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Discussion Starter #1 (Edited)
I just replaced the stock radiator with an aluminium Greddy radiator. I let it idle after putting the radiator in and noticed that after ~ 5-6 minutes of idling, the top of the radiator was scalding hot, while the bottom was room temperature. Also, after 10-15 minutes of driving my heater is putting out cold air. My temp gauge starts out at C, and gradually works it's way up to the middle where is stays for the rest of the time. Should these things be happening?

Thank you!

Edit: If the engine itself is overheating, would the oil temp get higher than usual before any damage is done?
 

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Discussion Starter #3
Yes. Also, the car is a 1992 R32 GTR. I found out yesterday that there is an air bleed screw on the block. I am going to try that out today.
 

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I just replaced the stock radiator with an aluminium Greddy radiator. I let it idle after putting the radiator in and noticed that after ~ 5-6 minutes of idling, the top of the radiator was scalding hot, while the bottom was room temperature. Also, after 10-15 minutes of driving my heater is putting out cold air. My temp gauge starts out at C, and gradually works it's way up to the middle where is stays for the rest of the time. Should these things be happening?

Thank you!

Edit: If the engine itself is overheating, would the oil temp get higher than usual before any damage is done?
After driving for a bit can you get hot air out of the fan?

If not it's probably the waterpump.

If yes then I'd look for blockages in the radiator. Try flowing water through it see what's what. I've been filling mine up recently (uprated rad) and I think I got a bit over 5 litres in.
 

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Discussion Starter #5
I am getting hot air out of the heater. I ruled out blockages by loosening the bottom hose and coolant flowed out. The bottom of the radiator is now heating up, but it seems a lot hotter than it should be. I am going to drive it around for a while and just watch the oil temp. The water temp gauge seems to just stop at half way. I thought it would at least move a little when the engine dumps water into the radiator. I also ordered up a new low temp thermostat and higher pressure radiator cap to make sure those are not causing any problems.

Thanks for the replies!
 

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Generally water temp gauges are built in with an engineered level of 'stickyness'. They tend to sit in the middle and not move unless you are miles above/below operating temp. I reckon it's a tactic used by manufacturers to stop people worrying about the water temp. If you saw the needle waggingly about you'd be bringing it back to Nissan to complain something's wrong (when actually it's fine). If it just sits there in the middle you'll be happy.

When my OEM rad was blocked I could get water to travel through the rad - just not enough to stop it overheating!

If your water pump is OK I'd be looking for a blockage in the system somewhere. If you're keen you could unbolt the stat and blast through the engine end of things to see if that clears things up. May worth putting some rad flush in too.

Personally I'd be looking at the rad. If you lived anywhere near me I'd be happy to give you my old rad for testing purposes - I'm fairly sure I've cleaned all the shite out of it now!
 

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Discussion Starter #7
Are the aftermarket gauges usually less "sticky"?

The entire radiator is now heating up as well as both hoses. I'm not sure what the heck happend, but water seems to be flowing now. I tried letting the car sit overnight and then unscrewing the bleed screw but i didn't hear any air come out with any pressure.

Even with the stock radiator, I always noticed that the engine bay would get crazy hot. Most of the time I would not even be able to touch the part that holds the hood up (does it have a special name??) because it would just be too hot.

The oil temp gauge has not been getting above 80-90 C, so I guess the engine isn't getting too hot (is that a safe assumption?). I'm really just worrying since the engine is something like $3000 used... So, I really don't want to break it!

Thanks for all the replies!
 

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Discussion Starter #9
How would I tell if there were an airlock? Should I just drain the radiator, unscrew the bleed screw and fill the radiator back up? I've tried squeezing the bottom hose to look for air bubbles and didn't find any.
 

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did you check water levels after you first filled it up? if you run the car for a while airpockets release resulting in a lower water level. also did you try replacing your rad cap. its a good idea to monitor water levels for a few days after a new bleed.
if the heater is working it means you have water flow, and if you feel the rad hoses and they're nice and firm (firmer than when its cold), means you got pressure
 

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even the stock water temp sensor will read out accurately - you need to read it off the ECU however, the dash gauge is useless.

Perhaps the "stickiness" of the water temp gauge is a good thing, because worry is precisely what I do, watching temperature go up and down by 10 degrees. I mainly use it to monitor if the engine has warmed up - I have forged pistons and they slap until everything is warm.

And the RB26 is a very hot engine. Completely stock, it's still a blast furnace under the hood. With upgraded cooling, the air is even hotter (heat energy pulled out of the engine and then put into the ambient air around the engine).....just get used to it :)
 

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i agree with the air lock in the system mate, loosen the rad cap one notch (so it's still on but not tight) take the car for a 5 min drive then carefully take the cap off (with a rag in hand) and top up the coolant, keep doing this till the coolant level doesnt drop then pop the cap on properly and check the heaters, if there hot you have cracked it ;)

alex
 

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either above or take rad cap off let it idle for a while , taking cap off will let the air in the system escape, also make sure the expansion bottle is toped up, that can case over heating, if theres no water in it it just sucks air back into the water system thus casing overheating.
 

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just had thought ive got greddy rad and its normally so hot you cant touch it, ali disperses heat better would say than stock rad
 

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Discussion Starter #15
Thanks for all of the replies! Sorry I haven't posted anything for a while. Totally forgot to check my E-Mail.

Everything appears to be better now. I replaced the radiator cap with a Greddy 1.4 bar one. After that things seemed to be a lot better (crappy stock cap?). I have not gotten my new thermostat in yet, but I did find something else out. Turns out that I basicly wasted $800 since it turns out that the crack in the radiator was just a crack in the plastic. It's just a busted lower radiator hose :bawling: Stupid me ordered a new factory water temp gauge a while back... $120 wasted since I will be putting in Deffie water temp, oil temp, and oil pressure gauges later. But, since I already ordered all the other parts and paid for them I might as well put 'em in! Thanks again for all of the help!!
 
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