Help i give up

1995 Honda civic lx 4 cy. 1.5— car was running great – son’s car— he got in a slight fender bender enough to cause radiator to leak-- bought new radiator,thermostat (no bleed screw on this car) and new prestone - started car let it run long enough, no leaks- noticed fan was not working (it was before) had on all heat elements on in car. plus no heat ( it did before) then the engine started to rev. up then down-- it did continue to do this.— shut it down. son hot wired the fan started it up fan worked let it run for while same thing happen engine rev. up then down-- still no heat? felt hoses bottom cool top hot. i did not check the heater core hoses i did not remember until i talked to my nephew. a good mechanic i am not. will ck. sat. what could be going on i gave up for today. any thoughts would be a nice start to a new year. car does have 150,000 mi. but it ran great before this accident and well taken care of " happy new to everyone"

One big question might be regarding this leaking radiator. What happened between the fender bender and the new radiator? Any driving and overheating between those 2 events?

The up and down idle could be due to a vacuum leak which may have been caused by the accident. Maybe a fault in the canister lines, etc.

if you listen to my son -not a lot?? the only thing that gave me hope was the car ran very good while it was warming up did not miss a beat.— until the rev. up and down. after it was repaired. would the car not act up from the get go if it was vacuum leak, I’m a little confused? if the problem was from overheating would it take that long to do the up and down revving instead of in the start up thank you o.k.4450

It does sound to me the thermostat is bad at least. Check the fuses for any blown ones for the fan circuit. If that is ok then check the thermoswtch.

I would also recommend replacing the thermostat and if the new thermostat does not have a weep hole in the housing drill one. Fill the cooling system and bleed it, repeatedly if necessary, to ensure that there is no air lock in the system.

Your coolant isn’t bled properly. There’s air in the system. That’s pretty much definitely causing the engine revs, and very possibly causing the no heat problem.

thanks for the comeback. i did clean the idle air control ( screen was dirty) and because no bleed screw i took off top hose until i saw prestone coming out. took car for a spin the heat came on and all was fine. took off the hot wire to see if fan worked and it did. i think there was a air bubble in the system just lucky

you are right on thanks for your reply

thermostat was replaced-- just needed to go a little further-- it was a guessing game for a while— I’m convinced it was air in system-- to bad there was not a bleed screw on this car. it would have saved me this headache thanks for you reply Happy New Year to all responders

thermostat was replaced— did want to eliminate that problem. came to conclusion air was in the system. later on ( for the heck of it ) i boiled some water to see if old thermostat was working — and it was thanks for you time answering my post