i just picked up a 1990 rx7 N/A vert. Friday night the radiator blew on it so i got one yesterday and put it in and everything was fine. well i took it out to get lunch today and when i got home and cut it off i heard a loud clunking noise in the engine bay. opened the hood and saw that the upper radiator hose was completely collapsed. so i let it cool off and then added some coolant thinking that it had just hit a air bubble.


fast forward to this evening i was on my way to my buddies house so he could look at it and see if we could figure it out. well it started over heating and i pulled over and shut it down. well it was making that clunking noise again and the hose was collapsed again. so i let it cool back off and topped the coolant off again. then tried to drive it again and made it almost a mile before it was overheating again. that was about 2 hours ago and i just got home. had to keep stopping and let it cool off again.

so, anybody have some ideas of whats going on?? thanks

 

also forgot to mention that when it first started overheating today i turned the heat on to help cool it off and there was no hot air. then right after i started the thread i went back out and used one of the funnels that has the rad. cap deal on it to let it burp some more. while it was running i did turn the heat on and it was starting to get warmer. but it was still collapsing the upper hose while it was running.

if anyone knows what a water hammering is (sudden drop or rise in water press.) thats what it sounded like when it was overheating right after i would turn it off. while i had the funnel on it there was still a good deal of bubbles. other thing that is kinda weird is that coolant would flow back into the funnel and start over flowing. but when i cut the car off about 2 minutes later it would all get sucked right back into the cooling system.

sorry for the long post, just want to give as many details as i can. this is my first rx7 and im just hoping i didnt buy a bad one.

 

The radiator cap is responsible for limiting pressure in the system, so maybe there's something going on with it. When the coolant heats up, it expands and pressure increases. When that happens, the valve in the cap is supposed to allow coolant to flow into the overflow tank. Is it filling up when the engine warms up? Or is it staying at the same level?

 

sorry, left that out. i got a new cap cause the old one didnt look so good. so when it started making the noise and all that the first time i went back to the old on. but that hasnt helped any. and yes it is filling and draining the overflow tank. actually it is filling it up to full then overflowing the tank.

its just weird because everything was fine before i swapped radiators. the stock one was leaking a little around the part number plate so i got some stuff to seal it. well guess the leak was hiding a bigger problem so it ened up splitting the upper plastic part all the way accross.

 

Replace the small-diameter hose that runs from the radiator to the overflow tank, and use zip ties to "clamp" the hose at both ends. The symptom you describe suggests a small air leak in that hose. This does not prevent the flow of coolant from the radiator to the overflow tank, but when the engine cools down, the air leak in the hose prevents the coolant from being "sucked" back into the radiator. Not sure this is the problem with your overheating, but replace the hose and see.

 

ok, just got me a new thermostat and new upper hose. going to replace them this evening and see what happens.


as for the overflow tank it does eventually suck the coolant back into the radiator. im just really confused with the upper hose collapsinf and the weird knocking noise from the radiator. its like a pulsation. hope i didnt buy a lemon of a car. there were no problems before i switched the radiator.


edit: anyone by chance know what size the hose from the rad. to the overflow is?

 

forgot to post this last night. i took video of it making the noise, not much to see but it should finally help explaining the noise.

http://s179.photobucket.com/albums/w...0719092045.flv

and everytime you hear the clunk most of the time the upper hose was collapsing.

 

ok, think we got it taken care of now. got home lastnight, replaced the thermostat and upper hose with new clamps. let the car idle for almost an hour with a lisle funnel on it. my buddy wasnt lying when he said sometimes these things take for ever to burp all the air out.runs cooler now also.

only problems as of right now is the add coolant and scare the crap out of you buzzer have come on a few times. but they only stay on for 20- 40 seconds. and it seems to do it more when making turns. so im guessing it might have a few more pockets of air in it. its not leaking the coolant any where and as far as i can tell its not burning it. no smoking and the car is running great.