Home  |  Forums  |  914 Info  |  Blogs
 
914World.com - The fastest growing online 914 community!
 
Porsche, and the Porsche crest are registered trademarks of Dr. Ing. h.c. F. Porsche AG. This site is not affiliated with Porsche in any way.
Its only purpose is to provide an online forum for car enthusiasts. All other trademarks are property of their respective owners.
 

Welcome Guest ( Log In | Register )

3 Pages V  1 2 3 >  
 Reply to this topicStart new topic
> over-pressurized case
bd1308
post Jul 14 2005, 09:58 AM
Post #1


Sir Post-a-lot
*****

Group: Members
Posts: 8,020
Joined: 24-January 05
From: Louisville,KY
Member No.: 3,501
runs great without oil filler cap. runs sucky with oil filler cap on. a bit overfilled (damn valvoline guy)....is this the reason?
User is offlineProfile CardPM
Go to the top of the page
+Quote Post
Mueller
post Jul 14 2005, 10:01 AM
Post #2


914 Freak!
***************

Group: Members
Posts: 17,150
Joined: 4-January 03
From: Antioch, CA
Member No.: 87
Region Association: None
better get out your tool box, a few more weeks and you'll be installing a new engine (IMG:http://www.914world.com/bbs2/html/emoticons/wacko.gif)


User is offlineProfile CardPM
Go to the top of the page
+Quote Post
bondo
post Jul 14 2005, 10:02 AM
Post #3


Practicing my perpendicular parking
****

Group: Members
Posts: 4,277
Joined: 19-April 03
From: Los Osos, CA
Member No.: 587
Region Association: Central California
I nominate you for a V8 conversion. I bet we could sell tickets to that. (IMG:http://www.914world.com/bbs2/html/emoticons/smile.gif)
User is offlineProfile CardPM
Go to the top of the page
+Quote Post
bd1308
post Jul 14 2005, 10:02 AM
Post #4


Sir Post-a-lot
*****

Group: Members
Posts: 8,020
Joined: 24-January 05
From: Louisville,KY
Member No.: 3,501
sigh.....

mike, is the oil being overfilled the reason i'm having my problems or is it blow-by?
User is offlineProfile CardPM
Go to the top of the page
+Quote Post
ArtechnikA
post Jul 14 2005, 10:04 AM
Post #5


rich herzog
*****

Group: Members
Posts: 7,390
Joined: 4-April 03
From: Salted Roads, PA
Member No.: 513
Region Association: None
what's "a bit" ? lots of AX guys run a qt overfull. is it more overfull than that?
if you think it's a factor (i don't...) drain it all and add 4 measured qts.

case pressurisation is usually a symptom of something else (bad ring seal, usually) but i can't tell you how the crankcase vent hoses should be vented, and i can't begin to guess what's been done to your engine...
User is offlineProfile CardPM
Go to the top of the page
+Quote Post
bondo
post Jul 14 2005, 10:06 AM
Post #6


Practicing my perpendicular parking
****

Group: Members
Posts: 4,277
Joined: 19-April 03
From: Los Osos, CA
Member No.: 587
Region Association: Central California
On a more serious note.. I doubt it's overfilling, people do that all the time for racing (so it doesn't get starved on turns). Taking off the cap is probably affecting the FI, through the PCV valve.
User is offlineProfile CardPM
Go to the top of the page
+Quote Post
bd1308
post Jul 14 2005, 10:08 AM
Post #7


Sir Post-a-lot
*****

Group: Members
Posts: 8,020
Joined: 24-January 05
From: Louisville,KY
Member No.: 3,501
its carbed. i think its rings. how much air is supposed to flow through the PCV? I am getting like 1/5 teh total air out of the PCV.
User is offlineProfile CardPM
Go to the top of the page
+Quote Post
ArtechnikA
post Jul 14 2005, 10:10 AM
Post #8


rich herzog
*****

Group: Members
Posts: 7,390
Joined: 4-April 03
From: Salted Roads, PA
Member No.: 513
Region Association: None
QUOTE (bondo @ Jul 14 2005, 12:06 PM)
...Taking off the cap is probably affecting the FI, through the PCV valve.

