Coolant bypass/crossover lines do I need?
Coolant bypass/crossover lines do I need? OK guys, as most know, I am in the middle of my 414" 6.0 L92 headed build. Do, I HAVE to have the coolant crossover line? Can I plug it off? The car is not a DD, but will see the street. If I do need it, don't they make 2 versions of it? I have not found too much info on it, other than most info I have come across says I need it, but does not say why? So, if I do need it, where can I pick it up, and if there are 2 versions, which one should I run, and if I don't need it, what caps/plugs/kit you guys using?
Yes, you need it. It vents to the coolant to ensure that the coolant reaches the highest point on the heads & doesn't get blocked by an air pocket. I would connect both, the rears together, the fronts together & then tie the rears to the front & run the line to the top of the radiator or highest radiator hose. Some will claim that the rears aren't needed. I'm not of that opinion. The rears are near the hottest two pistons, 7 & 8.
Part numbers; Sorry, I don't know, but am sure that a search for GM part numbers will reveal what is needed. If not, you can run the lines w/pipe nipples & fuel line hose if stock looks aren't important (this is how mine is done).
Part numbers; Sorry, I don't know, but am sure that a search for GM part numbers will reveal what is needed. If not, you can run the lines w/pipe nipples & fuel line hose if stock looks aren't important (this is how mine is done).
Yes, you need it. It vents to the coolant to ensure that the coolant reaches the highest point on the heads & doesn't get blocked by an air pocket. I would connect both, the rears together, the fronts together & then tie the rears to the front & run the line to the top of the radiator or highest radiator hose. Some will claim that the rears aren't needed. I'm not of that opinion. The rears are near the hottest two pistons, 7 & 8.
Part numbers; Sorry, I don't know, but am sure that a search for GM part numbers will reveal what is needed. If not, you can run the lines w/pipe nipples & fuel line hose if stock looks aren't important (this is how mine is done).
Part numbers; Sorry, I don't know, but am sure that a search for GM part numbers will reveal what is needed. If not, you can run the lines w/pipe nipples & fuel line hose if stock looks aren't important (this is how mine is done).
Ok, thanks. I will do a search and see if I can come up with the part numbers for teh fittings. Stock looks are of no importance to me, especially since the car is carb'd among other things
The crossover tube (LS6) is P/N 12568478 and the plugs are P/N 12562788. I'm also not a big fan of plugs in the back two cylinders and would at least prefer two crossover tubes. To connect the nipple off the front crossover tube to the radiator nipple you need 5/16" hose. If you run that crossover in the back (instead of plugs) you'll have to block off the nipple by capping, crushing & welding, etc.
Yes, you need it. It vents to the coolant to ensure that the coolant reaches the highest point on the heads & doesn't get blocked by an air pocket. I would connect both, the rears together, the fronts together & then tie the rears to the front & run the line to the top of the radiator or highest radiator hose. Some will claim that the rears aren't needed. I'm not of that opinion. The rears are near the hottest two pistons, 7 & 8.
Part numbers; Sorry, I don't know, but am sure that a search for GM part numbers will reveal what is needed. If not, you can run the lines w/pipe nipples & fuel line hose if stock looks aren't important (this is how mine is done).
Part numbers; Sorry, I don't know, but am sure that a search for GM part numbers will reveal what is needed. If not, you can run the lines w/pipe nipples & fuel line hose if stock looks aren't important (this is how mine is done).
12602548 Coolant crossover pipe LS3
12602540 Coolant Caps (need 2 if your going to block off the rear)
11588714 Coolant pipe/cap bolts (need 4 or buy M6 x 1.0 x 30mm bolts from a local source)
12551933 Coolant Seals, Head (need 4)
or you can buy these from Wegner and plumb your own lines:
Water Line Adapter
WA0214
GM GEN III/IV LS
Bolt on aluminum slug. Seals to the head with 'O' ring. Has 1/8" NPT female thread. Used to connect water steam lines or to block off water passages on LS engines.
http://s41657.sites80.storefront-hos...l.aspx?ID=3289
Last edited by 405HP_Z06; Jan 23, 2009 at 10:11 AM.
