Why do I see some high performance engines w/ breather caps on the oil spout??????

Stang_ROTY · 08-14-2001, 03:08 PM

Why, in the magazines, do I see breather caps on higher performance 5.0's and 351's instead of oil caps?? What does the breather cap do? Can I use it as a replacement of the PCV system? Will the engine run without the PCV? I'm really trying hard to avoid removing my lower intake to install the baffle plate, if possible.

------------------
Finally DONE!!
93 GT, 393 stroker w/ Edlebrock Performer heads and EFI, 30lb injectors, Dynamic Roller Mite C4, 8 pt cage, Sothside Machine bars & Sub-frames, 3.73's, '69 351W block w/SCAT crank.

08-14-2001, 03:47 PM

PCV (positive crankcase ventilation valve) allows fuel air mixture and combustion gases that leak by the rings to be reburned through the combustion process, instead of dumping them into the atmosphere (pollution control)..

So in theory, it's purpose is to reduce emissions by directing these unburned gases into the aircleaner to be reburned....

a breather cap just dumps the bi-products into the atmosphere..

------------------
Black,84 GT,ground effects,shorty headers, 'open' dual exh.,302 HO(no pollution control crap),T5,89 ported heads,edelbrock Performer manifold, Edelbrock 2122 cam,600 Holley, high volume oil pump...

Some day (3:73 gears & N2O)!!!

will this ever end????

PKRWUD · 08-14-2001, 05:51 PM

You can try installing breathers, but in virtually every engine I have seen, if there is not also a PCV system, you will end up blowing oil all over your valve covers at high rpms. The exception to this are the circle track engines with the tall breather extension tubes, but they only run for 10 minute stretches.

Take care
~Chris

------------------
Retired Moderator
MustangNet

My site: JimPorterRacing

RACECAR spelled backwards is RACECAR

HEY !!! Are you ASE Certified ??? If you are, ask me about iATN. The best tool you'll ever have, and it's free !!!

08-15-2001, 12:07 AM

or you can install the breathers, but to beat the 'oil all over your valve covers and engine', get QUALITY breathers with the hose connection nipple on them, buy some clear gas line of the same size, and route it behind the engine and down....

no oil on the motor, and you've evacuated the excess gasses, works great!!!!!

------------------
Black,84 GT,ground effects,shorty headers, 'open' dual exh.,302 HO(no pollution control crap),T5,89 ported heads,edelbrock Performer manifold, Edelbrock 2122 cam,600 Holley, high volume oil pump...

Some day (3:73 gears & N2O)!!!

will this ever end????

PKRWUD · 08-15-2001, 02:03 AM

Quote:

no oil on the motor, and you've evacuated the excess gasses, works great!!!!!

Works great at getting oil all over your undercarriage and your exhaust! Gotta admit, there's nothing as cool looking as smoke billowing out from under your car when you stop at the next traffic light! Give me a break.

~Chris

------------------
Retired Moderator
MustangNet

My site: JimPorterRacing

RACECAR spelled backwards is RACECAR

HEY !!! Are you ASE Certified ??? If you are, ask me about iATN. The best tool you'll ever have, and it's free !!!

84LX89GT · 08-15-2001, 02:42 AM

The GT i just bought has a K&N breather on where the oil filler cap used to be and i've driven it hard and haven't had any oil spillage problems. The guy who had it before me also routed a line from the throttle body to the oil filler spout like it was stock. I think it may be causing a vacuum leak large enough to bother the computer because when it's cold it has a surging idle and almost dies and another thing that annoys me is that i can hear a whistle whenever i give it gas or let off because of the vacuum through the breather. It seems to work well at getting rid of the gasses, though, but i'm eventually going to put it the way it is stock.

------------------
previous name: 84stangLX
'84 Mustang 5.0 LX
my LX
'89 Mustang GT
my GT

Mach 1 · 08-15-2001, 02:55 AM

The Ford 5.0 PCV system routes from the PCV valve in the lower intake to the upper manifold (plenem).

So, my question is, what does the hose from oil filler neck to Throttle body accomplish?

Additional ventilation?

By the way, Im running the K&N breather in place of the oil filler cap, my reasoning was since I removed the unsightly rubber hose from the oil filler neck to the TB, I would vent the byproducts overboard with the breather filter instead of sucking them back into my intake through the rubber hose.

