New engine coolant fill

[rob249]

Almost ready to fire my new engine, just have a question about the coolant. Truck is a 94' Yukon 4x4, rebuilt motor is stock, except for a roller conversion.

I put 2 gallons of coolant and 2 gallons of water, poured some in radiator, and some into the heater hose. Do I need to remove the thermosat and fill that too? My "GM Genuine" thermo doesnt have the air hole.

Id rather not remove the thermo, ground wires and soleniod mounted there, but I also dont want to burn up the top of motor before the thermo opens. Dont know exactly how the water sits in the motor before its burped the air out.

 

[PlayingWithTBI]

Do I need to remove the thermosat and fill that too?

No, just fill the radiator all the way, leave the cap off, and run it until the T-Stat opens. You'll see the level go down and coolant flowing across the top of the tank.

A better way is to use this funnel setup that attaches to you radiator, over fill it and run until warm again.

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[Schurkey]

Yup. There are NO worries about "burning up the top of the motor" due to an air pocket under the thermostat. MOST of the "air" will get blown-out via the heater core, since the heater core gets it's hot water from the thermostat area on TBI engines.

The bigass Lisle funnel is a GREAT idea. They used to sell a really-basic kit, seems like every time I search for it, they've put more adapters into bigger, fancier kits. This one is still fairly basic.
www.amazon.com/Lisle-24680-Spill-Free-Funnel/dp/B00A6AS6LY/ref=sr_1_1?

Beware the knock-offs on Amazon and other retailers.

 

[movietvet]

If you do the funnel and cannot see the coolant flow at the radiator cap neck, you will feel the hot coolant flow thru the upper radiator hose. Just keep a hold of it and when that thermostat opens, you will feel it.

 

[fancyTBI]

I always fill the block before putting the thermostat and neck on. But the way you’re going to do it will not harm it. Others have shared the best advice.

 

[rob249]

I put a new catalytic convertor on as well, it has a break in procedure.

Im suposed to idle for 5 mins, then hold 2500 rpm for 2 minutes, then shut it down and let it fully cool.

Should I leave the funnel on for the whole procedure?

Wait until the thermo opens, put the radiator cap on, then hold 2500 rpm?

Motor is a roller cam, so no cam break in needed.

 

[Schurkey]

I put a new catalytic convertor on as well, it has a break in procedure.

That's new to me...but OK.

Im suposed to idle for 5 mins, then hold 2500 rpm for 2 minutes, then shut it down and let it fully cool.

OK.

Should I leave the funnel on for the whole procedure?

I would. Especially at shut-down, the coolant may fill the funnel. Perhaps you want to remove the funnel and install the cap just before shut-down.

Wait until the thermo opens, put the radiator cap on, then hold 2500 rpm?

I'd do it just like they say--idle for 5 min, then hold 2500.

Make sure there is SOME coolant in the funnel, but not much. You'll likely be adding some during this run-time. Then when you shut-down, there's still room in the funnel to accept any overflow.

Or

Towards the end of the run time, just before shut down--remove funnel and install rad cap.

Motor is a roller cam, so no cam break in needed.

Good.

 

[rob249]

That's new to me...but OK.

Yeah, im glad I called them to ask. Apparently the cool down is very important, something about bedding the catalyst. It is surrounded by a material that burns and expands, locking it in place. Its a new Y-pipe with a new cat, made by AP exhaust, which owns Eastern catalytic. Figured it was time for a new one, at 250K miles on the original, about 50k of that with a miss in the #8 cylinder, no way it was still "catalizing".