Coolant disappearing from reservoir

[bans25]

cnn, what lab did you use for oil testing? Do they work via mail?

[cnn]

Our van is using coolant as well.. I will send out my oil and let you know what they find. I did change the oil about 500 miles ago, should I wait or take a sample now?

- I'd not wait. If the engine truely consumes coolant as in my case, coolant in engine oil is bad for the engine itself.
So do the oil test.

- I used a local company. In fact, if you can find any heavy machinery service place (such as service for Caterpillar, Earth digger, Farming equipment, Bull Dozer etc.), then they usually offer engine oil analysis for $15 or so. This is b/c these heavy equipment cost $200,000 all the way to $1M, so they do oil analysis all the time.

- If you have no access for local service, then search for "Blackstone Lab".

[William Wiles]

It really doesn't mean anything how high it is in the reservoir as long as there is enough to keep the pickup hose in the bottom of the tank under coolant. As the engine heats up the coolant in the engine expands and pushes any air and coolant out the cap to the reservoir. As the engine cools down it sucks the coolant from the reservoir back into the radiator preventing any air in the radiator. The main reason for the high/low markings is to ensure there is always enough coolant to prevent drawing air into the system and also a quick indication of usage which would mean a leak somewhere. You could fill it to the top if you wanted with no ill effects other than it would overflow when the engine overheated. Just don't let it get too low.
As a reference my 04 with 55k has never had coolant added.

[cnn]

Bringing an old thread back....

I have found that between oil changes (every 5K-6K miles), the coolant reservoir goes from Max to about 1" below Max.
Add 1/2 cup and it is back to Max (measured in the morning with COLD engine).

Assuming that:
1. Your engine is normal, no head gasket issues.
2. Your radiator and cap are fine, no leak.
3. Your reservoir and cap are fine.

What is your rate of normal evaporation from the reservoir?

[redmondjp]

cnn,

I don't think there is any normal evaporation rate. I haven't added any coolant to our 2001 for 2.5 years and its level has remained constant over that period. The coolant is due to be changed again, but I will wait for some warmer weather first).

[wild willy]

Bought my hunk of crap in Oct 2003. I never had to add coolant and I just dumped it Nov. 1st.

Now gas...that's another story.

[cnn]

redmondjp,

My question is mostly for 3rd gen Ody...

I sold my 2001 Ody in 2007, during my 6 years of ownership of the 2001 model, I never had to add coolant to the reservoir.

I bought the 2007 Ody new and there is something peculiar about 3rd gen Ody, the coolant seems to disappear slowly, either from evaporation from the reservoir or internal consumption (I will send my engine oil for analysis in the Spring and report back if there is any coolant in the oil, hope not).

Stopped my Honda dealership yesterday and the mechanics told me that at every oil change for their customers, whether it is Accord, Civic or Ody models, they frequently have to add 1/3 ---> 1/2 cup of coolant to the customers' cars.

My theory is: Honda (and many Japanese cars) have an open system where the reservoir can vent into the air (open system).
Whereas Euro cars (Volvo, BMW etc.) have closed system.

[kegunder]

I had the same issue w/ coolant loss this fall with our 2008 EX. I was able to spot a small leak in the radiator, about 6 inches up from the bottom. A new radiator fixed the issue. I feel really fortunate to have identified the issue. The leak had gotten so big that the coolant overflow tank would be emptied overnight. We park in a gravel parking spot, so I didn't notice coolant dripping on the ground.

I also plan on getting the oil tested to check for coolant contamination.

[redmondjp]

redmondjp,

My question is mostly for 3rd gen Ody...

I sold my 2001 Ody in 2007, during my 6 years of ownership of the 2001 model, I never had to add coolant to the reservoir.

I bought the 2007 Ody new and there is something peculiar about 3rd gen Ody, the coolant seems to disappear slowly, either from evaporation from the reservoir or internal consumption (I will send my engine oil for analysis in the Spring and report back if there is any coolant in the oil, hope not).

Stopped my Honda dealership yesterday and the mechanics told me that at every oil change for their customers, whether it is Accord, Civic or Ody models, they frequently have to add 1/3 ---> 1/2 cup of coolant to the customers' cars.

My theory is: Honda (and many Japanese cars) have an open system where the reservoir can vent into the air (open system).
Whereas Euro cars (Volvo, BMW etc.) have closed system.

I'm with you, but the 2001 has the overflow reservoir vented to atmosphere as well, so I don't know how that would explain the difference between that year and the 2007. I know what you are talking about with the closed systems (pressure relief cap on the plastic reservoir instead of on the radiator), and they were not limited to the foreign makes either - a lot of domestic vehicles have the same setup (such as 1996 Taurus I just worked on, my neighbor's 2000 Grand Am, etc.).

It is an interesting comment from the dealership though about having to regularly add coolant - I wonder if it has to do with the engine compartment temperature and the location of the overflow reservoir?

[DAP91Si]

Something I haven't seen mentioned, when your waterpump starts to go it will slowly leak antifreeze from the weep hole. If you have an older vehicle that is something to consider.