Coolant expansion tank question

Ken Roberts

Supporter
Has anyone connected their coolant expansion tank to the drivers side coolant pipe? My expansion tank is located on the drivers side bulkhead and the plumbing would be much easier if I just dropped straight down to the driver side coolant pipe instead of crossing over the front of the engine and connecting to the 3/4" heater hose at the water pump.

 
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Terry Oxandale

Skinny Man
Supporter
Considering these points on the LS are the highest points, I would think that would be ideal. I'm using the older LS1 4-to-1 tube, and it goes directly into an expansion tank behind the intake. No problems to note.
 

Ken Roberts

Supporter
If I remember correctly I think Howard was the only one to use the drivers side coolant pipe for the expansion tank.

It's too late for me now as today I've made brackets that support the 3/4" heater hose along the bulkhead just below the window. These brackets will also support the wiring harness and evap tube.
 
You want the bottom of the expansion tank/remote fill to run to the water pump inlet side (passenger) ... if forgot why now though, but i know it works well, heh.
 

Terry Oxandale

Skinny Man
Supporter
Perhaps the blue hose in Ken's photo is coming from the bottom of the tank, and into the pump housing. If this is a Moroso unit, it has a bung at the bottom of the tank.

As water (and/or air) is pushed out into the tank during warm-up, then you'd want only water to be sucked (pushed) back into the block on cool-down. If the fitting on the tank is exposed to air, I would think it would draw air back into the coolant system. If that were the case though, I'd think you'd notice some unusual heat issues...maybe. In my system the coolant return comes from the very bottom of the tank, and a noticeable drop in the tank's coolant level is observed after each of the first 2 or 3 heat cycles (after opening up the coolant system) as the air is incrementally expelled with each hot/cold cycle.
 
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If you run the coolant header tank of the pressure side of the pump it will blow water out every time, it Must come of the inlet side of the pump.
been there got the T shirt.

kaspa
 
If you run the coolant header tank of the pressure side of the pump it will blow water out every time, it Must come of the inlet side of the pump.
been there got the T shirt.

kaspa
Makes sense; that's must be why they say to do it on the passenger side (that's the inlet side on an LS)
 
One obvious question though..... Why do you have your radiator cap open while your engine is running? You have no coolant blowing out when the cap is closed. Correct?
 
If you run the coolant header tank of the pressure side of the pump it will blow water out every time, it Must come of the inlet side of the pump.
been there got the T shirt.

kaspa
I don't want the shirt, I have already 'made' too many for myself.

Good thread. As a result I have pulled the two most difficult to remove parts in my car to fix this error. I hope I don't have to pull the engine to put the pipes back in but, I might :( Way better now then later.
 
You guys have bad memorys.
I remember a thread on this and Jacmac posted the same as what John is talking about.
He even drew a picture,I used it and it works great.

Aaron I see what you mean but cant answer that for sure because your logic is correct.
Only thing I could think of is due to the radiator down the front or sides with the flow restrictions it see's a higher pressure on the hot side maybe.

Jim
 
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on a somewhat related question, how low to the expansion tank/remote fill can you place your puke tank, assuming you're "filling" the puke tank from the top (radiator cap) of the expansion tank to the bottom of the puke tank.

i was taught that it should be roughly equal to the expansion tank so the fluid is easily drawn back if it's puked out ever. Is this true, or can you put it a few feet below the expansion tank and have it still work well?
 

PeteB

GT40s Supporter
I don't know what the "correct" answer is, but I had the puke tank on my Cobra mounted about 12" below the expansion tank, and it worked just fine.
 
You guys have bad memorys.
I remember a thread on this and Jacmac posted the same as what John is talking about.
He even drew a picture,I used it and it works great.

Aaron I see what you mean but cant answer that for sure because your logic is correct.
Only thing I could think of is due to the radiator down the front or sides with the flow restrictions it see's a higher pressure on the hot side maybe.

Jim
This is my take on the logic of it, YMMV

If the pump is drawing from the cool side and the expansion tank is on the cool side then the tank will never see higher than the average pressure your system operates on. Also, if the tank is designed correctly then the pump will always be drawing from an air free coolant supply. If it's on the exit side of the pump then whenever you blip the throttle the pressure in the system will momentarily spike, thus (possibly) causing the pressure rating of your radiator cap to be exceeded.
 
You guys have bad memorys.
I remember a thread on this and Jacmac posted the same as what John is talking about.
He even drew a picture,I used it and it works great.

Aaron I see what you mean but cant answer that for sure because your logic is correct.
Only thing I could think of is due to the radiator down the front or sides with the flow restrictions it see's a higher pressure on the hot side maybe.

Jim
Yeah , I was going to remind them Jim, but most of these guys are using up most of their memory on their pin numbers, don't seem to be able to operate the search function either...sad really..:blank:
 
on a somewhat related question, how low to the expansion tank/remote fill can you place your puke tank, assuming you're "filling" the puke tank from the top (radiator cap) of the expansion tank to the bottom of the puke tank.

i was taught that it should be roughly equal to the expansion tank so the fluid is easily drawn back if it's puked out ever. Is this true, or can you put it a few feet below the expansion tank and have it still work well?
You could always try a little experiment yourself, get two containers of your favourite beverage, use a straw about 10" long for one and another straw about 40" long for the other, see if there is much difference in the time & effort to drink each one. No Cheating, each straw must be vertical during the process!!
 

PeteB

GT40s Supporter
Yeah , I was going to remind them Jim, but most of these guys are using up most of their memory on their pin numbers, don't seem to be able to operate the search function either...sad really..:blank:
You mean the search function that doesn't work in the SLC Clubhouse?
 
You mean the search function that doesn't work in the SLC Clubhouse?
Broaden your horizons, go into the GT40 world and look in the respective section for whatever problems your dealing with, most of these topics have been discussed at length before in relation to GT40 and other rear engine cars, that's why Howard is such a mine of info to you guys, he has done it all before:).

** The two bleed lines need only be -3 or 3/16" bore max, you only need to bleed air, not create an alternative coolant flow path... 21lb cap might be a bit low for more modern engine types.
 

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PeteB

GT40s Supporter

** The two bleed lines need only be -3 or 3/16" bore max, you only need to bleed air, not create an alternative coolant flow path... 21lb cap might be a bit low for more modern engine types.
Well, unless you want a heater, which most of us do. Unlike a SBF, a LS engine also has steam vent lines that need to be connected. But, I'm sure all these little LS engine details are in the GT40 section of the forum...
 
Well, unless you want a heater, which most of us do. Unlike a SBF, a LS engine also has steam vent lines that need to be connected. But, I'm sure all these little LS engine details are in the GT40 section of the forum...
Probably are as several GT40 builders have crossed to the dark side and fitted LS engines, steam vents are nothing new to the SBF guys who have used Audi & Renault transaxles which usually require fitting the engine in a slight nose down attitude. This causes an air lock situation at the rear of the cylinder heads which in turn requires steam vent lines to be installed at the rear corners of the intake, no big deal about the heater, just take the line off the top of engine ( where the OE application does ) to the heater and return to the inlet side of the pump. For efficient heater operation the heater circuit should operate on the engine side of the thermostat.
Some folk will suggest to you that once you have bled the cooling system initially that you should have no further issues..... unfortunately that does not allow for nucleate boiling ( caused by localised hot spots within the engine cooling system ) and the odd bit of aeration from slight head gasket leakage under hard use/detonation conditions, along with other sources like poor connections, water pump seals etc etc.
 
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