sr20det overheating after WOT pull

[1988montecarloss]

my sr20 has had zero cooling issues so far after a week and 600-ish miles of ownership...until this morning. I drove probably 10 miles from home just babying the car, made a 1st-4th WOT pull and kept driving along normally for awhile then turned around and started heading home, no issues at this point. On the way home i made another 1st-4th WOT pull and started smelling coolant and noticed my temp gauge was going up but hadnt quite made it to the "H" on the gauge. So i babied the car the rest of the way home, the temp gauge went back down and when i got home i opened the hood, there was coolant everywhere and i noticed the nipple for the expansion tank was broken.

so i figured my issue was that the broken nipple on the radiator let enough coolant out for the car to start running hot, simple enough fix. get a new radiator or fix this one.

after letting the car completely cool i took the rad. cap off, started the car and filled the coolant back up while the car was on an incline to bleed out any air that could have been in the system. I then ziptied a rag around where the broken piece was to keep it from leaking too fast and let the car sit there idling for 20 minutes to see if it would start running hot again. the needle on the temp gauge went to the middle and sat there like it always has. so i start driving again and just babying the car for the first 10 miles or so and make another 1st-4th WOT pull, no issues, car stays at operating temp like usual and i figure that must have been the issue, turn around and start heading home and halfway home do a WOT pull through 3rd and 4th and the car starts heating up again worse than the first time, the temp gauge gets to the top and i limp the car home with the gauge never falling to far from the top and hovering around there. When i get home i shut the car off immediately and open the hood. there are no leaks because of the rag ziptied around the cap neck but it is hissing and steaming from the thermostat area, there is also a leak coming from somewhere other then the radiator but im not sure where because i can only see it dripping from the bottom of the car.

heres the thing that stumps me though, it cant be a headgasket because there is no coolant in the oil or no oil in the coolant, but why does it not overheat until after a 2nd WOT pull? if it was the thermostat id think it would overheat while idling

at this point im thinking of just ordering another radiator and thermostat just to be able to rule that out for sure but i really dont want to spend the $200 if i dont have to.

the car is an S13 coupe with a stock (other than exhaust and FMIC) s13 sr20det in it at stock boost on a stock ecu. the radiator is an aluminum CXracing piece.

the speedo also stopped working last night as well but that has to be an unrelated issue, or at least i hope the fuck it is lol.

sorry for such a long read but im not sure where else to ask and need the car to be 100% asap as its my daily driver

[1988montecarloss]

UPDATE: started the car cold with the heat on full blast parked on an incline, filled the coolant and bled it, once the car was up to temp the thermostat opened and the coolant level went down so i know the thermostat works, the coolant wasnt bubbling or anything like that and i just let the car idle until it was warmed up with the cap off, temp stayed right where it should. then i revved the car while squeezing the hoses to see if the pressure increased and nothing happened, hoses didnt harden up from pressure getting into the system or anything like that, revved the car again until it got into boost and some spilled out of the radiator, but it was filled right to the top and not a lot came out so im not sure if its from pressure getting into the system or just the coolant level slightly rising from the water pump spinning faster. but there were still no bubbles or anything like that.

so i put the cap back on and let the car keep idling for 10 minutes or so and the temp never rose so i start driving and no issues just cruising along, even got into boost in 3rd at about 2/3 throttle and there was no issue, kept cruising along and decided id go WOT again. so i go WOT through 1st and 2nd and then just start cruising along at 40 and the temp starts climbing but doesnt quite make it to the top of the gauge and just stays there (posted pic)
i was only 1/2 mile from home at this point so just drove the rest of the way slowly and pulled into my driveway and while it was sitting there idling the temp actually started to go down, at this point i hear something leaking so i open the hood and can see steam coming from the intake area again like yesterday and then i notice a small steady stream of coolant coming out of underneath the intake towards the firewall right above the starter (posted pics of leak) so i shut the car off and put a drain pan under the leak and come inside and write this

also the whole time i was putting coolant in/bleeding the system and driving with the heat on it wasnt blowing hot as it usually does either

so could this be a bad heater core? leaking hose to the heater core?

there were also no leaks out of the hole where the broken expansion tank nipple is either but the car never "overheated" either like it did yesterday

my next plan of action is going to be a compression test but the oil and coolant are still clean and not mixed so i have a hard time thinking it would be a headgasket, the last picture is from the top of the intake looking down into the area where it was leaking, the hose on the barb in the center of the pic seemed to be on there tight when i pulled on it so i dont think thats what was leaking

[slideslidegnarslide]

