Overheating... SBC 350 (1 Viewer)

[jackbrad]

Yes I searched... and I have read to my hearts dismay

It seems like there are a thousand reason why one can experience over heating.

I have a TBI 350 with a serpentine system and long reverse flow chevy water pump
700r4 trans.
AC condensor in front of the radiator
Custom shroud.
electric fan.. (16 inch)
195 thermostat
no power steering, trans or oil cooler up front.
The radiator is a new 4 core brass and copper unit from radiator barn I bought in 06 with only about 2000 miles on it.

When I am idling and so on (driving in neighborhood) I stay around 200.
Any extended period of highway driving causes the radiator to boil over at what appears to be 240-260.
Underneath the hood is pretty hot but, I already have ceramic coated exhaust.

I have ran it up to temperature (240) in the drive way with a very large blower fan in front of the radiator with no shroud to ensure I moved ample air and and it does recover after I slow back to idle and let the fan run for 5-7 minutes it will recover. But, not if I maintain the RPMs at 3000

I am trying to decide if I just need to grab a different radiator... aka a Becool or other aluminum radiator.

 

[chevurai]

My vote is that it's the electric fan.
Run a 7 blade steep pitch mechanical fan with a temperature activated clutch, such as one designed for a truck. I have a sbc in a 40 and a 55. No cooling problems.
Has the setup that you described ever worked? If it did, has there been any changes to account for the over heating?
Yes there are many reasons an engine may be over heating.

 

[spotcruiser]

I don't have issues with my '96 5.7l. I'm using a Griffin 19x22 aluminum radiator with a homemade fiberglass shroud and a stock '97+ 11-blade plastic clutch fan. The thermo opens at 195 and the engine stays between 195 and 205, highway or trail.

 

[Brian in Oregon]

I'm running an 18" flex fan, a four core radiator, and no shroud. No overheating problems with my 350.

 

[jackbrad]

I don't have issues with my '96 5.7l. I'm using a Griffin 19x22 aluminum radiator with a homemade fiberglass shroud and a stock '97+ 11-blade plastic clutch fan. The thermo opens at 195 and the engine stays between 195 and 205, highway or trail.

Your shroud looks awesome. I don't think I have the skill to build that. I want to stick with some cool electric fan and shroud.

I am really considering pulling the trigger on the griffin radiator

 

[LandCruiserPhil]

Your shroud looks awesome. I don't think I have the skill to build that. I want to stick with some cool electric fan and shroud.

I am really considering pulling the trigger on the griffin radiator

If your plan is to stick with an electric fan plan on overheating issues.

Basiclly the same set up as you just add AC A 70's BB fan with shroad does my cooling without issue in AZ.

 

[Strait Cruisin]

Have you pressure tested the system and cap? even a little leak is bad as the coolant will boil at a lower temperature.

BTW, I am running a sbc, stock 4 core and a taurus fan. It works great.

 

[spotcruiser]

Actually, mounting of the radiator was more involved than making the shroud. The shroud was just made by stretching cloth over particle board forms and then adding layers of glass cloth/resin to the desired thickness.

If you have room for the clutch and fan, you might want to buy a used set and try it out with your existing rad.

Your shroud looks awesome. I don't think I have the skill to build that. I want to stick with some cool electric fan and shroud.

I am really considering pulling the trigger on the griffin radiator

 

[Texican]

http://www.pirate4x4.com/forum/showthread.php?t=374071&highlight=cooling

http://www.ebay.com/itm/170868735496?ssPageName=STRK:MEWAX:IT&_trksid=p3984.m1423.l2649

best cheapest option on radiator, have used 3 of these no problems at all


read this.........

 

[Sharp38]

I believe you can cool just fine with electric fans. But, you do need good radiator. If you are overheating at highway speed, it 's not an indication that you have insufficient fan. You have 60mph air flowing over the radiator. It's indicative you have too small a radiator. Fan issues show up at slow speed.

You need one of the aluminum cross flow radiators like Griffin makes. They have 27in and 32 in. You will have some installation challenges with the 32 like cutting the inner fender a bit. The come in 2X1 in core, 2X1.25 inch core and 2X1.5 inch core. You can mount the dual 11 inch spal fan on the 27 inch wide and the dual 12in spal fan on the 32 inch.

I have the 32 with dual 12 spal in my FJ40, SBC. Fans run independently. I have to really push it to get to 200 degrees. The second fan (set for 210) has never come on in this past year.

