John Deere 855 blow by. Is this excessive?

[Deere855]

Hello,
I have a small Deere 855.
A few weeks ago while running a finish mower, it lost power some. It was very noticeable. It was very hard to start afterward while hot. I was just about done with the work anyway so I parked it. It was about 97 degrees that day, and I was running hard for a few hours.

I have not needed it since but It is time to figure out what happened.
Basics.
Oil color is fine
Coolant level ok.

I came back to it a few days ago. It started fine cold, but I notice some more blowby than I remember.
I made a small video here:

- YouTube

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This looks excessive to me.
I have not driven it under load again, but I might do that today just to see.

I am thinking to start with.
Fuel Filter.
Compression/leakdown tests.
Injectors.

Thoughts.

 

[Roadworthy]

If you think you have blow by the compression test will answer a lot of questions.

 

[CoyPatton]

Hello,
I have a small Deere 855.
A few weeks ago while running a finish mower, it lost power some. It was very noticeable. It was very hard to start afterward while hot. I was just about done with the work anyway so I parked it. It was about 97 degrees that day, and I was running hard for a few hours.

I have not needed it since but It is time to figure out what happened.
Basics.
Oil color is fine
Coolant level ok.

I came back to it a few days ago. It started fine cold, but I notice some more blowby than I remember.
I made a small video here:

- YouTube

Enjoy the videos and music you love, upload original content, and share it all with friends, family, and the world on YouTube.

youtube.com

This looks excessive to me.
I have not driven it under load again, but I might do that today just to see.

I am thinking to start with.
Fuel Filter.
Compression/leakdown tests.
Injectors.

Thoughts.

Where does that hose connect?
My thoughts are to check/adjust the valve lash.

 

[BravoXray]

Sounds to me like possibly a broken compression ring.
Does it have a Yanmar 3 cylinder in it?
I sounds just like my 430 with a 3TNA-72UJ.

 

[Egon]

That amount of blow by is excessive. Suggest pulling the head to see where the problem is.

 

[rScotty]

That amount of blow by is excessive. Suggest pulling the head to see where the problem is.

I'd agree, but suggest that the owner first check the valve clearance and do a compression test to get some baseline information before taking the head off.

And I'd do the other things he suggested as well....although I don't think that they are going to fix this problem. And also take a look at the coolant to see if it has oil or is bubbling (head gasket). Wouldn't it be nice if it was just a head gasket!

Regardless, I always recommend that the head be very "faced" just to insure flatness before re-installing with a new gasket.
rScotty

 

[arto98607]

Hello,
I have a small Deere 855.
A few weeks ago while running a finish mower, it lost power some. It was very noticeable. It was very hard to start afterward while hot. I was just about done with the work anyway so I parked it. It was about 97 degrees that day, and I was running hard for a few hours.

I have not needed it since but It is time to figure out what happened.
Basics.
Oil color is fine
Coolant level ok.

I came back to it a few days ago. It started fine cold, but I notice some more blowby than I remember.
I made a small video here:

- YouTube

Enjoy the videos and music you love, upload original content, and share it all with friends, family, and the world on YouTube.

youtube.com

This looks excessive to me.
I have not driven it under load again, but I might do that today just to see.

I am thinking to start with.
Fuel Filter.
Compression/leakdown tests.
Injectors.

Thoughts.

When I bought my Ford 1310 back in 1997 it had very similar, but lesser degree excessive blow by and the engine ran fine, no oil / coolant was getting mixed at all and oil consumption was not excessive.
Since the tractor was new to me I had nothing to compare with as far as engine loss of power, so I ran it for 9 years like that without knowing better but the "blow by" was slowly increasing.


Long story short:
After I removed the cylinder head in 2006 I discovered blown head gasket, but the odd thing was there was no leakage externally or into the cooling system!

Instead it was blowing most of the middle cylinder "compression" into the crankcase through opening in the block where the push-rods are.

So in essence it was likely firing only on two (maybe 2 1/2 ??) cylinders and the middle cylinder was mostly just pumping air and some fuel down into the crankcase, which caused the excessive breathing from the vent tube!

I cleaned up everything, installed new proper head gasket and now 15 years later the engine still purrs like new (1000 hours on now) and never needs addition of engine oil.
Hardly any noticeable breathing from the vent tube.


Wish I had photo of the blown head gasket, but this is all I have:

 

[nyone]

Lol pull the head for a starting issue? Dont do the hardest thing first.

Just by the looks of the small bit of the machine (and we dont know the hours) clean your radiator and air filter. Do you have a working temp gauge on the machine?

Radiators can really get clogged up quick even though they look clean, blow air through them with a blow gun.

Also the blow by dosnt look excessive. What your seeing is pulses of the crank case getting pressurized by the pistons going up and down.

Have you started the machine after the hard start?

 

[Egon]

Lol pull the head for a starting issue? Dont do the hardest thing first.

Just by the looks of the small bit of the machine (and we dont know the hours) clean your radiator and air filter. Do you have a working temp gauge on the machine?

Radiators can really get clogged up quick even though they look clean, blow air through them with a blow gun.

Also the blow by dosnt look excessive. What your seeing is pulses of the crank case getting pressurized by the pistons going up and down.

Have you started the machine after the hard start?

The easiest thing first is to pull the head. If you do all the testing you’ll still be pulling the head!