STD Other Open what is blow-by?

what is blow-by?

what is blow-by?

 
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Purplecomputer
Slowness 220D

897
02-14-2012, 08:32 PM #1
This term comes up every once in a while in different forums and I dont know what it means...
Purplecomputer
02-14-2012, 08:32 PM #1

This term comes up every once in a while in different forums and I dont know what it means...

aaa
GT2256V

913
02-14-2012, 08:42 PM #2
Gases slipping out of the combustion chamber past the piston rings. A little of it is unavoidable, hence the crankcase ventilation hose on top of the valve cover. And the more that slips past, the less power you get from your engine (less compression).
aaa
02-14-2012, 08:42 PM #2

Gases slipping out of the combustion chamber past the piston rings. A little of it is unavoidable, hence the crankcase ventilation hose on top of the valve cover. And the more that slips past, the less power you get from your engine (less compression).

larsalan
Superturbo

1,272
02-14-2012, 08:43 PM #3
Gas from inside the combustion chamber sneaking past the rings into the crankcase. Where the gas is actually blowing by I dunno. Where did that term come from?

Rusted out beat down 300d turbo 82' -- RIP
Nice body, tons of ridiculous mechanical issues - 300d turbo 82' /motor 85'
larsalan
02-14-2012, 08:43 PM #3

Gas from inside the combustion chamber sneaking past the rings into the crankcase. Where the gas is actually blowing by I dunno. Where did that term come from?


Rusted out beat down 300d turbo 82' -- RIP
Nice body, tons of ridiculous mechanical issues - 300d turbo 82' /motor 85'

Purplecomputer
Slowness 220D

897
02-14-2012, 09:22 PM #4
Oh...I see. So how doe people check for blow-by?
Purplecomputer
02-14-2012, 09:22 PM #4

Oh...I see. So how doe people check for blow-by?

larsalan
Superturbo

1,272
02-14-2012, 09:30 PM #5
Take the oil filler cap off and watch the gas fly by. It looks like smoke. Mine varies depending on the operating tempo and the amount of boost.

Rusted out beat down 300d turbo 82' -- RIP
Nice body, tons of ridiculous mechanical issues - 300d turbo 82' /motor 85'
larsalan
02-14-2012, 09:30 PM #5

Take the oil filler cap off and watch the gas fly by. It looks like smoke. Mine varies depending on the operating tempo and the amount of boost.


Rusted out beat down 300d turbo 82' -- RIP
Nice body, tons of ridiculous mechanical issues - 300d turbo 82' /motor 85'

w123love
Stockish

354
02-15-2012, 12:47 AM #6
A good check is to unscrew the oil filler cap, and let the cap just sit while the engine is idling. Inevitably gasses will pass by the cap, and make it move a little bit. If it bounces the cap off the valve cover, then you have some SERIOUS blow-by. If it chills, you can chill.

if it don’t blow black...take it back.

1982 300TDT 4 Speed 196K Standard Beige “VEGEWGN”. 300GD FW. Walbro FRC-8 Fuel Pump. ZadaTech LCD Boost, EGT, & Fuel Pressure gauge. Non-EGR Exhaust and Intake Manifold. 3/2 Valves gone. Soon to have Elsbett WVO conversion
1981 300D 314K Midnight Blue “The Blue Car”, Lovecrap system, owned 25 years+
1985 300TD White 198K “Betty White” Pure beauty

The VEGEWGN
w123love
02-15-2012, 12:47 AM #6

A good check is to unscrew the oil filler cap, and let the cap just sit while the engine is idling. Inevitably gasses will pass by the cap, and make it move a little bit. If it bounces the cap off the valve cover, then you have some SERIOUS blow-by. If it chills, you can chill.


if it don’t blow black...take it back.

1982 300TDT 4 Speed 196K Standard Beige “VEGEWGN”. 300GD FW. Walbro FRC-8 Fuel Pump. ZadaTech LCD Boost, EGT, & Fuel Pressure gauge. Non-EGR Exhaust and Intake Manifold. 3/2 Valves gone. Soon to have Elsbett WVO conversion
1981 300D 314K Midnight Blue “The Blue Car”, Lovecrap system, owned 25 years+
1985 300TD White 198K “Betty White” Pure beauty

The VEGEWGN

sassparilla_kid
diesel > all other fuels

1,618
02-15-2012, 01:42 AM #7
How does it make its way to the valve cover, through oil passages and stuff?

