Mishimoto Coolant Hoses
 

Anybody have experience with the lower (specifically) and upper Mishimoto hoses? They claim 5 ply silicon.

This year I've started to see a bit of highway cruise temp creep. Got under the car and my lower hose is getting pretty squishy (no spring). I think the higher rpm's are slightly collapsing the lower hose.

My upper is in okay condition, but is pretty old.

Just looking for reviews basically, or suggestions on other hoses to look at. This is a 1969 Firebird.

Thanks!

Silicon hoses are a bad idea for anything other than a dedicated track car. It's only advantage is higher pressure and temperature resistance, and not by much. Silicone is five times more water permeable than rubber. The reason you're getting temp creep is that you're actively loosing coolant, and when you lose coolant pressure the liquid turns to steam and holds less heat. It's a common mistake in the import tune scene. There have been countless owners of s**tbox civics who've switched to silicone for the pretty colors, then experienced overheating and coolant loss.

Now about the lower spring, I know that it was common to have one from the factory. I don't know if I read it here or elsewhere but there were two interesting points raised. The claim was that the spring was there for the factory fill. Burping the cooling system was impractical for an assembly line so a vacuum was applied(I don't remember where) and coolant was drawn in and and the air was purged. The spring was there to keep the lower hose from collapsing, and I guess the upper one wasn't a problem. As well, a properly functioning cooling system is operating at 15-16psi. That amount of pressure would more than overcome any suction the water pump is exerting on the lower hose. Food for thought.

if you think the hose is collapsing, have someone rev the engine up while looking at the hose, you can verify if its collapsing.

i have never ran a spring in my lower hoses & never had a collapsing problem, this is with very old or new hoses, on mild 350-425hp engines or 500+ stroker engines, all have seen 5000-6000rpms regularly.

Does your temp keep rising and and rising without stopping on the highway? Temp creep at sustained highway RPMs is normal since higher RPMs means more work and heat generated, but it should eventually stop and level out not too far past thermostat temp.

I put an anti-collapse spring in my lower hose as an extra insurance measure, but technically, if the hoses are new and/or in good condition, the pressure maintained in the cooling system should be MORE than enough to prevent the lower hose from collapsing, like 78w72 said. If your temp keeps rising without stopping, I'd look into airflow or coolant restriction/flow issues.

Thanks for the replies and solid information.

I've not driven the car for long enough on the highway to really see if the temp stabilizes or continues to creep. The daily temperatures are starting to cool in Colorado enough that I won't be able to test that until next year.

Does anyone have a recommendation on quality hoses? I'll probably change these out over the winter. They're the same hoses that have been on the car since I purchased it in 1998 and I'm sure they were on the car before I purchased, so they could be 25+ years old at this point.

i think any name brand hose will be fine for your car. gates, dayco, ac delco etc. rock auto has some good prices fro ac delcos.

I’ll have to source elsewhere. Rick auto won’t ship to my city unfortunately.

really? is it rock auto or the standard carriers? UPS/FEDEX/USPS will deliver to almost any address/city in the country.

the hose brands mentioned can usually be purchased at local auto stores or from bigger places like summit etc that hopefully will deliver to you.

Colorado in general and some of it's cities and towns has stringent online taxation laws. You have to collect sales tax online, Rock Auto either can't or won't, so they won't deliver to me.

bummer. cities/towns in CO have additional taxes over the normal state sales taxes?

must be something above & beyond what most other states in the country that are now required to charge sales tax on all online orders, my state does it & rock auto charges the sales tax just like any other online company does.

should be able to find name brand hoses/belts locally or from other online sellers though.

Yes, we're taxed to death here. State income tax, state sales tax and then we typically have some city improvement taxes along side mil levies and bonds for school districts on top of vehicle registration fees. It's fairly terrible. If it wasn't so beautiful here and all my family lived here, I'd be moving.

yeah ive heard some horror stories about colorado governments...