How to refill coolant without overheating

[Mooseman]

Last time I drained out my V8's cooling system for the DOD delete, I had problems with refilling it properly and it basically got near overheating before the thermostat finally opened. I had opened the steam line on the heads to bleed the air but wasn't getting much coolant out of it.

This is not a full on how-to but this is a tip on on how I refilled it and it worked like a charm.

After installing the water pump and everything else, I left the top hose off and disconnected the small hose that goes from the heater hose to the steam line at the front right head. I then partially filled the radiator so that coolant would fill the lower hose to the thermostat. I then put a funnel into the pump's top hose inlet and filled it until I saw coolant coming out of the steam line's hose fitting. I put the small hose back on. I then topped off the water pump's inlet and reconnected the top hose. Filled the radiator to the top, squeezed the hose a few times and filled some more. Started the engine and topped it off some more. Closed the cap, done.

It got up to 194f highest, went back down to 192f and pretty much stayed there.

I think because of the dip the top hose does, it prevents the coolant from filling the water pump and block/heads properly. I had even used one of those coolant filling funnels and it didn't help. I just used a regular funnel this time with this method.

 

[C-ya]

I may try this. I had my water pump replaced after I had my heater core replaced. I didn't hear gurgling in the engine/dash after the heater core, done by a GM mechanic at his house, but I do since the water pump change, done at a dealership under aftermarket warranty. As an aside, the warranty did not pay for the serpentine belt that got shredded when the pump seized. Dealer wanted $80 for one so I told them to do the repair but not put a belt on and I would bring my own ($38 from Auto Zone). They did the repair and when I got there to pick it up, I put my belt on. Motor was warm. I figure they had to put a belt on to get it filled, but they may not have done a good job burping it.

 

[gmcman]

When I change my thermostat, I jack the front end up then refill..trying to keep the fill cap at the highest point. I'll let the engine run for a few min until the coolant is warm to the touch then see if it drops down or (burps). Once it stabilizes and starts to expand as it creeps up into the filler neck, that's when I cap it off.

 

[Mooseman]

Last time, I even used one of those spill proof funnels that automatically burps the rad but it never went down and coolant never came out if the steam bleed tube. Scared the bejeezus out of.me when it went to.almost overheat before the tstat finally opened. Like I mentioned, the dip in the upper hose under the air intake may have something to.do with that.

Btw, this is on a V8. Never had an issue on the i6.

 

[Reprise]

I've been lucky to this point, I guess. When I did my WP, I was able to bleed coolant out of the throttle body preheat hose / orifice, as per spec (I have the V8, too).

It may (?) have helped that I had worked on it overnight cold, so the t-stat was closed when I drained the rad.

The only 'goofy' part of my Envoy's cooling system is the reservoir - no matter how many times I fill it to the 'cold' mark, it'll lose 1/2" of coolant from that mark over the next day or so. But then it never moves again, if I leave it alone. I never see any white smoke out of the tailpipe after I've refilled it, so I have no idea where that bit of coolant goes to. Probably burns it, but since it's a small amount, it's indiscernible at the tailpipe. Not gonna worry about it while stable.

As I write this, I realize that it'll be time to replace coolant again next spring. Which would be a good time to get the parts & block off the rear HVAC, since I never use it. One less heater core (& outside supply lines) to worry about. 👍

Since we don't have petcocks in our (stock) radiators, I've found that breaking the bottom seal on the bottom hose with a flat-bladed screwdriver (with a pan underneath) is the least messy way to get the coolant drained. Leave the screwdriver in to keep it (slowly) draining, prying / widening the gap a little more as it slows down. Once it stops from there, you can break the seal the rest of the way around the hose & remove it from the neck - makes for a lot less mess, and if you're reusing the coolant, you'll recover more. If you have a pair of those locking hose clamps to squeeze the hose shut (I don't), it should be even easier, at that point.