Coolant level discrepancy?

[ltslimjim]

Hello, all. The '92 I recently had a used oil analysis on prompted me to fill the overflow tank with coolant about 7 weeks ago. I seem to get fluctuating levels to/frow from the overflow reservoir. The system, when cold, was full to under the radiator cap. The last person to touch it was the previous summer(2010) when the timing belt service(complete) was performed.

So, out of a 'slight' possibility of a coolant loss somewhere, I inspected/cleaned out/refilled the overflow tank. It hasn't necessarily 'consumed' any, but the level goes from being just below the max line and slightly over it(like I filled it initially; slightly over the max line), give or take 2-3 ounces at most. Is it proper for the cooling system to take more coolant from the overflow during operation(or vice versa?) and then put back while cooling off overnight?

 

[Colt45ws]

When heated, the coolant expands and it gets burped by the cap into overflow. Then as it cools it gets sucked back in.

 

[ltslimjim]

Ah, I see. I don't believe I have any kind of a major leak, therefore. It perhaps only has 'consumed' 1 or 2 ounces from the reservoir since filling and seems to have stabilized whatever it was slightly needing, but couldn't get from a dry reservoir. Thanks for clarifying. I thought I might have had it backwards with regards to hot/cold.

Not sure if it matters, I'm using Prestone's basic "Extended Life" 50/50 pre-mix. My Honda Master Tech uses that on all older model Hondas. Not sure if there would be anything better suited for this car.

 

[Colt45ws]

Yeah, after a service on a overflow-type system, I will overfill the overflow a bit as it will take some as it works the air out.

 

[Trav]

All of the above but you may want to check the cap.
I had a Venture here doing a similar thing,the level was up and down like a fiddlers elbow.
The cap was bad, when i put a new cap on it was fine.

 

[ltslimjim]

Thanks guys. Radiator cap, right? It looks like the original Japanese; so I'll probably pick one up at the local Dealer if I have to. I hear Honda's are finicky for radiator caps.

 

[Trav]

Yes sorry the radiator cap.
Sometimes when they get old they don't hold rated pressure well and the coolant just goes back and forth in and out of the overflow bottle/tank.
Cheap enough to give it a try i think.