OK guys, thanks for teh part #'s and helpful info. This is my first LSx build, and I am getting close to the end (being finished
) and trying to tie up all the loose ends. Schwanke, I will look into the parts and pricing, and get back with ya. Thanks for the offer!!
) and trying to tie up all the loose ends. Schwanke, I will look into the parts and pricing, and get back with ya. Thanks for the offer!! Trending Topics
LS1 Tech Stories
The Best V8 Stories One Small Block at Time
6 Common C5 Corvette Failures and What's Involved In Repairing Them
Pouria Savadkouei
Retro Modern Bandit Pontiac Trans AM Comes With Burt Reynolds' Autograph
Verdad Gallardo
Top 10 Greatest Cadillac V Series Performance Models Ever, Ranked
Pouria Savadkouei
Top 10 Most Powerful Chevy Trucks Ever Made!
Hennessey's New Supercharged Silverado ZR2 Has 700 HP
Verdad Gallardo
Coachbuilt N2A Anteros Is an LS2-Powered C6 Corvette In Italian Clothes
Verdad Gallardo
Awesome K5 Blazer Restomod Comes With C7 Corvette Power
Verdad Gallardo
10 Camaros You Should Never Buy
10 LS Engine Myths That Refuse to Die
Verdad Gallardo Agree 100%, you need them. Here are the part numbers :
12602548 Coolant crossover pipe LS3
12602540 Coolant Caps (need 2 if your going to block off the rear)
11588714 Coolant pipe/cap bolts (need 4 or buy M6 x 1.0 x 30mm bolts from a local source)
12551933 Coolant Seals, Head (need 4)
or you can buy these from Wegner and plumb your own lines:
Water Line Adapter
WA0214
GM GEN III/IV LS
Bolt on aluminum slug. Seals to the head with 'O' ring. Has 1/8" NPT female thread. Used to connect water steam lines or to block off water passages on LS engines.
http://s41657.sites80.storefront-hos...l.aspx?ID=3289
12602548 Coolant crossover pipe LS3
12602540 Coolant Caps (need 2 if your going to block off the rear)
11588714 Coolant pipe/cap bolts (need 4 or buy M6 x 1.0 x 30mm bolts from a local source)
12551933 Coolant Seals, Head (need 4)
or you can buy these from Wegner and plumb your own lines:
Water Line Adapter
WA0214
GM GEN III/IV LS
Bolt on aluminum slug. Seals to the head with 'O' ring. Has 1/8" NPT female thread. Used to connect water steam lines or to block off water passages on LS engines.
http://s41657.sites80.storefront-hos...l.aspx?ID=3289
TECH Regular
Joined: Sep 2005
Posts: 453
Likes: 0
From: 415 Northern CA
The crossover tube (LS6) is P/N 12568478 and the plugs are P/N 12562788. I'm also not a big fan of plugs in the back two cylinders and would at least prefer two crossover tubes. To connect the nipple off the front crossover tube to the radiator nipple you need 5/16" hose. If you run that crossover in the back (instead of plugs) you'll have to block off the nipple by capping, crushing & welding, etc.
OK, looks like I am all set up on parts and such, thanks again.
Now, I do have a couple questions again on WHY I need them. You guys are saying to eliminate any air pockets in the system, correct? Why do the Gen III/IV heads have this problem that the Gen I/II stuff don't?
Now, I do have a couple questions again on WHY I need them. You guys are saying to eliminate any air pockets in the system, correct? Why do the Gen III/IV heads have this problem that the Gen I/II stuff don't?
OK, looks like I am all set up on parts and such, thanks again.
