SR20DET Redtop overheating when driving more than 20 miles on highway

[Nissan2nr22]

Title pretty much sums it all

Engine is all stock, original.

I drive 15 miles from work to home daily twice and the cars fine, heat gauge is a little below half.

Yesterday I had to drive to Miami, at about 20-30 miles in heat slowly started rising till almost the top.

Obviously I pulled over before it hit the top, cooled the radiator down.

I noticed when I put the car in neutral while going 70-80 on the highway and just cruise the heat QUICKLY RISES after 20+ miles of traveling at 70+ MPH

Heres what friends are telling me:

1) From Previous owner, he said : Redtops arent made to go past 65mph and to be able to do that I'd have to get a bigger turbo and a 6 speed trans.

2) Friend said : It could be the water pump?

3) Mechanic said : You need a better radiator.



Does anyone here know or is familiar with this problem? How did you fix it? Please tell me I really need to be able to travel longer distances.

[No 240.. No id]

1) From Previous owner, he said : Redtops arent made to go past 65mph and to be able to do that I'd have to get a bigger turbo and a 6 speed trans.

This is a joke. So a car is not suppose to be driven over 65mph? lol
2) Friend said : It could be the water pump?
Possibly, something very common with sr's. Ill do the thermostat and the water pump at the same time.
3) Mechanic said : You need a better radiator.
Stock rad. should do fine if you are not abusing the car.

Do you have stock clutch fan? You got a shroud?

[ultimateirving]

Start with the fan and shroud if you dont have one.
Also have you opened up the radiator to see how much coolant? Any air in the system can cause it to run hot especially after a few miles of driving. Sounds to me like previous owner was an idiot so I would be going thru the whole cooling system to see what he has done.

[SharkMan]

First things first check the fan, do you have an e fan? Make sure that what ever fan you have is functioning properly. Second(most common) your thermostat, if its stuck closed of bad when your car starts to heat up if you top hose s bloating and hard to squeeze(careful could be really hot) then its closed and it should be open. Or you can always take it off and place it into boiling water and see if it opens. Either way if it doesn't its bad and needs to be replaced.

[fliprayzin240sx]

Start with bleeding the coolant system. Jack the front of the car up as high as you can, massage the upper radiator hose to get air out of the system, pop the radiator cap, turn the car on, turn your heater on full blast and continue massaging the upper radiator hose. Keep the car topped off, keep massaging until you start feeling the hose get hot. Put the cap back on and just let it run. Feel the lower rad hose to see if that gets hot after a few minutes, if it does, that means your thermostat is working and letting coolant back into the engine from the radiator.

[Nissan2nr22]

Thanks for your replies, I will do all the suggestions later today (7est) and get back.

I opened the coolant and it seemed fine.

I have the original fan with fan shroud, the one thats always spinning, so it can't not function right.

There isn't much of an opening for air to flow through, could that be the reason when my cars working harder?

Abusing? Thats the funny part I whip it all over the streets, on highway im just driving at 70-80mph @ about 3-4000 rpms and after about 20 miles it starts rising, driving normally.

[Prok0]

Do you have a thermostat in the motor?

If you do not its possible the coolant is moving too quickly through the radiator at higher engine revs and the coolant is not sitting in the radiator long enough to transfer heat and cool.

I noticed when driving down to south FL my car would start to get hotter, not really overheat, then I would clutch in and put the car in neutral, coast for 30-40 seconds and put it back in 5th and the coolant temps would drop a few degrees then start to climb back up slowly over time, as the coolant was pushing through the rad too fast I am guessing.

I have the Koyo Aluminum rad, C&R surge tank, and a stock thermostat drillled out to provide constant coolant flow to the surge.

[Nissan2nr22]

That could be it, it makes sense cause it only happens at high speeds!

[Croustibat]

Originally Posted by Nissan2nr22

Title pretty much sums it all

Engine is all stock, original.

I drive 15 miles from work to home daily twice and the cars fine, heat gauge is a little below half.

Yesterday I had to drive to Miami, at about 20-30 miles in heat slowly started rising till almost the top.

Obviously I pulled over before it hit the top, cooled the radiator down.

