coolant system pressure abnormally high

Hi,

This past summer I installed a new radiator into my 92 Civic. After filling up and bleeding the cooling system I noticed that my upper and lower radiator hoses felt like they were under more pressure than they had ever felt before the new radiator.

This concerned me becaue after driving it for a while they felt like they were under ALOT of excessive pressure.

About a week ago after getting off of the freeway my top radiator hose finally gave-away and died. I replaced it with a new one and re-filled the system.

My problem is that I need to figure out why it seems to be under such abnormal amount of pressure. Even cold the hoses feel unnessesarily stiff. I tried letting some coolant out but I think it just sucks more in from the resivour/overflow tank.

Someone suggested my thermostat was bad (Even tho there are none of the tale-tale symptoms), and someone else suggested that I should have flushed the system. Initally I thought the priblem was the mix of coolant I ended up using: I just topped off the system with Prestone when I had been using Honda's Green Genune coolant before (but the dealership switched the the new Blue stuff so no more green was avalible to top off the system). On the bottle of the Prestone coolant it said I could "Add to any color coolant" which implies it's compatible with other coolants so I picked it for that specific reason.

What could be my problem?

I doubt there is any problem at all, but if the pressure is really high, the thing to replace will be the radiator cap, since it has the valve controlling coolant pressure.

I doubt there is any problem at all, but if the pressure is really high, the thing to replace will be the radiator cap, since it has the valve controlling coolant pressure.

Yes thats what I was last told.

Then last night I started thinking... "maybe the old radiator cap isn't fully compatible with the new radiator" ?

or your cap died, replace the cap and let us know

Hey people, I replaced the radiator cap 2weeks ago, and have been doing extensive testing, and I'm back to report the problem is still present; That is, I still think the radiator hoses are exibiting signs of being under abnormall high amount(s) of pressure. Alot of times after a good drive or atleast after the car has reached operating temperatures they'll feel like they're full inflated and have little to very little deflection when you poke them with your finger...

I could have sworn before I changed this radiator they were never like this. When i Get some time and possibly money I'm going to goto some simple shops in this area that I can find and deem safe and ask them to tell me if the hoses feel strange to them too...


but yeah, I replaced the cap and still no go. Replaced it with a new one from Auto Zone, and even tried the cap facing in both directions..

Sorry, man, I don't see a problem here - there is nothing to solve or fix. Everything works as it supposed to.

Cooling systems can get to 15psi on a normal basis. That will leave the hoses very firm but again, it's normal. If you seriously think it's getting too high, take it to a mechanic and ask them to see if it feels to high.

your coolant hoses bursted because they needed to be replaced or clamped down better. no radiator pressure is going to bust them open otherwise.

Hate to break it to ya but..... your headgasket may be going :evillol: I noiced the same till BOOM!!!!! First I was blowing radiator hoses one by one.. I'd keep replacing each one as they blow up. They were old. Each time I replaced a hose, it never blew again since it's new and stong, but the weaker hoses were the ones to go in order... Eventually, all hoses were new... Now the hoses were so new, that they were really strong, not being able to break, so the next thing to go was the radiator. The radiator blew up.

The headgasket starts to go bad, coolant starts to enter your engine. And if coolant can get into your engine that means that pressure from the engine can get into your radiator. Here's a test.. With the engine cold, open your radiator cap, turn on the car, make sure the radiator is filled to the top. Let the car get to optimal running temperature and see if the coolant starts to either get sucked in or starts slowly spewing coolant from the radiator top. After about 5 or 10 min engine idling, turn off engine, fill radiator back up. (By now the thermostat is now fully open) and now try to start the car. If a headgasket is bad, the radiator will SHOOT that water from the top VERY violently. Do NOT let anyone stand in front of the car. My friend was shot by hot water (not coolant) and luckily it didn't hit his face.. If you dont have a thermostat, things will be worse being that the thermostat wont be there to block coolant for the first 5 min of engine warm up The high pressure will be constant.. Without a thermostat, even with the engine cold, trying to start the car with the cap off will immediately shoot that water out. Let's just hope it's not the headgasket :wink:

just to correct the above qoute...........what you are refering to is heat, not the the headgasket as the problem. the headgasket may be the problem.................but...........it is not the only reason why your car may overheat. there are plenty of reasons why a car will overheat. heat is the reason why we have pressure in our coolant system, because heat expands water. the radiator cap releases some of that pressure at 15 psi. if the coolant pressure builds more than that during normal operating temps, assuming you have a oem honda radiator, then, your cap isnt doing its job ;) unless there is an increase in your temp guage accompanied by the high pressure, i wouldnt worry about it.

If a headgasket is bad, the radiator will SHOOT that water from the top VERY violently

not necessarily. water still shoots from the top even at normal temps. the best way to check for a headgasket leak is with a comp and leakdown test.

My high radiator pressure ended up in this :)

http://www.automotiveforums.com/vbulletin/showthread.php?t=299403&page=2