Head gasket compomrised?
July 25, 2015 8:50 AM Subscribe
I have a 2002 Honda Civic LX which periodically overheats. If I refill the radiator with coolant/water, it'll go another 150 miles before overheating again. In principal I could just keep the radiator filled up, and go this way for quite a while. I don't want to do that, but I want to figure out as much as I can before committing to any expensive repairs like replacing the head gasket.
If you fill the radiator up and run the car with the radiator cap off, you can see a bubble appear at the top of the radiator every five or ten seconds. There is significant pressure in the radiator when the overheating starts. I have to release the radiator cap just a little to let it blow off before fully removing it. Even when the car's been sitting overnight and I take the radiator cap off to replace the coolant, there's enough pressure in there for it to blow off for a second or two. So I think the coolant system is keeping pressure pretty well.
It is pretty clear that the proximate cause of the over heating is the gas building up in the radiator. One evening I drove the car about 120 miles with no problem, stopped for an errand for 20 minutes, drove the car very slowly for about 200m, let it idle for about a minute while I got something outside, and by the time I came back the temperature gauge was up to three quarters and still rising. I sat and watched it rise further as it was idling. Refilling the radiator with coolant/water immediately corrected the problem.
A mechanic did a compression test, but found no leakage. He is nonetheless convinced it's a compromised head gasket and wants to replace it, an expensive proposition. He believes the leak is simply too slow for the compression test to give results. He tested the system for coolant leaks as well, and found none.
He said usually when you take the gasket off you can see some kind of residue where the gasket is blown, which verifies the gasket has failed. When I asked him to take a photo of the gasket once the head was off so I could see this, he backed away from this claim, saying that sometimes you can't see this residue if the leak is too slow.
I'm taking the car to another mechanic to get a second opinion. Is there anything else I should get tested to determine what's going wrong?
If you fill the radiator up and run the car with the radiator cap off, you can see a bubble appear at the top of the radiator every five or ten seconds. There is significant pressure in the radiator when the overheating starts. I have to release the radiator cap just a little to let it blow off before fully removing it. Even when the car's been sitting overnight and I take the radiator cap off to replace the coolant, there's enough pressure in there for it to blow off for a second or two. So I think the coolant system is keeping pressure pretty well.
It is pretty clear that the proximate cause of the over heating is the gas building up in the radiator. One evening I drove the car about 120 miles with no problem, stopped for an errand for 20 minutes, drove the car very slowly for about 200m, let it idle for about a minute while I got something outside, and by the time I came back the temperature gauge was up to three quarters and still rising. I sat and watched it rise further as it was idling. Refilling the radiator with coolant/water immediately corrected the problem.
A mechanic did a compression test, but found no leakage. He is nonetheless convinced it's a compromised head gasket and wants to replace it, an expensive proposition. He believes the leak is simply too slow for the compression test to give results. He tested the system for coolant leaks as well, and found none.
He said usually when you take the gasket off you can see some kind of residue where the gasket is blown, which verifies the gasket has failed. When I asked him to take a photo of the gasket once the head was off so I could see this, he backed away from this claim, saying that sometimes you can't see this residue if the leak is too slow.
I'm taking the car to another mechanic to get a second opinion. Is there anything else I should get tested to determine what's going wrong?
I had a thermostat fail that did warp the engine head. Make sure your thermostat is working, and any fuses that keep the cooling / heating system working.
posted by Oyéah at 10:09 AM on July 25, 2015
posted by Oyéah at 10:09 AM on July 25, 2015
It is very easy for a mechanic to definitively test for the presence of hydrocarbons in your coolant, such as you'd see if your head gasket leaked or your engine block were cracked. It requires a catalyst and a tester, such as is sold in this $42 kit from NAPA: http://www.napaonline.com/Catalog/CatalogItemDetail.aspx?R=BK_7001006_0361073538
My suggestion would be to ask your mechanic to do this test with this kit (there are clear instructions with the kit) or to do it yourself. It is very straightforward and will give you a clear answer, and then you can decide what your next move is. From personal experience this sounds just like a head gasket failure (or worse), but maybe it's something minor. Good luck!
posted by mosk at 10:52 AM on July 25, 2015
My suggestion would be to ask your mechanic to do this test with this kit (there are clear instructions with the kit) or to do it yourself. It is very straightforward and will give you a clear answer, and then you can decide what your next move is. From personal experience this sounds just like a head gasket failure (or worse), but maybe it's something minor. Good luck!
posted by mosk at 10:52 AM on July 25, 2015
There is significant pressure in the radiator when the overheating starts. I have to release the radiator cap just a little to let it blow off before fully removing it.