Comments?

------------------
1993 GT/AOD
'93 Mustang GT

crewzin · 08-15-2001, 05:55 AM

Put the breather caps with the small spouts on and run the line to a catch can. Make sure the can has a K&N filter on it. You wont spill any oil on anything this way. This is the best way I have found while running a supercharger. Go to Girls Can Too section and look at the new Mare of the Month pics. There you can see the lines coming off then into the inner fender.

08-15-2001, 08:05 AM

PK, if it is billowing oil smoke all over everything, the rings are weak....

I am running breathers on my new motor (the same way I described above), guess what, no noticable oil or smoke......

------------------
Black,84 GT,ground effects,shorty headers, 'open' dual exh.,302 HO(no pollution control crap),T5,89 ported heads,edelbrock Performer manifold, Edelbrock 2122 cam,600 Holley, high volume oil pump...

Some day (3:73 gears & N2O)!!!

will this ever end????

Stang_ROTY · 08-15-2001, 03:40 PM

Does anyone know if you can buy a breather cap for the valve covers like mine which originally come with the oil cap?

08-15-2001, 04:27 PM

YES..... two types (which you'll have to figure which you have) are sold, push in, or twist type....

most automotive stores sell both types..

------------------
Black,84 GT,ground effects,shorty headers, 'open' dual exh.,302 HO(no pollution control crap),T5,89 ported heads,edelbrock Performer manifold, Edelbrock 2122 cam,600 Holley, high volume oil pump...

Some day (3:73 gears & N2O)!!!

will this ever end????

08-15-2001, 07:31 PM

Ok, I thought the breather caps where for relieving some of the pressure a high compression or blown engine may create. I had poly comp vavle covers with a breather and it spewed oil all over the engine, the filter was just dripping. I got some fms covers with better baffles but now the breathers or catch can will not clear the intake

. I have both sides plugged for now and I've noticed that both valve covers have a leak now..

------------------
Rick
My 89lx(updated 7/20/2001)
Sold

08-15-2001, 07:38 PM

Crewzin, is there more than one type of catch can?? I'm trying to figure out how I would get a breather on the can I have and why..

08-15-2001, 09:57 PM

the valve covers have holes in them for two reasons...

1; obviously allows you to add oil...

2; to either have a pcv valve (which is routed to the intake or aircleaner to release and REBURN, gasses built up in the block) or for a breather to allow excess gasses to escape the block..

if you don't have one of the above systems (pcv or breather), the block builds up pressure, and something is going to leak.... Ring seal is not 100%, that's why pressure builds in the block, combustion gasses bleeding by the rings.....

------------------
Black,84 GT,ground effects,shorty headers, 'open' dual exh.,302 HO(no pollution control crap),T5,89 ported heads,edelbrock Performer manifold, Edelbrock 2122 cam,600 Holley, high volume oil pump...

Some day (3:73 gears & N2O)!!!

will this ever end????

08-15-2001, 10:05 PM

sorry m8, misunderstood the question, trying to do 50 thing's at 1 time.....

I thought I saw catch cans, with breathers in Summit....

check their web site.....

how many miles are on the motors spitting oil from the breathers???? mine old motor started doing it at about 98000...

------------------
Black,84 GT,ground effects,shorty headers, 'open' dual exh.,302 HO(no pollution control crap),T5,89 ported heads,edelbrock Performer manifold, Edelbrock 2122 cam,600 Holley, high volume oil pump...

Some day (3:73 gears & N2O)!!!

will this ever end????

stanger8172 · 08-15-2001, 10:18 PM

I have milled heads so should I have a breather that rbatson suggested? I have a tube running from the oil filler cap to the throttle body too ( yes, it is fugly!)
------------------
'91 LX convertible, T-5, ported/polished/milled .030 E7 heads, 1.94/1.60 stainless valves, 1.6rr, March Performance Pulleys and A/C Eliminator kit, short belt, K&N panel, electric fans, battery in trunk, glasspacks w/dumps, Centerforce Dual Friction, FMS adjustable cable w/quadrant

08-15-2001, 11:20 PM

Its has about 3000 miles, maybe alittle more on it now. Its been doing it since it was installed, its a Keith Craft 331. I've been told by many guys, who I believe know what they are talking about, that blowby is normal on a blown engine.