Don

 

[fieldsken1]

the first thing i would do is try a high flow thermostat. a stock thermostat will sometimes closed going down the hwy due to the pressure. besides its only 13 dollars and a good thing to have. if that does not help i would start thinking about putting a manual fan with a clutch and a good shroud. maybe something around 6/7 blade and maybe 17/18 inches. i dont use a clutch fan but one wont hurt

 

[fieldsken1]

The thermostat, a vital part of the cooling system, is not a good place to save money. A "balanced", hi-flow unit should be the minimum accepted. The dime store varieties actually increase their opening temperature as pressure builds. At higher RPMs, the water pump can create 30lbs or more pressure in the block against the outlet restriction of the thermostat. With that 30 lbs of pressure acting against a cheap design thermostat, the opening temperature of a 185 degree unit can be raised to 199 degrees !!! The "balanced" design has equal pressure on both sides of the sleeve, so opening temperature is independant of outlet pressure. If your overheating problem is at higher RPM, a cheap thermostat could be contributing to your problem.
Ask for a quality "balanced design" thermostat, and most knowelegable partsman will know what you are talking about

 

[Brian in Oregon]

Fascinating. I'll inquire about a "balanced thermostat" but I think I'll get a glazed look from the blister pack parts counter guy or gal, followed by "What make/model/year/engine/trasmission and does it have air conditioning?"

 

[tawright]

I had a similar overheating problem with my 350. At idle, the temperature was fine but once I drove it anywhere, it started to overheat. The cause for my overheating was that I lacked a coolant bypass. You don't have a picture so I can't tell what kind of 350 you have but mine is a crate motor with Vortec heads and Edlebrock intake. From what I understand, this bypass used to be part of the intake manifold on older SBC's but was not present with Vortec heads (or maybe my intake manifold lacked it). To get the cross flow of coolant from one side of the motor to the other, I added a T to the heater hose coming out of the water pump and ran that to the water port on the passenger side of the intake manifold and then connected the returning heater hose to the water port on the drivers side of the manifold. After I did this, I have not had an overheating problem since.

 

[Johns68]

Depending on the design, an electric fan and shroud will cause what you are experiencing by restricting air flow at hwy speeds I used to road race my 68 Camaro ... Started with a 4core radiator, factory shroud and alum flex fan. No issues on track. Switched to single large electric fan with full shroud so I could cool it in the pits and during staging. On track temps were 30-40 degrees higher immediately. I run a shroud and flex fan with a similar radiator to yours in my 40 ... No heat issues with a tbi 350.

Quick way to tell ... Take the electric fan and shroud off and take the truck out onto the hwy. If your temps stay sane, it's the fan, not the radiator. If not, it still may be air flow related ... Do you have a tall winch, aux lights, or other goodies mounted up front blocking air?

 

[Johns68]

... And your driveway fan test doesn't duplicate hwy airflow ... Good idea, but not the same. Ask any dyno tech ... They do the same thing with fans, but cars that don't overheat in track abuse will overheat on the dyno.

 

[ranger]

Do a search on taurus fans, might help.
The radiator Texican recomended works great, and is pretty inexpensive.
You can balance a thermostat by drilling an 1/8" hole in it.

If you're overheating at low rpms, like in rock crawling, usually it is a airflow issue. When you put winches, condensors, power steering and auto trans coolers all in the front of the radiator, airflow is really cut down. Stock radiator isn't going to cut it.
If you're overheating on the highway, usually the radiator surface area is too small for proper heat exchange. Try driving highways speeds, say around 65 mph, and watch your temp gauge. When its starts to get hot, turn your heater selector to high heat, and the fan on full blast, and see what happens. Temp should fall a little. It will work in a pinch, but I have to tell you driving around when its 90+ degrees with the heater on full blast just plain sucks!

One thing to note on overheating, there are a lot of variables that need to be considered. What works for one rig might not work in another.

 

[fieldsken1]

Fascinating. I'll inquire about a "balanced thermostat" but I think I'll get a glazed look from the blister pack parts counter guy or gal, followed by "What make/model/year/engine/trasmission and does it have air conditioning?"

A balanced one is just a high flow for sbc. There all the same

 

[jackbrad]

Fascinating. I'll inquire about a "balanced thermostat" but I think I'll get a glazed look from the blister pack parts counter guy or gal, followed by "What make/model/year/engine/trasmission and does it have air conditioning?"

lol..

This is actually what I hear from them every time I walk in regardless of the complexity of the part.

 

[jackbrad]

Quick way to tell ... Take the electric fan and shroud off and take the truck out onto the hwy. If your temps stay sane, it's the fan, not the radiator. If not, it still may be air flow related ... Do you have a tall winch, aux lights, or other goodies mounted up front blocking air?

I actually did this test and there was no difference in the temps.
There are tons of things up fron blocking (All hard to move.) Large bumper, lights, winch, AC condenser.