Oil Usage - The 1947 - Present Chevrolet & GMC Truck Message Board Network

sider68 · 09-01-2003, 09:17 PM

I have an 81 GMC 250 inline 6 using oil.There are no leaks but air filter is full of oil.What is the problem?Engine has about 80,000 miles on it.

TROYLV · 09-01-2003, 09:43 PM

i would pull the valve cover and make sure the oil return holes were clean.

gchemist · 09-01-2003, 09:46 PM

Check your PVC valve. You also have a leak only in the higher RPM range. Have some throttle the engine and check around the oil pressure sending unit and filter.

MylilBowTie · 09-02-2003, 01:32 AM

Doesnt that also mean that there is a chance of excess oil get in the breather do to blowby?

Mike76251 · 09-02-2003, 07:47 AM

I like that engine but it seems to always suffer from one problem......the cylinder closest to the firewall wears fastest and causes piston rock and blowby.

sider68 · 09-02-2003, 10:39 PM

Quote:

Originally posted by gchemist
Check your PVC valve. You also have a leak only in the higher RPM range. Have some throttle the engine and check around the oil pressure sending unit and filter.

I put in a new PVC and took it off and hear it still rattles.I assume therefore it is working.The other hose is a crankcase ventilation and it seems O K.What next?

82 Silverado 4X · 09-03-2003, 04:58 PM

If it isn't leaking oil then it must be burning it.

If the PVC is good then it's time you start looking again.

Does it smoke a bit when you first start it?
This could mean valve seals.

Does it smoke even the slightest bit when you are driving around?
This could mean bad rings.

sider68 · 09-03-2003, 10:57 PM

It doesn,t smoke.There is oil in the air breather and i,ve replaced air filter twice.

crackajacka · 09-04-2003, 12:37 AM

does it puff puff like this when u take the oil cap off while its running?

crackajacka · 09-04-2003, 12:38 AM

sry forgot pic

sider68 · 09-04-2003, 02:44 PM

What causes that?

crackajacka · 09-04-2003, 10:51 PM

worn piston rings or in my case the piston made a groove in the cylinder wall and all the compression was leaking into the crankcase.. have u looked at the valve springs? might get lucky and ones stuck open or something like that but if its that bad its rebuild time. another thing is hows the oil pressure? is it pegged out? if it is its compression getting to the crankcase

09-01-2003, 09:17 PM	#1
sider68 Registered User Join Date: Mar 2002 Location: newmarket,ontario,canada Posts: 936	Oil Usage I have an 81 GMC 250 inline 6 using oil.There are no leaks but air filter is full of oil.What is the problem?Engine has about 80,000 miles on it.

09-01-2003, 09:43 PM	#2
TROYLV Registered User Join Date: Oct 2002 Location: LAS VEGAS, NV. Posts: 157	oil in air filter i would pull the valve cover and make sure the oil return holes were clean. __________________ troy wilson

09-01-2003, 09:46 PM	#3
gchemist BAD BOW-Silverado XST Join Date: May 2000 Location: Senior Member from Austin, TX Posts: 6,431	Check your PVC valve. You also have a leak only in the higher RPM range. Have some throttle the engine and check around the oil pressure sending unit and filter. __________________ Gerardo a.k.a. Mad Chemist Silverado XST videos

09-02-2003, 01:32 AM	#4
MylilBowTie Right turn Clyde Join Date: Nov 2002 Location: Cincinnati, Ohio Posts: 2,911	Doesnt that also mean that there is a chance of excess oil get in the breather do to blowby? __________________ 1974 C25 LWB: 454 4bbl Carb / TH400 / 3.73 1992 Camaro RS 305 TBI

09-03-2003, 04:58 PM	#7
82 Silverado 4X Genuine Chevrolet Join Date: Feb 2003 Location: South West Pennsylvania. Posts: 582	If it isn't leaking oil then it must be burning it. If the PVC is good then it's time you start looking again. Does it smoke a bit when you first start it? This could mean valve seals. Does it smoke even the slightest bit when you are driving around? This could mean bad rings. __________________ George 82 Silverado LWB 4x4 350 SM465 NP208 77 Chevrolet Blazer Chalet 400 TH350 NP203

09-02-2003, 07:47 AM	#5
Mike76251 Senior Member Join Date: Mar 2003 Posts: 2,500	I like that engine but it seems to always suffer from one problem......the cylinder closest to the firewall wears fastest and causes piston rock and blowby.

09-03-2003, 10:57 PM	#8
sider68 Registered User Join Date: Mar 2002 Location: newmarket,ontario,canada Posts: 936	It doesn,t smoke.There is oil in the air breather and i,ve replaced air filter twice.

09-04-2003, 12:37 AM	#9
crackajacka Stylin Join Date: Sep 2001 Location: Tuttle, OK Posts: 620	does it puff puff like this when u take the oil cap off while its running? __________________ Ive been traveling for some time, with my fishin pole and my bottle of shyne. Most Girls like finished products and just dont understand what a good addiction does for you http://www.paulwall.us/

09-04-2003, 12:38 AM	#10
crackajacka Stylin Join Date: Sep 2001 Location: Tuttle, OK Posts: 620	sry forgot pic Attached Images __________________ Ive been traveling for some time, with my fishin pole and my bottle of shyne. Most Girls like finished products and just dont understand what a good addiction does for you http://www.paulwall.us/

09-04-2003, 02:44 PM	#11
sider68 Registered User Join Date: Mar 2002 Location: newmarket,ontario,canada Posts: 936	What causes that?

09-04-2003, 10:51 PM	#12
crackajacka Stylin Join Date: Sep 2001 Location: Tuttle, OK Posts: 620	worn piston rings or in my case the piston made a groove in the cylinder wall and all the compression was leaking into the crankcase.. have u looked at the valve springs? might get lucky and ones stuck open or something like that but if its that bad its rebuild time. another thing is hows the oil pressure? is it pegged out? if it is its compression getting to the crankcase __________________ Ive been traveling for some time, with my fishin pole and my bottle of shyne. Most Girls like finished products and just dont understand what a good addiction does for you http://www.paulwall.us/



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