Swap head without draining coolant

kinger

kinger

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Nov 12, 2004
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796
Location
Clear Lake, IA
Possible? Or do I have to drain the complete system again to swap the head out for a CPR head? I was thinking of sucking a little out on the resivoir and then tipping the sled back on the trailer so the head was the highest point and get the coolant out of the head back into the resivour and then when level no coolant would run back into the head. Do able?
 

I have just pulled the head off before without draining a thing, just let the little bit of antifreeze run out and catch it under the sled with a bucket (or just let it run out and use oil dry or something). Just dont let it sit on top of the pistons after you do this, you dont want it to go down into the bottom end. Suck it up quick with a turkey baster or something from on top of the pistons. When you are done, add a little coolant again, and bleed it a few times and call her good.
 
What is your preffered way to bleed the system? Everything says bleeding is hard and you must do it like a million times, is there a method that seems to work better then something else?
 
i guess i just do it over and over again at the rear and at the carb heater valve. I lift it up high on the end that im bleeding from as well.
 
Vipers have no bleed screw at the carb valve correct? So just lift the rear up high and keep doing it? Its fricken messy because the screw in the rear exchnager has to come all the way out and coolent just shoots outta there. I guess if that is the method I'm OK with it.

Thanks!
 
yes there is a bleed screw on the carb heater shut off valve, it is the little bolt right above it. Also, the bolts don't have to come all the way out to do this, loosening it up will allow the air to come out, when it is all coolant and no more bubbles you are good, but you have to repeat it several times. ;)!
 
Easiest way to do it is get a siphon hose, stick it down the through the cap and put it in somthing you can measure, then you'll know exactly how much to refill and should have a relatively small mess.... I did this years ago when swapping the pistons in my 97 600sx ... complete top end rebuild put it all back together and she's never had a problem since....about 7K miles.... good luck.
 
Boondocker-1 said:
Why not use the drain screw on the front of the engine? The one with the brass washer?
Click to expand...

You could use that too, hard to collect coolant from though unless it only comes out one hole in the belly pan.
 
to get coolent out of the viper , you need to loosen the allen nut that is near where the coolant hose comes off the head and to the carbs and near the on/off knob , it's up side down . , then lossen the drain screw on the top of the head in the same location , but before you fire the sled up , with a pair of channel locks turn and pull out on the on/off knob , you need that to come out alittle before any coolent will come out that drain hole if you cant get collent out of that hole keep pulling the knob out till it does , the thing that sucks is , once the head warms up, it is hard to move the on/off knob..it should only take a few times in the front , to get all the air out , its the back drain on the vipers you need to do over and over again , i just rebuilt the top on mine last week . good luck
 
No. Its not hard. I use a small cup and you don't need to take the drain screw out all the way. Just a few turns and fill the cup then close it (finger tight) repeat... If you have tripple pipes you will have to remove one or two pipes. I do it that way so I can keep evrything clean and re-use the coolant. If you do it right you will need very little if any additional coolant.
 
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