Blow by

[BenRoberts]

I have a nhc250 engine and noticed a bit of vapor coming out of the breather tube so i removed the oil cap and did notice some blow by. I have done some reading on here and noticed something about a particular model that had 2 pistons rising at the same time which causes some "windage" in the crank case and its normal. How do I know if thats what I have? I do not have excessive smoke of anything and it runs fine so im not sure what to think with this one. Its in a 1984 m923a0

 

[NDT]

One of my trucks was way overdue for an oil change and the road draft tube looked like a steam kettle. After 11 gallons of new Delo 400LE, visible vapor and blowby all gone. My 2 cents.

 

[BenRoberts]

That is possible. Looked like decent oil but its the oil that was in it when I bought it. only put a few 100 miles on it but its worth a shot, needs done anyway. My wife already threatened to revoke my credit card

 

[Two Stroke Madness]

I have a nhc250 engine and noticed a bit of vapor coming out of the breather tube so i removed the oil cap and did notice some blow by. I have done some reading on here and noticed something about a particular model that had 2 pistons rising at the same time which causes some "windage" in the crank case and its normal. How do I know if thats what I have? I do not have excessive smoke of anything and it runs fine so im not sure what to think with this one. Its in a 1984 m923a0

Every inline engine is designed like that. It's what makes them so well balanced. A little blow by is OK, you just don't want to see alot of smoke coming out. I wouldn't worry as long as the engine runs good, doesn't knock, or make any other bad sounds. Unfortunately engines are only new once, and every time we use them we are slowly killing them. Don't worry, the engine will let you know when it's time for a rebuild.

 

[TCD]

... doesn't knock, or make any other bad sounds...

My problem is that I can't hear/discern any "knock" or "bad" sounds over the diesel clatter!



tom n tyler

 

[Two Stroke Madness]

If you can't tell the difference between engine clatter and bearing knock then there is nothing to worry about. I've been around knocking diesels before. It's a gut-renching sound. Believe me you will be able to hear it.

 

[Two Stroke Madness]

If you plan on keeping this truck for a while and want real world info on the condition of the engine then change the oil and filter. Run the truck for 3000 miles then pull a sample of oil out and send it in for analysis. They will be able to tell you exactly what condition that engine is in, and what parts are wearing and need replacement if any.

 

[WillWagner]

You can't tell what kind of crankcase pressure an engine is making by looking at it, unless it is pushing out of the tube like an air hose. It needs to be measured with a manometer in inches of water. If you have good oil pressure, no hard start, white smoke out the tailpipe, banging around...believe me, you can tell a bang/knock from the normal marble rattle the NHC makes even if you know nada about engines...your engine is most likely fine. Drain the oil, take the oil filter out and cut the filter open to look for metal. Undesirable pieces of metal would include copper chunks/flakes, aluminum chunks/flakes and real hard steel. If there is none of the afore mentioned in the pleats, run it.

 

[Two Stroke Madness]

You can't tell what kind of crankcase pressure an engine is making by looking at it, unless it is pushing out of the tube like an air hose. It needs to be measured with a manometer in inches of water. If you have good oil pressure, no hard start, white smoke out the tailpipe, banging around...believe me, you can tell a bang/knock from the normal marble rattle the NHC makes even if you know nada about engines...your engine is most likely fine. Drain the oil, take the oil filter out and cut the filter open to look for metal. Undesirable pieces of metal would include copper chunks/flakes, aluminum chunks/flakes and real hard steel. If there is none of the afore mentioned in the pleats, run it.

Diesel engines don't wisper their complaints.

 

[BenRoberts]

oil change this week and im going to run her. i own other diesels and im very familiar with bad engine hammer and my truck has none of that. runs very well. it did have white smoke starting on a cold day, now that its warm i got virtually no smoke of any kind

 

[Floridianson]

Also there is blow by and moisture. A motor that has an open draft tube when cooling draws in moist air. They need to be run a good while to heat up the block /oil long enough to expel the moisture. So that blow buy is ether rings or just moisture so I myself when after a good hour run then check if the blow by tube has decreased or about the same.

 

[Scar59]

oil change this week and im going to run her. i own other diesels and im very familiar with bad engine hammer and my truck has none of that. runs very well. it did have white smoke starting on a cold day, now that its warm i got virtually no smoke of any kind

When you change the oil, upgrade to a spin on oil filter adapter. Makes future oil changes a breeze. I have them listed in the classified.
JC

 

[acesneights1]

I got two trucks with NHC250s in them. They both have a little out the breather. It's normal. Remember these are 30+ year old trucks that probably were not treated well and also sat. When it started puking oil out then worry. Even the 6bt's have catch cans on them from the factory....

 

[WillWagner]

Even the 6bt's have catch cans on them from the factory....

Only in VP44 powered dodges, real trucks, not.

 

[Two Stroke Madness]

VP pumps suck. Inline mechanical injection pumps are the way to go.