Cooling system from hell...

[evmal613]

The biggest problem I have had with my '91 s13 has been my slew of cooling problems. I recently updated my entire cooling system. Overheating has plagued this damn car and I am having second thoughts about the car. I bought and installed a new mishimoto radiator, hoses, water pump, thermostat, taurus fan, and coolant temp sensor. I drove around and i keep having very high temps. I burped the system of air pockets, with no avail.

I would love to get this crap fixed because its driving me nuts, I cant go over a mile without it overheating.

I've searched, and most people had to switch out the items I already replaced. This problem seems really strange and unlike what I have read in the past.

Help is definitely needed!

Thank You

[x757xEddie]

have you considered a bad head or head gasket leak?

[djsilver]

Let the car warm up then let it sit and idle with the hood up. Watch the overflow reservoir and look for bubbles. If it continues to bubble after the car has fully warmed up, you have a leaking headgasket. I had one with no oil in water or water in oil but the headgasket was leaking combustion gas into the cooling system and causing it to overheat. I hope that's not your problem but you need to check in order to narrow down what's really happening.

[TNathe]

yeah, the only thing left for you to do to resolve this is pull the head off the motor and find your ganked up headgasket. Does your car lose coolant (i dunno if you can drive it long enough to tell though)?

[evmal613]

I still need to test my head gasket, that is the other thing i suppose. It doesnt lose coolant, its all there. It doesnt bubble like it used to. If it bubbles after warming up, is a head gasket the only thing that bubbling could be caused by??

Can anyone fully describe the benefits of a swirl pot, or surge tank for my coolant??

Much appreciated

[djsilver]

If it's warmed up and continues bubbling in the reservoir then combustion gases are getting into the cooling system. It could be the headgasket or the head could be cracked. If the cooling system is not leaking fluid then the only way for air/gases to get into the system is from the combustion chambers because it's the only thing on the motor (except for the oil system) that's at a higher pressure than the coolant system.

Swirl-pot? The 240sx has an open surge tank connected to the cooling system by a single hose from a vacuum/pressure relief in the radiator cap. When the system warms up the coolant swells and it allows the extra to flow into the surge tank. If there's any air in the system, it will escape to the surge tank along with the extra fluid through the same hose. When the system cools off the coolant shrinks, which pulls a vacuum and draws coolant out of the surge tank and into the radiator.

Most newer cars have a pressurized surge tank. It's designed with the tank higher than the cooling system and has a direct liquid connection to the cooling system and a vent connected to a high point on the cooling system to allow any air to escape into the tank. On this type of system you wouldn't see any bubbles in the liquid because they'd escape through the vent line into the surge tank and be replaced with coolant through the liquid connection. With this style it's harder to troubleshoot but it would still overheat and the extra pressure from the gases would be relieved by the cap on the surge tank.

[evmal613]

thanks for the nice reply. I'm going to do a leak down test this weekend hopefully, and re-bleed everything to the best of my ability.

[evmal613]

Well, I haven't done the tests yet, but I bled the best i could with more overheating. Today, I put a pill wedged in between the thermostat to hold it open so i could bleed everything in full circulation. Cool concept, no luck. I just took out the thermostat and it ran fine all day. With my mishimoto and no thermostat was a little TOO efficient, and the car ran under the operating temp. I didn't really even kick on the e-fan either. I thought I would let you know I solved the issue (temporarily i suppose).
Thanks

[snappy]

I kind of skimmed over the responses but have you tried running the car at idle with the radiator cap off and take off the bleeder nut that sits near the upper radiator hose where it meets the motor? (It has a yellow sticker that says "Do not open when hot") I was having overheating problems with my S13 KA24DE and that was the solution, there was just a pocket of air in my radiator.

As soon as I saw the coolent level go down on the radiator I would top it off until bubbles stopped spiting out the bleeder nut opening and the top of the radiator liquid stopped going down. I put the bleeder nut back on and tightened it down all the way and put the radiator cap back on and haven't had a problem.

[dr.klawn]

since you said wen you take the t-stat out it runs under temp, try taking the thermostat & drilling 1 or 2 small holes on the flat surface of the t-stat where it's used for mounting. don't go larger than like 3/32'' and if u have a cple of extra t-stats u can experiment with diff holes #'s of holes and sizing. this way u can have water passing through b4 it opens to possibly keep it from overheating. don't go too large with the holes or it wont work well on the interstate. it's a common trick used on v8's and especially if you live in the south!!

[S14Serge]

Bleeding the cooling system in KA's can give you a hard time for sure, but just keep bleeding the system until you get all the air out....I advise you to unscrew the bleeder screw in the intake manifold, keep radiator cap off and let it idle for about 20-30 minutes while squeezing the top and bottom radiator hose.