I noticed when I put the car in neutral while going 70-80 on the highway and just cruise the heat QUICKLY RISES after 20+ miles of traveling at 70+ MPH

Heres what friends are telling me:

1) From Previous owner, he said : Redtops arent made to go past 65mph and to be able to do that I'd have to get a bigger turbo and a 6 speed trans.

2) Friend said : It could be the water pump?

3) Mechanic said : You need a better radiator.



Does anyone here know or is familiar with this problem? How did you fix it? Please tell me I really need to be able to travel longer distances.

considering what the previous owner said, i think the head is warped and the headgasket is gone. The 6spd is weak as shit, and the T28 turbo is good enough for around 300HP, which allows me to reach 160mph without much trouble. On a CA18det, so with 10% less displacement.

The oem fan CAN go wrong. There is a viscous coupler, which works just like a VLSD. When it needs cooling, the clutch makes the fan spins as fast as the pulley. When it does not, the clutch only transmits a fraction of power and the fan turns slower. Sometimes the clutch dies, and it cant spin fast. And sometimes it cant disengage. Trust me, you know when that happens.

Anyway yes it can go bad, and nearly no other fan system works better.

People go electric either because they want less load on the engine, or need more room, or because they want to follow the crowd, believing it is better ... but electric fans are no better. Your oem fans can eat quite some HPs (sometimes as far as 5 ...that is 3700W, which on a 14V system is 266 amps. Your alternator will never be able to produce that)


But seriously, find the previous owner and give him back his piece of shite for a full refund.

[pacotaco345]

Do you have proper fencing to your radiator? My car would always run between 175* & 185* in traffic and under little load, but on the freeway it would get to ~200 because the fan (whether it be clutch or electric) loses its efficiency after about 40 mph. I cut out some cardboard just to test if some shrouding would lower my coolant temps and guess what, it did, by about 15* on a stock radiator.

[OrangeVirus1]

Dude, an engine doesn't know what 65MPH even is. The engine doesn't care how fast it's going, the only thing the engine does is spin ( RPM ) lol...

Flush the coolant, check / replace water pump, and invest in some good fans.

[jr_ss]

Originally Posted by OrangeVirus1

Dude, an engine doesn't know what 65MPH even is. The engine doesn't care how fast it's going, the only thing the engine does is spin ( RPM ) lol...

Flush the coolant, check / replace water pump, and invest in some good fans.

You're missing the point...

Anytime your moving at speeds >25mph you really shouldn't need to have a fan engaged unless your beating the piss out of it. Obviously when your traveling at higher speeds youre creating more heat.

The cooling system is simple. Like others have stated;

-Check to see if you even have a thermostat
-Do you have all the factory ducting? Fan shroud is there, but what about the lower splash gaurd?
-Fill system up and bleed (Like Flip suggested)
-Pressure test the system to see if you have any visible leaks.
-With the cap off, see if there are continuous bubbles coming out (Lets hope not)

[Kingtal0n]

wow. this is my car. Everything is OEM and its perfect. His problem is that redtops are not designed to be at 3600RPM on the highway in Florida weather; thats it. the turbine is too small and the gearing is too short for it. If you disconnect the turbine it will no longer overheat because thats where all the heat is coming from. otherwise, I told him to just drive 65MPH @ 3000rpm because thats where engine vacuum is 10" about as low as you want to go for steady highway speeds.

At 80MPH and 3600RPM the vacuum is around 3"-5" the engine is damn near in boost and it gets hot after 50 miles on that T-25, yeah. I suggested the 6-speed because then you can run the 3.4x gearing and drop the cruise RPM. Likewise he can upgrade the turbo to something with a larger turbine and that will also remove the heat from the engine.

A; upgrade turbine
B; better gearing
C; drive slower (3000RPM and 10" vacuum)
D; disconnect turbine (free) highly recommended for highway drives if you are going to beat on the engine with outlandish RPM
E; cooling system upgrade (but I prefer OEM radiator)

the water pump is brand new I just changed it a month or two ago. It pressurizes just fine to oem specifications and you know damn well Its got the OEM thermostat.
some creative ducting might help; the issue here is not so much cooling as the fact the engine should not be sitting at 3500+RPM for any length of time, regardless of whether it overheats or not. period.

