Battle of the Bulge

[billschroeder5842]

My upper radiator hose just developed a big bulge just above the thermostat housing.

I've had no problems with the cooling system on the car (it has been hovering around 100 degrees in Texas lately) and everything seems to be in order. I have a 195 thermostat and it seems to be holding. On Friday I drove it at about 70mph for 20 minutes with the outside temp at 102. Gauge up a bit but steady-all normal.

I took the car out today for a ride. It is 85 outside, cooler than usual but super humid as it rained earlier. I drove the car about 20 miles and noticed that the gauge was a bit up from normal but below the highest it has ever been. The car ran normal.

I parked my car in the garage, popped the hood and noticed a big bubble or bulge around the bottom of the hose near the thermostat housing. It was a uniform all the way around. I let it cool a bit and the bulge shrank a bit, but the system is still under pressure.

So.....
1) is the hose just old or weakened? I have no idea how old the hose is--I bought the car last November.
2) is the thermostat stuck? I put the 195 in February and have had no issues. I ask because the gauge was slightly up over normal having just cruised around neighborhoods.
3) Is there any way to test the thermostat without removing it? I ordered a new hose (due tomorrow) but will change both if necessary.

Thanks!

Thanks!

[green69rt]

Old/faulty hose, replace immediately before it bursts and leaves you stranded.  Thermostat may be same vintage as hose, though bad of one part does not mean bad other.  It is a good time to replace both and replace coolant. Replace lower hose also unless you know it's recent.

[billschroeder5842]

Because I can't leave well enough alone....

I ran the car for a while in the garage and kept an eye on the hose. It seemed to maintain it shape when running but began to "blow up" after the engine was turned off. It seem to be under a LOT of pressure after being turned off until it cools off. Is that normal?

Random observation... the idle was up from 725 to about 900. No big deal and the car ran great (I but up the idle to 900 in winter anyway) but jumped up from yesterday for no apparent reason. Huh.

So....
Thermostat is new--4 months old--I'll not mess with that. Seems okay??
Change hoses and fluid--check.

Thanks!

[green69rt]

The swelling is just another symptom of a bad hose.  The pressure of the coolant changes.  That's why modern cars have recovery systems.  When you shut off engine the heat in the block heats up the coolant in the block and may even make it flash (probably not) but at least the coolant will expand.  Old cars had some vapor space where the coolant would expand into,  if the system was completely full it would push out thru the radiator cap and dump on the ground and when the engine cooled off a vapor space was created.   In modern cars it would push out into the recovery bottle then when the engine cooled off the coolant would be sucked back into the coolant system so there would be no vapor space. The bulging hose just means that the hose is weak enough that it is swelling instead of the coolant pushing out.

Also, notice that radiator hoses are really stiff and usually thick or have s spring wound inside them.  That's to prevent them from collapsing down when the water pump draws a big suction on the return hose (made worse when the radiator is partly clogged) and thus reduce or even stop coolant flow is the system.

Which brings to mind something,  you said that the engine temp is ok.  But even at that older systems sometimes need the radiator flushed.  The collapsing lower hose is a synonym of clogged radiator.  Just run the car while having someone observe the lower hose and gun the engine, no change in the hose is good.  Also if you ever have the radiator out most shops can flow test them.  Not trying to make work but something to be aware of.

Whew!!  Long post for me.

I'm sure that others have had similar experiences and comments?

[myk]

Yeah, no more experimenting-that hose is on borrowed time...

[68charger440]

I also had that bulge problem with my hose way back in the 70s.  I was poor and just let it ride for a while.  It never did blow but replacing it eventually with a new hose did fix it and the bulge never came back.

[Chargerguy74]

I experienced this with my '84 360 Ram about 8 years ago. I bought a new hose and threw it behind the seat, never finding the time to swap them. Same thing, the old hose would blow up like a balloon. I pretty much just forgot about it. Until I got into heavy summer traffic one day, stop and go, creeping along, not enough cooling, just minding my own business then BANG!!! It was like a grenade went off under the hood. When the steam cleared the first thing I noticed was my Ram emblem on the hood was now rotated nearly 180 degrees, and staring back at me. So I was forced to swap out the hoses in less than ideal condotions. Passers by were giving me bottles of water to top up. That was nice.

[billschroeder5842]

Made the switch..... top hose was very squishy and bottom what not much better.

I swapped both and did the test---all okay, no leaks and no collapsing.

Piece of mind is worth the 35 dollars.