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Is my Sonata really overheating? Can the head gasket be bad?


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jejmoe
Novice

Nov 10, 2007, 7:44 PM

Post #1 of 9 (2142 views)
Is my Sonata really overheating? Can the head gasket be bad? Sign In

SITUATION: I bought a 2000 Sonata with pretty low miles, and it reads hot as if it overheats.

The coolant was full of rust and looked like watered down mud. I had the radiator flushed and replaced the thermostat which was as stuck and rusted as they get.
Still runs hot.

I had it checked out and a mechanic told me the head gasket needed to be replaced. A second mech. did some sort of compression test using some gas? and said the head gasket was fine, no leaks.

I checked it over top to bottom best as I know how and even had a mechanic friend look it over. Nothing solid. There has never been a check engine light, the light does work, and no codes come up on an OBD scanner.

SYMPTOMS: The car runs great but the temp guage reads hot, and occasionally the heat wont work. I have driven it about 400 miles in its current condition and nothing seems to have gotten any worse.

The lower radiator hose doesn't get very hot and barely holds coolant running or not, overheating or not. The guage reads hot after driving over 40mph, but is fine until then. The temps I have gotten don't seem excessive, but are confusing. I have a Fluke IR Thermmometer and shot the externals of the following parts and here are the temp I have gotten:

Engine warm while temp guage read normal / while reading close to red
- Lower Radiator Hose = 75*F / 90*F
- Upper Radiator Hose = 90*F / 185*F
- Engine Block = 180*F / 210*F

We have also checked the pressure of the cooling system, the oil and 3 of 6 cylinders for signs of coolant mixing, all nothing? The car can be reading hot, and if I turn it off and back on, the guage will only be at the halfway mark, instantly it drops to that.

DILEMMA: I don't know what to do? Is it possible that I could have a head gasket leak and drive 400 miles, 250 of which were in a straight trip, and have no other noticeable problems?

I'd appreciate any insight and have probably left out some details so let me know if there are any further questions. Thanks

Is the intermittent heater related?


Tom Greenleaf
Ultimate Carjunky / Moderator
Tom Greenleaf profile image

Nov 11, 2007, 5:46 AM

Post #2 of 9 (2138 views)
Re: Is my Sonata really overheating? Can the head gasket be bad? Sign In

The temp reading you took look fine. The heater is probably still partially plugged but it you are overheating the heat will stop so that needs to be figured as a possiblility.

Your temp sensing gauge is in question here. I'm shocked at your description of how trashed the cooling system was. I think it needs a total flush again and this time look for lower water jacket plugs in the block and really go nuts on the thing.

If it really needed a head gasket job there would be some clear evidence that seems to be missing right now. Does the radiator stay full of just coolant? No air in there?

Gauge problem might be at dash - not sure yet with your observations with the IR tester,

T



jejmoe
Novice

Nov 11, 2007, 5:17 PM

Post #3 of 9 (2133 views)
Re: Is my Sonata really overheating? Can the head gasket be bad? Sign In

Tom

Thanks for the help.
The overheating is very intermittent and has worked 9 times out of ten. On the other hand, the car reaches HOT everytime I drive once I reach 40-60mph.

Is there a way I can check the heater core myself, with little auto know-how? I am pretty electrically and mechanically inclined, just never had many car problems. Also, if I were able to flush the heater, where could I do this without getting fined for pollution?

The radiator was awful, I'd imagine the guy was running straight water through it for a long time. I dont have the means to do all the flushing and work myself. Is there a certain type of mechanic that would be best to talk to? Unfortunately my last mech. screwed me, and I am not from around here so it makes it tough.

With the coolant looking like that, what else might be jeapordized that I haven't accounted for?

As for the radiator, it isn't leaking. Hard to tell if it stays full. It doesn't stay topped off but that is because it "drinks" right? As for air, I dont see bubbles, how can I tell? What about the water pump? Is that a possibility?

Again, thanks for all your help. This thing is a nightmare financially, and I am trying to learn and do as much as I can before I take it to another mechanic.


Tom Greenleaf
Ultimate Carjunky / Moderator
Tom Greenleaf profile image

Nov 12, 2007, 1:59 AM

Post #4 of 9 (2128 views)
Re: Is my Sonata really overheating? Can the head gasket be bad? Sign In

Gotta Stop Right Here! "The radiator drinks coolant and doesn't stay topped off." THAT'S THE WHOLE ISSUE RIGHT NOW AND MUST BE CHECKED OUT AND SOLVED BEFORE ANY OTHER COMPLAINT CAN BE ADDRESSED. That's not normal and by default is getting air into the system.