Sorry I'm on my phone but is that coolant spraying out of that hose? Looks like a stream of pee shooting out. If it's not coming from that hose find the leak find your problem

[1988montecarloss]

Sorry I'm on my phone but is that coolant spraying out of that hose? Looks like a stream of pee shooting out. If it's not coming from that hose find the leak find your problem

not sure, i couldnt see exactly where it was coming from

im really hoping i can fix whatever is leaking without having to take the whole intake assembly off :ugh:

[Driftzenki]

might be pushing coolant (boost getting in you're cooling system), had the same problem, under wot coolant would spit out through the radiator nipple, under normal driving everything was fine, tried rigging it but the boost blew my heater hoses, compression test wont due any good cause it only happens at full boost, compression will come out normal, the problem was my cometic head gasket not sealing properly, upgraded to apexi head gasket and fixed the problem

[1988montecarloss]

might be pushing coolant (boost getting in you're cooling system), had the same problem, under wot coolant would spit out through the radiator nipple, under normal driving everything was fine, tried rigging it but the boost blew my heater hoses, compression test wont due any good cause it only happens at full boost, compression will come out normal, the problem was my cometic head gasket not sealing properly, upgraded to apexi head gasket and fixed the problem

how tough is a headgasket on one of these? does the valvetrain have to come apart to get the head off?

im not as familar with sr20's as i probably should be, but i have done HG's on honda B and D series and multiple different pushrod V8's so im pretty sure id be capable of doing it

[slideslidegnarslide]

Similar to a b series. You have to take the cams out but everything else stays in place. Everything else stays in place. Obviously have to take out timing chain tensioner and cas

Also look up the torque specs and follow fsm sequence when tightening the head and cams back in. I forget but I think the head is between 80-100 flbs and the cams caps are 8.4. Not 100% and you tighten them in 3 passes

[1988montecarloss]

Similar to a b series. You have to take the cams out but everything else stays in place. Everything else stays in place. Obviously have to take out timing chain tensioner and cas

Also look up the torque specs and follow fsm sequence when tightening the head and cams back in. I forget but I think the head is between 80-100 flbs and the cams caps are 8.4. Not 100% and you tighten them in 3 passes

any idea what it is could be leaking under the intake? going to try to get that sealed up first before i take the head off

[iJDM]

Just an idea you may want to rent a coolant pressure tester from a local parts store to see if that helps identify your mystery leak. If you still can't find it you may want to dye the coolant which could help you find it regardless of where it is.

[jr_ss]

Just because you don't have fluids mixing doesn't mean your head gasket isn't blown. You could've open a wier to a coolant passage and when under boost you see this issue. A leak down test would give you a better idea of what and where it's happening. Another tool to use is a hydrocarbon test. Local Napa should have them. It will tell you that your head gasket is popped by testing the coolant.

Suggestion, quit beating on the car knowing you have an issue. A leaking radiator isn't something to take lightly.

[Kingtal0n]

If it only overheats (temp rises significantly) during/after WOT pulls, check your ignition timing, that is a symptom of retarded timing. Sometimes people put the timing light pickup on backwards and do not realize it, was the car recently timed?

It could also be a sticking thermostat if the engine was recently swapped and run for the first time in 15~ years.

Also, you should not rely on the OEM temp gauge. You do not need a permanent install gauge, just get something, anything better than the cluster gauge just for now at least, to monitor your precious engine, one good overheating and that's big problems.

[1988montecarloss]

Just an idea you may want to rent a coolant pressure tester from a local parts store to see if that helps identify your mystery leak. If you still can't find it you may want to dye the coolant which could help you find it regardless of where it is.

will do, thanks

Just because you don't have fluids mixing doesn't mean your head gasket isn't blown. You could've open a wier to a coolant passage and when under boost you see this issue. A leak down test would give you a better idea of what and where it's happening. Another tool to use is a hydrocarbon test. Local Napa should have them. It will tell you that your head gasket is popped by testing the coolant.

Suggestion, quit beating on the car knowing you have an issue. A leaking radiator isn't something to take lightly.

i will check the local napa tomorrow for a hydrocarbon tester

but its not like im taking the car out and thrashing on it for shits and giggles, i cant tell whats wrong with it without doing that since the only time this happens is after WOT, but after todays leak i dont even want to take it out at all anymore



If it only overheats (temp rises significantly) during/after WOT pulls, check your ignition timing, that is a symptom of retarded timing. Sometimes people put the timing light pickup on backwards and do not realize it, was the car recently timed?

