Hello all need some help.
Car 91 SE-R (stock except for fart can)
Problem. Today while driving in high 90s weather temp guage started moving east bound (towards hot). This seemed to only happen once I turned the A/C on, not possitive about that yet, but that is when I would notice it. There is coolant in the radiator, actually visable when opening cap, overflow bottle is about an inch over max level, coolant stays at same level when car is running. Both radiator hoses seemed to be hot (then again with the sun beating and engine bay being hot everything under the hood was hot).

1) Any suggestions on where to start looking for the cause of the overheating?
2) Any possible damage from the needle going half way between the temp symbol and the end of the curved line that stops just short of the H?

Riding for 25 minutes in a car with the heater on full blast in 90+ degree heat is not fun, especially when you have sunburn that is still heat sensitive.
TIA

Originally posted by NISMOrob
1) Any suggestions on where to start looking for the cause of the overheating?

Check to make sure your radiator fans come on (they should come on when you turn on the AC).

Check to make sure the front of your condensor is clean (nothing to restrict air flow)

Originally posted by NISMOrob
2) Any possible damage from the needle going half way between the temp symbol and the end of the curved line that stops just short of the H?

Not terribly likely for a relatively short period of time.

i would bleed the system, they can over heat if theres 1 little air bubble in the system. there is a bleeder where the bottom hose comes into the engine, and one more against the firewall.

Yah, bleed it & check those fans. They should always come on when the A/C is on. The other problems are as follows... Thermostat has broken and thus no coolant moving (not very common on Nissans) or a common problem on high mileage Nissans. The connection on the temp sending unit gets badly corroded and you get improper readings. The larger sensor is for the ECU and controls the fans. The smaller sensor (one wire) only goes to the temp gauge. I had this problem with the gauge sensor a while back. Hope this helps.

Cossie

If you haven't changed the fluid in a while (or ever), try that. Use as little anti-freeze as you can get away with. Most people don't understand that coolant/antifreeze actually hurts the waters ability to transfer heat. I use ~70/30 mix of water/antifreeze which is good to about -10F, and I put in a bottle of Redline Waterwetter.

Having had 'not new' Nissans for the last 20 years, my experience is that if you get overheating at speed in hot weather, but not in traffic jams, then if fans etc. are working it's usually the radiator at fault.

In my area (salty U.K. roads) it always seems to be the horizontal corrugated thin metal fins that rot and become so thin after about 8 years that they do nothing but slow down airflow through the gaps between the vertical water channels and do little to conduct heat away.

A proper amount of anti-freeze is important as it has several anti-corrosion chemicals in it. change it every year or so. There are several types of anti-freeze on the market so make sure you don't get the wrong stuff. Yes, there is such a thing as the wrong type. Some new cars use a different mixture that is not compatible with 1990s etc... cars and some old anti-freezes are not compatible either. In hot weather a safe bet is about 40/60% anti-freeze to distilled water. Adding Water Wetter is an outstanding idea. The stuff works great!!! Please, always use antifreeze.

Cossie

Replace your thermostat first. Its cheap, and it probably needs it. Mine went out at 130k miles.

BTW, there was a sidebar in an article in SCC on the 240SX. They checked the readings with a voltmeter, and essentially the temp guage had 3 settings.

They went on to say that most factory guages have three setting: cold, normal, and hot.

So if your needle was running "towards" the H, your engine was already at a "too hot" stage. Im pretty sure theres no "barely overheating" with these type of guages.

Someone stop me if Im BSing.

Overheating on the highway while moving is a common problem on B13 and P10 cars. We just had this discussion at E-Town Sunday. There are tons of threads on the SE-R mailing list archives and there is yet to be a solution. It is even worst on the NX2000. This problem only seems to occur at temps over like 92-93. Anything below that is it OK. I have done a flush, thermostat, waterwetter, cleaned the condensor and changes to a 1 bar radiator cap. Nothing seems to help. It is a cooling problem I suspect. Turning on the heat helps. But it is annoying. At highway speeds the fans shut off so the header heat is not helping the situation if it is being circulated around with 100 degree ground tempetatures to the radiator.


Steve B's explination is probally on point. It sounds very reasonable.

do the fans always shut off on the highway? i rigged mine up to run all the time instead of when it starts to get to hot. would mine still shut off?

Overheating on the highway while moving is a common problem on B13 and P10 cars. We just had this discussion at E-Town Sunday. There are tons of threads on the SE-R mailing list archives and there is yet to be a solution. It is even worst on the NX2000. This problem only seems to occur at temps over like 92-93. Anything below that is it OK. I have done a flush, thermostat, waterwetter, cleaned the condensor and changes to a 1 bar radiator cap. Nothing seems to help. It is a cooling problem I suspect. Turning on the heat helps. But it is annoying. At highway speeds the fans shut off so the header heat is not helping the situation if it is being circulated around with 100 degree ground tempetatures to the radiator.


i have nearly all the same symptoms as NISMOrob except for the fact that my p10 always ran a little cooler (yes during the summer) until i had it on jack stands for about a month waiting on parts to do a clutch job. now that the car is back on the road, the temp gauge definitely starts rising only at highway speeds and if i ride up to 3k-4krpm more often.

never happened in my nx though which is wierd cause cooling is worse in the nx:confused:

i hope flushing the radiator and changing the thermostat with avshi's help will cure this:D

do the fans always shut off on the highway? i rigged mine up to run all the time instead of when it starts to get to hot. would mine still shut off?

This is a 4 year old thread..

does it matter? people always talk about searching and this thread has some good info and i just want some more...

any cure for this yet? i still over heat and i took out my thermostat and my fans are working fine....but i do not coolant in it just water *** i drained it all out while messing with the thermostat....at night time it never ever over heats though

bad radiator

ice, im having the same ordeal with my g20 right now but will be giving the radiator a flush and replacing the thermostat and radiator cap so i'll let you know after sunday.

If you buy a Koyo radiator you will have no overheating issues. I live in Houston. I did everthing to stop an overheating problem in traffic with the a/c on (we won't even talk about track events). Even a new 2 row aftermarket radiator. I bought a Koyo a few years ago and have had no problems. For the few months after I tried to make guage budge and I couldn't. I know they are pricey, but it has been the best peace of mind upgrade I've done.

So what will work better: a rad cap of 1.1 or 1.3 bar instead of the 0.9 stock one ? Boiling point will be higher right ?

you can avoid buying a nismo radiator cap ( i think theyre $30?) and go with a latest 300zx radiator caps. i believe they are a 1.2bar. i recently purchased a rs type radiator cap (1.2bar) for $10shipped.

Junknstiff, have you tried running distilled water? it semmed to help with my stuff. of course i did the waterwetter aswell but this turbo is no joke.