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Converting to open radiator system

M

MudfrogK5

NAXJA Forum User
Location
Roanoke VA
Going to attempt the Moroso filler conversion (90 4.0) as I want to keep it fairly cheap. I'm going to bypass the heater control valve so no need for that.

I'm looking at the Moroso 63745 (1.25") and Moroso 16psi radiator cap.

Now for the Overflow bottle Jaz has two products. Both are 1qt but one states.

Vented Yes
Recirculating Yes
Drain Valve Included No

The other states:

Vented No
Recirculating No
Drain Valve Included Yes

I think in the how to I read they used the one that was not vented or recirculating, so would this be the correct one for what I need?
 
xcm said:
just recently switched from closed to open with a new radiator, i chose NOT to use an overflow bottle, and i havent seen anything go thru the overflow line yet.

things are ice cold, love it.
http://naxja.org/forum/showthread.php?t=1023591
Click to expand...

So, when the coolant heats up and expands, where does it go? As the coolant cools, and a vacuum is created in the radiator, what is sucked in?

Curious mind wants to know.
 
Ordered a jegs aluminium filler / 1qt bottle and radiator cap. Anything I should keep in mind while performing this swap? Should the top of the overflow bottle be higher than the radiator cap?
 
joe_peters said:
So, when the coolant heats up and expands, where does it go? As the coolant cools, and a vacuum is created in the radiator, what is sucked in?
Curious mind wants to know.
Click to expand...


great question! it would suck in air, overflow or no overflow. the stock overflow bottle has 1 inlet, and its up top next to the cap, so unless its full, your only gonna suck air back in.
 
xcm said:
great question! it would suck in air, overflow or no overflow. the stock overflow bottle has 1 inlet, and its up top next to the cap, so unless its full, your only gonna suck air back in.
Click to expand...
If you look at how a stock overflow (coolant recovery to be correct) bottle is made, the fluid is drawn out of the bottle from the bottom of the bottle.
 
xcm said:
great question! it would suck in air, overflow or no overflow. the stock overflow bottle has 1 inlet, and its up top next to the cap, so unless its full, your only gonna suck air back in.
Click to expand...

If the overflow hose enters the bottle at the top then there has to be enough hose inside the bottle so that it reaches the bottom of the bottle. As long as the fluid level is maintained it shouldn't suck air.
 
joe_peters said:
If the overflow hose enters the bottle at the top then there has to be enough hose inside the bottle so that it reaches the bottom of the bottle. As long as the fluid level is maintained it shouldn't suck air.
Click to expand...

Is this the stock configuration? If so, I'll need to check and make sure I still have that tube.
 
Speaking generic, some recovery bottles have the hose attach to a nipple on the bottom of the bottle, some have a hose that enters through the top and runs to the bottom of the bottle.

Either way, to maintain the system the recovery hose needs to be immersed in the coolant in the recovery bottle so that coolant, not air, is pulled back into the cooling system when the vacuum forms.
 
I just did this, goto the parts store and ge teh generic slimline overflow bottle, it's about 12 bucks. it fits nicely between the airbox and the drivers fender. I'll get some pictures tonight when I get hme, and I thnk I still have the package even. Bottle was at vatozone and fit very nicely.

you NEED a coolant recovery bottle. running it open will introduce air to the system, and it makes you an ass for dumping coolant onto the ground.
 
bigalpha said:
xcm - how's the coolant overflow delete working out?
Click to expand...


running schweet, no signs of stray coolant (probably happens at WOT, if any time, so it may piss on LA freeways.)

havent offroaded with it yet, but i'll post back when it see's a nice long 2-lo drag thru some deep sand for a real test.
 
xcm said:
running schweet, no signs of stray coolant (probably happens at WOT, if any time, so it may piss on LA freeways.)

havent offroaded with it yet, but i'll post back when it see's a nice long 2-lo drag thru some deep sand for a real test.
Click to expand...

You've missed the point.

without a coolant overflow bottle to hold the expanding coolant you WILL introduce air into the system.
there's no way around the physics of it.
when the coolant heats up, it expands, when it cools down it contracts. Without a tank and a tube below the coolant level in the catch tank to feed the coolant back into the radiator you WILL have air in the system.
Throttle position has nothing to do with it.

please, don't argue with me, it's physics and not negotiable.
put a damned catch tank on your junk for a whopping $12 and stop dumping coolant on the ground and having your cooling system filled halfway with air. Your 4.0 head will thank me before you hot spot it and crack it. Ever wonder why old cars have really tall radiators? It's because they didn't have pressure caps, so they left air in the system to allow for the expansion of the coolant, and that air needed to be above the cylinder head level.

and stop leading the newbs down your tarded path, you're simply spreading misinformation about it "working great"

and I'm totally nominating this.
 
Last edited:
bigalpha said:
So do you have to add coolant or do you let the system self-regulate the coolant/air levels in the cooling system?
Click to expand...

once it heats up one tie the system will have the space it needs for the expanding coolant, but you obviously didn't read my post.
THIS IS NOT A GOOD IDEA FOR YOUR MOTOR!

the top of the radiator in the XJ is below the head, without a catch tank to feed coolant back into the system
YOU WILL HAVE AIR IN THE BLOCK

it will cause damage in the long term, because the air will cause hot spots in the head.


I can't explain this any more thoroughly, do what you want, but when you come back asking about how to swap the head / head gasket I'm going to say that I told you so.
 
87manche said:
once it heats up one tie the system will have the space it needs for the expanding coolant, but you obviously didn't read my post.
THIS IS NOT A GOOD IDEA FOR YOUR MOTOR!

the top of the radiator in the XJ is below the head, without a catch tank to feed coolant back into the system
YOU WILL HAVE AIR IN THE BLOCK

it will cause damage in the long term, because the air will cause hot spots in the head.


I can't explain this any more thoroughly, do what you want, but when you come back asking about how to swap the head / head gasket I'm going to say that I told you so.
Click to expand...

I wasn't asking you - I was asking xcm. I understand the concept of the cooling system. I want to know what xcm has been doing.
 
bigalpha said:
I wasn't asking you - I was asking xcm. I understand the concept of the cooling system. I want to know what xcm has been doing.
Click to expand...

and if you read the first line of my previous post I gave you your answer.

You won't have to add coolant because once it gets hot and pisses enough coolant out on the ground to make space in the system it won't leak anymore.

but then that will leave a great big air bubble in the system when it cools down.

You obviously don't understand how the system works if you have to ask what happens when you run it without a recovery tank.

and seriously, I'm anot a tree hugging hippy, but you guys are alright with just letting your coolant hit the ground?

no wonder we're losing trails
 
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