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Old 12-17-2006, 06:40 PM
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Big Block Chev Coolant Bypass

So, the other day I finally removed the 160* t-stat and replaced it
with a 180*.

My 454 has the bypass hose removed.

With the 160 stat, the car would come up to about 175* and then rapidly
cool down to about 165 and then stabilize.

With the 180 stat, the car comes up to 210, then down to 165.
up to 200, down to 175----up to 190, down to 175.
Then it starts to just hang around at 180.

Is the lack of a bypass doing this???

This is NOT at idle----takes about 4 miles @ 40-45 to get up to the 210
mark.

I did drill four 1/8" holes in the 180 stat before installing.

The heater is a flow thru, with a valve to shut off the flow.
Would it be a good idea to open this valve for use as a bypass
'til the motor gets warmed up???----Or just leave it open
until I need the AC-----not a big deal----heater will only blow hot
if I turn on the fan.

Or---is this something I even need to be concerned about??

Bryan
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Old 12-17-2006, 06:52 PM
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Jack Wilson over at: http://www.stewartcomponents.com/ is the best guy to pose this question to IMHO. They have a Q&A forum where Jack answers cooling questions.
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Old 12-17-2006, 07:51 PM
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Well, that was a pain.
I posted there, but, It appears to me that with every post he is trying to sell something.

I guess we'll see

Bryan
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Old 12-18-2006, 06:50 AM
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Quote:
Originally Posted by Bryan59EC
Well, that was a pain.
I posted there, but, It appears to me that with every post he is trying to sell something.

I guess we'll see

Bryan

I agree. Got the same impression. I have a pretty aggressive 454 and I run the bypass. I have never ran it without it and I have no issues. I didn't drill the T-stat either. Mine hovers around 190 all day with a 180 T-stat.. I have a oem water pump with a 4 core rad. MIne is cold natured upon start up, but I contribute that to the Air Gap intake.
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Old 12-18-2006, 07:03 AM
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I run both a 396 and a 454 in my truck. I swap them out as I work on the other one. Anyways, my 454 ran better without the bypass hoses and the 396 would over heat the heads at the temperature sender but not the water in the radiator. Weird. It is strangle that two bbc's run different with the exact same cooling systems.

The only differences was the 396 used a high flow water pump and the 454 using a standard flow pump. I'm thinking the pump flow has something to do with it. I use the stock pulley diameters.

Also, the heater core acted like a water bypass since water flows through all the time in old Chevy trucks. However, I do have the water line to the heater core restricted down to 3/8 inch.

Try using the bypass and see what happens.
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Old 12-18-2006, 07:04 AM
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Went for coffee this morning
Opened up heater valve
Same results as before---with the heater valve open, would that not be a sufficient bypass.

Maybe the Stat is sticky
once it all evens out-----consistant 180 in the 50-70* outside temps.

Bryan

BTW----454 HO roller cam Crate------came with pump
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Old 12-27-2006, 01:27 PM
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Well---
Bought a new t-stat, 180*, drilled a couple of holes in it.
Silly car was getting to 230* with the heater hoses shut off.
Open the heater flow valve-----car cools right down (heater fan not on)

Go buy another stat this morning, 180*, did not drill holes, reinstalled the bypass.-----got up to 201*, fans kicked on---cooled to 190* and stayed there.
No change in temps on a 20 mile cruise in 4th gear (2700rpm) at all.

I just do not understand why this car was heating up with a 180* stat with holes and no bypass.

As soon as I closed the heater valve----temps spiked----

I was using a 160*, no holes, no bypass, heater flow off.----no isssues other than a cold running engine.

Attempt to warm it up a bit----headache city.

What changed to make me have to reinstall the bypass???

Now I need to get a higher temp fan switch.
Any ideas on a fan on temp???? 210? 225?
I would like it to shut off probably a 195*

It currently kicks on @ 200------Off @ 180

Bryan
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Old 12-27-2006, 01:48 PM
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Sounds like my latest experience. Needed the bypass hose to run at 180. It would run cool with an open T-stat (valve removed), but once the 180 T-stat was installed, it needed the bypass to run cool. I guess there is a lot of localized heating on the cylinder walls that requires a large amount of water flow at all times.

I run an electric fan on my sbc. It comes on at 215 and off at 195. I use a non-adjustable water temp switch that screws into the intake manifold water port. I use the water temp switch to complete the ground circuit to the fan relay.

Glad you got it figured out.
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Old 12-27-2006, 03:13 PM
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You get that switch at NAPA????
You wouldn't happen to have a part number or application for it, would you??

I'm just gearing up to go to NAPA's web site and do some looking.

Bryan
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Old 12-27-2006, 03:45 PM
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Wow, it has been so long since I bought that sensor that I can't remember even where I bought it. Man I'm getting old. I'm thinking that I bought it from a catalog that specializes in switches since Summit doesn't have it. It could also be a NAPA part. ??????

Summit does have a 200 on and 185 off but mine is a little higher than that. Summit also has some adjustable temperature switches (240 to 180) but if you get one, get the one that screws into the manifold water port. I think the painless wiring unit is like that. I don't like the flex-i-lite unit that sticks on the radiator or slides under a radiator hose.
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Old 12-27-2006, 04:25 PM
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I guess I will be going to the NAPA store in the morning.
The one @ 410 & Somerset.
Not really looking forward to this, as since Michelle left and the store moved--
service there is close to the same at AutoZone.
They need computers and applications for everything. The last couple of times
I went there, getting them to let me look at their catalogs---
---WAS LIKE PULLING TEETH---

I might even go to the warehouse and check their books.

(yep---1 wire switch in manifold)

Bryan
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Old 12-28-2006, 08:19 AM
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Yes, knowledgeable counter guys are hard to find.

I live on the north-side so I hit the Bandera store but it is the same thing there. The warehouse store is most likely your best bet.
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Old 12-28-2006, 03:21 PM
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Went to the warehouse after some research at the PaloAlto store.

Found a couple of switches I wanted to try but there was no ON/OFF temps listed.--These were GM applications.
Took those GM PNs to Vara Chevrolet to try to get the specs on em.

"We cant do this---we go by application---too much trouble to research
you are wasting our time"---etc.

Found a Ford switch----on at 213-227-------there was no "off" temp listed,
I'm hoping off at around 200. (napa# FS118 3/8 thread)

Napa's website USED to be user friendly---would let you search by item.
Now--You need an application to get anywhere. PITA

Oh well----trial and error-------only takes a few minutes to drain and change a switch-----takes a long time for the car to cool off enough to do that though.

Bryan
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Old 12-28-2006, 03:28 PM
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I will look at my switch tonight to see if I can see any numbers on it.


Might be worth buying an adjustable switch from summit racing. Then you can set it where you like.
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Old 12-28-2006, 03:40 PM
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Look up these part numbers at summit racing

DER-16749 (39.75)

and

PRM-18907 (61.88)
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