Topic: White sludge buildup on cb750 dipstick?

[chase2034]

hey guys. just recently bought a 1973 cb750. bike is in amazing condition. did an oil change about 2 weeks ago and i just went to check the dipstick to see how the level is doing and there was a white (melted marshmellow like) build up around the outer opening of the oil pan and the inside top of my dipstick. any idea what this is? its been cold here in the bay area lately but nothing to crazy. i use the bike about once a day to go to the gym.

the texture was oil like and it sort of smells like gas.

[KingCustomCycles.com]

That is water in the oil, it needs to be ridden enough to boil that off.

[petercb750]

Yeh, what KCC said - just a build up of condensation normally, I've had the same thing. Just make sure your breather pipe is clear and go for a decent ride.......should cure itself (well, it did for me).
Peter.

[chase2034]

cool thanks guys. i also found this thread. i love this forum. i will be using it a lot.

http://forums.sohc4.net/index.php?topic=62250.0

[nancy]

Chase,
As mentioned - check vent tubes - mine were connected incorrectly and I saw brown mayo on my cap also. In my case, caused by ejected water vapour from the head, via the vent connection on the back of the rocker box, connected by vent hose to my oil tank top connector...WRONG. This hose must go from rocker box and down to the ground.
regards
Mark

[Retro Rocket]

I would dump that oil straight away and put some new oil in. That moisture can cause some serious problems if it gets anywhere near any bearings. Dump the oil and refill then go for a good ride and recheck the oil..

Mick

[camelman]

Whoa!  Is your 750 water cooled?  You might have a headgasket leak.  Probably need to replace your head gasket.















Just kidding.  That is pretty normal if your bike has been sitting a while, especially if the ambient temp has changed a lot lately.  Just take it out for a ride and steam it off.  Water in oil does create acidity, but you can be the judge as to whether or not you need to change the oil.  Most vehicles experience quite a bit of water in the oil, but it usually isn't noticed.

Camelman

[754]

  Its normal..
 While everyone else went running for the cars, you are at least riding... good job  !!  !

 You can go lighter oil if it stays cold, but if its 40 degrees or above 40 wt should be ok.
 
 I try to warm up the motor till the valvecover starts to warm before riding in the cold.. it was about 20 -22 f tonite when I rode home.. Usually I let it run a minute or two before I kill the engine if it is 40 or lower..

 Still has the white cream though..

[ZanVooden]

Whoa!  Is your 750 water cooled?  You might have a headgasket leak.  Probably need to replace your head gasket.

Funny as soon as read the first post I almost closed it because the first thing I thought was blown head gasket. Then had to double take to realize the obvious.

[chase2034]

Chase,
As mentioned - check vent tubes - mine were connected incorrectly and I saw brown mayo on my cap also. In my case, caused by ejected water vapour from the head, via the vent connection on the back of the rocker box, connected by vent hose to my oil tank top connector...WRONG. This hose must go from rocker box and down to the ground.
regards
Mark

Anyone got pictures of these vent tubes? I can't seem to find them and I checked bike bandit and my manual.

[Terry in Australia]

Take your fuel tank off mate, and you'll see a black hose about 1/2" OD that travels from the back of your rocker cover over the top of your airbox and just vents out into the atmosphere. (or into the airbox on later models) There's another smaller OD hose that exits the back of the gearbox and is connected to the bottom spiggot at the back of the oil tank. There is then another bigger (1/2" OD approx) breather hose that exits the top rear of the oil tank that just vents into the atmosphere also.

What brand of oil are you using? I've only seen the white foam once before, caused by using shiitty Valvoline XLD oil, which is probably fine in cars, but it's no good for CB750's. I'd dump that oil (and filter) out and use some good quality motorcycle oil. Cheers, Terry.

