Engine sludge

I think I may have some sludge build up. What would be the best way to clean it out with out a tear down. Seafoam,,, suggestions.

 

The safest way would be to do several oil changes in the next couple of weeks. I've done the seafoam in the crank case and I do not know if it works any better and you run the risk of bearings failing. But then again some swear by and some (most on here) swear at it.

 

I used an oil flush on a 74 cougar a long time ago and the thing started smoking after it. Some one said that the stuff cleaned it to well causing the rings not to seal as well.

 

Seafoam is a solvent and will break down the oil. Several short mile oil changes as previously mentioned is the best way.

 

Ok thanks.

 

Based on some feedback I've gotten here a few years ago when I first got my 81 XJ750RH, I've used seafoam in my oil to clear it out before the first run of the season (and/or when I first got it). I've actually tested it a few different ways and based on feedback and checking its something I would use/do maybe once a season - mind you this is just what "I" did/do, so o buyer beware ;-)

I dump a full can of seafoam in the oil - I throw it up on the center-stand, point a box fan at the engine and put it on high, and then start the bike up - let it idle, run it through all of the gears (up and down the gears) and then shut it down (about 5-6 minutes). Then I leave it for an hour, and then I do it again. If possible I let it sit overnight and then do it again.

After the 'second run' on the second day, I do a full oil/filter change as normal while its still warm. While this gets most of the old oil/seafoam - it doesn't get all of it out; so after about 100 miles on the new oil, I do 'another' oil change and then ride with that and just do regular oil changes as needed.

Is it overkill, yes - probably and I wouldn't doubt it ;-) Does it give me the 'warm and fuzzy' that I've just gave my bike a good shot of 'colon blow' - yes ;-)


--josh

 

You could try what I did. I accidentally left the petcock on prime overnight and flooded the crank case with gas. A couple miles down the road and my rear tire was well lubed with the gas oil mix that vented out. Obviously I changed the oil. Later that year when I cracked the case open to replace the timing chain, there was no trace of sludge. It actually looked new inside. Probably not the smartest thing I have done, but it worked.
But seriously, have a laugh at my expense and don't try this .

 

The only reason why I think I have sludge, especially on top of the head, is when I first start the bike the oil level is ok. After a few minutes the oil light comes on. Then after a few more minutes the light goes out. So my thinking is the oil is pooling on top of the head then when the oil heats up its thinner. Therefor allowing it to drain faster from the head. I will know more later this week when I plan on changing out the valve cover gasket. Got a lo of bike toys coming from the xj Santa "chacal"

 

You have sludge buildup in the oil level sensor. It is a float type switch and sludge is making it stick. Next time you change oil remove it and clean it real good with a spray degreaser solvent. Be sure to spray inside the metal cage the float is in, thats where all the gunk is.

 

SF won't break down oil only mix with it and dilute it's viscosity. But I wouldn't put a whole can in there for sure. mlew is right about your oil sensor and it probably is just dirt that has built up. You could change over to the filter mod and use a premium screw on filter that would filter out finer particles. But just properly changing your oil/filter regularly and getting out as much of the old oil as possible should keep it from happening again.

 

Cool,,,, will do. This is my daily driver, and between teenage kids with one going in to th military, work and land to tend to I don't get to do the maintenance that I want/should do as often. I feel so ashamed

 

Over 10 years ago, my father learned a lesson about solvents in oil. He was at a gas station in Quebec, and they offered him this cleaning out of his oil system with a solvent. He took them up on it. Next time he was in, he asked for it, and was told they don't do it anymore. My Dad then starts to notice that his car started to burn oil. That solvent had eaten away at the coating that forms in the cylinders to make for a tight fit with the rings.

Remember how you can only break in a motor once, right? That lesson taught me never to do something similar. Several closely spaced oil changes as most suggest here would be my way to go.

 

Having seen comments from both sides of the fence, I think I will take the middle ground. Meaning, if I take the valve cover off and there is sludge. I will drain the oil. Then useing a brissle brush and some kerosene and clean the head up. Then fill the crankcase up with kerosene. Then let sit overnight but without running the bike. After a good soak and a good sloshing I will drain the crankcase and the middle gear. I will do this several times till the kerosene comes out realative clean. Then do a fresh oil change followed by several more in the following month.

 

Just be careful with the middle gear drain plug. It's easily stripped.

 

I don't plan on taking the drain plug out. You can drain the middle gear by taking the front tire off an let the bike rest on the fork's. I won't get it all out like this but what's left is very minimal.

 

I wouldn't. You'll saturate your clutch plates with kerosene.

Do repeated, "short" oil changes. The only thing you want to use to "flush out" the motor is clean fresh hot motor oil.

Anything else (like kerosene) is risking unforeseen side-effects.

 

+1 to the above

Kerosene has been used in diesel engines successfully but obviously not your mill type. If you are concerned about unseen sludge and you want to go the solvent method-then use SeaFoam or STP upper cylinder lube and follow the instructions (ie NOT the whole can), and then proceed with your oil change and getting most of the old out. Then another change within 100 miles or so.