Coolant temp fluctuating up and down

[JeremyNH]

This is the one I used when I put in a marine intake last Spring. Heats up steady to 210, then cools quick to maybe 170 as the radiator water circulates, then steadies back up to 195ish and stays there.

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[454cid]

The Vortec stats are taller than the old school ones and have a plunger on the bottom.

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Oh, I guess I've never thought about what that is.... or how it works.

 

[Supercharged111]

Oh, I guess I've never thought about what that is.... or how it works.

I don't know how it works, but it sounds like it routes a certain amount of coolant around the radiator and back to the block again to make it warm up faster.

 

[454cid]

I don't know how it works, but it sounds like it routes a certain amount of coolant around the radiator and back to the block again to make it warm up faster.

That's what I find confusing, since our engines already have a coolant bypass. TBI small blocks have it internally in the block, and Vortecs use an external hose, as do big blocks. I don't think I've ever looked inside the intake manifold to see how/where the bottom fits in place.

I think my Saturn has a similar setup.

 

[Supercharged111]

That's what I find confusing, since our engines already have a coolant bypass. TBI small blocks have it internally in the block, and Vortecs use an external hose, as do big blocks. I don't think I've ever looked inside the intake manifold to see how/where the bottom fits in place.

I think my Saturn has a similar setup.

Same as an LT1. There's a boss the thing sits down on top of. I think the functional difference may be that the Vortec turns the bypass on/off with temperature.

 

[Courchained]

So I'm thinking the kooler tstat is going to just allow more flow and not fix my temp fluctuation.
When I've bleed the coolant I have been using that funnel I have also tried lifting the front end up. I've even used the cooling system vacuum filler tool and still no success.

 

[Courchained]

Another bit of information is that I'm finding about a 30°ish temp lose through the upper radiator hose. Then it drops another 30°ish through the radiator. Would one brand coolant retain heat better than another brand? Is that a thing lol

 

[PlayingWithTBI]

So I'm thinking the kooler tstat is going to just allow more flow and not fix my temp fluctuation.

It does combined with a high volume water pump you'll see less temperature fluctuations. I have that T-stat with a Tuff Stuff water pump and a 3 row aluminum radiator which helps keep it cool in the summer around here but, as @Supercharged111 pointed out, that T-stat isn't even shown for a Vortec in "Applications" on Summit's site.

IMHO (In My Humble Opinion) it does sound like your T-stat is causing your issue.
Not saying you should but, years ago we used to drill a small hole in it to allow a little more flow when cold and warming up, YMMV

 

[Schurkey]

Another bit of information is that I'm finding about a 30°ish temp lose through the upper radiator hose. Then it drops another 30°ish through the radiator.

Measured HOW?

Infrared "temp guns" are notoriously inaccurate due to the emissivity different materials.

Would one brand coolant retain heat better than another brand? Is that a thing lol

Nope. The concentration of antifreeze vs. water makes some difference, but not the brand.

years ago we used to drill a small hole in it to allow a little more flow when cold and warming up, YMMV

Generally not a good idea. If the cooling system still has the OEM bypass, all that does is slow warm-up. If the OEM bypass has been blocked, you might need to drill the themostat--but why block the bypass?

 

[Courchained]

I wonder if my bypass is clogged causing poor flow. Also Could my bypass even get clogged?
Side question. If my heater core lines were reversed Could that cause poor flow?