81 Chevy 305H motor oil leakage prob - The 1947 - Present Chevrolet & GMC Truck Message Board Network

mattopia · 02-19-2004, 04:11 PM

I have a 305H in my 81 Chevy SWB and Ihave a problem with the oil foaming up out of the valve covers into the pcv valves. All the vacuum lines are hooked up right. It has Edelbrock valve covers on it. The motor is stock otherwise. It runs great it just leaks oil from these spots. The heads are not cracked. I am not loosing coolent. When I drain the oil it comes out normal, no foam. If I put a push on oil breather on it pushes oil out of it too. It also comes out the dipstick tube. Do these High Performance motors need the tall valve covers? Is there a blockage? Thanks for any help.

Jonboy · 02-19-2004, 07:15 PM

do you have baffles in the valve covers? that will probably help the oil coming out if you do not currently have them.

mattopia · 02-20-2004, 02:10 AM

Yea it has baffles

Jason Spears · 02-20-2004, 10:08 PM

Is the PCV valve functional?

This could cause pressure and blow oil out of the engine.

mattopia · 02-21-2004, 02:30 AM

It has new pcv valve that is fully functional. This is going to be an odd solution, not a common one. All the easy answers I have thought of and my friends have thought of. When I bought it, it had a bold missing on the front of the block that let out the pressure but also a small amount of oil mist when I pluged the hole it built up to much pressure for the pcv valve to handle. That is where the problem comes in. Are the High proformance 305s supose to have the tall valve covers? Does anybody have a high performance 305?

apstguy · 02-21-2004, 04:28 AM

I don't know of anyone that has a high performance 305 as 350 are cheap. You get more return from a 350. That isn't the point though. How many miles are on the engine? Have you done a compression test?

MylilBowTie · 02-21-2004, 08:29 AM

305 High Output Engine came with standard height valve covers. Do you have a way to post any picture? To see where the oil is coming from?

**swervin ervin** · 02-21-2004, 12:44 PM

A 305H is not a high performance engine. Same one that came in my truck stock.

Sounds like you have some internal problems somewhere.

CRRoy71 · 02-21-2004, 02:08 PM

I 2nd the compression test, you may be getting blow by from your rings.

Prerunner1982 · 02-21-2004, 03:14 PM

how long has it been since you replaced the pcv? there may be oil still build up in the hose and it is just cleaning it self out, i had this problem as well, i finally washed my engine again and havent had it since. after i replaced the pcv a month ago.. you might try replacing the grommet as well. my edelbrock valve covers dont have an oil cap so i pull the pcv to add oil. so the grommet maybe worn.

02-19-2004, 04:11 PM	#1
mattopia Registered User Join Date: Sep 2002 Location: Indianapolis Posts: 49	81 Chevy 305H motor oil leakage prob I have a 305H in my 81 Chevy SWB and Ihave a problem with the oil foaming up out of the valve covers into the pcv valves. All the vacuum lines are hooked up right. It has Edelbrock valve covers on it. The motor is stock otherwise. It runs great it just leaks oil from these spots. The heads are not cracked. I am not loosing coolent. When I drain the oil it comes out normal, no foam. If I put a push on oil breather on it pushes oil out of it too. It also comes out the dipstick tube. Do these High Performance motors need the tall valve covers? Is there a blockage? Thanks for any help.

02-19-2004, 07:15 PM	#2
Jonboy Slots go on anything! Join Date: May 2003 Location: Richardson, TX Posts: 5,957	do you have baffles in the valve covers? that will probably help the oil coming out if you do not currently have them. __________________ 1974 Jimmy- 5.3/4L80e/NP241

02-21-2004, 04:28 AM	#6
apstguy LED King Join Date: Jan 2003 Location: Sacramento, CA Posts: 2,087	I don't know of anyone that has a high performance 305 as 350 are cheap. You get more return from a 350. That isn't the point though. How many miles are on the engine? Have you done a compression test? __________________ Tyler 1985 C10 305 w/ Bowtie OD TH700R4 3.42 LSD 202,000 miles 2006 Ford Focus ZX3 5-speed Stick 2016 Chevy Spark EV Gone: 2002.5 VW GTI 24v VR6 Gone: 2008 VW R32

02-21-2004, 08:29 AM	#7
MylilBowTie Right turn Clyde Join Date: Nov 2002 Location: Cincinnati, Ohio Posts: 2,911	305 High Output Engine came with standard height valve covers. Do you have a way to post any picture? To see where the oil is coming from? __________________ 1974 C25 LWB: 454 4bbl Carb / TH400 / 3.73 1992 Camaro RS 305 TBI Last edited by MylilBowTie; 02-21-2004 at 08:39 AM.

02-21-2004, 12:44 PM	#8
swervin ervin You get what you pay for Join Date: Dec 1999 Location: Cherryville, NC Posts: 4,798	A 305H is not a high performance engine. Same one that came in my truck stock. Sounds like you have some internal problems somewhere. __________________ Mike 1985 Chevy C-10

02-20-2004, 02:10 AM	#3
mattopia Registered User Join Date: Sep 2002 Location: Indianapolis Posts: 49	Yea it has baffles

02-20-2004, 10:08 PM	#4
Jason Spears Registered User Join Date: Dec 2002 Location: Stoney Creek, ON Posts: 89	Is the PCV valve functional? This could cause pressure and blow oil out of the engine.

02-21-2004, 02:30 AM	#5
mattopia Registered User Join Date: Sep 2002 Location: Indianapolis Posts: 49	It has new pcv valve that is fully functional. This is going to be an odd solution, not a common one. All the easy answers I have thought of and my friends have thought of. When I bought it, it had a bold missing on the front of the block that let out the pressure but also a small amount of oil mist when I pluged the hole it built up to much pressure for the pcv valve to handle. That is where the problem comes in. Are the High proformance 305s supose to have the tall valve covers? Does anybody have a high performance 305?

02-21-2004, 02:08 PM	#9
CRRoy71 Registered User Join Date: Feb 2003 Location: Mont Belvieu, TX Posts: 852	I 2nd the compression test, you may be getting blow by from your rings. __________________ Chris '92 ext. cab s/b 4.3L "Sparky" '04 crew cab 2500 4x4 6.0L

02-21-2004, 03:14 PM	#10
Prerunner1982 Registered User Join Date: Oct 2002 Location: Edmond, OK Posts: 5,904	how long has it been since you replaced the pcv? there may be oil still build up in the hose and it is just cleaning it self out, i had this problem as well, i finally washed my engine again and havent had it since. after i replaced the pcv a month ago.. you might try replacing the grommet as well. my edelbrock valve covers dont have an oil cap so i pull the pcv to add oil. so the grommet maybe worn. __________________ Jon 1982 Chevy Silverado 350/th350.... RETIRED 1993 Jeep XJ 2 door(Cherokee) 4wd 4.0ltr/AX-15 (5spd)/NP231 .... Oklahoma Roll Call

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