Chevrolet Radiator Expansion Tank

[Stevemo]

Is there supposed to be a baffle in the expansion tank? When I fill it above the seam in the lower portion of the tank the coolant will just come out the overflow hose when I'm bouncing down the road. The end result is that the coolant level in the tank ends up back where it started.

[booster]

Originally Posted by Stevemo

Is there supposed to be a baffle in the expansion tank? When I fill it above the seam in the lower portion of the tank the coolant will just come out the overflow hose when I'm bouncing down the road. The end result is that the coolant level in the tank ends up back where it started.

Ours did that, too, and the thing is huge and always in the way of something.


I swapped out the tank for the one used in later years as it is smaller and works better for me. It is a drop in with maybe a small hose or two needed to be cut to fit the new one.

[dicktill]

Originally Posted by booster

Ours did that, too, and the thing is huge and always in the way of something.

I swapped out the tank for the one used in later years as it is smaller and works better for me. It is a drop in with maybe a small hose or two needed to be cut to fit the new one.

What model years? Part numbers? Thx, Dick

[booster]

It looks like the one we had is now not made anymore per Rock Auto. It looked like this one.




This is the smaller one we got and looks to now be all there is to get.

[peteco]

Originally Posted by booster

It looks like the one we had is now not made anymore per Rock Auto. It looked like this one.




This is the smaller one we got and looks to now be all there is to get.

Looks like the smaller reservoir would also dump excess coolant. How does it work differently from the earlier large design?

[booster]

Originally Posted by peteco

Looks like the smaller reservoir would also dump excess coolant. How does it work differently from the earlier large design?

I may have more rise so less likely to get there, or it may just have less slosh space, but it does seem to work better that way. Like the other one, you do have to keep the coolant level pretty low compared to what I am used to on other vehicles, except my old Buick which is similar level but with a pressurized tank.


The biggest reason to change for us was the space, especially when the second alternator went in and moved the harnesses a little so they interfered with the tank.

[peteco]

Originally Posted by booster

I may have more rise so less likely to get there, or it may just have less slosh space, but it does seem to work better that way. Like the other one, you do have to keep the coolant level pretty low compared to what I am used to on other vehicles, except my old Buick which is similar level but with a pressurized tank.


The biggest reason to change for us was the space, especially when the second alternator went in and moved the harnesses a little so they interfered with the tank.

So it sounds like no need to change to the smaller tank unless you need more space.

[booster]

Originally Posted by peteco

So it sounds like no need to change to the smaller tank unless you need more space.

I would agree with that, but a bit less mess is also a nice thing and a bonus.

[Stevemo]

That's great, the little one has a channel the coolant needs to pass through before pouring out.
The big one seems to be an open fitting on the side and the overflow hose drips right on top of the lower radiator hose which can cause confusion about the source of the coolant.
I'll probably get the little guy and put a long hose on it so that it drips past the radiator.

[Stevemo]

I went ahead and put on the smaller tank today. The Dorman tank doesn't have the warning sticker on it about the thermostat vent but I think it is pretty self explanatory.

https://www.youtube.com/watch?v=F4ZD8iL-XkY

[peteco]

Originally Posted by Stevemo

I went ahead and put on the smaller tank today. The Dorman tank doesn't have the warning sticker on it about the thermostat vent but I think it is pretty self explanatory.

Stevemo (and booster), has the new small tank reduced coolant usage?

I ask because I need to top up coolant occasionally. I just pressure tested the cooling system and have no leaks. I did have a bad cap and replaced it a couple months ago. I tested the cap and it was good. Still have a small bit of coolant usage. I have the old large tank.

[booster]

We have to add a bit maybe every other year so not out of line with most other vehicles I have had. I change it every 3 years or so and that makes the adding almost never done.

[peteco]

Originally Posted by booster

We have to add a bit maybe every other year so not out of line with most other vehicles I have had. I change it every 3 years or so and that makes the adding almost never done.

Did you notice a difference in coolant usage between the new and old tank?

[booster]

Originally Posted by peteco

Did you notice a difference in coolant usage between the new and old tank?

Yes it did get better with new tank, bit it was comparing to the old tank run lower in level than I liked just before I changed it so it was less than it would have been earlier.

[phantomjock]

This discussion got me thinking, wonder if a slightly smaller tank would be beneficial for those concerned about reducing underhood temperatures?

Less volume taken up by the reservoir and, potentially better airflow in the engine bay. The GMC Savana (and the Express) both have a smaller one for the 6.6L Diesel version in the 2500 and 3500 platforms.
Price seems reasonable @ $50.00-ish via Rock Auto and $80-ish on eBay.


With a bit of effort, other tanks could be modified and mounted over the battery to gain even more "ventilation potential" of the engine space.

Just thinking out loud.

Cheers - Jim