SBC 350 gets hot above 50MPH. Why?

[lcwizard]

Is any fan going to make more airflow than moving the whole truck at 50 mph?

This is why it's probably the shroud. I've seen shrouds done incorrectly so much
so that standing still air would draw in at the center and blow out around the perimeter of the radiator.
Remove the shroud and give it a test drive. It doesn't cost anything and will
eliminate one possibility

 

[nicholastheczar]

Sorry it has taken me so long to get back w/ pics, work has been crazy.

So I snapped a few shots, and noticed my water pump is totally rusted on the outside! It wasn't like this before, would too much heat cause this? This water pump was new when I put it on about a 1.5 ago. Also, my shroud may be some of my problem. I fabbed it up and it may or may not allow enough air to pass through as it should. Does anyone have a good resource for pre fabbed shrouds that I could buy and install for my application?

Here is the Flex a Lite fan I am running:
Flex-a-lite 5919 - Flex-a-lite Reverse Rotation Clutch Fans - Overview - SummitRacing.com

The Fan Clutch is from Napa and so is the water pump.

Nick

 

[hey you]

I had the same duel fan set up with my 60 and the same problem. I also had an external trans. cooler and a A/C condensor in front of the radiator. I had thermoswitch and a manual override and still the engine overheated on the road, but stayed cool on the trail. I fixed my problem by installing a 17 inch, single fan and shroud. I cut out a couple retangular holes in the shroud and made a ridged plastic flap, hinged on one side. So, at road speed the flaps opened up for more air flow. While on the trail, the flaps covered the holes. I figured that at road speed, the fans were restricting adequate air flow and causing the eng. temps. to climb. My setup worked great and cure my heating problems at speed.

 

[Elbert]

does the flat part of the shroud sit right up against the core of the radiator? if so that may be blocking air flow across the radiator, espically at road speed. I've had concerns about that on my own truck. If you look at various OEM fan shrouds to include toyota you will notice that the shroud ties into the side and top of the radiator, but then it either is spaced back to the rear or flares out to the rear allowing air to flow across the entire core of the radiator without as much restriction. I'll post a link to a shroud I noticed on one of the other sections that looks like it would be great.

I doubt the water pump is rusting due to the heat...most likely just bad paint.

Engine appears to be TBI setup. I would make sure that the water pump and fan are the correct rotation setup for the TBI engine. I think the term revers flow water pump only applies to the LT1 engine that came in teh vette and camaro? I may be wrong so I would make sure you have the right parts.

I would not swap out any parts just yet, expect maybe the thermostat..just because its real easy to do.

When the truck does get up to temp (not that its summer) and you get close to 210F or so...can you hear the fan clutch engage? And if so does the temp immediatley start to decrease? You should clearly be able to hear the fan clutch engage (roaring noise) and the engine temps should drop back down to around the thermostat temp rating. If thats not happening then fan clutch is the problem.

One thing I came across when I had similar fan on my 92 K1500 is that GM talks about the fan trotation one way and flex-a-lite talks about the fan rotation another way. As I recall one is from the driver's perspective looking forward and the other is from outsdie the vehicle looking toward the radiator as in standing in front of the truck.

 

[Elbert]

I had the same duel fan set up with my 60 and the same problem. I also had an external trans. cooler and a A/C condensor in front of the radiator. I had thermoswitch and a manual override and still the engine overheated on the road, but stayed cool on the trail. I fixed my problem by installing a 17 inch, single fan and shroud. I cut out a couple retangular holes in the shroud and made a ridged plastic flap, hinged on one side. So, at road speed the flaps opened up for more air flow. While on the trail, the flaps covered the holes. I figured that at road speed, the fans were restricting adequate air flow and causing the eng. temps. to climb. My setup worked great and cure my heating problems at speed.

Do you have pictures of the "flapper valves".... I notice that SPAL has them on some of their dual fan shroud setups and some of the OEM car mfg run them as well.

 

[Elbert]

Here is one pic I've come across on "custom" fan shrouds. If I had the skills of this guy I would be in another line of work... very nice. This pic illustrates what I was talking about regarding the fan shroud tieing in to the top and bottom of the radiator but then allowing air to flow acros the entire radiator core. I wish I had the skills to make something like this. Just posted up for others who may get some ideas. If I change my shroud it will be to go to something like what is in this picture.

See Post #97 on this thread.

https://forum.ih8mud.com/60-series-wagons/379330-60-build-moab-5.html

Different trucks and different threads but shrouds appears to be of similar design

see post #115 on this thread

https://forum.ih8mud.com/100-series-cruisers/446183-100s-cruise-moab-2011-a-6.html

 

[Brian in Oregon]

Sure doesn't look like the shroud stands off the back of the radiator by very much. The pics on that are not clear. Can you provide a measurement of the actual distance from the fins to the shroud?

From what I'm seeing, I sure would remove the shroud as a test. This has been already suggested by myself and others.

 

[nicholastheczar]

Yes there are points where the shroud is close to the fins, maybe 3/4" or so. I'll start by taking the shroud off and see what that does.

Nick

 

[Bret]

you can make on pretty easy out of fiberglass. I just made a mold out of florist foam covered in non-stick aluminum foil. The over a period of several days layered sheet and resin. Then when it cured fully I cleaned it up with a sander. I would try to leave maybe 2" between the back of the radiator and the shroud. The hardest part was measuring for where the centerof the fan was in relation to the rectangular portion.

 

[hey you]

Sorry, no pictures. On the pictures post prior to my post, on each side of the shroud, I cut out a couple of 2x4 holes and fabricated couple of flaps with ridged plastic and a piano hinge. It was really simple.

 

[camcruiser13]

s*** son. Bigger radiator and a Taurus fan and be done with it

 

[fj40scottb]

Nick

Your setup looks like the same issue I have. The shroud is too close to the radiator core. There's not good airflow through all the surface area of the radiator basically resulting in a smaller radiator. I agree with the other comments about having the shroud about 2" off the radiator.

 

[Bret]

s*** son. Bigger radiator and a Taurus fan and be done with it

He is running a 19x26 wich is a bit bigger than stock, the MKVIII fan may fit better. I thought the taurus fan fit the stock size radiator?

I'll look for the link...

https://forum.ih8mud.com/60-series-wagons/392223-v-8-conversion-cooling-3.html

Also shows a great way to make a shroud.

 

[fieldsken1]

you need to make the shroud fit better. i can see its up against the radiator you need to move it away from there and it needs to seal better. heres mine look at how it sits away from the radiator and seals all around