Now, I do have a couple questions again on WHY I need them. You guys are saying to eliminate any air pockets in the system, correct? Why do the Gen III/IV heads have this problem that the Gen I/II stuff don't?
Now, I do have a couple questions again on WHY I need them. You guys are saying to eliminate any air pockets in the system, correct? Why do the Gen III/IV heads have this problem that the Gen I/II stuff don't?
Ok, what you are saying then is they found out that the earlier Gen I/II stuff developed hot spots in teh heads, but they felt they could leave it alone? and tehn starting with a clean sheet (Gen III/IV) they would address it?
The crossover tube (LS6) is P/N 12568478 and the plugs are P/N 12562788. I'm also not a big fan of plugs in the back two cylinders and would at least prefer two crossover tubes. To connect the nipple off the front crossover tube to the radiator nipple you need 5/16" hose. If you run that crossover in the back (instead of plugs) you'll have to block off the nipple by capping, crushing & welding, etc.
Most that use 2 crossover tubes connect them together at the radiator connection hose. The thought being that water would circulate from the rear like the front and hopefully reduce the temperature of the rear two cylinders.
In the Gen II engine they introduced reverse cooling in order to address this issue. They also used a single air bleed on the thermostat housing to release trapped air from the system.
If you look at some of the hardcore Gen I circle track engines, they use many custom steam lines and other techniques in an attempt to keep the heads evenly cooled.
In the Gen II engine they introduced reverse cooling in order to address this issue. They also used a single air bleed on the thermostat housing to release trapped air from the system.
In the Gen II engine they introduced reverse cooling in order to address this issue. They also used a single air bleed on the thermostat housing to release trapped air from the system.
Yeah, I was aware of the Gen II reverse cooling (just sold my 97 WS6). I guess what I am saying is, are they REALLY needed? I mean, if I installed a bleeder in the upper hose, wouldnt that do the same trick as teh bypass line? My wife's Jeep GC 4.7HO has teh bleeder valve on the tsat housing on the upper hose. Isn't that basically serving the same purpose, or am I missing something else?
Sounds like you're trying to talk yourself out if of it. So, do it "because we said so." J/K 
Even if you bleed it properly, there is an added benefit (some dissagree) to the added & unrestricted circulation of coolant from the front & rear ports (tied together) & into the the radiator. The other advantage is when the owner lets the coolant level get low (not low enough for an CEL fault), the heads have some cooling from the coolant that manages to find its' way further up the heads because of the avenue created by the rear line that is connected to the fronts & the radiator.
Even if you bleed it properly, there is an added benefit (some dissagree) to the added & unrestricted circulation of coolant from the front & rear ports (tied together) & into the the radiator. The other advantage is when the owner lets the coolant level get low (not low enough for an CEL fault), the heads have some cooling from the coolant that manages to find its' way further up the heads because of the avenue created by the rear line that is connected to the fronts & the radiator.
Sounds like you're trying to talk yourself out if of it. So, do it "because we said so." J/K
Even if you bleed it properly, there is an added benefit (some dissagree) to the added & unrestricted circulation of coolant from the front & rear ports (tied together) & into the the radiator. The other advantage is when the owner lets the coolant level get low (not low enough for an CEL fault), the heads have some cooling from the coolant that manages to find its' way further up the heads because of the avenue created by the rear line that is connected to the fronts & the radiator.
Even if you bleed it properly, there is an added benefit (some dissagree) to the added & unrestricted circulation of coolant from the front & rear ports (tied together) & into the the radiator. The other advantage is when the owner lets the coolant level get low (not low enough for an CEL fault), the heads have some cooling from the coolant that manages to find its' way further up the heads because of the avenue created by the rear line that is connected to the fronts & the radiator.
OK, guys, THAT was what I was missing. Thanks! I figured I was missing soemthing for the sake of, if it wasn't REALLY needed, why is everyone for the most part, still using it. So, i figured there was SOMETHING that I was missing.
Thanks guys!
Thanks guys!