Air lock? thermostat? or........

[Realnez]

Ok I just did a SOHC to DOHC swap and got everything going today. I've replaced water pump and put a used DOHC rad because my SOHC rad started leaking after I did the swap. Ok my problem is my engine heats up very fast and the top rad hose is very hot and was leaking at the rad and steaming and the bottom hose is cold (this is after a 5 min drive around the block). Is this because my thermostat is stuck or do i have an airlock in my rad? If anyone knows what I should look for let me know. I'd rather figure it out then try take 45 mins to try and get the "air lock" out.

thanks
JAmes

[PF_Doom]

That is about the same problem I had with my car. I changed the thermostat and now it runs fine and doesn't overheat. Try replacing the thermostat since its only about 9 bucks to replace. Make sure everything is on tight. Turn on your engine and let it run for a while or take it down the block. If it begins to overheat again just post up any problems, I'll try to help out if anything goes wrong.

[NIK90s13]

Did you bleed the cooling system with the heater on? If you did go thermostat like ''doom'' said. I would bleed it first, of is your fan on backwards? No insult, I bought my car cheap because it was over heating, Changed thermostat, blead blead, well the fan was backwards!!

[g6civcx]

There shouldn't be any leaks. Pressure-check and fix as necessary.

[Realnez]

the fan is supposed to blow on the rad right?

[ledzeppelin240]

No it sucks air through the rad. I would change the thermostat and then what you do is fill the system with coolant, leave the rad cap off run the vehicle at 1500rpm till it gets to operating temp. This is how I have always bled coolant systems after being filled and have not once had an air lock.

[Realnez]

i just realized that the clamp on the rad hose on the top of the rad was completely loose. I think this could have been the problem because the air flow was being pushed out at the hose and causing rad fluid to leak out and steam up. But Im still gonna change the thermostat and everything and will bleed the cooling system like you just told me to led, thanks guys if I still have a problem I will post it

[NIK90s13]

Good to hear it is that easy. Check the flow on the rad. like they said it should blow on the motor.

[Realnez]

nope its not that easy lol now its worse...went n started my car let it run for a bit, it got hot quick again and now theres a puddle of coolent under my firewall from the lower hose (heater core?) but the hose isn't clamped there either it was just this ghetto clamp that has no pressure on the hose. So hopefully it isn't my heater core because I herd they are a HUGE pain in the ass on s13's. If anyone has any suggestions please let me know

thanks

[ledzeppelin240]

As you said it is a lovely and involved job to change the heater core. I would get some new claps and replace all the clamps. Then get the coolant system pressurized to see if there are any leaks. This sounds stupid but you do have a belt on your water pump right. Even though it is a new water pump it might be faulty. Is it a Nissan OEM?

I say this because my friend replaced a water pump on a VW and it kept overheating, took abou 8 hours to realize that the new water pump was faulty...

[g6civcx]

It's not that bad to replace the heater core. You have to drop the dash and remove the crossbar. Otherwise just get a new heater core from Performance Nissan. It's only $140, which is a lot less than what I found at other places.

Chances are the core you have is clogged any way.

Also check your heater hoses. Most people don't install them correctly.

[Realnez]

well I clamped the one and its not leaking, but there is no hot air comming from the heater? The car still gets hot and the top hose on the firewall is hot and the bottom is cold is that normal? also I noticed that my water pump might be leaking a tiny bit even after I replaced the pump and seal. Anyone?

[ledzeppelin240]

I think you water pump has failed, put a new water pump in and I bet everything will work...

[g6civcx]

Both heater hoses should be hot. If not, you have air.

[Realnez]

K im gonna do the water pump, thermostat, and bleed the coolent. If this does not work I will be driving off the bridge with my car most likley over heating on the way down

[NIK90s13]

Did you bleed it after you clamped the heater hose? And don't forget the thermostat!! If your water pump is leaking from the pully or weep hole it is bad, If not is the gasket leaking?

[Realnez]

I did, I got my water pump, thermo and belt out right now and Im gonna replace them. I noticed that I had the pully at the crank for the water pump, ps pump was like hand loose. So maybe this was making the belt slip and not turn the water pump? either way Im replacing everything then bleeding the coolent and that should work. Also when I got back from a drive around the block the heater started blowing hot air. So i think it was just the water pump got turning at all times. let me know if anyone has any other suggestions

thanks

[NIK90s13]

Sounds like you got it down! Be Sure that the littel bleeder on the thermostat is on top when you install, if you didn't know.

[g6civcx]

Jiggle valve faces up on the thermostat.

[Realnez]

ok good to know cuz I put it in on the bottom haha, got everything in now Im just waiting for the shit to dry

[ledzeppelin240]

I asked you about the belts and now you find that out, bummer dude. But let us know how it goes when you take it for the next drive.

[NIK90s13]

You changed the thermostat, right? where the bleeder is on top, right?

[Realnez]

changed the thermo and the bleeder is on top(at first I put it on the bottom so at midnight I was out there changing it lol) , I also changed the water pump. I have to wait 24hrs for the sealer shit to do its work then I can test everything out.

