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Cat 951c engine, oil in exhaust manifold

sergioannis

Active Member
Joined
Dec 3, 2018
Messages
37
Location
italy
Hello,
I have a problem with the 951c crawler loader motor.
Unfortunately enough oil comes out of cylinder 3 in the exhaust.
I disassembled the exhaust and o saw that it leaks a little from everyone, but especially from number 3.
This was sudden, I started to see cold engine smoke and obviously blue smoke.
When the engine warms up it no longer emits smoke and no longer leaks oil. This crawler loader had been standing still for years when I took it, and when I unloaded it it didn't emit any smoke. I parked it to make various repairs and after the tests I noticed this problem.
I have noticed that under the valve cover, the spring and valve are moving up and down by half a millimeter. Can this affect and let oil enter the cylinder? Only when cold enters oil, then how it heats are the losses irrelevant?
The engine is powerful, it doesn't lose revs, it starts immediately.
Every so often when cold cylinder 4 emits bursts, such as cough, injector?
I am attaching images.
I ran the engine on max for 1 hour.
has dirtied everything ..
oil comes out of all cylinders.
all this oil possible?
all piston rings damaged?
possible valve guide?
I am desperate...
IMG_20210707_190820.jpg IMG_20210707_190808.jpg IMG_20210707_190758_1.jpgIMG_20210707_190752.jpg
Tank you all.
 

Welder Dave

Senior Member
Joined
Oct 11, 2014
Messages
12,257
Location
Canada
Is it oil or fuel? You could get the injectors checked as they could leak diesel into the cylinders if not working properly. If it clears up when the engine is warm, run the machine and make it work hard. It may clear up. Stuck piston rings and/or valves out of adjustment could be the cause of oil loss.
 

sergioannis

Active Member
Joined
Dec 3, 2018
Messages
37
Location
italy
Hello it's oil.
In two hours she consumed 2 liters, lots of blue smoke and the smell of burnt oil.
I did the test with the engine at maximum revs. Without working on it, I sped up and let 2 hours go by
Oil everywhere at first then passes. At full throttle, no oil leaks. If I go to half throttle, a lot of blue smoke starts again and oil comes out ..
The engine is fine except for a few coughs at low revs, it sounds like irregular bursts, then it passes ...
valve guides?
 

Nige

Senior Member
Joined
Jun 22, 2011
Messages
28,973
Location
G..G..G..Granville.........!! Fetch your cloth.
Post a Serial Number please.

First thing you should eliminate is the turbo. Remove the hose between the turbo and the cylinder head. (This may be easier to say than to actually do)
Check for oil in the compressor side of the turbo or inside that hose.

When was the last time the engine valve clearances were adjusted.?
 

Welder Dave

Senior Member
Joined
Oct 11, 2014
Messages
12,257
Location
Canada
No turbo on a 951C, 955L has a turbo. I had my 3204 rebuilt and it went through oil like crazy and had no smoke at all. Seems the rings didn't seat but thankfully it was covered by warranty. Could the crankcase vent be plugged and is the air filter clean? Maybe adjust the valves and work it and see how much oil it goes through. Running at full throttle is not the same as working it and putting a load on the engine. Have seen slobbering/smoking engines clear up after being put to work.
 

Bluox

Senior Member
Joined
Jun 19, 2010
Messages
1,960
Location
WA state
Hello it's oil.
In two hours she consumed 2 liters, lots of blue smoke and the smell of burnt oil.
I did the test with the engine at maximum revs. Without working on it, I sped up and let 2 hours go by
Oil everywhere at first then passes. At full throttle, no oil leaks. If I go to half throttle, a lot of blue smoke starts again and oil comes out ..
The engine is fine except for a few coughs at low revs, it sounds like irregular bursts, then it passes ...
valve guides?
Check air filter .
Most likely rust in the cylinders may have lapped in the rings.
The miss may be nozzles going away.
Bob
 

Welder Dave

Senior Member
Joined
Oct 11, 2014
Messages
12,257
Location
Canada
I guess a serial number is in order. I know someone with a 1975 951C and it doesn't have a turbo. Maybe some versions had a turbo but all the brochures I could find don't list a turbo, just 95 H.P. 3304. Maybe a turbo was an option but then why not just get a 955 that is also a bigger machine.
 

sergioannis

Active Member
Joined
Dec 3, 2018
Messages
37
Location
italy
Hello
the 951c has no turbo.
i had 3 crawler loaders 951, turbo is not expected.
The serial is 69h3944.
Is it possible to remove the pistons and cylinders without removing the engine?
 

sergioannis

Active Member
Joined
Dec 3, 2018
Messages
37
Location
italy
Hello
New symptoms more corrected.
The engine starts very well, holds idle and has excellent compression.
The problem of smoke and oil leaking from the exhaust occurs when the engine is hot and at medium and high rpm. It is not clear but after about 20 minutes when it is warmed up enough by some bursts, if I accelerate it still works well, but blue smoke and oil comes out.
In short, when cold as it seemed, it does not drool and does not smoke.
And when it is hot it behaves like this.
If they were the rings it would do it a lot more cold (I think).
Could it be the valve guides?
is it possible and from where does the ignition pump pass oil and from where?
What can I check without disassembling the whole crawler loader?
 
Last edited:

sergioannis

Active Member
Joined
Dec 3, 2018
Messages
37
Location
italy
IMG_20210703_182609.jpg
I noticed something else.
The ignition pump, the regulator is very hot, it is as hot to the touch as the oil filter. It's normal ?
I noticed this right away.
Is it possible that oil passes into the pump and is sprayed into the combustion chamber?
 

sergioannis

Active Member
Joined
Dec 3, 2018
Messages
37
Location
italy
IMG_20210708_183027_1.jpg IMG_20210708_183005.jpg IMG_20210708_183014.jpg IMG_20210708_183018.jpg
the oil is on the bar arrived on add. it was full level.
he ate almost all the oil in the tests
I just wanted to know if by removing the oil pan I can remove all the pistons and cylinders
 

Bluox

Senior Member
Joined
Jun 19, 2010
Messages
1,960
Location
WA state
As I recall your engine has a flat plate on the bottom over the hard bar and the sump is on the front half so may be difficult to remove back pistons . take a look .
Bob
 

sergioannis

Active Member
Joined
Dec 3, 2018
Messages
37
Location
italy
As I recall your engine has a flat plate on the bottom over the hard bar and the sump is on the front half so may be difficult to remove back pistons . take a look .
Bob
bob do you think it's a problem with rings?
I wouldn't want to take everything apart for no reason
 

Bluox

Senior Member
Joined
Jun 19, 2010
Messages
1,960
Location
WA state
Kinda hard to check oil control rings with out looking at them.
,Did you move any hoses or lines while you were starting this motor?
Have you checked the air filter?
How much blowby do you have?
Bob
 

sergioannis

Active Member
Joined
Dec 3, 2018
Messages
37
Location
italy
bob, air filters I even removed them for testing, however it is new.
blow by absolutely 0 absolute, none not even a small breath.
I checked everything, I don't understand why you eat all this oil.
I tried air compression tests, even the fan moves.
Is it possible that the valve guides are so shabby?
 

Dave Neubert

Senior Member
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Jul 18, 2018
Messages
1,649
Location
Monroe NC
How does the blow by look coming out of the breather my guess is stuck rings also bad valve guides can cause this. normally if its rings it will burn it but exhaust valve guides will leak oil into manifold and run down block
 
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