It could also be a sticking thermostat if the engine was recently swapped and run for the first time in 15~ years.

Also, you should not rely on the OEM temp gauge. You do not need a permanent install gauge, just get something, anything better than the cluster gauge just for now at least, to monitor your precious engine, one good overheating and that's big problems.

timing has not been touched since ive owned the car and it had no issues when i bought it, i even drove it 3 hrs home and have put 600 miles on it since so i dont think it will be the timing, but what should the timing be set at? everything is worth checking at this point. :facepalm:





im almost to the point where im just gonna bite the bullet and redo the whole cooling system and replace the headgasket/bolts just so i know i have all my bases covered but even then i still dont know what caused it in the first place. i want to buy a wideband and boost gauge and run the car on an enthalpy tuned ecu on the stock turbo at 12psi eventually, what headgasket should i run and what headbolts? OEM nissan?

[Croustibat]

timing has not been touched since ive owned the car and it had no issues when i bought it, i even drove it 3 hrs home and have put 600 miles on it since so i dont think it will be the timing, but what should the timing be set at? everything is worth checking at this point. :facepalm:


A worn cas can retard timing, which makes a lot of heat and leads to cooling system failure. It pairs with losing power, too.
Your head might lift under boost too if it has not been correctly fastened, but it is unlikely at 12psi. And a weak fuel system makes it run lean, which can also produce heat (but you may have felt some hiccups while driving)

Thing points to a damaged HG, but the head and block need to be checked for flatness at the same time. If one of them is warped, changing the HG will lead to blow it again fast. But HG failing is merely the result of another problem. The HG acts somewhat like a fuse. Just as stamped steel suspension arms bend on a crash, preventing damage to expensive subframes and knuckles, the HG blows, preventing head and block cracking. Switching to a stronger HG means you are removing that fuse, so you'd need serious monitoring to react before damage occurs.

And as kt said, get an aftermarket temp gauge. The temp sensor is fine, but the gauge is designed to prevent the user from being afraid. it nearly does not move from 60 to 95°C... Basically, when it moves up, you are already overheating and your HG may have taken a shot.

Boost gauge is a bit useless imho, and redundant if you have a boost controler.
IMHO the best gauges to monitor problems are AFR and EGT ones, these can tell you immediately when something goes wrong, before it breaks the engine.
You can't see your EGT shooting through the roof, but with a gauge telling you it is happening you can immediately back up and prevent damage.
Oil pressure sensor helps detecting when there is not enough oil, or when it needs changing, or when the oil pump is worn. Other temperature gauges ...

Well they are don't really tell you anything except your cooling system has reached its limits, which should not happen at 12psi with a bigger radiator, even if you track the car on a twisty, slow track, on hot day with slick tyres.

[1988montecarloss]

A worn cas can retard timing, which makes a lot of heat and leads to cooling system failure. It pairs with losing power, too.
Your head might lift under boost too if it has not been correctly fastened, but it is unlikely at 12psi. And a weak fuel system makes it run lean, which can also produce heat (but you may have felt some hiccups while driving)



the car is not down on power at all and has a walbro 255 and stock 370cc injectors and is just running at stock boost 7psi



And as kt said, get an aftermarket temp gauge. The temp sensor is fine, but the gauge is designed to prevent the user from being afraid. it nearly does not move from 60 to 95°C... Basically, when it moves up, you are already overheating and your HG may have taken a shot.

Boost gauge is a bit useless imho, and redundant if you have a boost controler.
IMHO the best gauges to monitor problems are AFR and EGT ones, these can tell you immediately when something goes wrong, before it breaks the engine.
You can't see your EGT shooting through the roof, but with a gauge telling you it is happening you can immediately back up and prevent damage.
Oil pressure sensor helps detecting when there is not enough oil, or when it needs changing, or when the oil pump is worn. Other temperature gauges ...


will a cheapo parts store temp gauge suffice? and where is the coolant temp sender on this motor?

can you also explain why a boost gauge would be redundant? how else would i know what psi it is at? i just plan on running a manual boost controller, nothing fancy

[Croustibat]

i just plan on running a manual boost controller, nothing fancy

I am a strong follower of "Do things properly or don't do them".

MBCs are crap and will always be unreliable crap. EBC have become way cheaper than before. I suggest you go that way, even if it cost a couple more hundred bucks.

If you can't shell out a couple hundred bucks for an EBC, sell that car because its maintenance cost is way too high than what you can afford.

[1988montecarloss]

I am a strong follower of "Do things properly or don't do them".

