it will run on diesel fuel in the sump...

I've done the ATF trick a few times. The way I do it is one quart of regular oil, then fill to capacity with ATF. Start and let it run for a while, 20-30 minutes, long enough to get hot, but don't put any real strain on the motor by driving it or anything. Drain it, pitch the filter, then refill with fresh oil and a filter. Whenever I've done that on an old motor, the ATF comes out very black and thin, so I figure it's doing something.

Tom_Spangler said:

I've done the ATF trick a few times. The way I do it is one quart of regular oil, then fill to capacity with ATF. Start and let it run for a while, 20-30 minutes, long enough to get hot, but don't put any real strain on the motor by driving it or anything. Drain it, pitch the filter, then refill with fresh oil and a filter. Whenever I've done that on an old motor, the ATF comes out very black and thin, so I figure it's doing something.

I've heard of people running 20~25% ATF with a regular service interval. Could do one and then the other.

GameboyRMH said:

Tom_Spangler said:

I've done the ATF trick a few times. The way I do it is one quart of regular oil, then fill to capacity with ATF. Start and let it run for a while, 20-30 minutes, long enough to get hot, but don't put any real strain on the motor by driving it or anything. Drain it, pitch the filter, then refill with fresh oil and a filter. Whenever I've done that on an old motor, the ATF comes out very black and thin, so I figure it's doing something.

I've heard of people running 20~25% ATF with a regular service interval. Could do one and then the other.

Once every 10k due to my car burning oil, I top the last of the 5qts up with a qt of ATF withing 250-500 miles of oil change. You would be blown away with how much grime it clean out. 

Yikes.  Sorry guys, but I have to disagree with some of these things.

ATF won't do the trick.  People pull apart transmissions and see how clean they are and assume that it's because ATF has more detergents.  This is not the case.  ATF has fewer detergents.  The reason transmissions stay clean is because they don't have to deal with combustion blowby.  It won't necessarily hurt, but it won't help either... at least no more than just a few quick flushes with motor oil.

Don't go throwing random oils like Marvel or ATF in it.  Your bike has a wet clutch which is why it calls for specific oil.  If you accidentally get the wrong oil with things like hypoid additives or something incompatible with the clutch, you'll damage it and likely fry it the first time you use it.

You need a solvent.  Seafoam, motor flush, or just good old fashioned kerosene or diesel fuel in a 1:5 ratio (1 part solvent to 5 parts oil.)  Run it, but don't blip the throttle, don't drive it, just let it idle for 15-20 minutes.  Drain, change the filter, and inspect.  You many consider using one step higher viscosity for the oil part during the flush.  If it has hydraulic lifters, they will likely clatter and click.  It isn't the end of the world, but the hammering on the valves and followers could accelerate wear.  The other main thing is that (since you're concerned about starvation with a clogged filter) is this:  If you use a thicker oil to prevent the valve ticks, then you'll know if oil starvation starts to happen.  Make sense?  If you maintain enough viscosity that initial startup reveals no ticks, then you know you might be losing oil pressure from a clogged filter.  If you just add diesel to the oil and it starts clicking right away, you won't know if it's ticking because of low viscosity or oil starvation.  The viscosity isn't a problem at idle.  The starvation is.

Curtis beat me to it for the kerosene trick.

Works like a charm.

Another vote for kerosene. Works like a charm!

Let's not beat kerosene to death, but that's my suggestion, too. 

I worry about crud that is harmlessly stuck on a part of the engine suddenly becoming unstuck and involved in something with clearances.

Pete

To be different, I would suggest adding Bardahl Engine Flush to the....oh yeah, that's kerosene.

I'd just tear it down and hot tank it, if it's that bad..

I usually see BG EPR/MOA recommended for car gas engines.

For carbon cleaners (for hand-cleaning disassembled parts)- Ford PM-3 Carb tune up cleaner, Chrysler/Mopar 4318001AD Combustion Chamber Cleaner (CCC Cleaner), ACDelco X66/X66P Fuel Inj & Upper Engine Cleaner, Johnson Evinrude Engine Tuner Tune Up, and then Permatex Gasket Cleaner & Amsoil Power foam- though these may be discontinued. Some of them are only ~$7-15/can.