through the PCV valve, across the room, and onto the bench where all the FI parts sit in a pile...

as you may (not) recall from an earlier episode of our ongoing adventure serial, BD's engine is now running on a single central Holley (or Harley, i forget...) carburetor. last i heard it was running great; now, evidently not so, ("sucky" was used...) but i may have missed an episode or two between then and now...

you gotta keep up on this stuff - it won't be into re-runs until Fall...
User is offlineProfile CardPM
Go to the top of the page
+Quote Post
Mueller
post Jul 14 2005, 10:11 AM
Post #9


914 Freak!
***************

Group: Members
Posts: 17,150
Joined: 4-January 03
From: Antioch, CA
Member No.: 87
Region Association: None
single carb........

do you have a line going from the crankcase to the carb or airfilter?

if so, what is happening is that the oil vapor is being ingested into the combustion chamber, oil vapor displaces air and does not burn...so you have a crappy air/fuel ratio


if the crankcase does not connect to the intake one way or another, you need to get a puke tank and a larger diameter hose to relieve the pressure....seems like an odd thing to be happening, but who knows???
User is offlineProfile CardPM
Go to the top of the page
+Quote Post
bondo
post Jul 14 2005, 10:13 AM
Post #10


Practicing my perpendicular parking
****

Group: Members
Posts: 4,277
Joined: 19-April 03
From: Los Osos, CA
Member No.: 587
Region Association: Central California
I thought a PCV valve was supposed to be pretty much closed at idle.
User is offlineProfile CardPM
Go to the top of the page
+Quote Post
ArtechnikA
post Jul 14 2005, 10:13 AM
Post #11


rich herzog
*****

Group: Members
Posts: 7,390
Joined: 4-April 03
From: Salted Roads, PA
Member No.: 513
Region Association: None
QUOTE (bd1308 @ Jul 14 2005, 12:08 PM)
... how much air is supposed to flow through the PCV?...

there isn't supposed to be *any* air...

practically, there may be a little.

if your blowby is overwhelming the PCV valve -- assuming it is the right valve, and working properly, and plumbed where it's supposed to be -- to the extent that it's affecting proper engine operation - that's too much ...
User is offlineProfile CardPM
Go to the top of the page
+Quote Post
bd1308
post Jul 14 2005, 10:15 AM
Post #12


Sir Post-a-lot
*****

Group: Members
Posts: 8,020
Joined: 24-January 05
From: Louisville,KY
Member No.: 3,501
rich, IIRC the crankcase pressure has NOTHING to do with the induction system....whether carb'd or FI.

i get no oil smoke out of the exhust, so im wondering why the pressure is so high in the crankcase....

the carb episode is finished. DVD coming out soon.
User is offlineProfile CardPM
Go to the top of the page
+Quote Post
Allan
post Jul 14 2005, 10:16 AM
Post #13


Teenerless Weenie
*****

Group: Members
Posts: 8,373
Joined: 5-July 04
From: Western Mesopotamia
Member No.: 2,304
Region Association: Southern California
How do you know what the pressure actually is?
User is offlineProfile CardPM
Go to the top of the page
+Quote Post
ArtechnikA
post Jul 14 2005, 10:18 AM
Post #14


rich herzog
*****

Group: Members
Posts: 7,390
Joined: 4-April 03
From: Salted Roads, PA
Member No.: 513
Region Association: None
QUOTE (bd1308 @ Jul 14 2005, 12:15 PM)
rich, IIRC the crankcase pressure has NOTHING to do with the induction system....whether carb'd or FI.

i agree.

so i guess i donno what point you were trying to make.

excessive crankcase pressure will make a boxer motor run bad. it has nothing to do with the induction. it has to do with trying to compress the air between the pistons in the case.
User is offlineProfile CardPM
Go to the top of the page
+Quote Post
bd1308
post Jul 14 2005, 10:19 AM
Post #15


