I think this whole radiator thing is overrated - plus once you get rid of all of the hoses, radiator and fans it really cleans up the engine compartment

 

Since you don't want to listen to anybody offering sound advice, why don't you just search and see how many people had trouble with capped air bleed lines? SEARCH IS YOUR FRIEND, learn to use it

 

Post a link to a single thread. I have yet to see one.

This isn't a challenge and it isn't anything personal. I am listening and looking for solid information. Not BS like "GM decided to save some money.." Unless someone KNOWS GM did it for that reason that don't make things up and state it as fact.

The same way a submarine can cavititate the props if the throttle man isn't careful. The boiling point of water varies with pressure. The impeller causes a low pressure point at the inlet of the pump causing the water to flash into steam. As the water then travels off the prop/impeller it moves back into a high pressure area collapsing back into water. In a sub this creates a lot of noise. In a pump it reduces flow and can damage the impeller.

No air, just hot water flashing into a gas in a low pressure zone. By your logic, how does the gas get out of the pump without a vent? By my logic in condenses back into a liquid when the pressure is returned.

Local hot zones occur in a reactor for the same reason. With a 15 pound pressure cap the boiling point of water raises to 250 degrees. A little more with antifreeze. If you have localized hot spot in a head it can create a steam bubble. Steam does not absorb heat like a liquid will. The bubble also blocks the flow of water further increasing the heat build up at the point of the steam bubble. It can even back up flow through the entire head.

The important thing to note is the hot spot doesn't have to be at the top of the coolant passage. It will occur at a heat source. That can be anywhere in the head, most likely near the combustion chamber.

The solution to localized hot spots? Don’t let the water temp get near saturation for the system pressure you are running. Adding another vent isn’t going to help that.

Like I said, post a link to a thread. I would love to see it. Might even join the side of people saying to not block the vents.

 

So they ran thier cars low on coolant and didn't expect issues? Thats a poor example to respond with.

If you have a properly filled system and your fill point is higher than the heads, where can this lead to trouble? I think GM has done away with these on some light trucks and vans and they have the cap high.

Does anyone think that the steamlines are just to stem warranty issues from the people who don't properly service thier car?

 

I did do a search and came up with over 200 hits, but do you think I'm going was waste my time reading them, just to respond to the OP who isn't going to listen to logic.
As far as your explanation of the pump, I can get a cold fluid to cavitate a pump, so that puts your steam pocket explanation in the dumpster. Before I'd blocked them I'd want proof positive that it will not effect anything.

PS Nothing personal in this, In fact I'd agree with a good percentage of the posts you make.

 

I was recently researching this and came across some good threads.
I have decided to have a bung welded to my radiator for the steam vent lines.
Mostly from this thread

In it, they state:
"I got a little curious about this so I checked and found according to the GM LS1 swap installation guide ( pn 88959384 ) it states on page 7;

Quote:
Connect cylinder head air bleeds and coolant return line to outlet radiator hose or return side of radiator. Cylinder heads air bleeds must connect to fill bottle or highest point of cooling system above coolant level!


That's an exact quote they even put the exclamation mark so....

Then it says;

Quote:
NOTE: failure to connect the cylinder head air bleeds properly can cause an internal air lock and result in engine damage

Anyway, It isn't a huge deal to approach it in a few ways.
There are people that have plugged them and did not have any problems.
There are those people that say that the lines were put on for a reason and if they could be eliminated without harm, GM would have done so to lower production costs.

Searching for "steam" in the conversions and hybrids forum will show how a lot of people have routed them.
Tapping the top of the water pump.
Tapping into a radiator hose.

I'm keeping my lines as they were set up on my 2006 L59.
The rears are capped and the fronts are tied together and will run to the radiator. Piece of mind is worth more to me than pieces of engine.

 

how come everyone is getting so worked up over this. I was simply asking the people on this forum who has capped them and who hasnt. its not that im not listening to logic, these ideas are your peoples idea about why not to cap them. Like i said in an earlier post, it makes sence to have them there and connected, obviously i undertand GMs logic. you nay sayers are just giving un proven ideas about why they cant be capped. My question wasnt the reasoning behind it, just simply who has and who has not capped them.

for the record, i plumbed the vent to the coolant pump becasue it was cheaper than buying the caps or perminently plugging the tube.

