Hyundai Forums banner

1 - 16 of 16 Posts

·
Registered
Joined
·
15 Posts
Discussion Starter #1
My 2000 Accent with 164,000km is not overheating but is dumping coolant into the reservoir so that the radiator is about a quart low. I did have a few problems with it overheating in the past month, but that was solved by thermostat removal (always above 80F here). I stopped before the overheats reached the redline and allowed the engine to cool before continuing, no known adverse performance during the overheats. No water in oil.

Failed troubleshooting:

Drained and replaced coolant x3
New radiator cap
* No thermostat.
 

·
Registered
Joined
·
3,151 Posts
i would suspect head gasket. you could be blowing exhaust through a HG break into the coolant system, pressurizing it and then coolant goes into overflow tank.

start with a compression test. should do the trick. another option is one of the coolant/gas analysis kits that tests for exhaust gasses in your coolant.
 

·
Registered
Joined
·
15 Posts
Discussion Starter #3
Thanks zero_gravity, do you know of anything I can pour into the radiator to help with this problem? Or is the only fix an overhaul?
 

·
Registered
Joined
·
3,151 Posts
no. don't even think about that. there is nothing you can put in your rad to fix anything, at any time, ever.

there are some stop leak additives that can stop very small leaks...they can work, yes i have seen them work. however, you're taking the chance on gumming up your coolant system. small chance or not, i'd rather fix the problem right myself and know its not a temporary fix.

but we're talking about a head gasket here. that is simply not an option in any way due to pressures and temperatures involved.

best advice here is to test for blown HG before you do anything. always confirm the diagnosis.
 

·
Registered
Joined
·
1,215 Posts
Use a thermostat as your system is designed for it. Your ambient temperature has nothing to do with not using one. Have a cooling system pressure test done before you decide it is a head gasket.............. that is not common. Leaking coolant systems are much more common.
 

·
Registered
Joined
·
3,151 Posts
Use a thermostat as your system is designed for it. Your ambient temperature has nothing to do with not using one. Have a cooling system pressure test done before you decide it is a head gasket.............. that is not common. Leaking coolant systems are much more common.
didn't see the t.stat removal. good catch.

leaking coolant system is out with this one. no way would he be blowing coolant into the reservoir when not overheating with a leak. this requires some sort of pressure on the coolant to push it in there.

now that i see the overheated before t.stat removal, my guess is the t.stat failed closed, overheated the engine and warped the head. result is blown head gasket and now exhaust/compression stroke gasses push coolant into the overflow.
 

·
Registered
Joined
·
1,215 Posts
didn't see the t.stat removal. good catch.

leaking coolant system is out with this one. no way would he be blowing coolant into the reservoir when not overheating with a leak. this requires some sort of pressure on the coolant to push it in there.

now that i see the overheated before t.stat removal, my guess is the t.stat failed closed, overheated the engine and warped the head. result is blown head gasket and now exhaust/compression stroke gasses push coolant into the overflow.

Your guess is just that - a guess. He needs to have a pressure test done. I think we can agree on that. That is the first thing any reputable shop does when there is a cooling system problem. Easy and cheap. If he were in the USA, I would suggest a free tool rental at AutoZone or similar.
 

·
Registered
Joined
·
3,151 Posts
actually its a lot more than a guess. name one other thing that is going to throw pressure into his rad. this is experience and process of elimination.

that is why i suggested the compression test and not a rad pressure test. if he really wants to get fancy, a leak down test is a much more comprehensive test - that will probably show the same thing.
 

·
Registered
Joined
·
1,215 Posts
Nothing wrong with a compression test also, but a pressure test is more revealing given what he told is. But a blown head gasket could cause driveability problems, loss of power, codes, tailpipe discharge, etc. He reported none of this.

I am not ruling out what you suggest, just not to jump to a conclusion with partial information.
 

