What kind of problems are you having? Overheating? Or is your only problem that the bottom hose is not as hot as the top hose. And the top hose looks "like it's bulging or over-pressurized?"

What problems are you having?

What problems are you having?

 

OK, Last try and I'll give up like most of the rest of the posters here have done. You have not posted what started you on this witch hunt. So we are baffled as to why you keep thinking you have a problem with various parts of the cooling system.

1. If the radiator hose is bulged or looks bad, replace it.

2. The water pump does NOT pressurize the system.

3. Pressure in the system is caused by heating the coolant and restricting the expansion of the coolant. This restriction and pressure regulation is done by the radiator cap. I have never seen a radiator cap go bad and cause over pressure. They usually fail the opposite way (low pressure) or have a leak in the seals of the cap.

4. The thermostat regulates the operating temperature of the engine. If the thermostat was failing to open your upper hose would NOT get hot.

5. If your thermostat was stuck open then the engine would run too cool.

6. The water pump provides little if any pressure. It is strictly a circulation pump. The pump tries to force cool water into the bottom of the engine all of the time. The thermostat is located in the top of the engine and it blocks the flow of the coolant UNTIL the engine reaches a prescribed temperature which is usually 195 degrees F.

So if you removed the upper hose and started the engine no (or very minimal) coolant will flow until the coolant reaches 195 degrees F. At 195 F. the thermostat will open briefly to allow some coolant to flow. As soon as the coolant around the thermostat cools to below 195 degrees F. the thermostat will close again and stay closed until the temp raises to 195 F. again.

7. Water pumps seldom fail. When they do fail they either leak around the front seal or the front bearing goes out and the shaft wobbles.

I suggest that you:
1. put everything back together.
2. replace the upper hose if you think it is bad.
3. replace the cap (they are cheap) if you think you need it.
4. fill then entire cooling system with 50% ethylene glycol antifreeze / 50% distilled water.
5. be done with this project.

Note: After filling the cooling system, it is normal for the coolant level in the cooling system to drop a little after you drive the car. This may happen after the first two or three times you heat the car up and it cools down again. This is the system expelling any remaining air that it is in the cooling system. Just top off the level in the overflow bottle. The level should stabilize after 3 or so driving heat and cooling cycles.

If you still think you have a problem after that, then tell us your symptoms and we will try to help you diagnose the cause.

A hot upper hose and a cool lower hose is not a problem unless you are having an over heating problem with the engine.

Good Luck

Ken B.

 

Well said.

 

What bothers me on this forum is people that show up with a problem and then disappear. We never know what the resolution to their problem was. Posting an "I fixed it" entry with what they did would help us all.

 

Agree... Only bothers for a while then you get used to it... OP's next post will be another "What's wrong/help/panic"-type again...

I call them "One-hit wonders." Hit you up once and leave you wondering... until the next car hiccup!

 

Agreed. I see this same problem on every car and motorcycle forum I belong to, which is about a dozen.

 

Hi all

Where is the thermostat on an Honda Jazz 2007.

I beleive it to be faulty because the top pipe is bulging and too hot to touch.

Your help would be appricated

Richard

 

Thanks to every one how helped with my problems

I found that my water pump was leaking so I have real sealed it because the impeller was fine.

I have flushed the radiator out to make sure there were no leaks.

I have replaced the radiator cap.

It seams to be fine now.

I could not check the Thermostate because the wiring loom was over the top of it.

If the problems reoccur I have to try to move the wiring loom

Once again thanks to all you have help me lean as I repair my car.


Dave

 

My car the thermostat is not at the top but at the lower hose ..so in my case you'd be wrong suggestion top hose wouod be cold if thermostat was stuck closed . Thought I'd mention it....2 reasons i know 1) you can see the housing ..2) ive changed it alomgvwith other bits