# Should my lower radiator hose have a spring in it?



## whwright (Jul 16, 2003)

Hey guys.

I recently bought an '86 C-10 with a 305. When I replaced the radiator hoses, the lower hose I took off didn't have a spring in it, and the new hose didn't have a spring in it either.

Should this spring have been there?

Thanks.

Wayne.


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## wyldman (Jan 18, 2001)

The spring doesn't have to be there.It's just there to prevent the hose from getting sucked shut (vaccum from water pump inlet),or from kinking when the hose gets old and soft.If you can find a spring,or a hose with a spring in it,it wouldn't hurt to use it,but if not,don't worry about it.Just make sure the hose is always in good shape.


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## whwright (Jul 16, 2003)

Hello again Wyldman. How did I know you would be the one to respond?

Since we have the dialog started, I'll give you some more background. I thought about putting all this in the original post, but I was chicken.

As you probably recall, the truck has a TH350C tranny. The previous owner had the transmission replaced just a few weeks before parking it in his field (I basically paid for the transmission and got the entire truck).

I didn't know it at the time, but the reason they had the transmission replaced was "because the radiator couldn't keep it cool and the transmission burned up." Those are the previous owner's words, but keep in mind this is the same guy who told me he put an "oil pump" on it when he really meant a fuel pump (and he screwed that up). They also used the truck to pull some really heavy loads, and my guess is that they just worked the transmission to death.

The truck is now running pretty good, but it seems to run hot on the highway. I have replaced all the belts and hoses, and installed a new 195 degree thermostat. With the engine idling in the driveway I can see coolant circulating through the heater hose, so I know the water pump is working. I have also double-checked the thermostat to be sure I didn't put it in upside-down.

When I drive to work the gauge gets up to 240 degrees within about ten minutes. That seems really fast, so I took a thermometer with me the other day. When I got to the office I left the engine running and sat the thermometer on top of the intake manifold. The thermometer got up to 210 degrees, and it would make sense to me that the intake would be hotter than the coolant since it has the exhaust crossover in it. This leads me to believe the coolant is about 195 degrees, just like it should be. The temperature gauge read about 240 degrees at the time, but as I let it sit and run it came down to about 220 degrees.

Consequently, I'm not sure I trust the temperature gauge. I replaced the sending unit with a Borg-Warner replacement, but it didn't make any difference.

Do the gauges go bad? Do you think it's telling me the truth? Am I missing something simple (again)?

I'm tempted to install an "idiot light" since my 16-year-old son will be driving it, and he wouldn't notice the gauge reading hot anyway. Well, maybe I should put a BELL on it, or maybe a relay that turns off the radio, or maybe...

Thanks again.

Wayne.


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## wyldman (Jan 18, 2001)

The idiot lights sometimes don't come on until it's already overheating.It's still a good idea though if your son is going to be driving it.

Is the read in decent shape ? Sometimes the fins will rot away,and they are what dissapates the heat from the cooling tubes in the rad.

Get a cheap $20.00 mechanical temp gauge from the auto parts store,and pop it in the intake to test the actual temperature.Your gauge just might be off.Only way to tell is to verify it.

Did you finally hook up the vacuum advance ? ******** timing will really make it run hot,but not actually overheat.

I'd also pick up a small cheap tranny cooler,and install that as well,it's cheap insurance.


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## whwright (Jul 16, 2003)

The radiator appears to have been recently replaced.

I did get the vacuum advance hooked up. It is connected exactly like the diagram shows, TVS's and all.

I have a "Suntune" gauge from an old project, but there are no spare openings in the intake manifold. What would happen if I just drop it in the radiator filler and took it for a ten minute drive?

Thanks.

Wayne.


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## wyldman (Jan 18, 2001)

It may overheat with the cap off,but I guess you could get away with it to just verify the gauge acuracy.You could also pop one of the TVS's out of the t-stat housing or intake and put it in there.


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## whwright (Jul 16, 2003)

I would prefer not to mess with the TVS's if I can avoid it. I have a tendancy to break them getting them out.

Why did Chevy design it so that you have full flow through the heater core, even if the heater isn't on?


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## wyldman (Jan 18, 2001)

They use the full flow design to help bleed air out of the system,as it can be hard to get out otherwise.It also helps prevent a surge of very cold coolant rushing in when the thermostat first opens.The extreme temp change,or thermal cycling can be harmful to the engine.


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## whwright (Jul 16, 2003)

On another thread I noticed that somebody suggested that the heater hose be "pinched off" during the summer months. I take it that you don't necessarily agree with this practice.


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## wyldman (Jan 18, 2001)

No,never.The small block chevy's need the heater circuit for the bypass.You can get away with looping the two heater hoses together,but never pinch or block them off.

If you eliminate\pinch or block those hoses,you have to bypass the coolant somewhere or you'll get hot spots and start popping head gaskets or cracking heads.


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## whwright (Jul 16, 2003)

OK. I hereby vow to never pinch a heater hose on a small-block Chevy.:salute: 

I let the truck sit for about two hours after getting home tonight, popped the radiator cap, and dropped the "Suntune" thermocouple in the radiator. It went about three-quarters down in the fluid. Incidentally, the radiator was completely full, and the overflow jar was just above the "full cold" mark.

I sat my little round thermometer on the intake manifold, right below the throttle linkage.

Within a few minutes, both had settled in at about 115 degrees. When I turned on the key, the gauge in the dash went to about 160 degrees.

I started the engine and let it run, with the A/C on (it works!). After about 15 minutes, the thermometer and the "Suntune" were sitting at about 170 degrees. The gauge in the dash said between 210 and 240 degrees. I revved the engine a few times and watched for flow in the radiator to see if the thermostat was open -- it was.

After another 5 minutes or so, the thermometer and the "Suntune" read 180 degrees, and appeared to be staying there. The gauge in the dash read just under 240 degrees -- not quite as high as I see it get when I drive to work, but almost there.

I let the engine run for another 5 minutes, and all three indications stayed the same. The ambient air temperature through all of this was about 102 degrees, with no breeze. The only airflow through the radiator was that created by the fan.

I did not bother taking the truck for a drive with the radiator cap off, as I felt I had figured out that the gauge in the dash is not accurate. Do you agree with my assessment?


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## wyldman (Jan 18, 2001)

I don't think you need me to agree,you just proved it to yourself.

The gauge is bad,or possibly the sender you have may not be correctly calibrated to the gauge.If the gauge seems to be fluid,and work OK,except for being a little high,then I'd just fix it.Pull the needle off when it's at operating temperature,and the key is on,and then put it back on where you think it should be.


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## whwright (Jul 16, 2003)

What a simple solution!

I wish I had thought of it.

Thanks Wyldman!

Wayne.


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## wyldman (Jan 18, 2001)

Your Welcome.


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