 

If you read the thread I linked, it answers your question.
There are people in that thread that say they have them capped.

 

Chose not to cap mine......tied it into upper hose..


T,

 

Well, no, it helps to prove my point. 80 degree water will boil if you put it under enough vacuum. This link plots the boiling point of water vs. temperature.

http://www.engineeringtoolbox.com/bo...ter-d_926.html

here is another link describing cavitation. air ingestion isn't cavitation.

http://www.mcnallyinstitute.com/01-html/1-3.html

Google cavitation and there are other.

yeah, I don't understand all the angst.

I have to agree with tomcowle on the low on fluid issue. If that is why their engine was damaged then not something I worry about. That will ruin an engine even with vents. Seems to me, an this is speculation on my part, but once the air is out it is out. I know uncapping a vent sure allowed me to speed up filling the engine with coolant. It will also get the air out.

Has any one stopped to think that the only reason GM left the vents on the front is because it is the most convenient place to get a source of hot water for the throttle body? Just as plausible of an explanation as cost. Now that obama is running GM maybe they will take the vents off the fronts to help pay back some of the bail out money.

 

this is the only info in this thread thats seems reasonable

 

10,000 + miles...and no issues with plugging it off. I ran it from the stock front head bolt nipples to a plug, and hooked the line to the bottom of the t/b so you didn't have to see an empty nipple sticking out...

 

i used my front ones, because they are higher than the waterpump outlet-i
am using an AFCO conv. radiator, and just welded a 1/8" pipe bung in the side of the tank next to the inlet, then just ran the line to it
if you look at the pic, you can see it-it made since to me to make sure water got to all parts of the engine/head-people can do what they want, this was my choice

 

I can get my comercial pool pump to caviate at 15" of vacuum with the water at 80 degree F, look at your chart, the boiling point of water is at least 100 degrees higher then that at that pressure.

If companies thought you could safely block off the air vent lines, then why, when they sell their throttle body heat bypass kits, do they give you fittings to couple the 2 hoses together, instead of plugging them off?

 

It couldn't be cheaper then plugging the line. If you truely wanted to know who did it and who didn't, you would have had a poll, and you wouldn't have questioned, or taken sides

 

This is what I always thought it was for, to help heat up the air for cold starts or something like that.

If air pockets develop in the heads, whether it be from pressure/cavitation or just a random bubble somehow sucked in there, since the heads are slightly above the water pump, I can't see the air having anywhere to go since it always wants to travel up. Even if people have had success capping the crossover line to "vent" possible trapped air, I would think this just means that little/no air is trapped in there, and whatever air is in there isn't doing a ton of harm. But I personally wouldn't want to run the risk, I'd just route the crossover back into the water pump or upper hose so the air can travel to the true highest point, which should be the cap.

 

Just an innocent question, but I've seen them capped off and no problems occured. I've looked at the left over pieces and it doesn't seem like alot of fluid can travel through the lines. The little nipple that inserts into the head on the bottom of the blocks is even smaller then the lines. Just curious as to how much cooling actual could occur through such a small passage?

 

I think it's more about making sure no air/steam is left trapped in there. It doesn't need to be the size of a garden hose or need to flow half the coolant through, just to provide an escape route for any trapped bubbles, so the reasoning for the size... my guess is it's just big enough to get the job done??

 

Look at the first entry in the table. How do you know you are only drawing 15" of vacumm in the center of the pump impeller?

[img]http://www.engineeringtoolbox.com/docs/documents/926/water-pressure-boiling-temperature-2.png[\img]

So if I had to summarize the answer for the original question, I think it would unquestionably have to be "depends". Like I said earlier, there is some debate on this issue. I don't know the no **** answer, but 100 thousand miles and no problems tells me what I need to know.

 

Moot point. The tube is still there on the gen 4's which don't have water through the TB. They actually changed the tube slightly. On the new SC'd factory motors, the tube setup is actually more elaborate.

I view this like torquing bolts on the car. If I don't torque every little bolt on the car, will things probably be OK? Yes, but why chance it. The steam tube is easy enough to set up, so why would I want to experiment? It's simply not worth it to me to modify something that has no benefit.