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Discussion Starter #1 (Edited)
Radiator is out of the ‘56 chasing down overheating issue – was difficult to extract due to a shroud being there. Did all that with the fan still bolted on.

Am thinking for re-install I’ll take out the fan so I can replace the shroud AFTER I have the lower hose and trans cooler lines connected up. Would others do the same?

Also, the lower hose has no spring in it. Should I get a correct one in place? Does top hose need a spring in it as well?

Cheers

John
 

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Originally, both the lower radiator and heater return hoses connect to the water pump could collapse under high suction if they were flimsy hoses blocking coolant flow creating and overheating problem.

Some brands may be thick walled and stiff enough not to collapse, just depends. I would find or make springs for both hoses just to be sure yours never collapse, especially the lower radiator hose.

The upper radiator and heater supply hoses do not need springs as they are under pressure rather than suction.

It will be next to impossible to install the fan with the radiator and shroud in place. Just getting your hands between the fan and the radiator will be very difficult, especially with the shroud in place.
 

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If you have room, think about studs for the pump flange. It was always easier for me to hang a fan on the studs than try to hold it, spin it to try and find the holes and get bolts in. Some fans have slotted holes that make it easier but....

Usually you can leave the shroud loose and shoved back toward the engine, slide the radiator down in and mount it, then bring the shroud back up to the radiator and mount it. Putting a fan on with the shroud in place is pretty tough. It can be done but be prepared with extra bolts, washers etc so when you drop them into the black hole you will have more. Also, keep the kids away so they won't hear the cussing.
 

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Like Tri 5s just said,

You need to put the shroud in first back next to the engine, install the fan, drop in and mount the radiator ¾” from the fan, then mount the shroud to the radiator.
 

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Discussion Starter #5
Many thanks, gentlemen!

So ... that will be reverse order of the removal. Except I will fix the radiator BEFORE attaching the bottom hose and trans cooler lines. Then loosen radiator again to attach the shroud. (Shroud is still in there.)
 

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Discussion Starter #6
Btw, the symptoms here are overheating on the road ... more so in very hot weather.

The dial is generally at 7-9 while driving, and at the top when hot ... but it never boils or loses water.

Radiator has had a flush already ... but that made no difference. Maybe there's gunk in there that can be rodded out.

If that doesn't fix it, we are figuring it is in the block. :(
 

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Consider putting a piece of cardboard taped to front and back of radiator while installing. Insurance against tweaking the radiator fins.

Fuzz

:gba:

MAGA
 

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This may sound like two silly questions, but they're not.

When you say the temperature gauge says it's overheating, are you talking about the factory-installed temperature gauge, or an after-market accessory gauge?

Also, are you sure it's actually overheating?

If you're using the factory gauge with the wrong sending unit installed in engine block, it may indicate overheating when in fact everything's fine. Contrary to popular belief, all Chevy engines do NOT use the same sending unit. Even though they may look the same, they're calibrated differently.

The original engines were designed to use 180 to 185 degrees Fahrenheit thermostats. The gauges were therefore designed to read half-scale or slightly less at that temperature. If you're using a 192 to 195 degree thermostat, it will read hot (the top of the scale is about 200 degrees or so).

If you hadn't already pulled the radiator, you could do a quick check of the intake manifold temperature with an infrared thermometer gun. (I recently bought https://www.lowes.com/pd/Southwire-Digital-Infrared-Temperature/50125849.) Since you've already already pulled the radiator, I'll suggest you do the "tried and true" temperature gauge test listed below. It's worked quite well for me over the years, as it measures the gauge versus known water temperature.

First, confirm you have the correct thermostat, and it's opening at 180 or 185 degrees Fahrenheit (82 degrees Celsius) by heating it on the stove in a pot of water and checking against a thermometer.

Next, check the engine sending unit for proper calibration. To do this, remove the sending unit from the block. Reconnect the wire, and ground (earth) the body of the sending unit.

Now, get a thermometer and boil a pot of water on the stove.

Go back out to the car. Turn on the ignition and set the sensor in the water (keep the terminals above water). Observe the gauge versus the thermometer in the pot of water. You will quickly know the actual temperature versus the position of the gauge's needle.

Now, let me demonstrate the "geek" in "stoveboltgeek". :)

I don't have a '56 temperature gauge handy, but I suspect that it has 2 wound coils (electromagnets) that set the actual position of the needle. I also suspect these coils are mounted with screws in a bracket with elongated holes.