[No 240.. No id]

Originally Posted by kingtal0n

wow. This is my car. Everything is oem and its perfect. His problem is that redtops are not designed to be at 3600rpm on the highway in florida weather; thats it. The turbine is too small and the gearing is too short for it. If you disconnect the turbine it will no longer overheat because thats where all the heat is coming from. Otherwise, i told him to just drive 65mph @ 3000rpm because thats where engine vacuum is 10" about as low as you want to go for steady highway speeds.

At 80mph and 3600rpm the vacuum is around 3"-5" the engine is damn near in boost and it gets hot after 50 miles on that t-25, yeah. I suggested the 6-speed because then you can run the 3.4x gearing and drop the cruise rpm. Likewise he can upgrade the turbo to something with a larger turbine and that will also remove the heat from the engine.

A; upgrade turbine
b; better gearing
c; drive slower (3000rpm and 10" vacuum)
d; disconnect turbine (free) highly recommended for highway drives if you are going to beat on the engine with outlandish rpm
e; cooling system upgrade (but i prefer oem radiator)

the water pump is brand new i just changed it a month or two ago. It pressurizes just fine to oem specifications and you know damn well its got the oem thermostat.
Some creative ducting might help; the issue here is not so much cooling as the fact the engine should not be sitting at 3500+rpm for any length of time, regardless of whether it overheats or not. Period.

wow.......

[240boi115]

how the hell are you going to say a motor cant operate properly at its factory settings? if that were the case the motor wouldnt have been put in the nissan cars.... maybe im missing the point here.. has anyone considered a freezeplug issue? no fluids are leaking?

[Kingtal0n]

Originally Posted by 240boi115

how the hell are you going to say a motor cant operate properly at its factory settings? if that were the case the motor wouldnt have been put in the nissan cars.... maybe im missing the point here.. has anyone considered a freezeplug issue? no fluids are leaking?

I am going to humor everyone in this thread for fun that doesnt know me. For those of you that do... sit back and enjoy the show.


now, I wonder who is missing the point here. I love this.
Since when was this engine installed in any Nissan cars in America? Hmm I wonder why it was never installed in Nissan cars in America. I wonder if it has anything to do with our... climate... whos to say


I am not going to be gentle so do your homework before you post up

next question

[cotbu]

I just skimmed through this thread, but OP, seems like you got beat! aka sold a lemon! Fact, Florida is not the hottest place in the united states. The next few days temps in Arizona will be hotter than Florida for instance.

Being that we/I know were the seller stands on the performance of a stock engine, I think that he actually believes what he is telling you, when he said

Redtops aren't made to go past 65mph and to be able to do that I'd have to get a bigger turbo and a 6 speed trans.

wow. this is my car. Everything is OEM and its perfect. His problem is that redtops are not designed to be at 3600RPM on the highway in Florida weather; thats it. the turbine is too small and the gearing is too short for it. If you disconnect the turbine it will no longer overheat because thats where all the heat is coming from. otherwise, I told him to just drive 65MPH @ 3000rpm because thats where engine vacuum is 10" about as low as you want to go for steady highway speeds.

At 80MPH and 3600RPM the vacuum is around 3"-5" the engine is damn near in boost and it gets hot after 50 miles on that T-25, yeah. I suggested the 6-speed because then you can run the 3.4x gearing and drop the cruise RPM. Likewise he can upgrade the turbo to something with a larger turbine and that will also remove the heat from the engine.

A; upgrade turbine
B; better gearing
C; drive slower (3000RPM and 10" vacuum)
D; disconnect turbine (free) highly recommended for highway drives if you are going to beat on the engine with outlandish RPM
E; cooling system upgrade (but I prefer OEM radiator)

I really don't think you should take on this project, there's definitely issues somewhere, be it a blown, warped or just a shitty build. Maybe you could get a refund or have the seller fix the obvious issue of overheating.

[OrangeVirus1]

Originally Posted by Kingtal0n

D; disconnect turbine (free) highly recommended for highway drives

yes OP, just take the intercooler pipe off the turbo. the maf is useless anyway.


