Honda Element coolant recovery tank has never worked

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Y'all:

I am the original owner of our 2010 Honda Element SC. From the day we took possession I've noticed the coolant recovery tank doesn't function properly.

If I fill the radiator to the very top when cold, the tank will collect the overflow when the engine gets hot. However, it never draws the coolant from overflow tank back into the radiator when the engine cools. If I remove the cap with the engine cold the radiator won't be full and is instead down 12 ounces or so. If I don't top off the radiator for, say, a month the coolant level never gets lower than this (being down about 12 ounces).

Over the years I've replaced the cap and overflow tube, probably more than once, but no luck. I recently replaced the electric cooling fans and installed a brand new Honda OEM radiator (which came with a new OEM cap) it still does this. Why?

Has anyone else experienced anything like this?

Scott
 
The return of coolant from the overflow is a siphon action. You need a vacuum to siphon. I imagine the empty space you see relates to whatever vacuum "pressure" (or lack thereof) is needed to send the coolant back.

Removing the rad cap to inspect it allows air in, of course, ruining the siphon. But it'll be back the next pressure cycle.

12 ounces sounds like a bit much-- I'm used to about two ounces on my vehicles.

I assume the rate of the loss of coolant, if any, is satisfactory. A pressure test of the radiator might shed some light on this.

What happens if you take a warm (or cold) car and squeeze the upper radiator hose? Can you send coolant to the overflow? Will it go back when you let go? Do you see any collapsed hoses ever?
 
I surfed a bit after posting and it seems like this problem is not unheard of - and sometimes there seems to be no explanation.

First, I think my original 12 ounce statement is incorrect. It's probably more like 2, 3, or 4 ounces.

Although I haven't done a leak down test I'm confident the head gasket is good. The hoses remain hard long after a hot engine shut off and multiple oil analysis have never indicated coolant in the oil. I've done compression tests more than once and they're always good (and they're still on the high end of OEM spec after 250K miles!).

Thing is, once the coolant is down a couple of ounces it never gets and lower than that. It's as if it reaches its "set point".

I've never seen any collapsed hoses. Given the fact that I recently installed brand new OEM radiator, cap, and overflow tube I was hopeful that this would have corrected the issue somehow....but it didn't. And once again, I've noticed this behavior from the day we bought the car new.

After all these years it's not a big deal. Instead it's one of those little mechanical mysteries gear heads like us like to solve.

Scott
 
Y'all:

I am the original owner of our 2010 Honda Element SC. From the day we took possession I've noticed the coolant recovery tank doesn't function properly.

If I fill the radiator to the very top when cold, the tank will collect the overflow when the engine gets hot. However, it never draws the coolant from overflow tank back into the radiator when the engine cools. If I remove the cap with the engine cold the radiator won't be full and is instead down 12 ounces or so. If I don't top off the radiator for, say, a month the coolant level never gets lower than this (being down about 12 ounces).

Over the years I've replaced the cap and overflow tube, probably more than once, but no luck. I recently replaced the electric cooling fans and installed a brand new Honda OEM radiator (which came with a new OEM cap) it still does this. Why?

Has anyone else experienced anything like this?

Scott
Some vehicles need a vacuum, or specific procedure to ensure there aren't any air pockets. Subaru comes to mind. Have you looked into a Honda specific forum, or looked to see if there are any specific recalls or issues that cause this?
 
I surfed a bit after posting and it seems like this problem is not unheard of - and sometimes there seems to be no explanation.

First, I think my original 12 ounce statement is incorrect. It's probably more like 2, 3, or 4 ounces.

Although I haven't done a leak down test I'm confident the head gasket is good. The hoses remain hard long after a hot engine shut off and multiple oil analysis have never indicated coolant in the oil. I've done compression tests more than once and they're always good (and they're still on the high end of OEM spec after 250K miles!).

Thing is, once the coolant is down a couple of ounces it never gets and lower than that. It's as if it reaches its "set point".

I've never seen any collapsed hoses. Given the fact that I recently installed brand new OEM radiator, cap, and overflow tube I was hopeful that this would have corrected the issue somehow....but it didn't. And once again, I've noticed this behavior from the day we bought the car new.

After all these years it's not a big deal. Instead it's one of those little mechanical mysteries gear heads like us like to solve.

Scott
Scott,

We have a 2003 Element with 238,000 miles on it that was purchased new. It does not exhibit the behavior that you have experienced, but I had a close friend who had a 2001 Accord (with the F23A engine, not K24) that kept losing small amounts of coolant in the radiator without drawing any coolant from the overflow reservoir/expansion tank. I performed the pressure test twice and combustion gas test once to check for head gasket and hose leakage. Found no issues at all; however, a few months later, we discovered the OEM radiator cap was not sealing 100% of the time, so a replacement cap fixed it.