-1982 300D Turbo, 280k miles, ALDA apparently maxxed, fram 8038, 12 lbs boost, non-egr manifolds, W/M injection, 4 brake light mod, Gen II w126 front rotors/calipers, 4-speed swap
In the works: A/W IC, adjust pump, turbo rebuild (w/60 trim comp wheel)
-1980 300SD, 110k, project car. Goal is to get it lookin' like it did on the showroom floor (body and interior wise, not necessarily under the hood )
-1974 240D, FRESH PAINT!!!!!!
sassparilla_kid
02-15-2012, 01:42 AM #7

How does it make its way to the valve cover, through oil passages and stuff?


-1982 300D Turbo, 280k miles, ALDA apparently maxxed, fram 8038, 12 lbs boost, non-egr manifolds, W/M injection, 4 brake light mod, Gen II w126 front rotors/calipers, 4-speed swap
In the works: A/W IC, adjust pump, turbo rebuild (w/60 trim comp wheel)
-1980 300SD, 110k, project car. Goal is to get it lookin' like it did on the showroom floor (body and interior wise, not necessarily under the hood )
-1974 240D, FRESH PAINT!!!!!!

dieselboy
Rotatin 5500 times a minute

680
02-15-2012, 02:18 AM #8
Blowby is also water steaming off and other chemicals being evaporated from hot oil.

-Jesse

80 300sd hy35, front mount intercooler, w115 intake, rack limiter removed, Alda removed, full load turned up, boost, ebp, trans, pyro, egr delete, 3.5" exhaust, e-fan, 16x8 rims with, 245/50 tires, lowered, bilstien 5100's, 12" front brakes, 2.65:1 diff.
97 f250 psd 4x4, crawler
70 f250 390
83 Volvo 242, lots of mods
66 Volvo amazon

10 mistsubishi fuso service truck.
dieselboy
02-15-2012, 02:18 AM #8

Blowby is also water steaming off and other chemicals being evaporated from hot oil.


-Jesse

80 300sd hy35, front mount intercooler, w115 intake, rack limiter removed, Alda removed, full load turned up, boost, ebp, trans, pyro, egr delete, 3.5" exhaust, e-fan, 16x8 rims with, 245/50 tires, lowered, bilstien 5100's, 12" front brakes, 2.65:1 diff.
97 f250 psd 4x4, crawler
70 f250 390
83 Volvo 242, lots of mods
66 Volvo amazon

10 mistsubishi fuso service truck.

Captain America
Boostin' & Roostin'

2,221
02-20-2012, 12:21 AM #9
Compression/Boost is lost past the rings on the compression stroke. It goes into the crankcase and raises up through the oil drain back passages to escape out of the valve cover hole. It is easiest if you leave the oil fill cap and take off the breather tube. While the engine is running you can cap the hole for a few seconds and when you release you will hear a whoooosh of air pressure.


1982 300D Turbo ... 3,6xxlbs, No fan, No AC, Hood Stack, No ALDA, No rear bumper and stuffed front, A/W Intercooled, Injectors by Greezer and HUGE Pre-Chambers with help from OM616 & Simpler=Better, Fuel Cranked up, 60 Trim Compressor wheel, EGT, EMP, Boost 50" Rigid Radius bar on roof Aux tank for a total of 48 Gal Of Diesel! Odyssey PC-1750 Battery in trunk, 27"x8.5"/R14 Maxxis BigHorn Mud Terrains, In June '14 issue of Off Road Mag

AX15 Jeep Trans swap in progress....

Captain America
02-20-2012, 12:21 AM #9

Compression/Boost is lost past the rings on the compression stroke. It goes into the crankcase and raises up through the oil drain back passages to escape out of the valve cover hole. It is easiest if you leave the oil fill cap and take off the breather tube. While the engine is running you can cap the hole for a few seconds and when you release you will hear a whoooosh of air pressure.



1982 300D Turbo ... 3,6xxlbs, No fan, No AC, Hood Stack, No ALDA, No rear bumper and stuffed front, A/W Intercooled, Injectors by Greezer and HUGE Pre-Chambers with help from OM616 & Simpler=Better, Fuel Cranked up, 60 Trim Compressor wheel, EGT, EMP, Boost 50" Rigid Radius bar on roof Aux tank for a total of 48 Gal Of Diesel! Odyssey PC-1750 Battery in trunk, 27"x8.5"/R14 Maxxis BigHorn Mud Terrains, In June '14 issue of Off Road Mag

AX15 Jeep Trans swap in progress....

 
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