Coolant hoses keep blowing

[sjbsuperman1425]

I've repaired 3 coolant hoses within the past 4 weeks. It's mostly the hoses under the manifold. They are all brand new now. Any suggestions as to why this keeps happening? I had a cxracing rad cap on and just put the stock one back on today.

[TheMAN]

the simple matter of the fact is the coolant pressure is too high... the cap might be bad and going way past what the advertised spec is... I noticed many off-brand caps to be off spec, performance or not

if I were to put in a higher pressure cap, I'd either put in a real nismo, stock Z32, greddy, arc, blitz, or even a stock mazdaspeed6 cap... they're all high quality and probably come out of the same japanese factory... all are 1.3bar except the Z32 one

as for hoses, use either the OEM nissan hoses, or high quality silicone ones such as samco or hose techniques... none of the cheap ebay crap... off-brand garbage also have low burst pressure... they're just not built the same

you get what you pay

[sjbsuperman1425]

Well I didn't "cheap" on hoses. I buy all my hoses down the road at the auto parts store. It's like I've been slowly weeding out the weak hoses as the last one that blew was the last Nissan oem hose that came with the engine.

I used the "off-brand" cap because it came with the radiator. Like I said, I just put the stock one back on. My radiator is leaking and I need a new one soon so I'll probably buy a nice cap when I get the radiator.

But nothing else would Other than weak hose or a bad cap would cause this? I've never had overheating problems either.

[TheMAN]

nope, only weak hoses or bad cap can do this too much pressure can break radiator end caps and burst hoses

I don't consider hoses found at the parts stores to be good quality ones either... they're fine for a normal car, but not for performance applications... OEM hoses are better in this regard because they are built to a higher standard

if you just want to get a good cheap 1.3bar cap, get a stock mazdaspeed6 cap from a mazda dealer... it's only 20 bucks and I'm pretty sure it fits... I looked at the cap size and snout before and it looks like the nissan one... the cap won't say anything fancy of course, but it works and it's good quality... an 06 or newer RX-8 cap also fits and is also 1.3bar


but since your system is marginal right now and you're susceptible to bursting, I recommend sticking to stock or lowering to 13psi (0.9bar).. you won't have a very good boil over protection, but it'll reduce the likelihood of the system blowing out and leaking out all the water which will strand you on the side of the road

[sjbsuperman1425]

I have all molded hoses from advance auto on the under the manifold lines, one of which has been on there since the swap and it hasn't burst. The old oem hoses blew out and then I had bulk heater hose blow out on me. Other than that, everything seems to be good.

I'm pretty sure the cap played a big part. I ditched that knock off cap and wi just keep the oem one on there now and see what happens. No leaks or anything and my temps are good. I'll go play in a parking lot this weekend and see if my repairs hold up now lol

[biosehnsucht]

Any hoses that came with your motor are on borrowed time anyways. Once you've replaced them all, they'll probably be ok...

A stock Z32 cap should be safe (slightly higher pressure) or just go with stock, as far as those go, if you're going OEM. No need for NISMO fancy pants stuff.

[themadscientist]

I blew a hose under the manifold once. I heard it, smelled it then my nuts got sprayed with hot coolant. I had a hole in the floor from frame rot. I ripped all those little bastards out. The hoses, not my nuts. When I was done there was just that main run down the side of the motor. I ran like that for a while with no issue.

[Spawn_CA18]

compression blow-by to water system from head gasket?

[float_6969]

I thought of that too, but the shady radiator cap is the more likely culprit.

[TheMAN]

compression blow-by to water system from head gasket?

if there's a head gasket leak, there will be air bubbles in the system... with a cooling system operating within spec, the air bubbles will just get forced out of the radiator into the overflow tank instead

[sjbsuperman1425]

old thread, but Im looking at radiators right now so I came back to it.

head gasket was replaced two winters ago(?) so i dont think its that. No signs of bubbles in the system and no smell of coolant in the exhaust.

I got a drunk driving a few months ago (Sept. 13), so I'm limited on funds. Fortunately for me i got it dropped to a reckless...funny thing is i got pulled over for a loud exhaust..how lame. regardless, Im at a toss-up between the Isis, Mishimoto, and Koyo...Im thinking about going Koyo since my last "knock-off" radiator failed me. But idk if its because of a bad cap, or weak design.

[Chris859]

My 240 has had a koyo for quite some time with no issues.

[TheMAN]

go with koyo.... tried and true japanese design/engineering
mishimoto is a faux japanese brand... an american company on the east coast and it's not even a japanese word! their branding has preyed on unsuspecting people into thinking they're buying japanese!

[Shagi]

I recommend a Koyo too.
52mm one, with air con cranked and doesn't get to 100C.

[float_6969]

Don't fix it if it ain't broke! LOL, I'm running a new, stock sized (but with metal end caps) Advanced Auto radiator. Have been since the 1st rebuild 7 years ago (I guess it's not new anymore). I've NEVER had my engine temps be an issue, and it gets HOT in Kansas and I beat the heck out of my motor ever time I drive it. This combined with a GOOD electric fan will be fine for just about anything, except for A LOT of drifting. I've done some minor drifting with this setup and never had an issue, but there is nothing harder on the cooling system than drifting. Lots of heat, no air flow.

[biosehnsucht]

That 52mm is great until your tstat is stuck open, and to get it to even budge the needle moving you have to stick a piece of cardboard with a small square cut out in the middle of it in front of the radiator to even let it warm up ...

[sjbsuperman1425]

my radiator leaks on the passenger side and the drain plug threads are stripped out so I have a brass fitting jammed in there that threaded itself with teflon tape to keep it from leaking. My Radiator is fubared to say the least. I'm thinking Koyo might be the way but I may be able to get one from a local radiator company my dealership deals with for a cheap price.

[sjbsuperman1425]

I never posted that I fixed this problem. The CXRacing radiator cap that came with the radiator was crap. I have a HKS radiator Cap now and i've never had any problems with coolant leaks again (besides loose clamps).

I did get another CXRacing Radiator FWIW. No leaks, no problems.

[Sideways s12]

what do you think of the mishimoto rad I bought one that im going to install in the next week also got the fans that fit the rad as well I haven't heard anything bad about them

[sjbsuperman1425]

I've never had experience with Mishimoto, but I did almost get one of their radiators when mine needed to be replaced, but CXRacing on eBay for $120 was to good to pass up..I'd imagine they are of similar quality but can't say for sure. But I'd use either a quality radiator cap or an OEM cap just to be safe

[Sideways s12]

Ok. Yeah the mishimoto was about the same in price with an extra hundred for the fans I bought them seperately though....