Diesel engine blow by

[Scott037]

I have a Kubota B21 backhoe/loader with 3 cylinder diesel with 1200 hours. From reading earlier posts I believe that the engine is experiencing some degree of blow by. I have started to notice slight "puffing" smoke coming from the vent tube, however, there is no sign of any oil leaking from the tube or engine. The engine doesn't smoke from the exhaust except for a puff of black smoke on start up.

I don't experience any power loss while using the hoe, however the engine does bog down significantly with some smoking when I am using the FEL (even picking up light objects). I have also noticed quiet a bit of engine oil viscosity break down very quickly after a fresh oil change.

My main question is will I do damage to the engine running it with this amount of suspected blow by as long as I frequently change the engine oil? Is this relatively normal, or should I be saving my pennies to get this in to the shop? /forums/images/graemlins/confused.gif

 

[Egon]

</font><font color="blue" class="small">( engine oil viscosity break down very quickly after a fresh oil change. )</font>

How do you tell this??

Does the tractor use oil?

1200 hours is not much time on the engine. My B7100 engine has always had a little blow by but uses no oil.

Compression check may be the fastest method to get an answere.

Egon

 

[RalphVa]

My old 1972 Benz with almost 200,000 miles on it started building up a little pressure in the crankcase, enough to leak a tiny bit of oil around the oil fill cap. Now, my 1983 Benz with almost that many miles is starting to show the same thing. They were/are tied into the suction line. Excess vapors go to the intake manifold. Both of these used some oil. Benzes are supposed to, up to a quart/500 miles. These both used a quart about every 2,000 miles. Oil was changed at 3,000 miles (at least before switching the present one to Mobil 1; will be 5,000 miles now).

I'd try a different oil, maybe even a synthetic one. Could cause things to tighten up. Usually works on transmissions and power steering systems, not necessarily engines.

Ralph

 

[KennedyDiesel]

I would do a compression or leakdown test and also test the injectors. A steady stream of vapor is expected with an older engine, but puffing typically indicates a problem with a single cylinder.

 

[SkyPup]

Could easily be the brand of oil you are using too.

A full synthetic with low <5% Noack volatility will produce allot less crankcase pressure than a lesser oil that loses 15% or more of its volume to evaporation at operational temperature.

 

[Charolais]

Where is the vent pipe connected to the engine?

I have a Fiat engine that's vented from the side cover under the head. I have a Perkins engine that's vented from the valve cover(on top).

Both have vapors present. The Perkins has far more than the Fiat. Oil consumption is zero(I don't add between oil changes). The Fiat is 100 hr. oil changes and the Perkins is 150 hr's. at present with 200hrs. on the next change. I use 15w-40 Amsoil HD Marine Diesel syn. oil in both.

When the humidity is high I see more vapor. It also seems the Perkins being vented from the valve cover has more positive pressure than the Fiat that's vented from a different area of the engine. I only see vapor from both. Not smoke. The Fiat has 1000+ hrs. on it. The Perkins is just under 200 hrs. (new engine) The vapor is normal for both engines.

It has been my experience that vapors are normal. If you see drops of oil or blue smoke from the vent you then have a wear problem. If you want to see what's being vented hang a small container right under the end of the vent pipe. Do not block the vent pipe. Then check the container every 5-10-20 or what ever hours you like. If there's liquid being forced out of the pipe you can see what type liquid it is.

I'll finish with I've seen engines run thousands of hours with even some oil smoke and drops of oil coming from the vent. Just have to keep the oil level topped off and remember to check it often. A little oil usage is cheap when you're talking about an engine rebuild or replacement. Just depends on how much power loss the engine has.

 

[Jagmandave]

I wonder if you have an injector hanging open or leaking slightly, diluting your oil?

 

[Scott037]

Thanks for all the responses. I am not experiencing any oil consumption, but when I check the oil after about 20 hours of use the oil just drips off of the dipstick like dirty water. When I rub it between my fingers, it doesn't feel like oil (doesn't seem thick and slippery) but more like water. I was concerned that it was being diluted by fuel.

