R32 gtst with rb25 swap. overheating BAD!

[w240p]

ok this isnt just another crazy 'my car overheated today, what do i do" topic. my friend just brought his skyline from japan after doing and engine swap. the engine sat for 3 years he told me. but heres what we have done. at first it had a blown hg. so we put a cometic and arps on, new water pump, timing belt. it has an aftermarket massive rad. with 3 fans 2 pullers one pusher. well it still started getting warmer than normal. one day it got HOT. so he took the thermo out. same damn thing happened! so tonight we were cruising, it was about 70 degrees out here and we couldnt go 2 miles without it getting to the notch before the H. and another weird thing is when you put the heat on it blows cold until it reaches the notch before the H on the gauge. also all the hoses have JUST been replaced TODAY. so... what kind of recomendations do you have? i keep telling him that we should throw some flush in but he dont think thats it. as far as bleeding he said it didnt have a bleeder screw on it, and since he said that i didnt bother to look. but you can look in the rad and see its flowing like a champ...?? help. please! lol hes so pissed at it he wants to burn it to the ground. but once again, 3 fans blaring, no thermo, new coolant perfect 50/50, and NO leaks what so ever. oh and even at highway speeds with a nice breeze. it still got hot.

[TSL]

It does have a bleeder. Bleed it properly.

[Cjmartz2k]

A flush ain't going to help that, and if the gage moves from the middle, it's already to hot. Mine doesn't budge until it gets over 105*. If it's getting near the H, that ****'s WAY too hot. Do a compression test, and look at the coolant to see if you have any oil in there again. Maybe the HG is blown again, or never installed properly. Could also have a warped/cracked head.

[rb25drag]

First I would get a 200% accurate gage that reads actual temps VS a letters.

2nd, you need to bleed the system, At least jack the fron end in the air and turn the Heater wide open until the thermo opens and it starts flowing good. Top it off and it will be bled correct.

3rd, Put the thermo back in, I ran mine without it for a While, Its fine in 40-60 degree weather, Anything Hotter it will heat up fairly quickly due to water just constantly flowing, It has no time to cool.

Did he re-surface the head when changing head gaskets?

He also might not have a good set of fans on it.

Make sure it has a Shroud so it will keep the air constant threw the radiator and not around the sides.

Thats about all you can do.

[mello88]

as far as bleeding he said it didnt have a bleeder screw on it, and since he said that i didnt bother to look.

There's the problem.. There's air in the cooling system, and there IS a bleeder screw. Reference the FSM if you're not sure where it is. Bleed it properly, put the thermo back in, run some water wetter and a low mix of coolant to distilled water (30/70). Get an aftermarket coolant gauge to keep an eye on temps, the factory dash gauge is next to worthless.

[matafied]

are you sure its overheating?? also dumb question but did you swap the sending unit from the rb20 over to the 25? are they the same? just a thought b/c if their different the gauge would be way off and possibly show it running hot when its not. just a thought

[tek747]

I think its the sending unit that is screwy. Check it! Replace it! If it is definitly getting up there........ you would be seeing some steem. right?

[Cjmartz2k]

The sending units are different, but it goes the other way IIRC. I had the 25 one in mine at first, and it read low, until I put the 20 one back in it.

Also, I just assumed that if he was mechanicaly inclined enlough to swap heads and the like, that he knows he needs to bleed it. Whoops Even so, after a couple of weeks of driving, it should bleed itself most of the way as long as you keep the overflow full.

[w240p]

the fans it has on it are 2 2000cfm 12s on the rad. which are pulling, one is a 14 inch 2150 cfm pusher on the ac condensor. he asked some people on a local nissan forum and showed him where the bleed screw was. i was in the process of changing my headgasket today so i couldnt help him much but bleeding it did help a little.he put a new thermo in and he bled it for about 3 hours. he would warm it up, pop the screw until it shot strait antifreeze out, then would fill it up. drive it then come back pissed cause it still got hott. then bled it again with all the time alot of air came shooting out. he did it 4 times and after that it still got warm. it went about 3/4 thru the gauge. before the notch thats before the "h". now it is ok driving it normal but if you get on it it will start to climb, then he would turn the heater on full blast. but still it would hold that position until we would stop then it would go back down. we did a compression test after the hg replaced and we took our time doing the whole hg change. his friend from japan hooked him up with a full walkthough of it and we followed every step. but the reason why i mention doing a flush is that while the head was off i noticed alot of scale build up. hence the engine was sittin over 3 years and he knows that for a fact cause he got it from his friends r33. but like a said its been bled until no more is coming out and only coolant. but still it gets warm, were both still stuck lol. but thanks for all the advice so far!

[w240p]

First I would get a 200% accurate gage that reads actual temps VS a letters.

2nd, you need to bleed the system, At least jack the fron end in the air and turn the Heater wide open until the thermo opens and it starts flowing good. Top it off and it will be bled correct.

3rd, Put the thermo back in, I ran mine without it for a While, Its fine in 40-60 degree weather, Anything Hotter it will heat up fairly quickly due to water just constantly flowing, It has no time to cool.

Did he re-surface the head when changing head gaskets?

He also might not have a good set of fans on it.

Make sure it has a Shroud so it will keep the air constant threw the radiator and not around the sides.

Thats about all you can do.

forgot to add in my last post, he took the head to a shop and used a strait edge + feeler gauge. it was fine. so he didnt need to resurface it.

[w240p]

are you sure its overheating?? also dumb question but did you swap the sending unit from the rb20 over to the 25? are they the same? just a thought b/c if their different the gauge would be way off and possibly show it running hot when its not. just a thought

nah it ran normal until about 2 months ago it would get hott. and we thought it was the hg.... so we changed it lol

[rb25drag]

forgot to add in my last post, he took the head to a shop and used a strait edge + feeler gauge. it was fine. so he didnt need to resurface it.

With a Cometic Head Gasket it need a nearly mirror finish to seal 100% properly. I bet there is a HG leak you don't know about.

How did you clean the head and block?

Also with the Thermo in can you leave the cap off the radiator and see the water start flowing in the radiator When it warms up?

What Temp thermo did he put in?

[CarolinaR32]

I have an identical setup 93 R32 GTST w/ Series II RB25, stock radiator and fans and I never run any hotter than 87C or mid way on the factory gauge.

[Cjmartz2k]

Hey Carolina, what's your email addy? I'm coming back to NC in about a year and I want to see about getting a R32 GTSt over there and swapping all my **** into it instead of trying to bring my car back.

Thanks!

[CarolinaR32]

[email protected]

[mattleegee]

This might seem like a dumb question but could a guy take a head in to get it resurfaced without taking out/off the vales/springs/retainers ?