Sir Post-a-lot
*****

Group: Members
Posts: 8,020
Joined: 24-January 05
From: Louisville,KY
Member No.: 3,501
theroretically what would happen if the oil was overfilled past the "safe for racers" point?
User is offlineProfile CardPM
Go to the top of the page
+Quote Post
Mueller
post Jul 14 2005, 10:24 AM
Post #16


914 Freak!
***************

Group: Members
Posts: 17,150
Joined: 4-January 03
From: Antioch, CA
Member No.: 87
Region Association: None
QUOTE (bd1308 @ Jul 14 2005, 09:19 AM)
theroretically what would happen if the oil was overfilled past the "safe for racers" point?

what do you think will happen....it's called path of least resistance...if the pressure is too much, the air and oil will find a way out of the motor...blown valve cover gaskets, pushrod seals, rear main seal...etc...etc...

normally too much oil equals smoke from oil seeping past the rings or valve guides (that would have to alot of oil), esp. on a flat motor
User is offlineProfile CardPM
Go to the top of the page
+Quote Post
bondo
post Jul 14 2005, 10:27 AM
Post #17


Practicing my perpendicular parking
****

Group: Members
Posts: 4,277
Joined: 19-April 03
From: Los Osos, CA
Member No.: 587
Region Association: Central California
QUOTE (bd1308 @ Jul 14 2005, 09:19 AM)
theroretically what would happen if the oil was overfilled past the "safe for racers" point?

Oil hits crank, crank whips oil up into foam, foam takes up more space, so level gets even higher, and gets more foamy. Eventually your oil pump ends up picking up oil with imbedded air, which it can't pump too well, and doesn't lubricate to well. Oil pressure drops, and bearings die.
User is offlineProfile CardPM
Go to the top of the page
+Quote Post
bondo
post Jul 14 2005, 10:29 AM
Post #18


Practicing my perpendicular parking
****

Group: Members
Posts: 4,277
Joined: 19-April 03
From: Los Osos, CA
Member No.: 587
Region Association: Central California
You have a dipstick, right? I've had it as high as about 1/2" above the full mark with no apparent problems. Where are you at?
User is offlineProfile CardPM
Go to the top of the page
+Quote Post
bd1308
post Jul 14 2005, 10:31 AM
Post #19


Sir Post-a-lot
*****

Group: Members
Posts: 8,020
Joined: 24-January 05
From: Louisville,KY
Member No.: 3,501
less than half inch
User is offlineProfile CardPM
Go to the top of the page
+Quote Post
mudfoot76
post Jul 14 2005, 10:34 AM
Post #20


Currently teenerless :-(
***

Group: Members
Posts: 946
Joined: 18-March 04
From: Carmel, IN
Member No.: 1,814
Region Association: None
QUOTE (bd1308 @ Jul 14 2005, 11:31 AM)
less than half inch

Do you have a working oil pressure gauge?

How are you measuring case pressure?

I routinely run with oil level about 1/2 qt high, esp for HPDE events. High speed corners a'plenty at Putnam Park. I've not had a starvation issue, nor an overpressure issue on the new engine...
User is offlineProfile CardPM
Go to the top of the page
+Quote Post
« Next Oldest · 914World Garage · Next Newest »
 

3 Pages V  1 2 3 >
Reply to this topicStart new topic
1 User(s) are reading this topic (1 Guests and 0 Anonymous Users)
0 Members:

 

Display Mode: Standard · Switch to: Linear+ · Switch to: Outline

Track this topic · Email this topic · Print this topic · Subscribe to this forum

- Lo-Fi Version Time is now: 31st October 2024 - 08:24 PM
Invision Power Board v9.1.4 © 2024  IPS, Inc.
All rights reserved 914World.com © since 2002
914World.com is the fastest growing online 914 community!
We have it all, classifieds, events, forums, vendors, parts, autocross, racing, technical articles, events calendar, newsletter, restoration, gallery, archives, history and more for your Porsche 914 ...