08-15-2001, 11:29 PM

Aahhh, I just reread the post... I gotcha crewzin. I will have to check out that link you gave. It sounds like you are familiar with the problem I have. Must be a blown stroker thing. Oh and I have a pcv valve also.

DemonGT · 08-15-2001, 11:48 PM

my freinds stang has a 347 and it had alot of vacuum..he was geting so much oil in the upper intake it was coming out the TB..so he rerouted the pcv from the lower intake to the oil filer neck with a breather cap...fix the prob

------------------
'91 GT,91K,T-5,air silencer removed,HD clutch,K&N air filter,Mac long tubes,Cat-back,off road H,FMS 9mm wires,180 thermostat,Competition gauges,C&L 76mm MAF,Accufab 70mm TB,TFS street heat intake

Waiting install:Nothing

Future Mods:3.73's,Pro 5.0,TFS heads,TFS stage 1 cam,lakewood struts/shocks,nitto DR's
ICQ#35670781

84LX89GT · 08-16-2001, 03:45 AM

I have open motorsport breather caps on my '84 carbed engine and with 150,000 miles it doesn't spit any oil onto the engine (i think it'd be kinda hard to because there's a big baffle underneath the cap opening to keep oil from sloshing up), and the GT has 115,000 miles and it hasn't had any problems yet to my knowledge.

------------------
previous name: 84stangLX
'84 Mustang 5.0 LX
my LX
'89 Mustang GT
my GT

08-14-2001, 03:08 PM	#1
Stang_ROTY Registered Member Join Date: Feb 2001 Location: Berkshire County - Massachusetts Posts: 735	Why do I see some high performance engines w/ breather caps on the oil spout?????? Why, in the magazines, do I see breather caps on higher performance 5.0's and 351's instead of oil caps?? What does the breather cap do? Can I use it as a replacement of the PCV system? Will the engine run without the PCV? I'm really trying hard to avoid removing my lower intake to install the baffle plate, if possible. ------------------ Finally DONE!! 93 GT, 393 stroker w/ Edlebrock Performer heads and EFI, 30lb injectors, Dynamic Roller Mite C4, 8 pt cage, Sothside Machine bars & Sub-frames, 3.73's, '69 351W block w/SCAT crank.

Similar Threads
Thread	Thread Starter	Forum	Replies	Last Post
Will the 5.0 become obsolete	vetteeatr	Blue Oval Lounge	36	07-11-2002 08:39 PM
High Performance Parts....	cyberstang5.0	Blue Oval Lounge	1	02-11-2002 10:46 AM
High Performance sticky tires	sgwinn	Windsor Power	2	03-14-2001 03:28 AM
97-98 High Performance Computer	St_Brawler	Modular Madness	0	05-16-2000 02:05 PM

08-14-2001, 03:47 PM	#2
jerryIII Guest Posts: n/a	PCV (positive crankcase ventilation valve) allows fuel air mixture and combustion gases that leak by the rings to be reburned through the combustion process, instead of dumping them into the atmosphere (pollution control).. So in theory, it's purpose is to reduce emissions by directing these unburned gases into the aircleaner to be reburned.... a breather cap just dumps the bi-products into the atmosphere.. ------------------ Black,84 GT,ground effects,shorty headers, 'open' dual exh.,302 HO(no pollution control crap),T5,89 ported heads,edelbrock Performer manifold, Edelbrock 2122 cam,600 Holley, high volume oil pump... Some day (3:73 gears & N2O)!!! will this ever end????

08-14-2001, 05:51 PM	#3
PKRWUD Junior Member Join Date: Mar 1999 Location: Ventura, California Posts: 8,981	You can try installing breathers, but in virtually every engine I have seen, if there is not also a PCV system, you will end up blowing oil all over your valve covers at high rpms. The exception to this are the circle track engines with the tall breather extension tubes, but they only run for 10 minute stretches. Take care ~Chris ------------------ Retired Moderator MustangNet My site: JimPorterRacing RACECAR spelled backwards is RACECAR HEY !!! Are you ASE Certified ??? If you are, ask me about iATN. The best tool you'll ever have, and it's free !!!