·
Registered
Joined
·
3,151 Posts
i'm not suggesting that he go and replace a head gasket without a test.

however, i do not see another option - again, do you see anything else?

if a small coolant jacket break noticeable loss of power may not occur. neither will codes since there will be no misfire, and many people miss tailpipe discharge. this is especially true if the gasket only leaks at certain engine temperatures.

this isn't partial information. always test to confirm the few oddities, but let's look at the facts:

something is pushing coolant out of his rad into the overflow tank. this means a motive force is getting into the coolant system and displacing the coolant in the radiator. that requires something with a pressure greater than that of the coolant system that can interface with the coolant system if a failure occurs.

well that leaves us with engine compression and oil. the intake is under vacuum so that's out with regards to coolant in the throttle body. why not oil? not enough mass flow rate to displace coolant like that. plus it would be VERY obvious once mixed with coolant.

so that leaves us with one possible scenario by process of elimination: a break from a cylinder into the coolant system, likely very small. that could be by damaged head gasket, warped head, or even a cracked head.

to further add to the data we already have, the OP has stated that he already overheated it. overheating is likely caused by one of 3 faults: coolant loss through leak (regardless of location), thermostat failed closed, or failed pump.

we can eliminate the failed pump, its obviously working now. it would still overheat without a t.stat without the pump. coolant loss is a possibility, but i would expect a dry rad rather than coolant blown into the overflow. that indicates a small loss not a large one. that would be through the overflow tube or burning in cylinder(s).

the failed t.stat is simply most likely. removing it has stopped an overheating process. if he removed it, he would have mentioned the coolant system being dry and filled it back up - in fact would have likely not even removed the t.stat in that case. even the worst car owner out there can figure out what happens when the coolant system is dry.

so that leaves us with a failed t.stat being the most likely scenario.

couple that with biggest cause of above theory of head gasket. overheating is the biggest cause of failed HG's.

so, once again, do you see another option? do you find fault in my logic?

i suggest test for blown head gasket. IF that test is negative (weather it be leak down test, compression test, or chemical test to show gas in coolant) then start looking elsewhere.

so why not pressurize the rad? simple. lower pressure and leak may not be apparent if small without the use of a scope. it will be much easier to test for engine compression and then move on from there.
 

·
Registered
Joined
·
283 Posts
i would suspect head gasket. you could be blowing exhaust through a HG break into the coolant system, pressurizing it and then coolant goes into overflow tank.

start with a compression test. should do the trick. another option is one of the coolant/gas analysis kits that tests for exhaust gasses in your coolant.
This would be my guess as well, Do you have white smoke or water vapor coming out your exhaust?
 

·
Registered
Joined
·
15 Posts
Discussion Starter #14
Thanks for the replies everyone. I haven't taken it to a mechanic yet to have it formally diagnosed so I'm just dumping the overflow back into the radiator. It is pretty uniform on the amount purged from fill up despite varying distances of 25-50km's. Buying a second car soon and after that maybe my first ever head gasket swap aided by youtube and this forum. What's the worst that could happen...
 

·
Registered
Joined
·
3,151 Posts
the worst? you get the head off to find that the gasket was fine - the head is cracked lol.

a head gasket is not actually a hard job, just need a lot of attention to detail and a bit of time to do it. not a job to rush.

- get a compression tester and confirm diagnosis. they're not expensive and the test is easy. plenty of resources on google/youtube.

- send the head into the machine shop to get surfaced.

- take extra care when removing any of the old gasket material from the block. sure its cast iron, but doesn't mean you can't put a pit in it if you really want to.

- new head bolts. don't reuse old bolts. they are torque to yield and can only be used once.

- a torque wrench is absolutely necessary as well as a torque angle guide.

- all your specs are on www.hmaservice.com for free :)

let us know how it goes! its a big job to tackle if you've never done it before, but its not difficult if you do your homework beforehand.
 

·
Registered
Joined
·
15 Posts
Discussion Starter #16
Ok... I'm back again. And I have found the culprit, it was a bad radiator cap. I had the exact same problem on my second car (nissan) for no reason, just one day it started pushing coolant into the reservoir. I though it was vapor in the system (just replaced coolant), also removed and cleaned reservoir which didn't fix anything. Anyway, I'm not sure how I came upon this conclusion, but I took the cap off and tried to pull down the little silver disc on the bottom... and it wouldn't move.

Its not just a "cap", its a two way valve that allows the coolant to expand into the reservoir tank when hot, and then allows the coolant to flow back into the radiator after the car is turned off and is cooling down.

My bad cap was allowing the coolant to expand out, but not flow back in when the car cooled down. Both cars made a very distinctive suction sound when I removed the cap, $10 later the problem is solved.

Thanks to everyone that commented to help me out... Sorry it wasn't something sexy like a bad head gasket!
 
1 - 16 of 16 Posts
Top