What's new
CK5
Register an account today to become a member! Once signed in, you'll be able to participate on this site by adding your own topics and posts, as well as connect with other members.

1969 C10

Slow process of putting it back together.
Overview Gallery Discussion
I've always run a 16 psi on my trucks' small blocks and had no problem. (A 305 and now a 325hp 350). With a factory style heavy duty radiator and mechanical fan. But my truck is a manual so there's that. I did live in the southwest with this rig for quite some time so I know how hot the Phoenix area gets.
 
I have a 13psi on it now.l replacing the rusty 19psi. I saw this from gooooooogling that 18psi is maximum recommend psi for small blocks

The radiator company recommends 19psi with their radiator. I assume that can very depending on the engine you're running.

So, how will I know if 13psi isn't correct and maybe going upto 16psi is better or if the manufacturers 19psi recommendation is what is ideal for this small block? And if 18psi is the maximum psi for a small block why do they recommend 19psi?

I'm going to get a 16psi cap today and see what happens. Granted the heat out here isn't helping and as @6872xtc noted from my comments, my heat gun didn't notice anything crazy heat wise and was contrary to what my temp gauge in the cluster was stating.

The only or main reason this is dragging on, as per my usual in threads, is for me to learn about radiator caps and the function in the vehicles system. And also what proper psi does.

While 19psi seemed fine, I'm replacing it because it's all gunked and I think 16psi will hopefully be better. I don't know.

Some info pertinent to the topic, at least for me: Radiator cap function

6563C8C9-1FB9-4E5F-A23A-388BBD15E47B.jpeg
 
Last edited:
The radiator manufacturer probably doesn't have a clue of what the engine needs. The higher pressures can cause early failure of some gaskets or possibly the heater core.

Or someone typing up the installation notes poked the wrong button.

You need enough pressure on the cooling system to avoid boiling in the system. If the engine were to get overheated somehow, and the coolant begins to boil out of the radiator, then you would need more pressure.
Boiling coolant is not the same as the system pushing small amounts out from thermal expansion. Without an overflow bottle, the coolant needs space to expand inside the radiator to avoid pushing coolant out during warm up.
 
I found and overflow im looking into buying

azproperformance.com

Champion Stainless Steel Overflow Tank

These Champion Cooling overflow tanks are built from 100% stainless steel including the cap and brackets. Standard in a highly polished finish.
azproperformance.com azproperformance.com

I could just this bottle I have the bracket already

Bottle
 
Last edited:
water at sea level boils at 212° by adding pressure to the cooling system you can raise the boiling point. At 13 psi your boiling point will be @ 245-246° 16psi would be in the 252° range. I myself would not want to put my cooling system under high pressures, is why I recommended 13psi. The key here is have a cooling system large enough for your engine and in good condition. Using higher pressure to solve overheating issues is a band aid at best, and not what I would recommend at all. 19-20 psi is for racing, on cars that get attention in between heats. To much pressure for our needs.
 
Wes Harden said:
water at sea level boils at 212° by adding pressure to the cooling system you can raise the boiling point. At 13 psi your boiling point will be @ 245-246° 16psi would be in the 252° range. I myself would not want to put my cooling system under high pressures, is why I recommended 13psi. The key here is have a cooling system large enough for your engine and in good condition. Using higher pressure to solve overheating issues is a band aid at best, and not what I would recommend at all. 19-20 psi is for racing, on cars that get attention in between heats. To much pressure for our needs.
Click to expand...
I have the 13 as you recommended I ordered the 16 just to have incase 13 doesn't work and I'd just have it
on hand if that happens. I trust your advice.. I'll probably just return the 14-18 psi one I ordered and keep the 16 but we'll see. hahahahahah

My Blazer which has an aluminum radiator as well came with and still has its 13psi cap.

At the very least, I've learned more than I thought was possible about radiator caps the last few days... hahahahahahah

I haven't had any overheating issues thus far and just needed a replacement cap. Which spiraled into this. Hahahaha
 
Since we're here how do these caps work? It says minimum 14psi max 18psi but listed at 16psi

How does these caps regulate between those psi's and be a set psi?

00D5FFB9-BA8A-4D9A-A799-A31867FF85FB.jpeg

E26CAECE-7CDC-44ED-983D-45837F93739F.png
 
Probably rated for 16 with manufacturing/applications tolerances allowing a 14-18 range of function for individual caps?
 
Rigged up an overflow using the washer fluid bracket and container. Hopefully it works... used the tape to hold it in place while I drilled 3 holes.

I couldn't really get it any lower unless I mounted it on the driver side fender or driver side of the core support. I suppose I could mount it on the inner fender at an angle but, we'll see how this does first.

09079324-345C-4378-A993-5A767EEEC26F.jpeg

5A0A776E-171D-4BEE-A6FD-81C1E77BA798.jpeg

16DC5AF8-5502-4656-BE93-80D746048541.jpeg

35E15CCA-6DCC-41DC-8B31-43F3C35975D6.jpeg
 
Last edited:
Been a minute fellas...been MIA for a bit. No money to fix'em so haven't been driving them, other than the Blazer. So, I relented and took the c10 out, then this.

I'm also considering selling the C10 as I don't have enough extra income to maintain to classics and I prefer my Blazer anywhow. So...


took this out for a cruise came back and saw coolant dripping on the ground from on top passenger inner fender..

Why? I don't know, I tightened down the clamp, was ok. Never dripped from there before, so why now? I haven't checked inside the cab yet..

It's the lower hose into the fire wall

CEA95FD3-8EF8-4D04-A4E9-D39C6D3E1A9C.jpeg
 
Last edited:
Could the hose has a cut inside and coolant is leaking in between the layers. Might the heater core.
Check inside for wetness.
If carpet is wet you need to pull it up and dry it.
 
Wes Harden said:
Could the hose has a cut inside and coolant is leaking in between the layers. Might the heater core.
Check inside for wetness.
If carpet is wet you need to pull it up and dry it.
Click to expand...
Would running the heater or ac help? It's odd it happened now. I've only used the AC once or twice since it being done, which was over a year ago.
 
has nothing to do with a/c. a leak is a failure of some component, since you have checked that the clamp is tight.
 
Wes Harden said:
has nothing to do with a/c. a leak is a failure of some component, since you have checked that the clamp is tight.
Click to expand...
I just started it up in the garage for about 10min... and nothing, cab is dry as well. Welp, I'll just keep and eye on it. I tightened the hose clamp down a tad more and well see. Hahahah
 
TJ1978 said:
I just started it up in the garage for about 10min... and nothing, cab is dry as well. Welp, I'll just keep and eye on it. I tightened the hose clamp down a tad more and well see. Hahahah
Click to expand...
Wes Harden said:
has nothing to do with a/c. a leak is a failure of some component, since you have checked that the clamp is tight.
Click to expand...
So coolant is always flowing through those hoses? Or?
 
Pretty much yes. Unless you have a shut off valve in a hose. The heater core is used as the by pass when thermostat is closed on many sbc applications
 
You must log in or register to reply here.

Latest Posts

Top Bottom