Could the uneven cut of the upper radiator hose below cause my coolant leak? I have that hose clamp as tight as it can be.

 

I would cut it straight. Then slip it up as high as it can go. It looks like you have alot of space on the low side. That could break the seal from the pressure. Also make sure your clamp is level as well, so it makes a good seal.

 

Yes, it only leaks when it's in operating temperature so it's under pressure. I'll try and cut it straight then or buy a new hose altogether.

 

buy a new hose. the factory hoses do not like to be cut.

get them from ray crowe at malloy mazda. phone is in the FAQ

 

I would be more likely to suspect corrosion deposits on the surface between the hose and the nipple it's clamped to. Pull the hose off and look for whitish crud on the inside. If it's not that, then maybe the hose took a set from previous use, and the contact surface is deformed, preventing sealing. Cutting the end of the hose, in itself, should not make it leak.

 

^It actually can with the way that hose is. Both the upper and lower rad hose are formed to taper and snug down a bit at the mounting points. When I experimented with cutting brand new OEM hoses to fit my custom v-mount setup, they wouldn't seal properly. The internal diameter actually differs through the length of the hose.


Get yourself a new hose and get the OEM clamps. The OEM clamps have the correct torque so the hose won't get chewed up over time by those worm type hose clamps.

 

Interesting - maybe in add'n to the taper you mention, the rubber is actually thicker at the ends to aid sealing. Have you sectioned one of these hoses to to see if the cross-section varies in add'n to the diameter changing?

 

As hoses age, they stretch. Years of heat and pressure will cause the hose to expand below the clamping point. By cutting the top part of the old hose off, you are now trying to seal the stretched portion of the hose over smaller tube. The hose is simply too big now, and wont seal properly. Get a new OEM hose. Don't buy some crappy Autozone (or Napa ...etc) garbage

 

I don't remember the rubber being thicker at the mounting points. I just remember that it tapered down. That was totally unexpected and I wasted days trying to get the leaks to stop. That was with a brand new OEM hose btw.

To make matters worse is that if the seal between the hose and the pipe isn't very tight, the system can and will suck air in from tiny pin hole leak spots where coolant wouldn't normally leak out of. Remember that when you turn the car off, the cooling system will suck coolant, air and anything else it can back into it as the fluid contracts. If the hoses are all tight, it will only suck in whatever is in the coolant expansion tank. If they aren't tight, the system will suck in some air leading to air bubbles and hot spots in the sytem.

It took me a good many months of troubleshooting this and other odd coolant component issues until I finally had a rock solid cooling system.

Figuring out that the worm type hose clamps suck was another revelation. After a few heat cycles of expansion and contraction, those things loosen up. So if you are using worm type hose clamps, keep your eye on them. Another thing that sucks even further with the worm type clamps is that if you tighten them up too much to try and get around the fact that they will loosen up over time, they can dig into the hose cutting it up a bit until it eventually develops tiny tears and starts leaking.

I swear I could almost write a chapter in a book about my experiences with this crap.


I also recommend OEM hoses and OEM clamps like adam_c said.

I wound up having to use silicon coolant hose with fancy/expensive Breeze constant torque clamps on my custom vmount setup but I would have gladly used the OEM rubber if I could have avoided that.

 

I recommend you replace with a new OEM hose and use a scrubby thing on the end of a dremel (you can get these from Dremel) to clean off the crud from where the hose fits on.

 

I'm pretty sure mine has 2 clamps on it where that hose is.

 

Change the hose. The pair is like $50. Make sure you clean off any built up crud on the water pipe or the hose may not seal.

 

Does anybody else use worm style clamps for this hose? Does it leak with it?

 

i had this problem when i first got my FD, i used the worm type just like the one your using, and cut my old hose. It was fine when it just sat around but when i pressure tested it at 13 psi, it would keep leaking no matter how tight i screwed the clamp.

I made sure to scrub off all the gunk, and it still leaked. Bought a new hose from mazda, used the same worm clamp, and never had the problem again.

Although, with the new hose, it would leak from the part that connects to the radiator because of the weird angle, i had to use 2 clamps for that.

 

BAKER PRECESION has some of the best hose clamps that I could find.

Note - also make sure it is not your coolant level sensor gasket that could be dripping on it's bottom.

Later

 

Bumping this up, I'm having the same exact problem right now. Twice in a week the regular worm clamp I'm using has ripped holes in brand new upper coolant hoses. Luckily I have a PowerFC and can monitor the water temps without relying on the shitty stock coolant gauge or my motor might have been fried twice already.

What clamp do you guys use? I went to Baker Precision as recommended right above and they have ABA clamps and also T-clamps for coolant hoses but I dont know which would be better for me. I have a Greddy FMIC so Im using the water pipe they gave me also if that makes any difference. http://www.bakerprecision.com/silicone.htm

 

I would go with the T-Bolt clamps.

 

I used these:
http://www.breezeclamps.com/ct.htm
I think McMaster Carr stocks them but so do other Breeze retailers.

Don't bother with the ABA clamps. T bolt clamps are OK but I like the constant torque clamps better b/c of the constant torquing characteristics.