The water system is supposed to be pressurised. It is kind of dangerous to remove it when it is hot as it runs pressurised to allow the water to be at a higher temperature without boiling.
Even when the car's been sitting overnight and I take the radiator cap off to replace the coolant, there's enough pressure in there for it to blow off for a second or two.
This, however, is a problem. Once the cooling system is at atmospheric temperature (ie when cold) it should not at all be under pressure. So my suspicion is that your head gasket is leaking and pressurising the cooling system past that which the natural expansion of heat to the water produces.
So what is likely happening is this:
Water expands as it heats, creates pressure, holds pressure. Engine - through its operation at normal temp with the leaking head gasket most likely - is leaking cylinder pressure into the water jacket and adding pressure to the water system. The radiator cap bleeds off this additional pressure (as designed) to keep the pressure manageable. Unfortunately, the only way it can do this is to let out water (because the system is full). So water volume is reduced the longer the car is running and each warm up cycle will produce more pressure and bleed more water out to control it until there is no longer sufficient water volume in the cooling system to cool the engine and it overheats.
If you fill the radiator up and run the car with the radiator cap off, you can see a bubble appear at the top of the radiator every five or ten seconds.
This could initially happen on a newly filled engine as it is filled and air locks are worked through. But after maybe 10 minutes of running (or if you try this after the car has been run for a while) then this is a sure sign of air being introduced into the cooling system. I'm pretty sure the head gasket is compromised too.
None of these symptoms would be consistent with a thermostat or a fan issue. That would be straight overheating. The fact that the system is still pressurised when the engine is cold is the most damning evidence of the gasket failure to my mind. That is almost impossible without pressurised air (at a higher air pressure than the water system) being present and getting into the water system. The only place that pressurised air is present is in the combustion chamber.
posted by Brockles at 11:30 AM on July 25, 2015 [3 favorites]
The water system is supposed to be pressurised. It is kind of dangerous to remove it when it is hot as it runs pressurised to allow the water to be at a higher temperature without boiling.
Even when the car's been sitting overnight and I take the radiator cap off to replace the coolant, there's enough pressure in there for it to blow off for a second or two.
This, however, is a problem. Once the cooling system is at atmospheric temperature (ie when cold) it should not at all be under pressure. So my suspicion is that your head gasket is leaking and pressurising the cooling system past that which the natural expansion of heat to the water produces.
So what is likely happening is this:
Water expands as it heats, creates pressure, holds pressure. Engine - through its operation at normal temp with the leaking head gasket most likely - is leaking cylinder pressure into the water jacket and adding pressure to the water system. The radiator cap bleeds off this additional pressure (as designed) to keep the pressure manageable. Unfortunately, the only way it can do this is to let out water (because the system is full). So water volume is reduced the longer the car is running and each warm up cycle will produce more pressure and bleed more water out to control it until there is no longer sufficient water volume in the cooling system to cool the engine and it overheats.
If you fill the radiator up and run the car with the radiator cap off, you can see a bubble appear at the top of the radiator every five or ten seconds.
This could initially happen on a newly filled engine as it is filled and air locks are worked through. But after maybe 10 minutes of running (or if you try this after the car has been run for a while) then this is a sure sign of air being introduced into the cooling system. I'm pretty sure the head gasket is compromised too.
None of these symptoms would be consistent with a thermostat or a fan issue. That would be straight overheating. The fact that the system is still pressurised when the engine is cold is the most damning evidence of the gasket failure to my mind. That is almost impossible without pressurised air (at a higher air pressure than the water system) being present and getting into the water system. The only place that pressurised air is present is in the combustion chamber.
posted by Brockles at 11:30 AM on July 25, 2015 [3 favorites]
My car was overheating every 2 to 3 months. I replaced almost every component of my cooling system - sometimes twice.
My husband got suspicious and had a friend help him inspect the car after the mechanic told us it would be another $400 repair. My husband discovered our mechanic was soldering the Fan Relay ($35 part) into the system, bypassing the connectors that come with the Relay. The car saw two other mechanics during this time, neither of them noticed or alerted me to what were engineered failures. One charged me $50 and said they could not find the problem. Another was happy to replace the radiator. And another time, the fan.
This is a long way of telling you that you need to find a new mechanic. Ask friends. The guy who was ripping me off came through AAA, the other two from Yelp reviews.