By the way, I can make engine Vacuum whatever I want at whatever RPM I want... I can have 20" at 8k rpm..

[jr_ss]

Kingalton, I drove my S14 sr20det w/ BPU's without one issue of overheating on the interstate at 80mph set on cruise w/ stints of 100mph pulls. I never once had to pull over to cool the car down. Regardless of how well you took care of your car, there is an underlying issue here and it needs to be fixed and/or upgraded.

With that said, don't play that drive at 65mph/>3000rpms crap. All cars in this day and age cruise at 80mph and 3500rpms and dont over heat. Hell my STI at 80mph was at 33-3400rpms, was probably at 6-7inhg and I never overheated.

And why the hell would you ever recommend to disconnect the Turbine?

[OrangeVirus1]

Since when does your vacuum have to do with overheating anyway, I cruise at 0'' vacuum all the time

[ultimateirving]

Originally Posted by Kingtal0n

wow. this is my car. Everything is OEM and its perfect. His problem is that redtops are not designed to be at 3600RPM on the highway in Florida weather; thats it. the turbine is too small and the gearing is too short for it. If you disconnect the turbine it will no longer overheat because thats where all the heat is coming from. otherwise, I told him to just drive 65MPH @ 3000rpm because thats where engine vacuum is 10" about as low as you want to go for steady highway speeds.

At 80MPH and 3600RPM the vacuum is around 3"-5" the engine is damn near in boost and it gets hot after 50 miles on that T-25, yeah. I suggested the 6-speed because then you can run the 3.4x gearing and drop the cruise RPM. Likewise he can upgrade the turbo to something with a larger turbine and that will also remove the heat from the engine.

A; upgrade turbine
B; better gearing
C; drive slower (3000RPM and 10" vacuum)
D; disconnect turbine (free) highly recommended for highway drives if you are going to beat on the engine with outlandish RPM
E; cooling system upgrade (but I prefer OEM radiator)

the water pump is brand new I just changed it a month or two ago. It pressurizes just fine to oem specifications and you know damn well Its got the OEM thermostat.
some creative ducting might help; the issue here is not so much cooling as the fact the engine should not be sitting at 3500+RPM for any length of time, regardless of whether it overheats or not. period.

Hey buddy, i Drive 80 mph to work daily in ARIZONA ie 115* heat easy in the summer. Now this is with the a/c on and the stock radiator And i am not overheating. S13 sr with 91 or e85 it doesnt matter what tune im on.

[13esim]

So on the highway it overheats? not the city? Your fan is fine, the fan is there to bring air through the radiator when your car is moving slower or at a stop. On the highway you already have air flowing through the radiator so the fan shouldn't even be functioning. The problem lies within your radiator.

Do a visual and look to see if there is anything noticeably wrong with your radiator (Plastic bag stuck, trash leaves stuck, damage etc.)

Also look at the fins on the radiator to see if they are damaged or if they look greenish

[Kingtal0n]

#1: I put the car together FOUR years ago and daily drove it for four years thousands of miles and never had a single issue.

Then, suddenly, a new owner takes it and it's "over heating" ? interesting.


#2: Since I daily'd that car for four years, I know everything about it. I know exactly what it takes to overheat that engine on the highway. It needs to be run hard in 5th gear for 5-30 miles to see the temp gauge start creeping up. Not actually overheating, notice he never said radiator was leaking or blowing smoke or anything like that; its just getting hot and the temp gauge is walking up.


To cotbu: you shouldnt fuck with people like that on the internet, especially noobs. This kid doesnt know anything about cars and he might take you seriously. Theres a video somewhere of him free-revving it in neutral for @#(* sake.

To people with T-28's: This is not a S14 sr20det, this is a 1990 redtop with a T-25 from a 180sx that had 33,000miles when I swapped it into that vehicle with ALL oem equipment. If it does ANYTHING its because the OEM components are not up to the challenge. After cruising for 20 minutes at 80MPH the hot pipe is over 150*F and impossible to touch.