[nancy]

+1 on getting your old oil out of there promptly..but don't rush new oil in there,...else you will have to repeat that process over and over till you establish the cause. I did just that. Did a lube and filter change when I found the water in my oil tank with some sludge on the cap. Another day or so and it was back,..as I had not solved the problem.
You can easily pull down your oil tank while full to check the hose connections at the back. Just undo the 3 mounting bolts and the tank will stay in place - but provide it some support in case your feed lines get compromised. You should see one vent tube at TOP of tank - this goes down between swingarm to ground. The bottom vent should be connected to back of your crankcase/gearbox area. If you confirm all is well - I guess you can assume the crap is caused by inactivity and/or riding behaviour. Note: oil is supposed to be changed after TWO months irrespective of the milage you have riden. Seems a bit excessive - but I don't let mine go past 3 months.
The other tube that I had wrong - comes from the motor - back of rocker and does NOT go near the oil tank - it goes to the same spot - between the gap in the swingarm (very little gap)..or in my case,. I have left this vent open at back of rocker till I get a new vent tube from David Silver.
Regards
Mark

[754]

 I am not in full agreement on having to change the oil..
 if you continue riding (under same conditions), it will just come right back..

 I ran all last winter, with same oil in it, not saying its a good idea, just saying it wont nrecessarily take out your engine..

 its getting up to the mid teens.. , time to go for a ride...

[Retro Rocket]

Believe it or not, i have never seen water in the oil of any old Honda i have owned or worked on. I think our hot weather keeps the water at bay, our winter temps in Brisbane are hotter than some of our members summers....

Mick

[solo 2]

Believe it or not, i have never seen water in the oil of any old Honda i have owned or worked on. I think our hot weather keeps the water at bay, our winter temps in Brisbane are hotter than some of our members summers....

Mick

That's just a mean thing to say!...-23 deg.C right now

[TwoTired]

I am not in full agreement on having to change the oil..
 if you continue riding (under same conditions), it will just come right back..

+1.   You just need to get ALL the oil hot enough to vaporize the condensate collected inside.

[HondaMan]

Yeah, what Terry said, above...

I'm working on a kitbashed "F" right now that has oil in it that looks like chocolate milk mix that hasn't been stirred up well.    If this oil is not removed at least twice in the next few weeks, and run for at least a couple of hours each time, the moisture can cause small-end rod rust (as seen in my book) and future problems with the tops of the rods.

One thing that can help in cold weather: use 10w40 (petroleum-based) oil, install D7EA sparkplugs, ride for as much as you can for a week. Then change the oil, do it again. Finally, change that oil, too. This method should burn off most of the condensation inside the cases and help keep it dry. Run 20w50 (petroleum) weight in the summer (or at least 15w50 synthetics) to keep it happy.

[KingCustomCycles.com]

I would dump that oil straight away and put some new oil in. That moisture can cause some serious problems if it gets anywhere near any bearings. Dump the oil and refill then go for a good ride and recheck the oil..

Mick

Of course that will eliminate the condensation.  Maybe, he should change the oil after every ride?  It is common practice to eliminate the build-up of condensation by operating the engine. No harm will be done.

[TwoTired]

The time that the water coexists with the oil is an important factor.
When water combines with the organics in the oil, it forms amino acids.  Acids in the oil, as you might imagine, will convert metal in a corrosive situation.

So, the oil change imperative must be weighed with how long the water existed in the oil.   For example, if the water only existed in the oil from overnight condensation, vaporizing the oil during the next day's engine run will save both oil and engine.
However, if the oil has had water in it for the last 3 months, then an oil change is recommended.

Cheers,

[chase2034]

The time that the water coexists with the oil is an important factor.
When water combines with the organics in the oil, it forms amino acids.  Acids in the oil, as you might imagine, will convert metal in a corrosive situation.

So, the oil change imperative must be weighed with how long the water existed in the oil.   For example, if the water only existed in the oil from overnight condensation, vaporizing the oil during the next day's engine run will save both oil and engine.
However, if the oil has had water in it for the last 3 months, then an oil change is recommended.

Cheers,

makes sense. i think since i just changed the oil a couple weeks ago ill give it a few more rides and see if it burns off. if not ill replace the oil...then maybe again.

[Retro Rocket]

I would dump that oil straight away and put some new oil in. That moisture can cause some serious problems if it gets anywhere near any bearings. Dump the oil and refill then go for a good ride and recheck the oil..

Mick

Of course that will eliminate the condensation.  Maybe, he should change the oil after every ride?  It is common practice to eliminate the build-up of condensation by operating the engine. No harm will be done.

