Blingin' eBay Catch Can Warning
Jan 29, 2005, 08:11 PM
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Blingin' eBay Catch Can Warning
This is from a recent post to the MR2 board:
"Ebay catch cans - a warning
--------------------------------------------------------------------------------
Im noticing a lot of people going out and buying ebay catch cans recently without realising how dangerous this can be for your motor so I thought I'd start this 'awareness' thread.
The oil breather on the cam cover is primarily there to vent crank case pressure which is caused by blow-by during combustion. Some people associate blow-by with tired engines but all engines have an element of blow-by, even brand new motors using gapless rings.. and especially turbo motors due to higher cylinder pressures. The idea is to keep blow-by to a minimum.
And the breather vents these gasses and prevents pressure buildup in the crank case.
Why is pressure build up bad? Well especially as far as turbo cars are concerned, crank case pressure if not vented will travel up the turbo's oil dump and eventually blow oil out of the turbo's oil seals.. this is one of the biggest causes of turbo oil seal failure.
So, why are the majority of ebay catch cans so bad? The internal diameter of the stock breather line is 14mm or more all the way through. I am seeing more and more cans pop up that have fittings that are around 4mm in diameter.
Do the math.. thats 154mm sq of flow area compared to 12.5mm sq.
Only 8% of the flow capacity of the stock line!
Last night a customer brought his car to me. The motor had recently been rebuilt but after fitting a catch can, he complained of his dipstick popping out and oil spraying everywhere... I identified the catch can as the problem but did some other tests on the motor to make sure.
175psi compression across all four cylinders and very low blow-by.. it was a perfectly healthy, low km motor.
And yes, the catch can was an infamous ebay style job .. it had massive 20mm hoses but the fittings that screwed into the can only had an internal diameter of 4mm. No surprise the pressure was building up enough to pop the dipstick out.
Thankfully in many cases the dipstick is like a fuse for the turbo.. but in many other cases the dipstick doesn't budge and the turbo is the next thing to let go.
Other dangers include oil onto the exhaust or heat wrapping ... heating up and igniting... causing engine fires. It happens far too often.
So - you have been warned! Use decent gear and if you're already using one of these cans, look into having the holes drilled out for larger fittings. I would personally not in any situation run less than 10mm ID fittings and lines... with 14mm being recommended.
-Tristan"
-- DavidV
"Ebay catch cans - a warning
--------------------------------------------------------------------------------
Im noticing a lot of people going out and buying ebay catch cans recently without realising how dangerous this can be for your motor so I thought I'd start this 'awareness' thread.
The oil breather on the cam cover is primarily there to vent crank case pressure which is caused by blow-by during combustion. Some people associate blow-by with tired engines but all engines have an element of blow-by, even brand new motors using gapless rings.. and especially turbo motors due to higher cylinder pressures. The idea is to keep blow-by to a minimum.
And the breather vents these gasses and prevents pressure buildup in the crank case.
Why is pressure build up bad? Well especially as far as turbo cars are concerned, crank case pressure if not vented will travel up the turbo's oil dump and eventually blow oil out of the turbo's oil seals.. this is one of the biggest causes of turbo oil seal failure.
So, why are the majority of ebay catch cans so bad? The internal diameter of the stock breather line is 14mm or more all the way through. I am seeing more and more cans pop up that have fittings that are around 4mm in diameter.
Do the math.. thats 154mm sq of flow area compared to 12.5mm sq.
Only 8% of the flow capacity of the stock line!
Last night a customer brought his car to me. The motor had recently been rebuilt but after fitting a catch can, he complained of his dipstick popping out and oil spraying everywhere... I identified the catch can as the problem but did some other tests on the motor to make sure.
175psi compression across all four cylinders and very low blow-by.. it was a perfectly healthy, low km motor.
And yes, the catch can was an infamous ebay style job .. it had massive 20mm hoses but the fittings that screwed into the can only had an internal diameter of 4mm. No surprise the pressure was building up enough to pop the dipstick out.
Thankfully in many cases the dipstick is like a fuse for the turbo.. but in many other cases the dipstick doesn't budge and the turbo is the next thing to let go.
Other dangers include oil onto the exhaust or heat wrapping ... heating up and igniting... causing engine fires. It happens far too often.
So - you have been warned! Use decent gear and if you're already using one of these cans, look into having the holes drilled out for larger fittings. I would personally not in any situation run less than 10mm ID fittings and lines... with 14mm being recommended.
-Tristan"
-- DavidV
Last edited by DavidV; Jan 29, 2005 at 08:18 PM.
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Feb 22, 2005, 08:08 PM
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You know it kinda pisses me off when ppl feel that they are an "ebay" brand. Seriously ppl can sell Greddy Catch cans on ebay! Doesnt mean they're crap! All im saying is - don't be afraid to bid on ebay, just make sure you know what you are bidding on. Bid carefully that is what I say 
Krunal
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Feb 22, 2005, 08:12 PM
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Originally Posted by platinumspecv
You know it kinda pisses me off when ppl feel that they are an "ebay" brand. Seriously ppl can sell Greddy Catch cans on ebay! Doesnt mean they're crap! All im saying is - don't be afraid to bid on ebay, just make sure you know what you are bidding on. Bid carefully that is what I say
Krunal
Krunal
but bid carfull get as many pics as possible and dont be afriad to ask questions
also thanks for teh warning on the catch can
Feb 22, 2005, 11:13 PM
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The Evo General forum is for threads specifically pertaining to the Evo. This one does not. I am moving it to the engine tech forum.
SC~
SC~
Feb 26, 2005, 06:47 AM
#12
Well it seems to me the guy who started the topic sure had it in the right place. A few of the others were just commenting on the general concept. I think things like this help raise the awareness of the dangers of blinging your car out. There are alot of neophytes (like me) who would be totally unaware of this.
It's a principal to keep in mind when making any mod. Easy to understand, but oftern forgotten when the "purdy shinee culurs' catch your eye.
I gotta go install sum underglow now ...... ooooooo ... purdee https://www.evolutionm.net/forums/ne...e=1&p=1685482#
It's a principal to keep in mind when making any mod. Easy to understand, but oftern forgotten when the "purdy shinee culurs' catch your eye.
I gotta go install sum underglow now ...... ooooooo ... purdee https://www.evolutionm.net/forums/ne...e=1&p=1685482#
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