08-15-2001, 12:07 AM	#4
jerryIII Guest Posts: n/a	or you can install the breathers, but to beat the 'oil all over your valve covers and engine', get QUALITY breathers with the hose connection nipple on them, buy some clear gas line of the same size, and route it behind the engine and down.... no oil on the motor, and you've evacuated the excess gasses, works great!!!!! ------------------ Black,84 GT,ground effects,shorty headers, 'open' dual exh.,302 HO(no pollution control crap),T5,89 ported heads,edelbrock Performer manifold, Edelbrock 2122 cam,600 Holley, high volume oil pump... Some day (3:73 gears & N2O)!!! will this ever end????

08-15-2001, 02:42 AM	#6
84LX89GT Mustangs Join Date: Jul 2000 Posts: 1,938	The GT i just bought has a K&N breather on where the oil filler cap used to be and i've driven it hard and haven't had any oil spillage problems. The guy who had it before me also routed a line from the throttle body to the oil filler spout like it was stock. I think it may be causing a vacuum leak large enough to bother the computer because when it's cold it has a surging idle and almost dies and another thing that annoys me is that i can hear a whistle whenever i give it gas or let off because of the vacuum through the breather. It seems to work well at getting rid of the gasses, though, but i'm eventually going to put it the way it is stock. ------------------ previous name: 84stangLX '84 Mustang 5.0 LX my LX '89 Mustang GT my GT

08-15-2001, 02:55 AM	#7
Mach 1 Registered Member Join Date: May 1999 Location: Georgia Posts: 3,866	The Ford 5.0 PCV system routes from the PCV valve in the lower intake to the upper manifold (plenem). So, my question is, what does the hose from oil filler neck to Throttle body accomplish? Additional ventilation? By the way, Im running the K&N breather in place of the oil filler cap, my reasoning was since I removed the unsightly rubber hose from the oil filler neck to the TB, I would vent the byproducts overboard with the breather filter instead of sucking them back into my intake through the rubber hose. Comments? ------------------ 1993 GT/AOD '93 Mustang GT

08-15-2001, 05:55 AM	#8
crewzin Registered Member Join Date: May 2001 Location: Sour Lake, TX Posts: 211	Put the breather caps with the small spouts on and run the line to a catch can. Make sure the can has a K&N filter on it. You wont spill any oil on anything this way. This is the best way I have found while running a supercharger. Go to Girls Can Too section and look at the new Mare of the Month pics. There you can see the lines coming off then into the inner fender.

08-15-2001, 08:05 AM	#9
jerryIII Guest Posts: n/a	PK, if it is billowing oil smoke all over everything, the rings are weak.... I am running breathers on my new motor (the same way I described above), guess what, no noticable oil or smoke...... ------------------ Black,84 GT,ground effects,shorty headers, 'open' dual exh.,302 HO(no pollution control crap),T5,89 ported heads,edelbrock Performer manifold, Edelbrock 2122 cam,600 Holley, high volume oil pump... Some day (3:73 gears & N2O)!!! will this ever end????

08-15-2001, 03:40 PM	#10
Stang_ROTY Registered Member Join Date: Feb 2001 Location: Berkshire County - Massachusetts Posts: 735	Does anyone know if you can buy a breather cap for the valve covers like mine which originally come with the oil cap?

08-15-2001, 04:27 PM	#11
jerryIII Guest Posts: n/a	YES..... two types (which you'll have to figure which you have) are sold, push in, or twist type.... most automotive stores sell both types.. ------------------ Black,84 GT,ground effects,shorty headers, 'open' dual exh.,302 HO(no pollution control crap),T5,89 ported heads,edelbrock Performer manifold, Edelbrock 2122 cam,600 Holley, high volume oil pump... Some day (3:73 gears & N2O)!!! will this ever end????

08-15-2001, 07:31 PM	#12
rbatson Guest Posts: n/a	Ok, I thought the breather caps where for relieving some of the pressure a high compression or blown engine may create. I had poly comp vavle covers with a breather and it spewed oil all over the engine, the filter was just dripping. I got some fms covers with better baffles but now the breathers or catch can will not clear the intake . I have both sides plugged for now and I've noticed that both valve covers have a leak now.. ------------------ Rick My 89lx(updated 7/20/2001) Sold

08-15-2001, 07:38 PM	#13
rbatson Guest Posts: n/a	Crewzin, is there more than one type of catch can?? I'm trying to figure out how I would get a breather on the can I have and why..