MBCs are crap and will always be unreliable crap. EBC have become way cheaper than before. I suggest you go that way, even if it cost a couple more hundred bucks.

If you can't shell out a couple hundred bucks for an EBC, sell that car because its maintenance cost is way too high than what you can afford.

any recomendations on an ebc? and can you explain why a boost gauge is redundant?

[cotbu]

A boost only gauge maybe redundant, but a boost/vacuum gauge isn't. MHO.
If boost is set, then it's set, but other things can happen, when part throttle that a boost/vacuum gauge can show you right away, but a wide band might not react to immediately, and an egt gauge won't even flinch at. Because not a race car!

I like blitz dsbc's simple, easy to use. I'm sure there are many just like it cheaper or more expensive. They have a built in boost and vacuum gauge display go figure. Over boost pretection, warning feature 4 boost settings, 5 if off and using waste gate, and scramble boost.

I don't like the avc-r's, to complicated for what I want or need.

From a Highly Tuned Note 4.5!!!

[corby_baby]

had the EXACT same problems and spent countless hours narrowing down the solution. The only way to determine what it is would be to cross them off one by one (probably starting with easiest first).

First check your radiator cap and make sure it holds the pressure it states.

Since you have already determined your car heats up and runs fine when you baby it means your thermostat is working properly and coolant system is fine. Since you overheat right after boosting, you could very well be lifting the head in boost and pressurizing the coolant passages (causing instant overheat).

When i pulled mine apart i had the head checked just in-case with no issues. Only thing i figured was the head was not torqued down properly from previous owner.

Good luck!

[1988montecarloss]

UPDATE 2: wanted to rent a hydrocarbon tester so i drove the car to autozone, babied it the whole way, never got into boost, never revved over 2k, was fine the ride over (3 or so miles) and about halfway home started heating up but the needle on the gauge never went above 3/4. got home let the car cool down before i took the cap off, started it back up and let it get up to temp. did the coolant test (liquid is supposed to turn from blue to yellow if it comes in contact with exhaust gases) the liquid stayed blue, revved the car up got it into boost, still stayed blue, let it sit there running and it didnt start overheating but the coolant started pissing out where it has been under the intake.

all im thinking at this point is maybe its not the boost causing the overheating but just the high rpm?

bubbles in the test liquid are just from the tester, not pressure getting into it

ill probably take the intake off tomorrow to see what leaks i can find and order a new radiator and cap while im at it since the expansion tank nipple on mine is broken anyway

[coupesallday!]

Get a new radiator with fans and wire them properly. The thermostat is a autozone one so maybe it's getting stuck? Also it might be leaking from a heater hose connection under the intake manifold you might as well buy a intake manifold gasket pull it off and see what's leaking.

[slideslidegnarslide]

Find where it's leaking from!

[cotbu]

coolant started pissing out where it has been under the intake.You have to fix all the leaks in the coolant system before you can even consider the coolant bled and working properly. Air could be getting in the system just as easily as coolant pours out.

From a Highly Tuned Note 4.5!!! Using the Spen😱

[1988montecarloss]

tomorrows plan of attack is taking the intake manifold off and seeing what i find, is the intake manifold gasket on the rwd sr20 the same as a fwd sr20? think a parts store will carry one?

[1988montecarloss]

got the intake off and found where it was leaking from, going to be replacing all the hoses and clamps under there within the next few days and getting it back together. going to order a different radiator/cap/hoses and thermostat too

[1988montecarloss]

finally got the rest of my stuff in today, replaced the radiator and hoses since it still had a KA radiator in it and put an OEM thermostat in while i had it apart, also replaced all the old dry hoses and clamps that were under the intake and the car doesnt overheat anymore, so that must have been my issue, thanks for the help guys :)

[jr_ss]

I'd keep an eye on things for a few days. Just because you replaced hoses doesn't mean it won't over heat. What boost pressure are you running at? Was this ever asked?

[TheRealSy90]

It's a stock redtop at less than stock boost ~7psi.

Idk why everyone was getting all technical when he stated in the first post that he had a coolant leak, and then posted pictures of it leaking... MUST BE THE TIMING.

[1988montecarloss]

I'd keep an eye on things for a few days. Just because you replaced hoses doesn't mean it won't over heat. What boost pressure are you running at? Was this ever asked?

It's a stock redtop at less than stock boost ~7psi.

Idk why everyone was getting all technical when he stated in the first post that he had a coolant leak, and then posted pictures of it leaking... MUST BE THE TIMING.

yup motor is at stock boost, but im definitely not going to venture to far from home for a few days to make sure its fine :2f2f: