viktornguyen

Was driving the other day and the engine started to sound louder than usual. I think the fan came on ( about 30 degrees F or less outside). Turned up the heater and it was blowing cold air.

The engine temp seemed normal. About 35-40% up from the C.
This sound like the start of a bad thermostat??

njmodi

iTrader: (4)

A stuck open thermostat would cause your car to run cold (especially in winter)... i.e. the gauge needle would not indicate what you consider "normal" temp.

You could have a clogged heater core, bad heater control valve...

darklegend06

iTrader: (11)

I had the same problem, but since I changed the thermo thing. It's too hot in my car. Once in a while I have the problem with it not blowing hot air, so I turn it off once and turn it back on to fix the problem. I have and auto temp controller.

TurTLe*

iTrader: (11)

it really doesn't, but i could be wrong. A bad T-stat stuck open will cause your car to take a long time to get up to normal temp, because its allow coolant into the raditor too soon. A t-stat stuck closes will more then likely cause you car to overheat, not allowing coolant to flow into the raditor. Thats kinda how i like to think about it. I haven't seen any cases of the t-stat stuck half-closed.

njmodi

iTrader: (4)

You could also have air in the cooling system... did his problem start recently? did you do cooling system flush or radiator drain/fill recently?

viktornguyen

It doesn't happen all the time... just weird how the heater gets "cold/not as hot" occasionally. Thought it's a symptom showing something worse will happen.

Tfvesquire

iTrader: (2)

Hope you didn't drive it far. I had the same problem on another car and it ended up being a pin hole in the thermostat housing gasket. I turned on the heater full balst to try and cool the engine, but all i got was cold air even though the temp gauage kept climbing until I pulled over and shut it down for awhile. Did the temp guage go higher than normal (ie: is 35-40% up from C normal?)? I don't know if you have a leak, but even if you did, the engine shouldn't get louder because of it. Sounds to me like, you are really low on oil!! Have you checked the oil level lately?

Normally, if the thermostat fails, it will get stuck closed and the car will heat up rather quickly, causing the fan to kick in sooner. I've had them get stuck open, but it's rare -- in that case, the car will take forever to heat up and blow hot air.

Check the oil level first, then the coolant reservoir to see if it's empty. Also, check for any coolant leaks while the engine is running. Good luck!!!

KRRZ350

iTrader: (29)

Have you checked your coolant? The heater core is the highest thing, and it's easy to get air in there. Don't check it at the overflow either, take the cap off and check it there, but ONLY IF YOU CAN HOLD YOU'RE HAND ON THE RADIATOR!!! When was the last time you serviced your coolant anyways?

viktornguyen

So the car could be overheating without the needle showing it?

KRRZ350

iTrader: (29)

wow! everybody answered at the same time! Where it is always at is normal, I'd consider it like 45% (50% being staight across) nissan was clever enough to even put a tiny white dot right below where the needle sits!!

KRRZ350

iTrader: (29)

If you're overheating you'll know it, check the level under the cap first.

viktornguyen

I changed my oil&filter about 2 weeks ago. Haven't checked the coolant level tho. I had an aftermarket radiator put in about 1.5 years ago.
I'll check my coolant level and post...

njmodi

iTrader: (4)

How is his temperature and heating problem in any way related to being low on oil?

Wrong again. Thermostats are designed to fail OPEN. Obviously running cool does much less damage to the car then overheating - and this is why the are designed this way. They fail OPEN far more often than closed.

Maxima-4DSC

iTrader: (1)

no hot air = one of two things most likely...bad heater core....door flap from hot to cold is stuck. i also have ACC

Tfvesquire

iTrader: (2)

"How is his temperature and heating problem in any way related to being low on oil?"

Man, beating up on a fellow Chi-town member. If you run the car (any car) low on oil, that will create more friction. More friction creates more heat. Plus, this would help explain the louder engine noise he was referring to.


"Wrong again. Thermostats are designed to fail OPEN. Obviously running cool does much less damage to the car then overheating - and this is why the are designed this way. They fail OPEN far more often than closed."

I agree newer thermostats are designed to fail in the open position -- I don't know how old the member's 'stat is. Because he said the fan kicked in way to early considering the outside temperature, that would lead me to believe it was either stuck closed or he is low on coolant. BTW, I have actually heard of more thermostats getting stuck closed versus people complaining their cars won't heat up in the winter.

njmodi

iTrader: (4)

Nah - I wasn't beating up on you man... I just like using that smiley... I just didnt want any mis-information. I still don't think low-oil will cause "overheating"...

"Newer" is relative.. my first car (a 1988 year) also had a thermostat that failed - it stuck open...

I know you're trying to help - so no harm done. You've had a lot of good things to say (in general) - I just thought you were off the mark on this one... feel free to correct/teach me when I'm out of line ...

Do you work on cars for a living? (I don't)....

Cheers.

Tfvesquire

iTrader: (2)

That's ok, I have tough skin. (smile) As for the low oil causing "overheating" I highly doubt it will cause the car to get to the point of boiling over, but it will cause the temperature to raise and can cause an audible "knock" as the valves start banging against the camshafts due to reduce lubrication.

I still stand by my thermostat review based on my personal experience. And yes, I have worked on, rebuilt and overhauled more cars in my short life than I care to admit. Just replaced a thermostat in a 1996 Camry last wknd that was stuck closed and caused the fans to kick in after only driving the car 20 mins or less. And that was with no leaks and full coolant level.

I have followed your posts and can say the same for you -- you have a lot of good information and advice for fellow members. I don't claim to know everything about every car and appreciate when a member steps in to steer me in the right direction.

Take care.

ImmaSquashYou

iTrader: (7)

if your needle goes from cold to normal when parked, and when you turn on the fan, n cold air is coming out. It most likely isn't a thermostat problem. When i had a thermostat problem i knew it right away. My car was blowing hot air when i was parked stopped, n once i started driving, i guess the cold air cooled the car more n the needle started to drop n i started to loose my heat. But if the temp guage is at normal, n cold air is still blowing out, it might be your heater core. Try to flush out ur coolant n see if there is gunk coming out.

KRRZ350

iTrader: (29)

Actually I have to agree with checking the oil, I went to a vo-tech school for auto repair back in high school, and one of the things they stressed was that regardless of what the problem is, if the car is having any performance or engine related problems, you should always check the oil first. It's easy to overlook the simple things.