Engine flush risks?

tyr_shadowblade

tyr_shadowblade

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Jan 3, 2006
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Hey,


As some of you know, I recently acquired a trike with a 307 Oldsmobile engine.

Have replaced the rear tires, belts, hoses, filters, battery, and master cylinder.

Engine probably has over 100K on it, and I was talking to my mechanic the other day about flushing the engine. He said they don't normally do that, because there is a risk that after the engine is flushed a bit of gunk could plug the oil intake. He said he could use a detergent additive instead.

What do y'all think of this? What if I just dump a pint of Sea Foam in the crankcase shortly before my next oil change? What about Marvel Mystery Oil? And I'm planning on switching to a high mileage oil like Valvoline MaxLife -- but would a synthetic be better?

Thanks.
 
Run Shell Rotella diesel engine oil for a few changes, this will clean a gas engine up real well.

Risk is that any place there was dirt/gunk/crud/sludge plugging a possible oil leak in the engine will now leak/drip oil.

Change the oil often when using diesel rated oil in a gas engine untill the engine gets clean inside because it will take all of the accumulated sludge and dump it in the filter at a higher rate than with normal oil.

By often, I mean every 1,000 miles untill the oil runs clean longer than that.
 
I've done a home-made flush for years with no problems. Start with a warm motor. Drain a quart of oil and replace the plug. Spin on a new filter. Top off the crankcase with kerosene. Start it up and let it idle for 10 minutes or so. Don't rev it up. Idle only. Then drain, replace the filter and fill it with a standard grade dino oil. After a hundred miles or so, drain, new filter and fill with your choice of oil.

Seafaom works great in the upper heads. WARNING: DO THIS OUTSIDE! You're gonna see a smoke show like you've never seen before! It's also much easier to do with 2 people. Pull the vacuum to carb intake line (usually the line with the PCV vlave). Pour the Seafoam in a bowl, and stick the hose in the bowl. Crank it just enough to suck in the Seafoam, but not to start (in a high compression motor, all it takes is a bump or two of the starter). Let it sit for 45 minutes or so, then start it up. It will want to stumble at first, so use just enough throttle to keep it running. Once the smoke show starts to clear up, take it for a ride. As the smoke continues to clear, start getting on the throttle harder. Eventually it will clear up, and all the carbon build up on the valves, gunk in the head, etc. will be gone.

Do the Seafoam clean before you do the crankcase flush, as some of the build-up will blow by the rings and wind up in the crankcase.

As for which oil, either synthetic or dino is fine. The additive packets in the synth's last a little longer, but it's your choice. I've found that different motors like different oil.

If you ever have any questions about oil, check out www.bobistheoilguy.com. These people are as anal about oil as we are about knives!
 
Personally, before doing any flush like this, I would drop the oil pan and manually clean out any sludge or junk. The built up crap in the bottom of the pan is the stuff you need to worry about dis-lodging. Removing it also lets the engine flush work on the rest of the oil system more effectively. This would also give you a good visual to see if any of the rod bearings had overheated, or find any chips or shreds (evidence) of any failed bearings/lifters etc. It really isn't hard, especially if the trike doesn't have any frame member or driveshaft running underneath the pan.
 
I don't like the Kerosene idea... kerosene is flammable and there are plenty of flames in the combustion chamber.

The mechanic told you there is a risk only because he didn't want to do it, probably doen't have the machinery to do a "proper" flush.

to do a "ghetto" flush, you should use nothing other than ATF. drain the oil, change the filter, fill engine with ATF and idle for roughly 15 min. this is when you can clean the inside of the oil pan if you wish. drain, change the filter, and put in engine oil.
 
I'd recommend the Rotella or another diesel motor oil. granted, it will take the longest, but it is the easiest on the engine, and won't remove things like the carbon ring at the top of the cylinder, and will provide good lubrication. Alternately the detergent is a good idea.
if you have the equipment, I agree with XDSshooter as well. doing a pan drop is a good idea.

kerosene in the oil just thins it out, possibly too much, ATF in the intake will clean out the carbon in the cylinders, which may not be a good thing, most "engine oil system cleaners" are just kerosene or worse, and they will cause engine damage as the quickly remove all lubricity from the oil.

also, if you have an IR thermometer, monitor the oil filter temp, once it starts to drop, you know its plugged and bypassing.
 
