72 lower radiator hose???

[Bern74]

Hi
I have replaced the old 72 motor with a 350 from a 1991 GMC, I kept the front pullies from the 91.
I am having trouble getting a lower rad hose that will fit. I originally used the hose from the 91 and it did seem to fit pretty good but there was a kink in it close to the rad outlet and I had alot of overheating due I think to that kink in the line.
The local suppliers don't have much in the line of flex hose and I am thinking of getting one from Summit Racing. The problem is how long a hose do I need? I am thinking 30 inch??
Does anyone one out there have some experience with this situation?
Can you reccomend a hose length or is there some other thing I could try? I did keep the original radiator shroud so the hose will have do some fancy bending to work with the new water pump location

Thanks

[67swb72klb]

maybe you have the wrong radiator that bottom hose should go up some not straight out ?

[Bern74]

It's the original radiator that I had rebuilt, the water pump on the 91 block is orientated differently than the 72......so the hose wont fit plus the serpintine belt assembly is in the way........I think it has to come out of the radiator bend down and out then bend up ......

[Lee H]

I have 92 GM serpentine system, 92 water pump, stock radiator and the stock 72 C10 lower radiator hose fits fine, a little twisting to get is in but once there it's fine. The hose fits between the lower idler bracket and the frame.

[71meangreenc10]

I have 95 serp on mine and the stock hose works ok.

Smitty

[MikeyMan]

Sometimes the radiator hose needs to be trimmed. They do say "cut to fit"

I just replaced the lower hose (Dayco 70664) on my 71 with stock V8. Ended up cutting off 3-4 inches at the radiator side. The hose is now "stretched out" and no longer wants to kink at the turn. Another trick I used, chopped the middle section out of the old hose and slit it down the middle. Then took that piece and wrapped it around the new hose, creating a double wall section where it sometimes rubs the frame and/or inner fender.

[Bern74]

Turns out it might not be the hose after all.
I was out last night trying to figure out why it was overheating so badly and checking the hoses for kinks and what not when it suddenly dawned on me that the air flow through the radiator was going in the wrong direction.

I remember that the fan from the 91 motor wouldn't fit into the 72 fan shroud so I managed to install the old fan onto the pulley and it fit real nice. However the fan pully on the 91 spins in the reverse direction to the original 72. So now I have the air flow going in the wrong direction. I think this is the cause of the over heating.

Would flipping the fan over 180 change the air flow direction?

I suppose I could try to cut back the fins from the 91 fan but that could cause some balance problems if I don't get it all even.......I guess I could go electric but I think I would like to keep the old fan system.


Any ideas?

[kwmech]

You need both the fan and fan clutch for the reverse rotation water pump

[Bern74]

Originally Posted by kwmech

You need both the fan and fan clutch for the reverse rotation water pump

You don't think flipping the fan 180 will reverse the air flow??

[JointTech]

Originally Posted by Bern74

You don't think flipping the fan 180 will reverse the air flow??

reversing the blades will change the air flow. But if the clutch is spinning the wrong way it will be always on I would assume. Or maybe never on. Not sure what happens when you spin the clutch backwards.

[koda360]

Try flipping the fan and bolting it to the later model clutch...

[Street Smart]

I don`t think a stock blade is gonna really like the be "flipped". It might be ok to test with, but there is a difference.

[old Chevy guy]

Flipping wont change the flow it will be the same thing.

[68gmsee]

Agree with old chevy guy. Don't waste your time flipping it. It won't reverse the flow of air.

Also, the fan blades are curved in such a way to create a maximum forced air to be pushed back to the engine.

[MikeyMan]

Are you sure about "overheating"? Or is your gauge reading hot? What sending unit are you using?

Do a little research on temperature sending units and you'll find original factory gauges in our trucks are temperamental (pun intended). If your using the temp sender from the 91 or certain replacement part store senders, you may be getting a false reading.

Confirm the actual temperature before making drastic changes to the cooling system.

[68gmsee]

Originally Posted by MikeyMan

Are you sure about "overheating"? Or is your gauge reading hot? What sending unit are you using?......

He found out engine has reversed fan blades.

[68gmsee]

Bern74:

Let us know what direction you go in case someone else encounters the same problem.

[Bern74]

Originally Posted by 68gmsee

Bern74:

Let us know what direction you go in case someone else encounters the same problem.

Well this has been a really interesting experience and while I am not 100 % sure I have found the problem .......once I decide if I'll go with a new counter clockwise Flex fan or electric fan I'll be sure to post the answer..............but here are the details.

Original motor had a catostrophic failure and rebuild was impossible, found an 1992 GMC with good motor for a donor vehicle, installed 1992 motor and for many reasons decided to keep the pully system.
Found out the 1992 fan was to big to fit into the 1972 fan shroud so did a little custom work and installed the fan from the original motor. It's been like -20 degrees for most of the maiden runs for the truck so overheating wasn't a big deal but as the weather warmed up it started to actually boil over and spit out antifreeze.........that started all the head scratching and trying many things to solve it. That was when I found that the air was flowing in the wrong direction
BTW the original fan setup did not have a clutch on it but was just a direct bolt on of the fan to the pully............everyone above is correct flipping the fan will not work...........I'll keep you all posted and thanks for all the help

[koda360]

I'd try removing the fan all together. As long as the truck is moving (forcing air through radiator) it should not overheat. This wont work sitting still, or driving in traffic, and you'll have to put a fan on it eventually, but this will tell you if you have other problems to fix as well...

[MikeyMan]

Use the Fan & Fan Clutch from the 92 and leave off the fan shroud. I ran with no shroud for many years, just keep hands and fingers out of the way. The fan will still draw air through the radiator.

[koda360]

...and if the fan is about an inch away from the rad, you won't need a shroud at all.