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Modshack · 03-05-2010, 09:53 AM

Hose Blow-off analysis

What we know:

1) Both Socketless and Braided hoses have separated in 3 reported instances.
Not sure if Travis's was hose related, so that could be 4

2) Neither of those hose types and attachment styles have regularly reported failure rates.

3) Both hose/end styles are rated well above the expected temps and pressures

What we don't know:

1) install specifics/variables.

One of the comments from the Jack above stuck in my mind: The hose needs significant slack.. Both Cab and Mike report they had slack in their installs. I have no reason to doubt that. One thing not taken into consideration is the Torquing of the motor on it's mounts. Under acceleration and compression braking, the motor could be moving around the axis of the mounts by as much as an inch. Certainly in Mike's case, under track conditions, this could be even more. As the motor rocks on it's mounts, alternate stretch and compression forces are applied to the fitting. I suspect enough of these cycles, with a tad too little slack, and the barbs wore through the inner hose liner. At that point the structural integrity of the hose was gone and it blew off. But I had enough slack you say...Alternate theory #2: The hose, as laid out, passes under the sway bar. Lottsa clearance when up on a lift, not so much when on the ground. Compound that with a lowered car (CAB, not sure of your suspension) and you may have the sway bar working and flexing on the hose close to the fitting. This may potentially cause a similar failure by compromising the inner liner. Be sure the hoses are routed to cross under the swaybar close to the pivot point to minimize this. I'll put some cautions up on page one. I'd also recommend, on new builds, extending the hose lengths by 1" as Mike did after his incident. (My dimensions quoted BTW are cut end to cut end and DO NOT include the fitting.). It is always best to actually make up the hose lengths by fitting to the particular install before final socketless (or other) end assembly. A little too short and you run the risk of hose failure because of the above.

03-05-2010, 09:53 AM	#170 (permalink)
Modshack A True Z Fanatic Join Date: Mar 2009 Location: Greenville NC Posts: 2,883 Drives: 370Z Sport Rep Power: 976	Hose Blow-off analysis What we know: 1) Both Socketless and Braided hoses have separated in 3 reported instances. Not sure if Travis's was hose related, so that could be 4 2) Neither of those hose types and attachment styles have regularly reported failure rates. 3) Both hose/end styles are rated well above the expected temps and pressures What we don't know: 1) install specifics/variables. One of the comments from the Jack above stuck in my mind: The hose needs significant slack.. Both Cab and Mike report they had slack in their installs. I have no reason to doubt that. One thing not taken into consideration is the Torquing of the motor on it's mounts. Under acceleration and compression braking, the motor could be moving around the axis of the mounts by as much as an inch. Certainly in Mike's case, under track conditions, this could be even more. As the motor rocks on it's mounts, alternate stretch and compression forces are applied to the fitting. I suspect enough of these cycles, with a tad too little slack, and the barbs wore through the inner hose liner. At that point the structural integrity of the hose was gone and it blew off. But I had enough slack you say...Alternate theory #2: The hose, as laid out, passes under the sway bar. Lottsa clearance when up on a lift, not so much when on the ground. Compound that with a lowered car (CAB, not sure of your suspension) and you may have the sway bar working and flexing on the hose close to the fitting. This may potentially cause a similar failure by compromising the inner liner. Be sure the hoses are routed to cross under the swaybar close to the pivot point to minimize this. I'll put some cautions up on page one. I'd also recommend, on new builds, extending the hose lengths by 1" as Mike did after his incident. (My dimensions quoted BTW are cut end to cut end and DO NOT include the fitting.). It is always best to actually make up the hose lengths by fitting to the particular install before final socketless (or other) end assembly. A little too short and you run the risk of hose failure because of the above. __________________ Steal my car! (SOLD)...Now Porsche Cayman S Oil Cooler DIY: Here! Last edited by Modshack; 03-05-2010 at 11:49 AM.