Overheating and i replaced everything.

For the past few months my car has overheated 4 times. I have replaced the thermostat each time. But i noticed that it has only failed when the car has not been moving. So that means to me my fans arent working. So i just replaced the thermosensor on the bottom of the radiator. But the coolant still is having trouble flowing through the engine. I dont have any leaks either. 88 DX Carb

Symptoms

• Radiator hose to top of radiator is hot
• Radiator hose from bottom of radiator COLD
• when i turn off the engine with the cap off, half of the coolant will overflow out of the radiator cap. Its never used to do this before the overheating problems
• Overheats when car is not moving, but not all the time

Things i have replaced

• Engine was rebuild recently (maybe)(a long story)
• Thermostat replaced (even had a failsafe one fail within 1 week)
• Waterpump only has 10,000 miles on it
• Thermosensor on bottom of radiator (this is the last item i have replaced)
• All hoses
• Coolant has been replaced several times due to replacing the thermostat several times
• Radiator was replaced (10,000 miles on it)

Things i have tested

• The fan relay does work, i jumped the two wires and the fans turn on
• I grounded the sensor that displays the temperature on your guage cluser, and it is working properly

Have you bled the air from the cooling system?

Have you changed the radiator cap.

Run a bybass hose to isolate the heater core. To rule out a clogged heater core.

Pull the radiator, flush it to ensure flow.

Use a failsafe thermostat. Pull the thermostat and run the engine w/o the thermostat. Its a last resort.

I once had a car where I replaced the heater hoses, heater stopped working, turned out that one of the heater hoses had a piece of wood that clogged it. Don't ask me how it got in there. Just make sure you check all hoses before putting o the vehicles.

+1 on the hoses
My buddy had a similar problem and one of the radiator hoses ended up being collapsed on the inside. I looked perfect from the outside so there was really no way of visually knowing. Once the motor got a little warm the inside of the hose got lazy and flapped over restricting coolant flow.
Damn strangest thing I've ever seen. Hope this helps.

Sounds like what mine was doing when I first got it. Check your fuses. There is one in the engine fuse box and one in the fuse box under the dash. The one under the dash was blown on mine and someone replaced it with the wrong amperage. If I jumpered the sensor at the bottom of the radiator the fans would kick on, but wouldn't by themselves.

ok, i will bypass the heater core, check all the hoses, flush the radiator to see if there is a blockage and i have already checked the fuses

Just so you know i am trying to bleed the air from the system, but cant because it seems to not want to circulate now.

I will let you know the results tomorrow.

Only an Honda OEM thermostat will bleed the air out.

Quote:

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Originally Posted by nswst8

Only an Honda OEM thermostat will bleed the air out.

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There is a way around that, you drill 1/8 hole in the thin metal between the spring & outside edge. You then mount the hole facing north with you install the t-stat.

Quote:

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Originally Posted by ddude2uc

There is a way around that, you drill 1/8 hole in the thin metal between the spring & outside edge. You then mount the hole facing north with you install the t-stat.

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I've done that before and all worked out well

I forgot to add that little piece of info, Thanks guys.

by north do you mean up, or towards the passenger compartment

Quote:

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Originally Posted by conozo

by north do you mean up, or towards the passenger compartment

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hole at the top position

The other thermostats i purchased from every auto store already has a hole there.

So yesterday i checked everything. I found that the thermostat is working properly, there arent any blockages in the engine, heater core, radiator, or hoses, all hoses are new and good. I filled it up with fluid and ran the car for about an hour trying to get all the air out. The car did not overheat either, infact it felt only warm to the touch. So then i turned the car off, ate dinner, and started it up again, this time i held the throttle at 1500rpm and the enigine heated up quickly and everything seemed hot, such as the hoses, engine, radiator(top and bottom), and the hoses had a lot of pressure in them. The fan still did not turn on and i beleive the hoses felt hard because the coolant was about to boil again, but im not 100% sure on that.

I dont know what else to try, im going to try running it again and see if i can bleed any more air out of it.

is the coolant low each time you check it? my car did the same thing a few weeks ago. found a pinhole in one of the small hoses under the intake mani. replaced and all was good

What about your water pump, how old is it?

If I recall correctly, this is the long story on the rebuilt engine: https://www.3geez.com/forum/showthrea...hlight=lawsuit

I'm not sure how you are verifying the flow of the various cooling components, but from what you describe (the fact that you can't bleed the system and that certain parts of it are overheating, while others are not) there is a restriction. The sad fact is that you have had bozos working on the cooling system and bozos break things very creatively. It's a gift really. You can take the car back to the shop that installed your water pump and tell them to fix it right this time, but then you're back to the whole bozos working on your car problem.

If it were mine, I'd start with a cold engine, remove the rad cap and start it up. When the t-stat opens, you should be able to see the water circulating in the radiator. At some point after that, the cooling fans should turn on. That will give you a good idea of how the system is working overall. When you are done, remove your t-stat and blast a garden hose into the cylinder head. You should get water coming out of the upper hose in torrents. If it trickles out, you'll know there is a restriction. In that case, you start taking stuff apart until you find the restriction. If water rushes out, then you can suspect that something is up with your water pump. If so, you'll need to remove it. As I said, bozos break things creatively. You may find that somebody broke all the fins off the new pump before putting it in. Or you may find that the old, bad pump was WD-40ed to make it quiet and put back in. Or you may find somebody's sneak-a-toke wedged in there or God only knows what else.

Anyway, keep us posted on what you learn.

Coolant is not low. I did blast water through every hose and place where coolant normally goes and it all flowed nicely. My water pump only has 10,000 miles on it, but i guess its the only thing left for me to look at.

When i was working on it yesterday i followed these instructions. https://www.3geez.com/forum/showthread.php?t=66456 I even had coolant flowing out of the bleeder bolt when filling the radiator with the engine off unlike the others had mentioned.

There is a tester than call tell if you have combustion products in the coolant. I'm wondering if you have a small head gasket leak, which could be pumping up the system in the wrong way, maybe intermittently.

did u replace the water pump & oil pump???

When you say overheating what is it doing? Stock guage or aftermarket. I'm trying to see what your defintion of over heating is.

One thing I would do is remove the T=stat and try running it to see what happens.

Also if you used tap water that has alot of limestone in it it may have clogged the rad already. It only takes maybe 2 years to clog a rad with some water.

wp

there is this pressure tester...you put it where the radiator cap goes and pressure to 15psi and see if your pressure drops

The water pump and oil pump are new with only 10,000 miles on them

When i say overheating the coolant boils, and you can hear it when you turn the car off. Its done that 4 times, but i have noticed it right away and turned the car off. The stock temperature guage shows the temp high also.

The radiator is not clogged, i put the garden hose to it and it flowed out freely, in both directions.

Today i tried to use a block tester to see if i have a blown/leaky head gasket. But i could not use it because everytime i put the tester in the radiator the coolant would rise quickly and coolant would get into the tester. So i stopped, then the coolant started rising and it flowed out of top of the radiator. So i quickly turned off the car, and it flowed out for another 15 seconds. I lost half of my coolant and it wasnt even hot to touch. This is also what it keeps on doing, the over flowing when i turn the car off with the cap off. If the cap is on, everything looks fine.

After that i took off my water pump and it looks new and spins freely.

The next thing i will try is put everything back together and try to run it without the thermostat.

sounds like your having an ass of a time. i reckon it has to be a small head gasket leak. I had the same problem with another engine i had, was only a pinhole leak but was enoguh to make the car overheat after 20 minuites of normal driving

Maybe I missed it but have you had the radiator cap tested or replaced it?