High crankcase pressure on new rebuild.

Ted337 · Post by **Ted337** » Sun Sep 25, 2016 7:38 am

I have a td 400 engine in a 450c dozer. I got the engine from a guy who said it was rebuilt a year ago but never used. He wasn't sure what it had for oil so I drained it and put in the John Deere break in oil.
After some trouble getting the injectors to prime I got it running, everything seems Ok (runs smooth, good power) but there is a lot of blow back coming out the crankcase vent. Also there is enough pressure to cause oil to weep out some of the front gaskets.
I have only put about an hour on it and it has lost a half quart of oil. The break in oil seem very thin could this be normal??
The guy at the local JD dealer said after an hour of running I should put it right to work but I'm afraid of running the RPMs up with so much pressure.

gregjo1948 · Post by **gregjo1948** » Sun Sep 25, 2016 4:48 pm

I'm not familiar with a TD 400 but I'm guessing it's a diesel. That being said, diesels have a lot more compression, therefore, before the rings seat, you'll get more air past them into the crankcase causing more than normal blowby coming from the vent pipe. I don't think it should be weeping/leaking out of the front gaskets but perhaps tightening the bolts would stop the weeping.

Ted337 · Post by **Ted337** » Mon Sep 26, 2016 3:00 am

Yep, Sorry it is a 4 cyl diesel. I think the TD400s were in tractors in the late 60s early 70s.
I have tightened everything (I think). I guess my question is if anyone has used the JD Break In oil and if they saw something similar with it.
I guess I will just have to run it and keep a close eye on the oil level and pressure.

mini kahuna · Post by **mini kahuna** » Mon Sep 26, 2016 9:56 am

it is not normal to have gaskets weeping oil out during an engine break in period.
I have never used a break in oil, always used regular oil that engine called for.
I run them up to temp for the first time, for maybe 20 mins or so and shut them down and drain oil and change filter.
you have something going on that is not right.
seen something similar in a gas engine and the cause ended up being all the ring gaps being lined up when it was put back together.
if you have good power and running well maybe your crankcase vent is blocked somehow ?

Ted337 · Post by **Ted337** » Mon Sep 26, 2016 12:07 pm

Well the vent isn't clogged. That was the first sign that it might have blow by(the amount coming out the vent).
Possible the rings were not installed right but if that is the case I'm out of luck as the engine was done a year ago an there is no warranty.
Could be that everything is not tight or gaskets not installed properly.
Jd dealer said to run it for a 100hrs before changing oil??

Al Swearengen · Post by **Al Swearengen** » Mon Sep 26, 2016 2:45 pm

Ted337 wrote: Jd dealer said to run it for a 100hrs before changing oil??

I could see MAYBE 10 with on/off load; heat/cool down periods in between.

Ted337 · Post by **Ted337** » Mon Sep 26, 2016 2:56 pm

I talked to 2 different service managers at 2 different shops and they do say to run it for 100 hrs before taking the break in oil out. Seems like most people disagree, not sure what to think.

pop pop · Post by **pop pop** » Mon Sep 26, 2016 3:45 pm

run the break in oil as recommended otherwise improper break in and the rings will never seat resulting in a smoker.

gregjo1948 · Post by **gregjo1948** » Thu Sep 29, 2016 3:59 am

pop pop wrote:run the break in oil as recommended otherwise improper break in and the rings will never seat resulting in a smoker.

Pop Pop--Can you tell me why a special oil is used for break-in? Does it not lubricate the cylinders as much as "regular" oil, causing the rings and cylinder walls to wear a tiny bit? Is this tiny bit of wear call "seating the rings"?
gregjo1948

gregjo1948 · Post by **gregjo1948** » Thu Sep 29, 2016 4:08 am

I'm wondering what Lavoy and Stan D. think about "break-in oil".

Stan Disbrow · Post by **Stan Disbrow** » Thu Sep 29, 2016 4:54 am

Hi,

That is exactly what break-in oil does. Allow some wear to occur before the metal hardens too much.

Stan

gregjo1948 · Post by **gregjo1948** » Thu Sep 29, 2016 5:38 am

Stan Disbrow wrote:Hi,

That is exactly what break-in oil does. Allow some wear to occur before the metal hardens too much.

Stan

Do you have a time span for running break-in oil before changing to recommended oil weight? Also would you recommend a specific break-in brand or isn't there a notable difference? Thanks, gregjo1948

Stan Disbrow · Post by **Stan Disbrow** » Thu Sep 29, 2016 6:47 am

Hi,

It will tell you when it is time as the blowby and oil consumption taper off. It does vary by engine job. I would go at least 50 hours on it, changing it at 25 - mostly so I can eyeball the metal flakes on the bottom of the drain pan in bright sunlight. Those flakes also taper off and are another clue as to when you are done. If you decide to go past 50 hours, check again at 25 hour intervals.

While running it, don't work the machine hard and keep thinking to vary the engine speed. Also, don't speed it up too far. Nice and easy does it. I usually just drive around doing nothing for an hour at a time for the first 10 hours, stopping it and letting it cool each hour. After 10 hours doing light work would be ok, but don't get into a Big Dig until you're off the break-in oil....

I know this sounds like a PIA, but a few hours of care up front equals thousands of hours extra later.

Stan

gregjo1948 · Post by **gregjo1948** » Thu Sep 29, 2016 7:03 am

Would it suffice to leave the machine setting still and running the engine at different rpms for those first 10 hours or does it help to put a little stress on it by driving it around?

Post by **Lavoy** » Thu Sep 29, 2016 9:24 am

Run the break in oil at least as long as they recommend. Idling does nothing to break in an engine, put it to work like it was designed to do, anything less will not seat the rings as well.
Break in oil has nothing to do with weight, that is no different than regular oil. The difference is in the additive package and the way it is made. It is designed to allow the rings to effectively seat without causing wear on other parts of the engine that you want good lubricity on such as the camshaft.
Without seeing your engine I can't say of your blowby is excessive, but you really only have 2 choices at this point. Work it and get hours on it to see if the blowby decreases, or tear it down and look for a mechanical error.
Two cylinder gas engine when I dyno a fresh rebuild takes at least 45 minutes to a couple hours at full rated load before the blowby decreases.
Lavoy

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High crankcase pressure on new rebuild.

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