Q: Thermostat isn't getting any hot water to open up.

asked by on December 22, 2016

Symptoms: Over heating Cold air only out of heater Reserve tank overflowing

I've flushed my radiator and engine, however the heater pipes were clogged up.

As the car cools I can see the water pipe out of the engine implodes. When I open the radiator cap is sucks in air like it was gasping for air.

Overheating temp gauge, the water pipe out of the engine is hot however the one at the bottom that leaves the radiator and leads to the thermostat housing is cold and high pressured.

I suspect the hot water out of the engine should be passing through the radiator and cooling, however not so cool that the thermostat won't open to replenish the water in the engine block.

Any ideas of what could be causing this?

My car has 70000 miles.
My car has a manual transmission.

The hoses are collapsing due to the radiator cap and passage to the overflow is clogged. The cap needs to be replaced and the passages to overflow cleared. If the thermostat is not opening then replace it also. Make sure to flush out entire system and replace radiator and heater core if clogged and cannot be cleared.

The statements expressed above are only for informational purposes and should be independently verified. Please see our terms of service for more details

Get an instant quote for your car

Our certified mechanics come to you ・Backed by 12-month, 12,000-mile guarantee・Fair and transparent pricing

What others are asking

Bypassed my heater core and refilled my reservoir tank for coolant checked it after two days it's getting low again

I can't help but think that there is a little more back-story here. But I presume you bypassed the heater core because you had a leak inside the car. That's something you can do if you don't need heat of...

My car has an electrical failure due to rain leaking inside, what do I need to repair?

This could end up being a costly repair unless the pigtail replacements for the wiring harness are available. First, the water intrusion has to be repaired. The water has to have been leaking inside the vehicle for some time or...

My all wheel drive light keep going on and off. My abs light stays on.

There could be a wheel speed sensor that could have failed and is not functioning properly that is causing the ABS and AWD lights to come on. The AWD light will come on in the event that the transmission is...

Air conditioning blowing hot and won't keep charge

If the AC system won't hold a charge, there is a leak somewhere in the lines or other components. Leaks can be tested for by using a UV dye. Due to the danger involved, I would recommend having a mechanic...

car making chirping noise on start up

Hi there. It sounds like the belt may be worn/loose and causing the noise. A quick visual inspection may reveal that the belt is indeed worn and in need of replacement. A belt tensioner that is struggling to maintain the...

Car won't move only buzzes when in gear and rolls in park.

Check the shifter cable to the transmission and see if it has broken off the transmission. The buzzing noise is the hydraulic fluid going around the main valve on the transmission and the valve is stuck in between a gear....

How long does it take to install a block heater?

Hi there. Installing a block heater for your vehicle depends on what type of heater you are installing. Some heaters are externally mounted to the bottom of the engine oil pan and other heaters are inside the engine oil pan....

One headlight working

If you only have one head light that is not working it is typically caused by a bulb that has failed. One your vehicle I have had a lot of bulb connections fail and cause this. I would typically start...

Can I change the transmission fluid

Hi, thanks for writing in. That "debris" you feel is usually clutch material. Clutch material inside automatic transmissions is very similar to manual transmission clutch material as well as brake pad material. It generally appears as a fine dust. While...

Related articles

Industry News for Automotive Techs: November 5 - November 11
Tesla buys Grohmann Engineering, Ferrari's future hybrids, next-gen Dodge Charger and Challenger, Nissan e-Power system, and YourMechanic recognition.
The Best Used Cars to Buy If You're a Teacher
If If you are a teacher, probably foremost on your mind is getting to school on time. You would also probably like a used car that is easy on gas and not terribly expensive, and will hold your gym gear...
Symptoms of a Bad or Failing Coolant Recovery Reservoir
Common signs include constantly having to add coolant, visible coolant leaks, and the engine overheating.