+ 1 to rotella. I run nothing but diesel truck oil in my gas trucks. Higher detergent package. I change out my filters about every 2000km's and the oil every 5000Kms. Diesel oil is dirt cheap too, a 5 gallon pail is about $30 bucks.
 
qqfob said:
I don't like the Kerosene idea... kerosene is flammable and there are plenty of flames in the combustion chamber..
Click to expand...

:confused: Gasoline is in the combustion chamber, too. In theory, if everything is working properly, all that should be there is gasoline. There's a whole lot of combustin' going on in the combustion chamber. If there weren't, the internal combustion engine wouldn't work. ATF for that matter is flammable, too. But still :confused:

As for the ghetto flush, I've been doing it for 38 years, and have never had a problem. But that doesn't mean everyone will want to do it. Tyr asked for suggestions...and I told him how I do it.
 
My biggest concern with the kero flush, and I've done a few, besides the fumes you breath, is that its really easy to over do, and possibly do engine damage. ever see what a small engine that has been running way rich looks like on the cylinder walls, scored to hell. I have no doubt that it works, or Gunk wouldn't sell it. But I think we have better ways.
I thing qqfob means extra flammable fumes in the crank case, but as far as I can tell, it wouldn't ignite there, and at worst if the fumes were drawn in though the PCV (positive crankcase ventilation) all it should do is over-rich the engine and stall it. no big.
I've heard this debate tossed around in a few shops, and honestly with all of the high end, new products nothing is a guarantee, the shop I worked at killed a car by doing the oil change, it hadn't had one in 150,000km and I guess whatever crap was still in it was holding it together, because it wouldn't run once the fresh oil was in. without a teardown, or a borescope, there is no way to know.
 
SPXTrader said:
If you ever have any questions about oil, check out www.bobistheoilguy.com. These people are as anal about oil as we are about knives!
Click to expand...

That link was very informative. :thumbup:

They seem to think a product called "Auto RX" is the only oil additive to use . . . but I can't find it anywhere locally. Marvel Mystery Oil is recommended for the petrol, but not the oil.

Anyone know which retailer stocks Auto RX?
 
I think I'd pass on the Kero in the crankcase as well.

Buy a case of your favorite Dino oil and a can of SeaFoam. At 1000 mile intervals go through two cycles of SeaFoam, fresh oil, and a new filter. Third cycle should be fresh Dino oil & filter only. After the next 1000 miles on the oil / filter only cycle swap to whatever you intend to run for the long haul. Although I'm a synthetic fan, I think I'd stick to a diet of Dino oil in a older motor with 100K on it. Good luck.
 
I had an old timer tell me years ago to use automatic transmission oil. 1 qt in the crank case and run for a while. Depending on how old the motor is I sometimes put it in and run around town for a few days. Has always worked great. I guess it is very high detergent. Ever seen the inside of an automatic transmission? They're always clean. I have also used the kerosene but never drove, just allow to idle for a few minutes. I've done this with small engines, tractors, cars and trucks. Never a problem. I wouldn't do it to something new but for older things I've never worried.
 
Do you actually know that the engine needs a flush?

Usually, just doing a few quick oil changes will clean things up. If it really is full of sludge, nothing short of taking off the oil pan, and cleaning out the pan and the oil pump will be useful.
 
some engines, like the 345 IH that is in my scout... Have small oil return holes that can plug easily. not sure if its the case with yours, but it did kill off my scout. speaking of which, anybody want a fun little toy?
 
FWIW i worked in an auto machine shop for several yrs.

i wouldnt flush an engine, not unless someone had put somethijng funky in it, something like that, if its got a lot of crud build up due to bad rings and such & being hi mileage it could break some loose and clog something important up like an oil galley, and even if it doesnt do that i dont know that it accomplishes anything, i would just change the oil and filter at regular intervals and start saving the $$ to rebuild/replace the thing.

i also wouldnt run ATF in the crankcase, just doesnt sound like a good idea to me lol.

used to be an urban myth if ya poured ATF in thru the carb it would "seat" your rings, lol, dont know about that but it sure makes a lotta cool smoke, i have never understood the logic behind that particular one if ya have the correct rings and the cylinder walls have been surfaced correctly and all is in spec the rings should "seat" anyway, if they dont i dont know how a quart of ATF is gonna help, ya have serious problems ie something aint right if they dont seat.
 
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