You are right that water only was probably in the system way too long. Without seeing a leak the engine could be burning coolant thru and out the tailpipe unseen which is almost always a head gasket problem which is where you started and I'm sorry if we wasted some time but that must be corrected or all other diagnosis would be inaccurate.

This thing has probably been a problem for a good while now and was just tolerated by adding water all the time. I understand and agree with your concern about the haz-mat waste of flushing a system. I will only do that at my own shop when a vehicle is void of the standard EG (Ethylene- Glycol) anti-freeze which is toxic and 100% fatal if you purposely drank it!

Let's see if we can diag the head gasket now and pick a plan on that. Start with system full as you can and engine cold. If not too cold where you are just use water for now. Start with feeling the lack of pressure in like a radiator hose and start the engine and let it warm up. Feel that hose as it should stay cool till t-stat opens and will lack pressure for a while and you should notice it slowly warm, will get to hot to hold (careful of course) and build pressure. Fan(s) will eventually come on and you can feel the warm air transferred from the rad. That's what you want. If the pressure builds up right away or withing a minute it's about certain that the engine is putting gasses into the cooling system which would indicate a fault with head gasket or (arggh!) a head or manifold crack - that totally not good. That air could also allow coolant to get into combustion areas unseen and burn it out. When that is extreme you see it as white vapor out of the exhaust - which is normal on a cold day for a while with just water vapors made as we have all seen. That can get so bad you can see anti-freeze come out a tailpipe which is a total extreme and that problem would be noticed so quickly and car woud be unusable till fixed.

What is your working place - like driveway, garage, parking lot or what? What is your expected low temp right now? That plays a role where I am already as I just saw 20F which could crack an engine with just water in it - game over!

Let's see if we can pick the most cost effective approach as you indicated that matters here,

T



jejmoe
Novice

Nov 12, 2007, 5:17 PM

Post #5 of 9 (2124 views)
Re: Is my Sonata really overheating? Can the head gasket be bad? Sign In

Tom, thanks much. I am in Northern VA so we are getting freezing temps at night also. I will fill and observe as you said and let you know what happens.

So what you are saying is that the raditor should stay completely topped off, as well as the reserve? I thought it was normal for the thing to drink. I will be working in the parking lot since I live in a condo. The temps are definately too cold for water only. I can afford to expend a bottle of coolant or two, need be, so that if I do have to take it to a mechanic to get fixed, I will at least have an idea of what we are dealing with.

Again, I'll make the observations and let you know what I find. It might be a few days, as I will probably work past dark most of this week. Thanks again


Tom Greenleaf
Ultimate Carjunky / Moderator
Tom Greenleaf profile image

Nov 13, 2007, 12:37 AM

Post #6 of 9 (2122 views)
Re: Is my Sonata really overheating? Can the head gasket be bad? Sign In

Ok: Just for the knowledge base..... Your cooling system and all others are not made to consume any coolant. This expansion tank think goes way back as long ago cars got lower hood lines and a tall radiator just didn't work so the flow is sideways and there's less room. The universal answer is to maintain radiators at total full all the time which uses every square inch of it all the time when old stuff you just filled a radiator and left it low for the expansion common way till the 1970s. Forget those days for this now.

Coolant expands when heated and since we want radiator full all the time it goes to a tank when fully warmed up (expanded) and when cools it draws the same stuff back. That tank will be marked usually with a Min and Max line reflecting the expected level for cold or hot. It should never be below the min line as if it's there when hot it may draw back air when cooled off.

For the most part coolant does not get consumed or evaporate. If after five years you add a pint just once that should be noted but fine. At that amount of time you really should consider flushing out a system anyway. EG is the common coolant/anti-freeze and can be various colors but usually green. It is toxic but works well and prevents corrosion so it's still the most common. Plain water can actually work better but doesn't help with rust or freeze protection. EG should not be left around in open buckets or whatever as animals or worse children might drink it as it does taste semi-sweet like gator aid --- PLEASE FOLKS AND READERS DON'T FREAKING TASTE IT TO FIND OUT!!!!

The freeze protection does not degrade with this product but rather gets diluted with people just adding water for some problem and forget to check on it when cold weather comes.

Side note: FREEZE PLUGS.... Are not there to protect your engine in the case of freezing. They may pop out in a frozen engine but the engine probably cracked also. They are there for the manufacturing process of the block of the engine and are called "core plugs" but the name "freeze plugs" stuck since that was the name for them with like a model T!!

You said you would be working in a parking lot. Best to try to contain any messes as best you can. Plain clay cat litter will absorb it and can be discarded that way.

You might lose some in the diagnosing process and they do sell a non toxic formula that would be friendlier if spilled but it's not harmless either.