08-15-2001, 09:57 PM	#14
jerryIII Guest Posts: n/a	the valve covers have holes in them for two reasons... 1; obviously allows you to add oil... 2; to either have a pcv valve (which is routed to the intake or aircleaner to release and REBURN, gasses built up in the block) or for a breather to allow excess gasses to escape the block.. if you don't have one of the above systems (pcv or breather), the block builds up pressure, and something is going to leak.... Ring seal is not 100%, that's why pressure builds in the block, combustion gasses bleeding by the rings..... ------------------ Black,84 GT,ground effects,shorty headers, 'open' dual exh.,302 HO(no pollution control crap),T5,89 ported heads,edelbrock Performer manifold, Edelbrock 2122 cam,600 Holley, high volume oil pump... Some day (3:73 gears & N2O)!!! will this ever end????

08-15-2001, 10:05 PM	#15
jerryIII Guest Posts: n/a	sorry m8, misunderstood the question, trying to do 50 thing's at 1 time..... I thought I saw catch cans, with breathers in Summit.... check their web site..... how many miles are on the motors spitting oil from the breathers???? mine old motor started doing it at about 98000... ------------------ Black,84 GT,ground effects,shorty headers, 'open' dual exh.,302 HO(no pollution control crap),T5,89 ported heads,edelbrock Performer manifold, Edelbrock 2122 cam,600 Holley, high volume oil pump... Some day (3:73 gears & N2O)!!! will this ever end????

08-15-2001, 10:18 PM	#16
stanger8172 Registered Member Join Date: Nov 2000 Location: Milwaukee,Wisconsin Posts: 380	I have milled heads so should I have a breather that rbatson suggested? I have a tube running from the oil filler cap to the throttle body too ( yes, it is fugly!) ------------------ '91 LX convertible, T-5, ported/polished/milled .030 E7 heads, 1.94/1.60 stainless valves, 1.6rr, March Performance Pulleys and A/C Eliminator kit, short belt, K&N panel, electric fans, battery in trunk, glasspacks w/dumps, Centerforce Dual Friction, FMS adjustable cable w/quadrant

08-15-2001, 11:20 PM	#17
rbatson Guest Posts: n/a	Its has about 3000 miles, maybe alittle more on it now. Its been doing it since it was installed, its a Keith Craft 331. I've been told by many guys, who I believe know what they are talking about, that blowby is normal on a blown engine.

08-15-2001, 11:29 PM	#18
rbatson Guest Posts: n/a	Aahhh, I just reread the post... I gotcha crewzin. I will have to check out that link you gave. It sounds like you are familiar with the problem I have. Must be a blown stroker thing. Oh and I have a pcv valve also.

08-15-2001, 11:48 PM	#19
DemonGT Registered Member Join Date: Aug 2000 Location: Wisconsin Posts: 879	my freinds stang has a 347 and it had alot of vacuum..he was geting so much oil in the upper intake it was coming out the TB..so he rerouted the pcv from the lower intake to the oil filer neck with a breather cap...fix the prob ------------------ '91 GT,91K,T-5,air silencer removed,HD clutch,K&N air filter,Mac long tubes,Cat-back,off road H,FMS 9mm wires,180 thermostat,Competition gauges,C&L 76mm MAF,Accufab 70mm TB,TFS street heat intake Waiting install:Nothing Future Mods:3.73's,Pro 5.0,TFS heads,TFS stage 1 cam,lakewood struts/shocks,nitto DR's ICQ#35670781

08-16-2001, 03:45 AM	#20
84LX89GT Mustangs Join Date: Jul 2000 Posts: 1,938	I have open motorsport breather caps on my '84 carbed engine and with 150,000 miles it doesn't spit any oil onto the engine (i think it'd be kinda hard to because there's a big baffle underneath the cap opening to keep oil from sloshing up), and the GT has 115,000 miles and it hasn't had any problems yet to my knowledge. ------------------ previous name: 84stangLX '84 Mustang 5.0 LX my LX '89 Mustang GT my GT