We have a great mechanic now. Via a friend's recommendation.
posted by jbenben at 2:36 PM on July 25, 2015
My husband got suspicious and had a friend help him inspect the car after the mechanic told us it would be another $400 repair. My husband discovered our mechanic was soldering the Fan Relay ($35 part) into the system, bypassing the connectors that come with the Relay. The car saw two other mechanics during this time, neither of them noticed or alerted me to what were engineered failures. One charged me $50 and said they could not find the problem. Another was happy to replace the radiator. And another time, the fan.
This is a long way of telling you that you need to find a new mechanic. Ask friends. The guy who was ripping me off came through AAA, the other two from Yelp reviews.
We have a great mechanic now. Via a friend's recommendation.
posted by jbenben at 2:36 PM on July 25, 2015
You need a proper mechanic and tell them to look over the ENTIRE cooling system. it could be as bad as a cracked head or busted head gasket all the way down to leaking old hoses or a rock in the radiator. Yes, this will cost you $100 or such just for diagnosis. Don't say what other people said, just tell him "periodic overheat, add water periodically... fix once and for all", then leave him the car.
posted by kschang at 2:47 PM on July 25, 2015 [1 favorite]
posted by kschang at 2:47 PM on July 25, 2015 [1 favorite]
He said usually when you take the gasket off you can see some kind of residue where the gasket is blown, which verifies the gasket has failed. When I asked him to take a photo of the gasket once the head was off so I could see this, he backed away from this claim, saying that sometimes you can't see this residue if the leak is too slow.
Just to reiterate - This is completely correct. You can have a faulty head gasket and see signs when you take it off, you can have no signs, or you can destroy all evidence in the process of getting the cylinder head off to get to the gasket. Any of the above can happen. His back pedal on that is no sign of a questionable diagnosis.
I am seeing absolutely no reason to doubt your current mechanic nor his assessment based on anything here. Quite the opposite. It seems to be a reasonable and likely conclusion from the evidence as presented. The people pushing you to get a second opinion are not actually basing that on zero knowledge of cars. I mean, a second opinion is always great and do this by all means, but there is absolutely no reason from my perspective to suggest it is going to give you anything in terms of a better diagnosis or service.
Just to make it clear from my perspective.
posted by Brockles at 5:41 PM on July 25, 2015 [2 favorites]
Just to reiterate - This is completely correct. You can have a faulty head gasket and see signs when you take it off, you can have no signs, or you can destroy all evidence in the process of getting the cylinder head off to get to the gasket. Any of the above can happen. His back pedal on that is no sign of a questionable diagnosis.
I am seeing absolutely no reason to doubt your current mechanic nor his assessment based on anything here. Quite the opposite. It seems to be a reasonable and likely conclusion from the evidence as presented. The people pushing you to get a second opinion are not actually basing that on zero knowledge of cars. I mean, a second opinion is always great and do this by all means, but there is absolutely no reason from my perspective to suggest it is going to give you anything in terms of a better diagnosis or service.
Just to make it clear from my perspective.
posted by Brockles at 5:41 PM on July 25, 2015 [2 favorites]
It's not clear from your question - are you loosing fluid? i.e. is the radiator level going down over time?
If so you can ask the question, "where is the coolant going?". If it is getting into a cylinder, then you would expect some rough running and most typically some white smoke from the exhaust. If it is getting into the oil pan, then you should see coolant in your oil. If it's not going to either place, then I would be looking for a leak.
If it's not leaking, but just overheating - I would be looking at the thermostat to start.
posted by NoDef at 7:26 PM on July 25, 2015
If so you can ask the question, "where is the coolant going?". If it is getting into a cylinder, then you would expect some rough running and most typically some white smoke from the exhaust. If it is getting into the oil pan, then you should see coolant in your oil. If it's not going to either place, then I would be looking for a leak.
If it's not leaking, but just overheating - I would be looking at the thermostat to start.
posted by NoDef at 7:26 PM on July 25, 2015
It's not clear from your question - are you loosing fluid?
It is pretty clear, though: If I refill the radiator with coolant/water...I take the radiator cap off to replace the coolant...Refilling the radiator with coolant/water immediately corrected the problem...
If it is getting into a cylinder, then you would expect some rough running and most typically some white smoke from the exhaust. If it is getting into the oil pan, then you should see coolant in your oil. If it's not going to either place, then I would be looking for a leak.
