Sirfixalot97

So, I had a blown head gasket, I replaced that torqued all to specs. Ran fine, then it would stop shifting all of a sudden. Got it home, read some posts that it could be the clutch cylinders. I replaced both. I have over 250,000 miles, so I decided to replace the clutch. Got it all apart and the pressure plate had a broke tooth not allowing the shift. After putting it all back together it started shifting great.

​​​​​​I then started to notice overheating, it would overheat with the hot air on, temp set to hot no air, temp set to cold with air. I got all the air out of the system, but it still overheats. When the fan starts it does bring the temp down but not to the mid point. When I idled at lights it would get hot. Once I drove and the fan kicked in it would go to the mid point. I re-timed it to make sure I wasn't having extra burn in the cylinder. I replaced all hoses, thermostat, replaced the heat sensors and switches. Also replaced the coolant fan switch on the the thermostat. The radiator is only a year and a half old. No water in cylinders, no oil in cylinders. What else can cause the overheating? Totally lost!

jorge74

Did you bleed it.

Sirfixalot97

Did I bleed the coolant? If that's what your asking. I'm not sure how that is done. I've done what I normally do to get the air pockets out of the system.

jorge74

Yea there are a few ways to bleed the coolant. I usually on a level floor leave the rad cap off turn on the car making shur its topped off while the heat is rising 10 to 15min should do the close the rad back up. Iv heard others jack up the car up front and bleed .

jonsey1886

https://www.ericthecarguy.com/faq/wh...ystem-problems

NotARaCist

iTrader: (1)

If you're doing it on level ground, you're doing it wrong. Maybe if OP actually told us what they did, instead of saying "what I normally do", we could actually help you out...

Sirfixalot97

Ok, so I did do it on level ground. I fill up the radiator, then I put a long funnel in the top of the radiator. One that won't leak out of the radiator. I squeeze the lower and upper hose to allow more liquid to be added. I've​done it with the heat on high with and without the air at full blast. I've used the 50/50 blend and just water. I haven't tried it on an incline with the radiator above the engine.

Jimi Hondrix

What caused the initial overheating that lead to head gasket replacement? Was that problem solved prior to installing the new head gasket?
Beside possible air in the coolant sysyem a weak/failing waterpump can cause intermittent overheating. A failing (not completel failed) water pump may or may not squeak or leak. Easiest way to check it to open radiator cap, rev engine and watch the cooling flow at operating temp.It should be moving swiftly when revved and thermostat is open. Of course be careful when removing cap if system is hot/under pressure. Stand back as far as possible, remove cap halway with a rag and allow pressure to escape for a minute or so before removing cap fully. Alternatively, you can remove cap at cold start and watch cooling flow after thermostat opens up.

As far as bleeding the air from coolant:
1) raise front of car on jackstands as high as possible
2) set climate control to max heat with dash fan off
3) optionally use a funnel in the radiator neck to avoid overspill
4) rev engine periodically for 15 to 30 seconds (around 2500 rpm) to help push bubbles/air out of system
5) do this process until as much air as possible is removed..
6) remember to occasionally check dash temp gauge for overheating and/or use a thermometer in radiator to monitor temps (195-205 degrees farenheight)
7) fill radiator and reservoir to the top and inspect both the following day when engine is cold. reservoir will most likely drop from full.

NotARaCist

iTrader: (1)

Jimi pretty much has it, although I don't do any revving. Just let the car idle for two to three radiator fan cycles while keeping the radiator full.

Sirfixalot97

I did replace the water pump when I did the head gasket. I replaced the timing belt as well. I will try the raising of the car and see what happens.

NotARaCist

iTrader: (1)

Raising the car is the most important part of bleeding the system. When trapped in a loop, air will find the highest point and just sit there. For 99% of cars, that point is somewhere inside the system. For 99% of Civics, that point is either within the IACV, or within the thermostat neck where the temperature sensor screws in. If air gets stuck in the IACV, you get a shitty idle. If it gets caught in the thermostat neck, you get a reading of high temperatures without actually having high temperatures. Gotta get that front end up, either on jack stands or on a hill. You're bound to have at least one friend with a hilly driveway.

Sirfixalot97

I'm back.

I put the car on an incline and raised the car on Jack's. Put a funnel in the top of the radiator and ran the car. The car started heating up once it got to just below the max heat the funnel started to overfill. I can't tell if it's air coming out or it's pushing water out. The fan kicks on and the water starts to go through the radiator, I have to fill up the funnel with fluid and it cools down. This went on for 4 fan cycles. Same thing heats up, funnel over flows, fan kicks on, put more fluid in, it goes to medium temp.

I had just the heat on no fan. Turned on the fan to high and it didn't overheat as fast, once the fan kicks on it cools to medium temp like normal.

With the AC on it heats up faster, each time funnel over flows then sucks fluid in then fan the temp gets cooler.

Driving will fluctuate hot to medium, fan comes on it goes down.

On a side note, can bad piston rings, or cylinder damage be causing overheating.

At a loss still!

mk378

The radiator fan may be coming on too late. Jump the fan switch (on the thermostat housing), so the fan runs all the time, and test drive. If no overheating, replace the switch.

NotARaCist

iTrader: (1)

Or the thermostat could be failing. Remove the thermostat and test it. If you don't have a kitchen thermometer you can use to test it with, just head to your local dealership and buy a replacement. Do not use a parts store thermostat.

Sirfixalot97

So I jumped the relay so that the fan comes on when the key is turned on. When it is cool outside we can drive the car from home to work, about 20 mins with no issues. Later in the day when the temp outside is getting in the 100s, and if driving more than 20 mins it still overheats with the fan always on. Totally frustrated!

Sirfixalot97

So, what about Cat Air Flow being blocked, could that be causing overheating?