By loosening the screws and moving the coils, the gauge can be recalibrated to read correctly, if need be. It would be a trial-and-error sort of thing (I did this once with a gas gauge).

Of course, the first thing to do is make sure you have the correct sending unit, or one as close as possible to the correct calibration.
 

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Discussion Starter #10
Thanks for the info, Ted.

Thermostat was replaced/checked as standard 180 a few weeks back.

We (mechanic and I) got a gun to measure block temps when it was running hot – was over 200. That's what corresponded to about 9.5 on the dial. (But I have never actually seen it boil ... and it doesn't lose water/coolant.)

Can't say whether it has the correct sender unit in it ... but there's no record of replacement in the comprehensive set of papers that came with the car. (Original motor ... 60K ... never opened.)

Ang, it has the correct fan in place. (Not like my '57, if you remember that ordeal!)

Especially with cooling system issues, I am of the mind to change one thing at a time to see what effects any change.

Interestingly, the radiator guy said the bottom hose was good and sturdy, even though it has no spring. The spring is mostly to prevent sucking flat at high RPM, right – not just regular 2000rpm driving? (Can get a replacement easily enough if needed.)
 

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Make sure the fan sits with the shroud in the middle of the fan blades. If it is in too far it will not pull air like it should and can actually be a detriment.
 

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Discussion Starter #12 (Edited)
Make sure the fan sits with the shroud in the middle of the fan blades. If it is in too far it will not pull air like it should and can actually be a detriment.
Thanks for the tip. There looks to be a small amount of adjustment forward/back on this one.

I can't actually figure why a shroud was on this car in the first place. It's was a cool climate car its whole life ... but I certainly found that it got hot on hot days driving the west coast last year.

Radiator is now back from the shop – they guy said it was dirty and a few of the pipes blocked ... also repaired two small leaks that sprung under pressure ... but did not say it was a real mess. Kind of hinted to me that something else was contributing to the o/heating. We'll see.
 

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Make sure the fan sits with the shroud in the middle of the fan blades. If it is in too far it will not pull air like it should and can actually be a detriment.
Good point. I retract my earlier statement to place the radiator ¾” from the fan. With a shroud that measurement is irrelevant. It is more important to have the fan half in/half out of the shroud rear opening.
 

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Discussion Starter #14
Ok, I have the radiator back in.

The shroud is as far forward onto the radiator as it can go, and this assembly as far forward against the radiator support bar as it can go – and I'd say only 1/3 of the fan width is clear.

Is that enough?

If not, I will have to remove the shroud and take 1/2" off the entire front edge of the thing to allow it to move forward?

Road testing the car tomorrow to see how it goes and checking the coolant – maybe that will hold my answer.
 

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Ok, I have the radiator back in.

The shroud is as far forward onto the radiator as it can go, and this assembly as far forward against the radiator support bar as it can go – and I'd say only 1/3 of the fan width is clear.

Is that enough?

If not, I will have to remove the shroud and take 1/2" off the entire front edge of the thing to allow it to move forward?

Road testing the car tomorrow to see how it goes and checking the coolant – maybe that will hold my answer.
The shroud sits so half of the fan blade is covered.
 

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Discussion Starter #17 (Edited)
Hey John,

Would this be of any use to you, haven't used it myself.

http://liquidintelligence.com.au/products/engine-cooling-system-cleaning-kit

Was there much gunk in the radiator when pulled apart?
Maybe there is a deeper issue in the engine block.

Chris.
Hey Chris

I don't really know much about this sort of stuff. Has anyone used it on an old block?

The weather is cool now, so when I run it on the highway is barely gets to the half mark on the temp dial. In fact, it was so cold and wet on a drive last week that it barely cracked the quarter mark – it was like it was UNDERheating.

Will look at it all again in summer.

Also ... any takers as to whether having 2/3 of the fan covered by the shroud is still ok?
 

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Discussion Starter #19
Also ... any takers as to whether having 2/3 of the fan covered by the shroud is still ok?
Does anyone have specific experience of this – one way or the other?
 

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John, look at this quick explanation of how the shroud placement affects performance>>>>

https://www.flex-a-lite.com/blog/the-perfect-fan-shroud-position/

It might make a difference if you still run on the hotter side. Remember, they were originally designed without a shroud. If you are really getting hot with a close to stock configuration, you might have another issue that you are trying to cover with a fan/shroud.
 
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