Correct radiator and fan for 350

[plagee]

How many rows should a 350 have and is the 4 blade fan large enough to keep everything cool? Mine keeps boiling over, not overheating though. Wondering if this could be also affecting loss of oil pressure when truck runs for sometime.

[jgreene0717]

A 3 or 4 row radiator in good working condition will keep your 350 cool. Does your truck have fan shroud? How does your engine run any strange noises? How many miles on engine?

[plagee]

Yes there is a fan shroud, I think the engine has about 60,000, this info according to previous owner. No noises. Just measured the core, I believe it is only a 2 row.

[jgreene0717]

How low does your oil pressure drop? I used to have a 83 C-10 with 350 and
even after rebuild at normal operating temperature it would drop down to about 10PSI at idle. My dad owns truck now and has well over 60,000 miles since rebuild. Do you no if gauges are operating correctly? Does it run hot at idle only or on highway? It may have a blown head gasket causing it to boil over or it may just be running hot and the gauge is wrong not sure.

[plagee]

Just like you said: drops to about 10 pnds. Oil pressure comes back up with engine rpm, why would pressure drop when at idle though? New gauge, in new cluster from Lmc, may not be perfect but should be close. Truck spews when turned off.

[jgreene0717]

It depends on the oil pump in most situations. My 2007 Silverado with 5.3 drops to about 25psi at idle and goes back up to 40 right off idle. Just the nature of the beast with an internal combustion engine I guess. My C-10 with new GM 350 crate engine at operating temperature is about 30 psi at idle and between 50 and 60 psi when cruising. What does your temperature gauge read before and after you shut off engine?

[Skirkpat]

Your oil pump runs off of your camshaft, through a gear in the end of the distributor, as Rpms rise, the oil pump turns faster creating more pressure.

You should have at least 10 PSI of oil pressure for every 1,000 rpm's , this is the bare minimum, if you are running 10 psi at idle, I would throw a higher viscosity oil in it and see if that helps any ( what are you running now?)

[plagee]

Don't know the exact temp but I can't keep radiator fluid above the fins otherwise it spews out overflow. Hoping a larger rad. will help.

I've set the idle at about 900 with about 12 pounds pressure, best idle condition for truck. Mostly I am worried that this isn't enough oil pressure. 10w40 is what is in there now.

[Green Machine]

Normal level for the radiator is 2-3 inches down when cold, full level might even be stamped on an orignal radiator. If you fill it too full, expansion of the water pushes it out the overflow, one of the reasons newer trucks and cars have overflow tanks.

[jgreene0717]

You might need to change radiator cap. You could step up to 20w 50 and see if that helps.

[Stocker]

Your radiator might be partially plugged and unable to provide adequate cooling. Before replacing it, try an inexpensive overflow tank. That way, you can fill the radiator to the top.... more coolant = better cooling. And you will need a cap designed for a sealed system.

You mentioned a 4-blade fan, and I'm guessing that a fixed-blade fan. That's probably part of the problem, too. My 350 has a factory 7-blade thermal clutch fan and doesn't overheat -- ever. You should be able to junkyard a used one cheaply, just measure the bolt pattern, shaft length, and fan diameter.