Hello,

I have only had the car for a short time, It seems like every journey i go on the pressure in the cooling hoses builds up. I have just changed both pressure caps today and the problem is still not solved . I would be grateful if anyone can get back to me with some suggestions?

Earlier today i had to pull over on the side of the motorway to cool down and slowly loosen the pressure cap to relief some pressure...

It's gettiing pretty desperate now it is running 13 pounds of pressure on 9 pound caps.

Thanks, Matty.

 

How do you know the pressure is getting too high? Is it spurting under the caps? (If it's actually a 9psi cap, there is no way it can retain 13psi).

Anyway, if you're not using OEM Mazda caps, install them instead.

If the engine is getting too hot, you need to stop driving it until you find out what's causing it. Overheating these engines will quickly have you shopping for an engine rebuild.

Dave

 

Yeah, I'm confused. Are you overheating? Because the cooling system works on pressure and boiling points. For every pound of pressure on the cooling system, you increase the boiling by about 3 degrees. That's why coolant systems get pressurized when they heat up.

 

Honestly, it just sounds like a new owner who's making something out of nothing. If at any point the temp gauge leaves the middle, pull over and turn it off. Until then, pressurized coolant hoses are perfectly fine!

 

I'm sure the stock cap is 13 psi....If your going to do anything in the way of changing your cap go with a 14 or 15 psi. I use a 15 psi and track my car weekly with no issues....

 

My car never goes over half temperature and i have just installed two brand new mazda caps on. My engine isn't overhearting. It spits when i loosen the cap but there is no smoke so it can't be the water seals (says dragon performance). Hope someone can help... thanks for all the replys so far.

Matty

 

Your coolant system is suppose to build pressure. Pressure is what increases your boil point.

 

...BUT there should not be excess pressure in the hoses, making them swell noticeably. Also if you start to have things break...the ast, old hoses, the factory radiator...then you can assume you have too much pressure building in the system.

That pressure can very possibly come from the compression/combustion inside the engine. Swelled coolant hoses is often the first sign of coolant seals beginning to lose seal. The quick test I do is grab the upper radiator hose and try to squeeze it together with my thumb and forefinger. Normally there is not much pressure and you can make the inside of the hose touch. IF there is so much pressure that you cannot, there's a good chance that you're building too much pressure.

 

1. How are you measuring pressure?
2. How are you measuring temperature?
3. What makes you think that 13psi is too much? Quite a few people have been using aftermarket 16psi caps with great success, myself included.


Recommended reading:

http://auto.howstuffworks.com/cooling-system.htm

https://www.rx7club.com/3rd-generation-specific-1993-2002-16/big-fat-fd3s-cooling-thread-571088/


-s-

 

I really hope you don't have a boost gauge in the car and think that's cooling system pressure....

Dale

 

Yes, so once again the question remains: where do you get the idea the pressure is too high?

Mazda caps = 13psi pressure. How you would measure that during a drive I have no idea.

Dave

 

That was a symptom I had before my rear seal finally gave up. Even though you didn't mention this, if your having to add water every other trip start saving for your next engine.

Also the stock gauge isn't a good thing to rely upon.

Hopefully there isn't a problem.

 

Don't really understand the question either, but FWIW it is possible to accidentally interchange the two caps (don't ask how I know), which can result in blowing coolant everywhere. Doesn't make sense to me, but that does happen. The cap with the yellow label marked "Filler Cap" goes on the thermostat housing toward the rear, and the Calsonic black-labeled cap goes on the Air Separation Tank at the front.