@suparoo,

I have a 2021 HR-V (Malaysia) and I noticed the same thing.

I bought a bottle of 1L Honda Type 2 genuine coolant and added a little to the radiator to bring it up to the top of the radiator so that the coolant can be seen as per the view on your picture. From memory I guess I added <100ml.

When I got the car in May 2021 I did notice that the overflow bottle level was below the max line when the engine was cold (overnight). I topped up around 200ml and it was actually slightly above the max line. I then monitored the over flow bottle level and it continued to be above the max line.
I just went out to the car and checked it just to be sure. Car is overnight cold and not started since yesterday afternoon.

I reckon as long as the overflow bottle level remains constant at the max line you should be good.

How much coolant did you top up at the radiator to bring it to the top of the radiator cap?

My next service is only due in December 2021 but maybe I'll drop by to local Honda dealer and check with their technicians on this.

 

@suparoo,

I have a 2021 HR-V (Malaysia) and I noticed the same thing.

I bought a bottle of 1L Honda Type 2 genuine coolant and added a little to the radiator to bring it up to the top of the radiator so that the coolant can be seen as per the view on your picture. From memory I guess I added <100ml.

When I got the car in May 2021 I did notice that the overflow bottle level was below the max line when the engine was cold (overnight). I topped up around 200ml and it was actually slightly above the max line. I then monitored the over flow bottle level and it continued to be above the max line.
I just went out to the car and checked it just to be sure. Car is overnight cold and not started since yesterday afternoon.

I reckon as long as the overflow bottle level remains constant at the max line you should be good.

How much coolant did you top up at the radiator to bring it to the top of the radiator cap?

My next service is only due in December 2021 but maybe I'll drop by to local Honda dealer and check with their technicians on this.

I never added any coolant, i used what was in the overflow bottle. I remove the cap from the overflow bottle and blow coolant back into the radiator via the overflow hose until the radiator is full.
The system was checked by the Dealership and they reported it as being all Ok!

 

I have a 21 HRV as well (USA version).

I felt the same as you guys and was concerned at first. Even had the dealer check it out. They said it was normal.

So i checked the owners manual and it states to only check the coolant level in the resivor, not the cap. (I shoulda checked that first. Lol)

Based on that, I’d say its normal and we are fine. Oh, and the reservoir level will go up and down if the engine is running vs sitting, and how hot it gets from what I’ve observed. So as long as the level stays between the Min and Max range, you’re fine. Mine sits in the middle when the engine is fully cool and off. But will rise up the the Max line when engine is running.

 

I've needed to add some Honda coolant in our '19 and '20 USA HR-Vs in the first few months.
Same with our friend's new Accord.

Seeing how the cooling system on most Hondas needs to be monitored after any service (yes, even after the initial assembly) I haven't been alarmed or worried. (It takes 5 - 10 drive cycles to purge air, especially with the CVT which keeps RPM relatively low, reducing coolant velocity through the engines)

 

Ill have to check my 21 (USA) and see. the coolant bottle has always been at max since delivery. Havent taken the cap off to check. The overflow bottle location to check levels is one of my biggest complaints about the HRV.-

 

I agree 100%.

I have used a bright LED torch and still cannot determine the water level in the overflow bottle.
I had the Dealership check the coolant system because of the receding water level in the radiator. That was done at 7400 kms (4598 miles).
The following is the report.

Complaint:
Customer checked radiator coolant level and can't see any coolant in the top tank. Vehicle isn't overheating, but customer concerned please inspect.

Result:
Inspected vehicle found no coolant leaks
Pressure tested system, no leaks detected
Level down slightly, topped up from reservoir
Ran engine to operating temperature,rechecked level again all Ok
Couldn't fault cooling system. In some conditions coolant will not be level with top of radiator filler neck

The coolant level has never ever returned to the top tank, I am always having to top it up from the overflow bottle.
It is a PITBA! I have never known this problem to happen with a "closed cooling system", as the water is heated and expands it is sent to the overflow bottle, as the engine cools down it siphons the water back in the radiator ensuring that it is always full. The only time this will not happen is if there is leak anywhere in the system.
Well that is my understanding of how it works, happy to be told otherwise.

 

So a near new 2021 Australian HRV...

You are correct, with a closed cooling system, the radiator should be full at all times.
Going by your posts, the actual coolant level is NOT going down. You have not needed to add any extra coolant.

I find the coolant level easy to check on our 2016 Canadian HRV.
Shine a flashlight at the plastic overflow tank, shake the vehicle slightly to see the fluid level.


I have seen several cases where the radiator does not "suck" the coolant back from the overflow tank when cooling down.
It's nearly always a small leak with the outer radiator cap seal or the hose between the radiator and overflow tank that lets air in preventing the siphoning affect. Usually the leak has no or minimal visible coolant leaking signs.

The outer radiator cap seal may not be fully sealing, letting air in.
There are 2 seals on every radiator cap, inner and outer and there is a 1 way flap (check valve).
The inner, spring loaded seal, provides pressure. The outer seal provides the seal for fluid flow to and from the overflow tank.
The 1 way flap seals pressure in and lets coolant flow from the coolant tank to the rad when cooling down.

I would remove the rad cap and clean it. I usually take the rad cap into the kitchen and run tap water over it.
Dry it, clean and check all the seals. Clean and check the 1 way flap also.
Also clean the all sealing surfaces on the radiator filler neck on the radiator.

I would also check the hose from the radiator filler neck to the coolant tank.
Make sure both ends are secure and no kinks or splits in that hose.

 

I have seen several cases where the radiator does not "suck" the coolant back from the overflow tank when cooling down.

This appears to be my problem too. However, as i previously posted, the Dealership pressure tested the system and found no leaks.
The pressure test should have exposed any water leak if there was one to be found.

I think I might take the car to a radiator specialist and have them check it out. 👍

 

Have you tried another dealership? My wife had a 04 malibu and it had a occasional misfire. The local dealership couldnt find anything wrong, and after several attempts, we took it to another dealer. They knew what the problem was in five minutes , ordered the part, and was fixed in less than a week. Could also try replacing the cap on your own. Bad ones do come down the line.

 

Next nearest dealership is 45 - 60 mins drive away, traffic dependent.
I have been contemplating changing the cap myself.

 

I've never had any of my Honda vehicles lose coolant over the last 29 years. I always use Honda Longlife coolant and change it at 30K mile intervals (radiator and reservoir drain and refill - no flush).

 

Suparoo, in another thread you mentioned that you are still concerned about your HRV's cooling system.

Do you have to add coolant occasionally to maintain the correct level in the coolant overflow bottle?

 

I agree about the radiator cap. Leave it alone. You may have ruined the ability for the system to expel air. Reservoirs were invented to prevent burns by opening the system under hot pressure. The cap is only to be removed when draining the system.
Its operating function is to expel air and draw in coolant with heating and cooling cycles.

 

Finally got my butt into gear and took my HRV to a radiator specialist. The radiator specialist couldn't find any problem/s either.
Wife & I are also going on a road trip soon. I didn't want to get caught between towns with a cooked engine, even if it is under warranty.

 

Yes indeed,and apologies -this post may be a little late;however,hopefully some owners may benefit.This situation comes about because the HRV overflow reservoir is sited too low in relation to the radiator fill/pressure cap.We are assuming a newish vehicle and therefore overflow system hose etc in good order.The system does in fact work as it should but coolant level falls out of sight before the siphoning effect occurs,because of siting as above.Not normally a problem if rest of cooling system healthy,as air is not being introduced into the top tank.An air void there would be cause for concern.Still annoying for the fastidious owner--as has been said,coolant should always be present at the pressure cap