I wasn't aware that I could use a full synthetic so I will try that. Can I use a standard filter with a full synthetic oil? Seems someone told me (or scammed me) when I went synthetic in my truck that you have to use a filter rated for synthetic oils.

Thanks for all the help!

 

[Av8r3400]

</font><font color="blue" class="small">( I am not experiencing any oil consumption, but when I check the oil after about 20 hours of use the oil just drips off of the dipstick like dirty water. When I rub it between my fingers, it doesn't feel like oil (doesn't seem thick and slippery) but more like water. I was concerned that it was being diluted by fuel.)</font>

/forums/images/graemlins/shocked.gif Slow down there. /forums/images/graemlins/shocked.gif

Is the level of your oil <font color="red"> INCREASING </font> during the time between changes? Has your fuel consumption gone up? If you have a stuck injector, this could cause some $$damage$$ to your motor. I would investigate this further.

 

[Egon]

If the oil is becoming diluted with fuel [ Which it sounds like ] perhaps a real checkup is in order at a proper Doctors office.

Egon

 

[rebelmedic]

If fuel is makeing it into the oil,, along with level rise on the dip stick you should easily be able to notice the smell of diesel in the oil on dip stick. Just don`t get too close to the nose the diesel smell will stay with you all day *S*

 

[normde2001]

"I am not experiencing any oil consumption, but when I check the oil after about 20 hours of use the oil just drips off of the dipstick like dirty water"

Maybe it is dirty water. I would suspect/inspect for a blown head gasket, etc. Check for bubbles in radiator when started up cold. Any sign of oil in cooling system? Drain the oil and let it sit in a clear container and check for water in the bottom after a while.

 

[Egon]

Water in the crankcase should form a whitish or dirtbrown emulsion.

Egon

 

[SnowRidge]

<font color="blue"> If the oil is becoming diluted with fuel [ Which it sounds like ] perhaps a real checkup is in order at a proper Doctors office. </font>

Gets my vote!

The puffs coming out of the breather may be fuel vapor. The "puff rate," for lack of a better term, tends to indicate it is related to something driven off of the camshaft. Fuel may be getting into the oil through a bad injection or lift pump.

A qualified diesel mechanic should be consulted right away. There may be a risk of significant additional damage if the machine is operated in its current state.

If atomized fuel is somehow present in the crankcase, there could be a risk of explosion. I suspect the risk would be low, but it should be considered.

 

[captain71c]

There are many companys that can do an oil analysis for you. Most parts stores or fleet repair companys can give you a company name. The analysis will also tell you if there is any excess wear or if antifreeze is in the oil. I'm not sure of the price but I think it is under $20. We do analysis on our trucks at work and were able to almost double the oil change intervals.

 

[Kiohio]

This doesn't look good, do you know the history of the machine?
Did someone by chance use ether on it??

KO

 

[Kiohio]

Also check the oil before start up, after it has set overnight. That way we can know if it is fuel or water doing the diluting. Sometimes a "little" water is hard to detect after the engine has been started. Also if you are saying it is thin when you drain it, if you run it it does thin out quite a bit when it gets hot. Most people run there engines before draining them. Just trying to cover all the bases /forums/images/graemlins/wink.gif
Hope you get this worked out.

KO

 

[Scott037]

Thanks for all the help guys. I haven't noticed a rise on the dipstick level, and I don't smell fuel in the oil. I think what I will do is submit the oil sample for analysis and go from there. I currently am not using the machine due to company down time, and will wait for the analysis before proceeding further.

Thanks again to all!

 

[bobcatman101]

i have a bobcat 763 kubota engine it leaking oil it has a little blow by do they have a little blowby

 

[art]

What have you been using for oil? It does make a difference from what we see in our shops. With no noticeable oil consumption how is it stored, in a heated garage, or cold? When you do run it, how long of an interval is normal?