Boiling over.......

[Sand85]

Originally Posted by Dead Parrot

Most SBCs specified a 195 thermostat. Haven't tested it myself but several folks claim that running no thermostat degrades cooling because the coolant moves too fast through the radiator. Maybe too much speed causes turbulence that limits heat transfer.

If that is a flex fan, add a stock 7 blade fan to your list.

Might research doing a switch to electric fans. May be cheaper then obtaining the proper parts to restore the OEM cooling setup.

My current fan has six blades and I don't see how one more blade would make a difference?

I have run a 93' Chevy 5.7 with no thermostat and it run fine but I put one in anyways because I was a lot more comfortable knowing it was there.

[Dead Parrot]

Originally Posted by Sand85

My current fan has six blades and I don't see how one more blade would make a difference?

I have run a 93' Chevy 5.7 with no thermostat and it run fine but I put one in anyways because I was a lot more comfortable knowing it was there.

If yours is a flex fan(hard to tell for sure from the pics), it probably has less pitch since the assumption is that it will be running at a higher speed most of the time. When it is running at high speed, it pulls enough air to keep things cool. At idle, not so much. Which is where you said your problem is.

The factory fan has more pitch since GM expected it to be mated to a clutch which allows some slippage. But at slow speeds, it moves more air across the radiator. The one extra blade isn't the advantage, the greater pitch is. If you wind up getting an OEM type fan, they usually come in 5 and 7 blade versions. Might as well get the 7 blade if you make the swap. Some flex fans won't mate to a clutch, depends on the fan.

Adding the shroud may fix the problem with no other changes needed.

[Sand85]

Gentleman, I haven't had time to work on the truck as I had promised. I do another question on weather a fan and clutch from a 79 GMC will work? I noticed that the donor has bolts coming from the water pump pulley and not going in like mine.

This is what I found yesterday in the scrap yard, would it work for mine?

[Dead Parrot]

Assuming the clutch is good, should work. You will need to pickup four water pump studs, nuts and lock washers if you didn't keep the four from yard donor vehicle. That looks like the same type of 7 blade fan mine has.

[Bluestep]

Although I would recommend running a fan clutch, this is not your problem. It will not make the fan turn any faster than the spacer does! The fan and clutch from the wrecking yard should work okay, if the clutch is working properly.
Running without a fan shroud will definitely move very little air at an idle.
Make sure that the coolant recovery system is all working properly so that you end up with no air in the system that can cause an airlock. Also make sure that your belts are properly tensioned.

[Sand85]

Originally Posted by Bluestep

Although I would recommend running a fan clutch, this is not your problem. It will not make the fan turn any faster than the spacer does! The fan and clutch from the wrecking yard should work okay, if the clutch is working properly.
Running without a fan shroud will definitely move very little air at an idle.
Make sure that the coolant recovery system is all working properly so that you end up with no air in the system that can cause an airlock. Also make sure that your belts are properly tensioned.

Bluestep, thank you. The coolant recovery tank is where the boiling water is going to when I hear and see it. I have picked the truck up on blocks to get any air pockets out of the engine and radiator while running, thus searching for the fan clutch and any accessories to go along with it. I really don't want to run electric fan(s) or new radiator.

[Sand85]

Originally Posted by Dead Parrot

Assuming the clutch is good, should work. You will need to pickup four water pump studs, nuts and lock washers if you didn't keep the four from yard donor vehicle. That looks like the same type of 7 blade fan mine has.

Thank you deadparrot, I will purchasing the fan and fan clutch tomorrow, along with fan shroud it looked it was in pretty good condition(shroud). I will try get everything I can off the donor has to offer.