Hissing Cap Normal?
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Hissing Cap Normal?
Just noticed that my cap on my degas bottle hisses after I run the truck; came out this AM with the truck cold and opened the cap and there was still pressure so is the hissing just keeping the pressure at certain level?
Feel stupid asking but want to make sure this is 'normal'.
Feel stupid asking but want to make sure this is 'normal'.
Post Fiend
Joined: Oct 2009
Posts: 12,123
Likes: 35
From: N. Fort Worth, tx
that would be the cheepist thing you could try. It would cost more to test it.
check fan operation next
from there you would need to look at engine oil temp and coolant temp.
after that you move on to test cooling system pressures under load.
check fan operation next
from there you would need to look at engine oil temp and coolant temp.
after that you move on to test cooling system pressures under load.
Post Fiend
Joined: Oct 2009
Posts: 12,123
Likes: 35
From: N. Fort Worth, tx
Also remember the guy doing your coolant flush most likly knows squat about your diesel engine.
this is not ment to be anything negitive but more eductional.
there is what is knowen as
A techs we are the ones that get the hard stuff to fix and diag. aka lead techs
B techs they are the ones with some knowledge, experence and training and dont require much in the way of help.
C techs most of them are helpers or somewhat fresh out of tech school. they can normally read a book and do easer repairs like water pumps.
then you have the guys that do the maintance work, ie flushes, lof and rotates. They can perfrom visual inspections and light testing but that is about as far as it goes.
thats the basic system of how must shops work.
this is not ment to be anything negitive but more eductional.
there is what is knowen as
A techs we are the ones that get the hard stuff to fix and diag. aka lead techs
B techs they are the ones with some knowledge, experence and training and dont require much in the way of help.
C techs most of them are helpers or somewhat fresh out of tech school. they can normally read a book and do easer repairs like water pumps.
then you have the guys that do the maintance work, ie flushes, lof and rotates. They can perfrom visual inspections and light testing but that is about as far as it goes.
thats the basic system of how must shops work.
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So the the cap is either past it's due date or the system is building up to much pressure.
What could cause it to build pressure.
Would a head gasket leak our problem cause other symptoms than just pressure building?
I've only had the truck for 3 months and it's been perfect so far so suspect it's just the cap.
Anyone else got a hissing cap?
You can't hear it with the hood closed but when the truck is hot and your checking your oil or something else it is apparent.
Thanks!
What could cause it to build pressure.
Would a head gasket leak our problem cause other symptoms than just pressure building?
I've only had the truck for 3 months and it's been perfect so far so suspect it's just the cap.
Anyone else got a hissing cap?
You can't hear it with the hood closed but when the truck is hot and your checking your oil or something else it is apparent.
Thanks!
Post Fiend
Joined: Oct 2009
Posts: 12,123
Likes: 35
From: N. Fort Worth, tx
either a failed cap, head gasket issues, or pluged oil cooler come to mind.
headgaskets will normally cause excessive venting from the degas tank on a non-na engine.
headgaskets will normally cause excessive venting from the degas tank on a non-na engine.
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Must be sunny & everyone's gone fishing our guys are afraid to check this out:
Anyone else got a hissing cap?
You can't hear it with the hood closed or the truck running but when the truck is hot and your checking your oil or something else it is apparent on mine.
Thanks!
Anyone else got a hissing cap?
You can't hear it with the hood closed or the truck running but when the truck is hot and your checking your oil or something else it is apparent on mine.
Thanks!
Hotshot
Joined: Aug 2006
Posts: 17,398
Likes: 317
From: Whittier, CA
Non-naturally aspirated. Meaning it is turbo equipped.
Hissing cap, definitely not normal. It means it is bleeding excess pressure, and that pressure is coming from somewhere. Even if you had a bad cap that only held a few pounds of pressure, it should not be a constant hissing. It might find equilibrium at only 5 lbs, when it should be 16 lbs, but nevertheless it should stop hissing.
Headgasket.
Sorry.
I can definitely be wrong, frequently, so look on the bright side.
Either way, it is not something to be ignored.
Hissing cap, definitely not normal. It means it is bleeding excess pressure, and that pressure is coming from somewhere. Even if you had a bad cap that only held a few pounds of pressure, it should not be a constant hissing. It might find equilibrium at only 5 lbs, when it should be 16 lbs, but nevertheless it should stop hissing.
Headgasket.
Sorry.
I can definitely be wrong, frequently, so look on the bright side.
Either way, it is not something to be ignored.
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It was the cap!!!!
New cap went on a lot tighter before it started clicking. Drove it hard for 20 minutes and turning off- not a peep.
Thanks for all the advice -even though the worst cases had me almost in tears....but we have always learned the KISS rule; I have had the truck for 3 months and figured if it was serious the symptoms of a serious issue would be more overt than a hissing cap?
Would an 2005 not have a 'check engine light' if there was a serious issue?
New cap went on a lot tighter before it started clicking. Drove it hard for 20 minutes and turning off- not a peep.
Thanks for all the advice -even though the worst cases had me almost in tears....but we have always learned the KISS rule; I have had the truck for 3 months and figured if it was serious the symptoms of a serious issue would be more overt than a hissing cap?
Would an 2005 not have a 'check engine light' if there was a serious issue?
Posting Guru
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It was the cap!!!!
New cap went on a lot tighter before it started clicking. Drove it hard for 20 minutes and turning off- not a peep.
Thanks for all the advice -even though the worst cases had me almost in tears....but we have always learned the KISS rule; I have had the truck for 3 months and figured if it was serious the symptoms of a serious issue would be more overt than a hissing cap?
Would an 2005 not have a 'check engine light' if there was a serious issue?
New cap went on a lot tighter before it started clicking. Drove it hard for 20 minutes and turning off- not a peep.
Thanks for all the advice -even though the worst cases had me almost in tears....but we have always learned the KISS rule; I have had the truck for 3 months and figured if it was serious the symptoms of a serious issue would be more overt than a hissing cap?
Would an 2005 not have a 'check engine light' if there was a serious issue?
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It seems the fluid level in the degas bottle is super critical. One Ford service bulletin eluded to making sure the tank only had fluid to the bottom mark when dead cold....and then they came out with the sticker on the bottle another 1/2 inch lower- seems pretty mickey mouse for $70k truck (yes that's what my truck was new in Canada). Glad I only paid $22k all in- with 55k on it. Of course with no warranty so my neck is out pretty far.
After reading repeated head gasket issues here and all the symptoms I figured I was OK.
I've never seen a head gasket go ' a little' they usually make a big mess in the middle of your vacation.
20 years ago I blew a lower rad hose on an old diesel Rabbit in the middle of know wear.
Now I change all my hoses at the first sign of trouble or when they are over 10 years old.
Thanks for letting me know you had a cap issue.
Post Fiend
Joined: Oct 2009
Posts: 12,123
Likes: 35
From: N. Fort Worth, tx
ben headgaskets on this engine dont do half of what it will in a gas motor.
it will cause issues with temp spikes, and puking but I have not seen it leave someone in the middle of nowear.... well not if they were paying attention to the truck anyway.
it will cause issues with temp spikes, and puking but I have not seen it leave someone in the middle of nowear.... well not if they were paying attention to the truck anyway.
Hotshot
Joined: Aug 2006
Posts: 17,398
Likes: 317
From: Whittier, CA
Really glad I was wrong. I don't know where the excess gas flow is coming from. But happy for you that it was such an easy fix.