Since you have replaced the cap and tubing with a new one and the problem persists, I just went out and traced the overflow path in our Element. As far as I can tell, the only thing left that can cause your siphon break situation is either a leak in the rubber siphon tube inside the overflow tank (at a location above the fluid) or a crack/pinhole in the tubing nipple on the reservoir's threaded cap. Also, consider using a small tie-wrap to secure both ends of the rubber tubing between the radiator neck and the reservoir's cap to ensure it is airtight.
 
Scott,

We have a 2003 Element with 238,000 miles on it that was purchased new. It does not exhibit the behavior that you have experienced, but I had a close friend who had a 2001 Accord (with the F23A engine, not K24) that kept losing small amounts of coolant in the radiator without drawing any coolant from the overflow reservoir/expansion tank. I performed the pressure test twice and combustion gas test once to check for head gasket and hose leakage. Found no issues at all; however, a few months later, we discovered the OEM radiator cap was not sealing 100% of the time, so a replacement cap fixed it.

Since you have replaced the cap and tubing with a new one and the problem persists, I just went out and traced the overflow path in our Element. As far as I can tell, the only thing left that can cause your siphon break situation is either a leak in the rubber siphon tube inside the overflow tank (at a location above the fluid) or a crack/pinhole in the tubing nipple on the reservoir's threaded cap. Also, consider using a small tie-wrap to secure both ends of the rubber tubing between the radiator neck and the reservoir's cap to ensure it is airtight.
Even though I replaced the tubing and the reservoir cap and elbow, I think I'm going to get some new tubing and run it directly into the reservoir. Doing so will eliminate 2 of the 3 slip on connections. Maybe I'll get lucky.

Scott
 
I had a similar issue with my 04 civic. It had high mileage when I got it and every once in a while when I checked the coolant the recovery bottle was almost full, and I would remove coolant from the recovery bottle and fill the radiator. This went on for years with no real problems. I tried replacing the radiator cap and overflow tubing, bleeding the coolant etc. with no change. Eventually it got worse to the point that I would empty the overflow bottle to fill the radiator weekly. I think it’s a head gasket. I keep a pump top to a hand soap bottle with some tubing to pump out the recovery bottle.
 
I had a similar issue with my 04 civic. It had high mileage when I got it and every once in a while when I checked the coolant the recovery bottle was almost full, and I would remove coolant from the recovery bottle and fill the radiator. This went on for years with no real problems. I tried replacing the radiator cap and overflow tubing, bleeding the coolant etc. with no change. Eventually it got worse to the point that I would empty the overflow bottle to fill the radiator weekly. I think it’s a head gasket. I keep a pump top to a hand soap bottle with some tubing to pump out the recovery bottle.
D17A1/2's were rather infamous for blowing their head gasket and causing the exact problem you described.

To the OP does the radiator cap hold pressure while it's hot? are the upper and lower radiator hoses firm?
 
D17A1/2's were rather infamous for blowing their head gasket and causing the exact problem you described.

To the OP does the radiator cap hold pressure while it's hot? are the upper and lower radiator hoses firm?
Hoses stay firm for a long time and multiple oil analysis have not shown coolant in the oil. It's done this since new.

Scott
 
Even though I replaced the tubing and the reservoir cap and elbow, I think I'm going to get some new tubing and run it directly into the reservoir. Doing so will eliminate 2 of the 3 slip on connections. Maybe I'll get lucky.

Scott
Did you replace the tubing between the nipple and the overflow bottle, or the tubing inside of the overflow bottle?

The only time I have seen this issue was when the tubing inside the overflow bottle was disconnected.
 
Did you replace the tubing between the nipple and the overflow bottle, or the tubing inside of the overflow bottle?

The only time I have seen this issue was when the tubing inside the overflow bottle was disconnected.
Yes, I already did that. In fact, yesterday I bypassed the elbow in the overflow tank cap and ran a new piece of tubing directly from the radiator to the overflow tank. This eliminates the elbow (which seemed to be leak free) and 2 of the 3 slip on connections. Maybe I'll get lucky.

Previous comments about the head gasket are possible I suppose, but I've done a half dozen oil analysis and not one of them showed signs of coolant in the oil. And, as I said, once the coolant level reaches what I call its "set point", it never gets lower than that.

The Element is 15 years old and has 258K trouble free miles on it. Everything works and it runs perfectly. Now it's more of a matter of just trying to figure out why it's always done this. It doesn't really matter at this point. I'm just curious.

Scott
 
Head gaskets can blow in many ways, combustion (150 psi) to coolant (15 PSI) can happen without it mixing with oil, showing outside, or causing driveability problems.
 
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