For puttin rad fuild in then bleeding. From completly empty I turn on the car with rad cap on, take the cap off and fill while the cars running? Im not 100% sure whats the correct way. Then when do I bleed, does someone want to tell me so I know exactly what to do?

thanks

[NIK90s13]

Try to have the car at an angle, nose up. level is ok, I filled mine with the motor off and the heater on the hot side. Pull the bleeder plug wile filling, when the fluid runs out of the bleeder, cap it off. Run the car see if it heats up and circulates. After it cools then recheck it.

[Realnez]

replaced everything....let it idle while filling it up with rad fluid. Sat for a while then I took it around the block. Everything seemed good, I only drove it for like 5 mins after letting it idle for 15. Temp was normal, then I parked it and let it idle for a bit longer. Temp went up again, so now wtf do I do, Maybe I didn't put enought fluid in? Im gonna let it cool off then top it off. Theres no more leaking anywhere, so I dont know what else I can do. I bought the rad used off someone maybe the rads faulty?

[Realnez]

topped it up, it needed alot of fluid but same thing drove it for 5 mins and brought it back and temp went high again. This time I filled the res up too and when I turned off the car I herd bubbling at the res and it sounded like the coolent was boiling hot at the rad cap. What the fuck is going on....this is really starting to annoy me. Do you think the rad has a big air bubble in it or sumthing?

[Realnez]

started it up, took the cap off....let it idle and slowly filled it whenever it bubbled...let it idle for 10 mins then took it for a 5 min drive then let it idle for another 5 and it never overheated. Im gonna let it sit for a bit and grab sumthing to eat then do it over again to see if it heats up. So right now its fixed, but we will see haha

[dopeassjackson]

you may need to heat up your car to operating temp then top off the rad and let it cool down. make sure you have coolant in the over flow tank. it should suck some out of the tank when it cools down. o and your bottom hose should be cold if im correct it comes from the rad. the top hose comes from the T-stat. on my sohc i have had the whole coolant system dry and never had a problem when you keep toping the rad off while the car is running.

[g6civcx]

Make sure you set the temperature control on full hot to open up the watercock for the heater core.

I had a nasty airlock in the heater core. The only way I was able to bleed it was by loosening the upper heater hose. As soon as air bubles percolated out and coolant started flowing, I tightened it. The heater started blowing very warm heat after that.

Nothing else worked. I jacked up the front of the car. I opened up the bleed bolt. I kept adding coolant and squeezing the radiator hoses for 30 minutes.

Just a thought :)

[g6civcx]

Don't know why it double posted :(

[Realnez]

ok soooooooooooooooooooo.....lol I went along and got a permit for 2 days, went to pick up my gf from school and everything was fine, I drove about 10 mins and decided to go get some gas. As i pulled into the gas station I noticed it got hot again. So now im raging but then I let it sit for 2 mins got gas and turned it back on. I turned on the heat to full blast and it didn't over heat. So i drove for another 10 mins around going a bit fast and up hills and shit and it never over heated. So I can drive it but I need to have the heat blasting? Anyone know what to look for now?

[ledzeppelin240]

Headgasket, cracked head, bad rad cap...

[NIK90s13]

Ya I was going to ask about the radiator cap, Is the rubber seal good, It may be old and not holding pressire.

[Realnez]

motor is freshly rebuilt and dropped in. Maybe the rad cap is messed up, anyways its running fine now I just have the heat on the second bar and it dont overheat. Im gonna get a new cap tomorrow but Its not overheating so Im happy for now lol

[NIK90s13]

Cool, Dumb question, we talked about the fan earlier, is it blowing in the right direction, twards the motor?

[Realnez]

yep its blowing towards the motor. But yesterday I drove it around pretty much all day and it was fine. Today I drove around a bit more for about 20mins then came home and it started to get hot again? Its like the air flow gets stuck or the thermostat doesn't open at all times, because there are times when it doesn't overheat and when it does. Anyone know what this is?

[Realnez]

its like the first time I drive the car in the day after 20 mins it gets hot, then I let it sit for 5-10 and drive again and nothing. Remeber at all times the heat is on. But I've never noticed it gettin hot when the heat is on 4. WTF could this be? It seems like the thermostat isn't opening at all times, because I did buy a cheap lordco one. Should I take it out and run no thermostat and see wut happens? Let me know wut u guys think.

Thanks

[slideways2004]

replace your thermostat with a quality unit. replace your radiator cap with a 300sx cap. and then, bleed the crap out of it, it should take like 30 min. if you do it right

[NIK90s13]

Yea you could pull your thermostat to test the system, and get an oem thermostat or better if running it without works.
I had a similar problem, I would overheat some not all the way. Changed stat cap bleed, bleed, bleed, Oh, AND the fan was on backwards when I bought my car. The stat and cap fixed it after I fixed the fan, but wile I was messing with that I went and ordered a koyo radiator to throw in in case it did need it. (excuse to get it)

[ledzeppelin240]

To bleed it all I have done was
-fill coolant system full, with rad cap still off start the engine
-run it at about 1500rpm or high idle untill the thermostat opens (adding coolant as needed)
-then you could most likely put the rad cap back on and there should be no air in the system.

[NIK90s13]

Don't forget the bleeder on the intake!!^