The more you know in advance about what you need to fix this the better. You probably will need a shop to finish this job so they would love to know what you have found but don't tell the shop exactly what to do as they may find things you missed or just do as told and that might not be the answer to the problems.

Do your best not to let it overheat as you don't need any further damage than is already at hand,

T



jejmoe
Novice

Nov 25, 2007, 11:51 AM

Post #7 of 9 (2097 views)
Re: Is my Sonata really overheating? Can the head gasket be bad? Sign In

Tom,
Again thanks for all of your help. I was mistaken the coolant must not have been entirely full, but it is not consuming fluid. I have topped oit off and it remains topped off. I replaced the Coolant Temp Sender and still the problem persists. I am not sure if there are any more guages to replace. Could the water pump be an issue? My biggest concern is whether or not it is actually overheating. I tried the infared Temp Gun and it doesnt seem like it is. Are there any other ways to check if it is trulu running hot? Is there any other sensor that could cause it to read false? Could it be the water pump and if so, how can I check?
I need a shop manual on this car but cant find one online or in strores anywhere. Haynes doesnt seem to make one for this year and the stores cannot even order one. I'm almost to the point of bringing oit to the dealer juzst want to do whatever i can.


Tom Greenleaf
Ultimate Carjunky / Moderator
Tom Greenleaf profile image

Nov 25, 2007, 12:54 PM

Post #8 of 9 (2095 views)
Re: Is my Sonata really overheating? Can the head gasket be bad? Sign In

Hi,

This is getting to be a read! Ok: Now that it's pretty much heat only season for both of us you could check the output temp of the heater with low fan. That would be just slightly less than the real coolant temp and should stay fairly steady. High fan could extract more or less available heat and wouldn't be as steady. If this has ATC = automatic temperature control, forget that test as it won't blow the hottest air it can - just more of it at a lower temp like a home does.

The dash gauge could be the issue and that would stink as they are a pill. Proper grounding of the panel that holds the gauges could be compremised and do funky things. There could be another sensor that hasn't been replaced yet. One could be to make the engine's cooling fan come on for the radiator but that should be just on or off. The temp sensing gauge is like a dimmer switch for lights. It ground to block with more ohms as the temp goes up and the needle responds to that. You would know you had the right one if you unplugged it and the gauge didn't work at all on dash.

Water pumps can fail by deteriated impellers but that is on the rare side. They are usually metal but if you had that much rust perhaps it has lost some pumping power. Wouldn't think it would be too erratic though?? I guess if it's an easy one just toss it to rule it out.

I'm forgetting all the progress so far. Is the cooling system all flushed out now? Has the thermostat been replaced? Not too common but they can be erratic. Funny but the inside temp of an engine is higher a few minutes after you shut it off as the circulation stops and the hot coolant just rises up to the sensors and the thermostat. When you start up you may see the temp up high for just a few seconds and it should drop right back down in short order when it circulates again.

I suppose the wire to the sender could be partially bare in an out of sight spot and get just a touch of grounding which would cause total hair loss to find.

This must be driving you crazy as it would me to figure this out and get to the bottom of it.

For a decent manual for the car that covers about everything would be AllData.DIY for about $25 for a year or I hear you can use a master edition as some public libraries but you would have to take notes as I can't imaging they would let you print out what you need. Some of the techs here have the monster editions for all cars and pay thousands for them and have to. Some will share the fine detail on a specific item if they have time to find it and post it here. Can't speak for other sites and I'm sure All Data doesn't allow it since it is copyrighted. AutoZone's site has a lot of stuff but not for all cars and not alway complete. Regualar Haynes manuals are limited at best and the price reflects that.

There's one more funky thing that can fool the best of them but is fairly rare. At certain temps and speeds the cooling system which is supposed to maintain pressure at an average of 15lbs can cool suddenly and lose that pressure for a while and when the engine is reved up or driving at higher revs the suction on the lower hose drawing in coolant to the engine from the rad can collapse stopping the flow of cooled coolant to the engine! They used to put a coil spring inside that hose to prevent that - usually in cars with long lower hoses. My own has one (89 Town Car) and they did it on some after that too.

I don't know how else to help you here. Ask away and I'll try my best,

T



jejmoe
Novice

Nov 26, 2007, 8:19 PM

Post #9 of 9 (2089 views)
Re: Is my Sonata really overheating? Can the head gasket be bad? Sign In

Yes, the cooling system is all flushed out, and the thermostat been replaced. Not sure at the moment what direction i am going to go. No further questions your honor. Thanks again for your help. I'll let you know whats new when I figure anything else out or if I have any more questions. Youve been a great help.






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