Stupid answer, you look for trouble dude, no where would i suggest changing the oil for every ride, thats just plain stupid. Like i said, if it were me and for the sake of 10 bucks worth of oil, i would dump it, to say "no harm will be done" is just a guess, and it may be common practise over there but in all the years i have been riding, building  and working in bike shops i have only ever seen it on water cooled bikes that had leaky head gaskets....If the bike isn't ridden far enough to get hot enough to evaporate all the water then he runs the real risk of damage through corrosion.....

Mick

[Terry in Australia]

Yeah, what Terry said, above...

I'm working on a kitbashed "F" right now that has oil in it that looks like chocolate milk mix that hasn't been stirred up well.    If this oil is not removed at least twice in the next few weeks, and run for at least a couple of hours each time, the moisture can cause small-end rod rust (as seen in my book) and future problems with the tops of the rods.

One thing that can help in cold weather: use 10w40 (petroleum-based) oil, install D7EA sparkplugs, ride for as much as you can for a week. Then change the oil, do it again. Finally, change that oil, too. This method should burn off most of the condensation inside the cases and help keep it dry. Run 20w50 (petroleum) weight in the summer (or at least 15w50 synthetics) to keep it happy.

That brought back a long-forgotten memory Mark, when I brought home my CB750F2 it was just as you've described, and not surprisingly, when I stripped the engine, it had a nice coating of surface rust on the crank and gears. I degreased everything and then washed all the rusted components in phosphoric acid, washed it all again, then dumped it all in my Kerosene bath to stop flash rusting. What a PITA! I must buy a copy of your book............ 

[HondaMan]

Yeah, what Terry said, above...

I'm working on a kitbashed "F" right now that has oil in it that looks like chocolate milk mix that hasn't been stirred up well.    If this oil is not removed at least twice in the next few weeks, and run for at least a couple of hours each time, the moisture can cause small-end rod rust (as seen in my book) and future problems with the tops of the rods.

One thing that can help in cold weather: use 10w40 (petroleum-based) oil, install D7EA sparkplugs, ride for as much as you can for a week. Then change the oil, do it again. Finally, change that oil, too. This method should burn off most of the condensation inside the cases and help keep it dry. Run 20w50 (petroleum) weight in the summer (or at least 15w50 synthetics) to keep it happy.

That brought back a long-forgotten memory Mark, when I brought home my CB750F2 it was just as you've described, and not surprisingly, when I stripped the engine, it had a nice coating of surface rust on the crank and gears. I degreased everything and then washed all the rusted components in phosphoric acid, washed it all again, then dumped it all in my Kerosene bath to stop flash rusting. What a PITA! I must buy a copy of your book............ 

It's actually a common enough issue with the long-sitting bikes that I have some pretty good pix of the events in the "Inspection chapter, showing how to identify it before it wipes out a wristpin.

The "F" I just drained the oil from actually splattered as the first oil came out of the tank: that's a lot of water... 

[Terry in Australia]

Yep, I know what you mean mate, I took a picture when I dumped the watery oil out of my F2, but I can't find it now, I've taken quite a lot of pics in the intervening 6 years.......... 

[Kong]

I just want to mention something for your consideration as someone who has never had this problem with a motorcycle.

Do not make the assumption that boiling off the water removes the entire problem.  There is no possibility at all that the water that found its way into that engine was pure, and whatever contaminants that came in with the water are still going to be there after the water heats, vaporizes, and maybe exits (or maybe not) the engine.

And again, on a personal note, it takes 17 quarts to change the oil in my truck.  I used to do it once every 5000 miles, but then I started having oil analysis* done and was able to switch to 10,000 mile intervals but more importantly I got early warning when one of my injectors started going bad and one report even told me to decrease my interval on air filter changes.  Folks, oil analysis can be the best twenty five bucks you ever spent.

* Blackstone's been doing it for years.  I have no affiliation with the company other than I have been a regular user of their services for the last six or seven years.  Take a look at one of their sample reports for a motorcycle, this isn't hype, its what a real report actually looks like. 
http://www.blackstone-labs.com/motorcycle.php