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Reservoir tank losing coolant, no leak on the ground

Hi all,
A few weeks ago my car over heated and stopped. I had it towed and the mechanic changed the water pump, timing belt, gasket cover and more.
About two weeks ago I noticed antifreeze on my drive way. Took it back in and the mechanic changed a clamp on the radiator. it continued to leak antifreeze. I took it to Pep Boys for a pressurized test, they couldn’t find a leak, but did say my radiator hoses needed changing and they suspect the radiator cap is the problem.
That was a week ago. I just got back from vacation and the reservoir keeps getting low every day, but not at the minimum line since the first mechanic fillied it to the top. There is not apparent leak under neath the car. No smell when I start. Oil is not milky. Any ideas. Called first mechanic he said sounds like a blown head gasket…SIGH

Car is Honda Accord 1999, 138K miles.

over heated and stopped.

You mean it overheated and quit running without you turning it off?

Yeah, I’d concur that it sounds like a blown head gasket, and on that vintage of Honda probably a warped head as well. No car likes being overheated, but Hondas are especially sensitive to it.

The first mechanic should have checked for this before he did the expensive t-belt/water pump. assuming you told him that it stalled after overheating.

Yes Shadowfax,
It overheated and stopped on me. It restarted and pulled off the road. The mechanic knew this. Do you think it’s worth it to repair a gasket?
What’s the estimate cost?

So, you’re adding coolant every day? How much?

Do you think it’s worth it to repair a gasket?

It’s really hard to answer that because I don’t know how much damage was done. If it’s just a head gasket then the cost could be anywhere from 600 bucks to almost 2,000 depending on your location and whether you have the 4 cylinder or the V6. If you have a warped head(s) then it’s going to be even more than that.

Were it my car, I’d just swap the engine, but then I can do that myself and save a fortune. Were it my car and I couldn’t do the work myself, I’d probably be strongly leaning toward junking the car and chalking it up to an expensive lesson on shutting the engine down immediately when it starts to overheat.

Because of the way that aluminum-head Honda engines tend to be damaged by overheating, I would assume that the cylinder head is warped, along with the head gasket being breached. Repair costs will vary considerably depending on where you live, but I think you should probably expect a repair bill in the area of ~$900.

Whether a 15 year old car is worth spending this much money for repair is a matter for the OP to decide. Two important points for the OP to consider include:

If the car has an automatic transmission…Has the transmission been serviced every 30k-40k miles? If the answer is no, then the trans will likely be the next item to need replacement–to the tune of ~$1,200-$1,500. Personally, I wouldn’t want to spend money for the head gasket/cylinder head resurfacing only to have to spend even more money in a few months on trans repair, but the OP may feel differently.

Does the body show any evidence of rust damage? If so, then I would say that it is definitely not worth investing the money for the head gasket-related repair.

Thanks guys. I inherited the car 2 years ago and do not know the history of the car maintenance. This year I spent 2K on repairs. I’m taking back to the mechanic who did the timing belt, water pump etc. He wants to see it, but I’m thankful for your advice, I’m gonna let it go if it is indeed the gasket.

Insightful not adding coolant everyday, I notice the overflow tank is less every morning. Haven’t been driving much since i’ve been on vacation, tomorrow I’m back to work and my commute is 20 miles. I’m taking it to mechanic, which is on my way.

Obviously, keep an eye on the temp gauge and coolant level. You can buy a lot of coolant for the price of a head gasket, but many people don’t want to deal with the uncertainly of another possible overheating episode or the hassle of checking the coolant level every day.

Budget about $1000 for a head gasket job if no other damage was done. If additional damage was done you would likely be looking at a replacement engine, no new of course.

Replace the radiator cap, clean the filler neck, the place the cap seats to, cross your fingers and hope it works. Step 1

If the engine actually conked out and completely stopped running at the time it overheated, there’s a pretty good chance the head gasket has been compromised by the excess heat. But there’s no way to know for sure without some add’l tests done. Unless of course there are massive white clouds of smoke out the exhaust pipe. I’m assuming that’s not the case.

But there are tests available. For example the cooling system can be pressurized, and see if it stays that way or not. And similar pressurizing experiments can be done with the cylinders. One other idea, this might be worth trying as it is fairly inexpensive, it is possible the problem is that in fact it is just an external leak, but it doesn’t produce enough liquid to drip on the ground. If the drip hits the exhaust manifold or something else that is hot, it might just evaporate. That would usually produce an odor, but unless you knew what to smell for, you might not notice it.

These kinds of leaks can be discovered by putting a special UV dye in the radiator, then after a day or two looking in the engine compartment using a special UV light to spot where it is leaking.

I do agree w/the post above, it is worth simply replacing the radiator cap too, another inexpensive thing to do. Other folks here posting similar woes have often reported back saying replacing the cap fixed the problem.

Replaced radiator cap, thermostat and radiator hoses and clamp. Prior to replacing the clamp I saw antifreeze on the ground. After all the changes no antifreeze on the ground, but the reseivoir tank is slowly going down every day. I check in the AM mostly and for one week car sat idle most of the week it’s been slowing losing coolant. (also note the mechanic filled the tank to the top way past the maximum line, does that make a difference?)

Thank you all for your comments. I’m such a nervous girl when it come to cars, having an internet forum is so helpful to help me understand!!!

“… the mechanic filled the tank to the top way past the maximum line, does that make a difference?”

If it’s too full, it’ll just overflow the reservoir as you’re driving. This is usually within an inch or two of the top of the reservoir. Is this a 4 cylinder? I hope so because then you have only one head gasket to blow.

How many miles on the car and how long do you plan on keeping it? Filling it past the max makes no difference.

Insightful, yes 4 cylinder.

Barkydog, 138K i would like to keep for 6 months

They can run a leak down test to prove the head gasket and prove that’s the problem.

Head gasket failures have occurred for a lot less. Even if you decide to do nothing to repair it, it still is worth a test at another shop to determine exactly what is going on. This isn’t something that gradually gets a little worse over time always. It could very well loose everything at the worse possible time and in the worse place…like on a bridge with no place to pull over. Personally, I would make a decision to make sure the car was more reliable. That means fixing or trading. Either way, expect to spend money if you want a reliable vehicle. If you feel confident in where you normally drive, wth, go for it and just drive it and add coolant and do the excellent suggestions to get you by…like changing cap and changing hoses.

As long as the reserve tank does not go below the “ADD” or “LOW” line, it’s OK. If it is overfilled it will spill its way down to somewhere between full and add. Check it every day, but don’t keep adding fluid unless it gets to the lower line.


If you take the car back to the mechanic, ask him to perform a “block test”

I’ll vastly simplify . . . it entails using a blue test liquid. If it turns yellow, you’ve got combustion gases present in the coolant. Which is often caused by a blown head gaskset