Diesel Dummie question

Orange man hero

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LX2610HSD
Mar 12, 2021
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Wasilla, Alaska
I noticed that when I started my new LX2610 if not plugged in even at 30 Degrees F the engine sounds like a connection rod is knocking on the piston bore wall. I know this is not the case but anyone know what that loud knock is? Pre detonation maybe. IF I plug the engine in for a half hour, the glow plug is not even needed and engine beautifully and smooth with no knock noise.
 

Justasquid

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L4240HSTC
Nov 2, 2020
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Michigan
Im no expert. But I’ve aways thought it was due to incomplete burned diesel fuel and it being injected into a cold combustion chamber. you will probably notice more smoke at start up as well. even when really cold, it should clear up within about 20 seconds or less.

Also, I usually hold the clutch in until the engine smooths out. So the engine doesn’t have the load of the hydraulic system on it
 
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B737

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B2601
Jun 9, 2019
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my 2601 sounded that way too as delivered, not even freezing cold, but just chilly was enough. I switched to 5-40 T6 at 50 hours and morning starts became much smoother. I dont know what the dealer had in there.
 

i7win7

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IF I plug the engine in for a half hour, the glow plug is not even needed
You can add glow plug heat to running engine 5 seconds or so to see if engine quits knocking
 
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Henro

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B2910, BX2200, KX41-2V mini Ex.
May 24, 2019
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I noticed that when I started my new LX2610 if not plugged in even at 30 Degrees F the engine sounds like a connection rod is knocking on the piston bore wall. I know this is not the case but anyone know what that loud knock is? Pre detonation maybe. IF I plug the engine in for a half hour, the glow plug is not even needed and engine beautifully and smooth with no knock noise.
I never worried about it, and just figured that "diesels do what diesels do..."

1800 plus hours on my B2910 and it still does what it wants to...and I just accept it...:)
 
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GeoHorn

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May 18, 2018
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Justasquid has it correct. When cold, excess fuel (unburned cold fuel) will create a “knock” which disappears as the engine warms us.
 

Orange man hero

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LX2610HSD
Mar 12, 2021
134
14
18
Wasilla, Alaska
my 2601 sounded that way too as delivered, not even freezing cold, but just chilly was enough. I switched to 5-40 T6 at 50 hours and morning starts became much smoother. I dont know what the dealer had in there.
Yea, my owners manual sez 10-30 oil which may be a little thick for cold weather???
 

nbryan

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B2650HSD ROPS BH77 LA534A 54" Martatch 42" forks B2782B WC68 BB1560 M5-4 hog
Jan 3, 2019
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Hadashville, Manitoba, Canada
Yea, my owners manual sez 10-30 oil which may be a little thick for cold weather???
I've been running 10W-30 semi-synthetic all year here, which includes -30C mornings sometimes. The operators manual indicates 10W-30 ok for all temp ranges, including below -10C. I always plug in the block heater for a few hours when it's below -5C or so anyway. Then when starting on those cold mornings, 10-15 seconds of glow plug does the trick. VERY little banging and smoke.
Some here have been using full synthetic T-6 5W-40 engine oil with success. As it's not listed in the manual, I've been sticking to the 10w-30.
 

nbryan

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B2650HSD ROPS BH77 LA534A 54" Martatch 42" forks B2782B WC68 BB1560 M5-4 hog
Jan 3, 2019
506
202
43
Hadashville, Manitoba, Canada
Yea, my owners manual sez 10-30 oil which may be a little thick for cold weather???
The other cold weather thing I do is cover all but about a 6"x6" area of the front of the rad screen with 6 mil poly taped around the edges of the screen, with that 6x6 hole cut out of the center. Basically a rad cover to allow the engine to actually reach proper operating temp in the cold. Before, I couldn't get it to go above 2 bars in the winter.
 

Orange man hero

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LX2610HSD
Mar 12, 2021
134
14
18
Wasilla, Alaska
The other cold weather thing I do is cover all but about a 6"x6" area of the front of the rad screen with 6 mil poly taped around the edges of the screen, with that 6x6 hole cut out of the center. Basically a rad cover to allow the engine to actually reach proper operating temp in the cold. Before, I couldn't get it to go above 2 bars in the winter.
Yea, I'm not even going to run mind unless I have to at temps below 30F
 

JerryMT

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Kubota M4500, NH TD95D,Ford 4610
Jun 17, 2017
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Remember that a diesel engine is a compression ignition engine, i.e. it relies on the heat of compression to ignite the fuel/air mixture. When the engine is cold, the piston crown and the cylinder walls are cold , as well as the cold air charge. That slows down the combustion chemical reaction. So the engine clatter and knocks for awhile until the reaction stabilizes.

When you use the block heater, it warms the coolant which warms the cylinder walls which helps sta.bilize the combustion reaction. It also warms the oil film and the oil will flow better on start up and it reduces the torque load on the starter
 

Orange man hero

Member

Equipment
LX2610HSD
Mar 12, 2021
134
14
18
Wasilla, Alaska
Remember that a diesel engine is a compression ignition engine, i.e. it relies on the heat of compression to ignite the fuel/air mixture. When the engine is cold, the piston crown and the cylinder walls are cold , as well as the cold air charge. That slows down the combustion chemical reaction. So the engine clatter and knocks for awhile until the reaction stabilizes.

When you use the block heater, it warms the coolant which warms the cylinder walls which helps sta.bilize the combustion reaction. It also warms the oil film and the oil will flow better on start up and it reduces the torque load on the starter
Good info...thanks