So this is my friends car. 1994 Accord LX F22 non vtec. I've been helping him with his car since he bought it. It had 190,000 miles on it when it was purchased last November. We brought it back up to speed. Passed smog, etc. Runs great. A few months after he bought it, it started to overheat. Water pump was leaking. No problem. Replaced.

Symptom: Car is fine when driving. When you come to a stop, it starts to climb up slowly. 1/2 then a little bit above half, then the temp stops climbing. When you rev it, it cools down.

This is what was replaced that can affect the cooling system:


New Water pump/Timing belt
New Thermostat
New Lower radiator hose
New Radiator and cap
System bled

Radiator fans work--I checked.



A few weeks back I was busy so he took it to a mechanic to have it inspected (pretty reputable shop). The guy said it's either the head gasket and the radiator, so he was going to test both. He said the head gasket was good, but the radiator was not flowing very well on the bottom end, and it needed a radiator. So I ended up replacing the radiator.

Coolant/oil isn't milky. Car now has 201,000 miles. What else can it be? Can it be a faulty temperature gauge?

 

It sounds like there's a blockage somewhere. When it comes down after revving the engine the water pump is working harder to push the water around the engine. However, if could be the thermostat closing up a bit. Take it out and run the car without it and see if it overheats. You should only be using OEM thermostats, it's worth the extra 5 bucks you spend at the dealer to get one. Make sure the fan is working when it starts to overheat. I've known of mechanics that said they changed the water pump, but didn't so in the future make sure you ask for all your old parts back.

 

Low coolant will do this. My '96 would lose a quart of coolant every ~200 miles and do what you described above, no other symptoms; no water in the oil, no oil in the water, no white smoke, plugs and compression were fine. A leakdown showed water being slowly pushed out of the radiator fill on 1, 2, and 3, no bubbles. Head gasket fixed it.

 

It's got an aftermarket thermostat. It did the same thing before we changed it though. I did all of the work, so I know all the parts are new. He jut took it to a mechanic to have it tested because I was busy a while back. The shop said the HG was good, but I'm not sure how they tested it.

I'm hoping it's not a head gasket. I don't see why the HG would go bad out of nowhere. It was fine when he bought the car for a few months.

 

You jump the wires to thermo A and the fans come on (key on).

 

Thermostats can have two problems.One, it could be opening up later than most, some thermostats have different opening temperatures. Also, some aftermarkets will be defective from the outset. Just go OEM and don't have to worry about bad thermostats.

 

We got a Honda thermostat. We are going to install it and update this thread.

 

Thermostat replaced with a Honda brand. Still same problem. I also forgot to mention coolant is getting pushed into the overflow reservoir.

 

when you bleed the system, do you let the fans go on twice?

is the temp dial on hot while you do this?

 

I actually did not have the bleeder screw open long enough for the fans to cycle twice, nor was the heater on... I am going to do this and update.

 

http://www.youtube.com/watch?v=zUpXg...8D5AF70B82EC06
http://www.youtube.com/watch?v=hUzOT...feature=relmfu

 

One of the most important parts is to turn the temperature control **** on the dash to "red" when doing any coolant related work. This opens up the valve all the way and releases air out.

We're not talking about turning the heater on, we're talking about turning the dial to full "red".

 

bleeding the air out of the coolant system is something that you have to do right. check that first

same thing happened to my old cd7. had a very small hole in a coolant hose. small enough to not be able to notice the leak. plus when it did drop it hit the exhaust and burned before hitting the ground. make sure there is no coolant smell anywhere and all the hoses are super tight- i like the clips that have the flathead screwdriver tighteners-obviously dont tighten to the point that its gonna cut into the hose when hot. my small hole would only leak with the engine warmed up.

i figured the small leak would cause a loss of pressure in the coolant system when warmed up which is why revving the engine cools it back down. mine would only overheat at idle. but then even on light acceleration it would go right back down. my coolant levels were fine and i was bleeding it correctly. found the leak. fixed the problem. bleed the coolant system again if you do find a leak