The fourth option is the most likely - that the water system is being pressurised and the pressure relief on the cap is overflowing and evacuating water to control the pressure. So there is no 'leak' as such, but a water loss through the overflow from the cap/header tank system.
posted by Brockles at 9:02 PM on July 25, 2015
It is pretty clear, though: If I refill the radiator with coolant/water...I take the radiator cap off to replace the coolant...Refilling the radiator with coolant/water immediately corrected the problem...
If it is getting into a cylinder, then you would expect some rough running and most typically some white smoke from the exhaust. If it is getting into the oil pan, then you should see coolant in your oil. If it's not going to either place, then I would be looking for a leak.
The fourth option is the most likely - that the water system is being pressurised and the pressure relief on the cap is overflowing and evacuating water to control the pressure. So there is no 'leak' as such, but a water loss through the overflow from the cap/header tank system.
posted by Brockles at 9:02 PM on July 25, 2015
The problem could also be with the radiator. It could be semi-blocked or leaking.
posted by Thorzdad at 6:21 AM on July 26, 2015
posted by Thorzdad at 6:21 AM on July 26, 2015
Make sure you stay on top of oil changes, especially until you get this diagnosed and fixed. I had coolant leaking into my oil. The oil turned to gelatinous goo at the bottom of the pan. It was like axle grease when I drained it. That caused engine lubrication failure, which caused one of the exhaust valves to seize. That punched a hole in the rocker arm, bent the valve and jammed the lifter. It almost certainly did other damage to the engine as well. My car is too old to be worth replacing the engine, so it's going to the junkyard this week. I didn't know the oil was turning to goo until it was too late because the oil at the top was still liquid.
posted by double block and bleed at 8:47 AM on July 26, 2015
posted by double block and bleed at 8:47 AM on July 26, 2015
Response by poster: Thanks for the suggestions, everyone. I have obtained some of the exhaust gas testing fluid, and I have exposed it to the gases coming out of of the radiator. So far, no color change (but it does change in response to my breath.)
I have hooked up a bag with a small amount of testing fluid to the radiator neck, and I'm letting the car run for 15 minutes. I'll see what happens.
posted by Coventry at 1:51 PM on July 26, 2015
I have hooked up a bag with a small amount of testing fluid to the radiator neck, and I'm letting the car run for 15 minutes. I'll see what happens.
posted by Coventry at 1:51 PM on July 26, 2015
Response by poster: So, that test was inconclusive. The test fluid became paler, but did not change color. I think it became paler only because essentially water was being distilled out of the coolant mix and into the bag. I let it run 30 minutes before giving up.
posted by Coventry at 2:22 PM on July 26, 2015
posted by Coventry at 2:22 PM on July 26, 2015
I might be having the same problem with my '03 Civic.... occasional loss of power, occasional overheating, loss of coolant, intermittent or slow heat.
My mechanic did something like the test previously mentioned and it indicates a failing head gasket, but its not terrible yet, hasn't got worse in about 6 months of driving it! I just keep topping off the radiator. I would have it fixed if I planned to keep my car for a while or it was worth selling (body is a mess), but I just want to last another 15,000 or so miles so I recently put some K-Seal stuff in, we'll see if that does anything.
It's something of a gamble not to fix it. It could suddenly really fail at any minute and really screw up the the head or who knows what else.
I have intermittent heat (or its slow to actually produce heat) so I'll definitely have to deal with it or get a new car before winter... Just make sure your car isn't overheating.
posted by thefool at 5:10 AM on July 28, 2015
My mechanic did something like the test previously mentioned and it indicates a failing head gasket, but its not terrible yet, hasn't got worse in about 6 months of driving it! I just keep topping off the radiator. I would have it fixed if I planned to keep my car for a while or it was worth selling (body is a mess), but I just want to last another 15,000 or so miles so I recently put some K-Seal stuff in, we'll see if that does anything.
It's something of a gamble not to fix it. It could suddenly really fail at any minute and really screw up the the head or who knows what else.
I have intermittent heat (or its slow to actually produce heat) so I'll definitely have to deal with it or get a new car before winter... Just make sure your car isn't overheating.
posted by thefool at 5:10 AM on July 28, 2015
This thread is closed to new comments.
Another cheap thing to do would be to replace the thermostat.
Scroll down to the 2nd answer on this page, the guy gives some more detailed things to check, in addition to the fan and the thermostat.
posted by Marie Mon Dieu at 9:08 AM on July 25, 2015 [2 favorites]