So I got it to overheat and brought it back to the shop. They did another hydrocarbon test and negative. They said there is some sort of resistance in the cooling system and since the fans or something were not spinning hard enough? this means that it rules out the head gasket, a bit confused by that maybe I misheard. But they seem certain that it isn’t the head gasket now. I asked if they were 100% about this, and one mechanic said that the “hydrocarbon test is usually a sure deal” and that “It’s possible it is the head gasket, but not probable”. So now they are testing the thermostat and inspecting into the water pump. Possibly due to the propellers breaking off or wearing down. Also, possibly a clog/resistance in the radiator.
Apparently this OP’s overheating problem has been going on since January or longer. You would think they would have found a mechanic to solve the problem by now. I would venture that anymore discussion is a waste of time.
@JimFrost You need a better mechanic, not just a tester of exhaust fumes. Cooling system problems are not that hard to diagnose.
+1 to Doc’s post.
It appears the OP is still struggling with the issue, so I’ll join in.
Engines generate a lot more heat at speed, so many overheating problems only occur at speed. That really means little.
Common causes of overheating include
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clogged or internally coated radiator (I see yours was changed, so you can rule that out)
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malfunctioning thermostat. These can be tested or changed very cheaply. With a chronic problem, it should be tested IMHO
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inoperative cooling fan(s). This is very easy to verify and is usually either the fan itself or the temp sensor, both of which are easy to test and (if necessary) replace.
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a collapsed inner liner in a radiator hose. With repeated overheating, it’s best to just change the hoses. These can be hard to verify, but hoses are cheap.
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eroded impeller in the water pump. This will show up in a “flow test”… which apparently is finally being done? These are usually nylon, and they can wear prematurely.
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intermixing of the tranny fluid in those vehicles that use a two-segment radiator to cool both the engine coolant and the tranny fluid (which is also tranny coolant). You radiator has been changed, so you can rule that out.
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the biggie: combustion gasses getting blown into the water jacket, commonly called a “blown headgasket”. A cylinder explosion can reach over 2,000F, and if the hot gasses blow directly into the coolant they’ll add heat to the coolant faster than the cooling system can dissipate it. Normally, in a healthy engine, most of the heat goes out the exhaust ports.
However in truth, there is more than one possible cause of the combustion gasses getting blown into the water jacket.
- The most common is a path blown through the gasket itself, allowing a path for the gasses to travel through.
- The second most common is a warped head that prevents the head’s gasket surface from properly seating on the head gasket and sealing the cylinder. This is very common in engines that have been repeatedly overheated. I think ultimately your head is going to need removal.
- In engines that have been blowing gasses into the water jacket for a long time, as yours has, it’s also common for a path to wear in the metal between the cylinder(s) and the water jacket.
All of the above will cause combustion gasses to blow directly into the coolant.
Unfortunately, your shop(s) don’t seem able to properly diagnose overheating. It ain’t rocket science. I agree with Doc that you need to find a competent shop. Unfortunately, the overheating has been going on too long and you may need more expensive work than you would have if a good shop had diagnosed the cause properly to begin with. As a matter of fact, if there’s a channel eroded into the top of the engine block that’s allowing passage of the combustion gasses into the water jacket you’ll be stuck looking at a new motor. Machining the top of the block is far from cost effective.
Sincere best.
The fact that it has been overheating this long is worrisome. If you like the car, have the head removed and everything inspected. Something else you might try with a COLD engine is to remove the radiator cap and start the car. ALWAYS DO THIS WITH A COLD ENGINE!!! It is dangerous to do this when hot. Let the car run and look into the radiator. If you see liquid flowing and moving around, that is fine. If you see bubbles, you have a failed head gasket. The fact the hydrocarbon test didn’t see anything may mean this might not happen.
Yes, change the thermostat. These things are cheap and you can do this job yourself for less than the cost of a test at a shop. If the shop you have been using hasn’t done this, I would be concerned and find another shop.
Definitely have the water pump and timing belt replaced if you take the head off. A test of the water pump flow is a good suggestion. I am not real familiar with Hondas but many cars have the water pump driven off the timing belt. If this is one, replace ANYTHING that comes in contact with the timing belt. This includes the water pump, idlers, tensioner, etc. If any one of these parts fails, then bye bye timing belt. If an interference engine, then bye bye engine. At this mileage the cam and crank seals are also due to be changed. They might not be leaking now but they probably won’t last another change interval. Leaking oil will shorten the life of a timing belt.
The fact that this car has been overheating for this long is a bad sign for the head gasket. Take it somewhere that knows what they are doing before any more damage is done. No, you cannot re-use or repair a bad head gasket. These are a throwaway item even if you remove the head and find that the gasket wasn’t bad. Parts are not the cost. The labor is. I work on computers and get people wanting things done as cheap as possible, even if it means compromising the integrity of the job. I have gotten away from dealing with these people. Don’t be one of those customers to a mechanic!