Lets get one more single thing straight: you do NOT run a redtop at 3500rpms continously because it will eat up the engine bearings. This is a 25 year old antique engine. I was able to drive it daily because I babied it and I told the kid that I did and warned him not to beat on it. I dont care if its "getting hot" or not; you dont run a redtop at 3500rpm+ continously on the highway. period. Anyone that disagrees has their own opinion and they can pay for his engine bearings when it develops a rod knock.

[Kingtal0n]

To the new owner: why dont you get a video of how you are driving the car when it starts "overheating"? That would settle this once and for all, wouldn't it? Hell, bring the car by me and I will take the video myself using my camera on I-95 and show everybody exactly what it takes to get that gauge to start moving up. I know exactly what you are doing to that engine. You need to drive it less aggressively or it will not last very long.

[Kingtal0n]

On some level I still feel like I own the car and that I need to depend on it daily to get me to school... that is why I express this level of concern regarding the RPM of the engine on the highway. The truth is... If the new owner understands the risks of operating the antique engine at 3500+rpm continously on the highway.... then I would simply recommend a bit of creative ducting or an upgraded radiator as a permanent fix to this "problem". JUST REMEMBER to add an oil cooler ALSO. And the reason it was never a "problem" for me was because I understand the limitations of the antique redtop engines having owned several of them in the past and I knew that I could never bring myself to steady cruise at 3500+rpm on the highway, therefore, an upgraded radiator was unnecessary.

Ive done fifty or more swaps, most of them documented, and at least 10 redtop swaps and this was the cleanest swap Ive ever seen. You cant ask for anything more than all oem equipment and every possible nut and bolt in the right place with the right torque specification. Thats exactly what he is driving. This is not a "build" this is an OEM engine with full oem equipment and around 50k miles tops.

"So kingtal0n, are you saying that a stock 180sx from Japan from 1990 if brought to Florida, and run on an 80*F day, at 80MPH+ and 3500rpm+ for extended periods of time some of which is spent in boost will probably get hot and move the temp gauge up?"

Kingtal0n: yes thats exactly what I am saying. And until I see someone with a 180sx here in Florida that can prove me wrong you just wont know. Sorry if I seem heated. No it doesnt get hot at night and no it doesnt get hot on a cold day either. And disconnecting the turbine is a GREAT way to preserve the life of the turbocharger AND the life of the engine oil on these redtop engines.

[240boi115]

Originally Posted by Kingtal0n

I am going to humor everyone in this thread for fun that doesnt know me. For those of you that do... sit back and enjoy the show.


now, I wonder who is missing the point here. I love this.
Since when was this engine installed in any Nissan cars in America? Hmm I wonder why it was never installed in Nissan cars in America. I wonder if it has anything to do with our... climate... whos to say


I am not going to be gentle so do your homework before you post up

next question

youre meaning to tell me that there is no other country with weather like flordia or worse in which the sr20 was used in a car??? really....i can agree with you on its age but im sure that the motor wasnt designed the way your saying it is.. im aware that we didnt get the sr here. im not stupid

[Nissan2nr22]

It actually gets hot at night too for driving in highway, even when its raining.

Im in the process of installing a new mishimito radiators with new hoses and fans.

Will post back with updates.

[OrangeVirus1]

Originally Posted by Nissan2nr22

It actually gets hot at night too for driving in highway, even when its raining.

Im in the process of installing a new mishimito radiators with new hoses and fans.

Will post back with updates.

Look the real reason it's overheating is because my penis is so small.


I'm sorry but if you listen to anything on this thread, you are retarded.

If you run your engine at 3500 rpm's it will eat the bearings.. because OIL has no fucking use at 3500 RPM
and disconnect your turbo

I mean Gesus fucking christ, even I don't say shit that retarded

[ultimateirving]

I dont agree with anything said about what kingtalon says.
Why would an engine that factory redlines at over 7k rpm, Have issues cruising at 3k
Eat up the engine bearings?
How do you come up with this?

[OrangeVirus1]

Originally Posted by ultimateirving

I dont agree with anything said about what kingtalon says.
Why would an engine that factory redlines at over 7k rpm, Have issues cruising at 3k
Eat up the engine bearings?
How do you come up with this?

Don't worry he also believes you have to Tune the Stock carbs on the SR to get full boost and that oil is optional.