Chevy 454 Replacement Thermostat

[SupercubPilot]

Sent: 3/28/2004

What temp water regulator should I be using?  My engine water temp never goes much past one eight of the way past C toward H.

[denisondc]

Sent: 3/28/2004

Before you conclude your water temp is too low, maybe replace the coolant temp sensor? I don’t know where yours is, but on the 350 it is on the drivers side engine head, real close to the front spark plug on that side. Easy to miss. Its also possible your thermostat has failed "open", especially if it was ever really overheated.
I don’t know what the standard thermostat temp would be for your engine. If there is a choice of temperatures I would take one like 180, even if it came with a hotter one. With motorhome use we usually don’t have a problem with the engine not getting fully warmed up. I am assuming yours has a carburetor, no fuel injection. If there is a choice of a higher flow rate thermostat, I would take it. Go to www.summitracing.com and do a part number search for MIL-16400, MIL-16401 and MRG-4365 to see what I mean. That is probably the type of thermostat your RV had when it was new. I always replace my thermostat when I put on a new top radiator hose. That’s another part that I don’t trust when it gets olds. It is possible the water pump your RV came with was a high flow item also.

[fgutie35]

Yeah! I would check the temp sensor. Usually these engines like to run after the middle mark. I replaced mine with a 160F thermostat cause here in South Texas gets pretty hot. On top of that, I had to manually rig the aux/AC fans because they were kicking in too late.

[Elandan]

In a warm climate, it is never a good idea to put a lower temperature thermostat in a rig.  I know it sounds like it makes sense but here is what happens:

You put a 160 Thermostat in your rig, the coolant port opens at 160 degrees.  Your rig is now working hard to keep it at 160 degrees.  In a warm climate, the ambient temp reaches over 100 regularly.  At 100 degrees outside, there is only a 60 degree difference in temperature so your cooling system has to work its youknowwhat off to keep it at 160 (which it will still run hotter) and your fan will never shut off because it will never get back to 160.

If you put a 195 in there, you are now 95 degrees away from ambient temperature which makes it easier to cool since you are further away from ambient temperature.

Best bet is to keep stock or close to stock which is usually 195.

[fgutie35]

In my own observations, I noticed that when the thermostat opens at either temp, it does nothing else but to circulate coolant thru the cooling system. Ultimately the cooling fan will be the one that dictates at what temp the engine is going to be running. To prove this, try running a vehicle without a fan and only with the cooling system running; is going to over heat. Now try to run a vehicle without a thermostat, but with a cooling fan in place and the temp will stay where it was designed for. The only difference, is that it is going to take a few minutes longer for the engine to reach its operating temperature from a cold start, that is all. I forgot to mention on my previous post that besides putting a 160F thermostat on mi rig, I also replaced the belt driven fan with an electronic fan that has adjustable temperature sensor, which I set for 160F.

[Elandan]

The only difference, is that it is going to take a few minutes longer for the engine to reach its operating temperature from a cold start, that is all.

Actually another difference would be that it wouldn't cool properly if you run w/o a thermostat.  As one function of the thermostat is to slow down the coolant through the cooling system which is why a lot of people that remove it, overheat because the coolant runs too fast through the radiator.

Now, with your 160 fan and thermostat, what temperature are you running at?  160?

[fgutie35]

Our Elandans do not have numbers on the gauges, but I can tell you that it runs just before the middle mark (about 2mm before).

[Elandan]

So does mine with a 195 degree thermostat on it and a mechanical fan.  You are spinning your wheels with the 160 as you are never letting the cooling system take a break.  Your fan is ALWAYS on and your thermostat is always open -- which isn't a bad thing -- but the fan would probably like a break once and a while as it is always trying to cool it to 160 which it will never be at after it warms up.

[RayCameron]

Hey folks how are you. We just had our thermostat replaced " can't remember the temp he told me " and he told me he made it warmer. It used to run about 1/4 the way between C/H but now does just a tad over midway point. He also told me to keep it below 60 as it does not have an overdrive " I was occasionally hitting 70  when we don't pull our toad. It seems to be doing OK with the higher temp but I was going to check with folks here to see that that was OK.

[Froggy1936]

Midway on the gauge is proper (if the gauge is accurate) the engine should operate at approx 180o   He probably replaced a 160o thermostat with a 180o Keep an eye on the gauge going up long hills till you see how it responds It is normal to climb to 3/4 under strain but should recover quite fast when normal load is resumed  Frank

[RayCameron]

That sounds familiar as he said it was only a change of 20 deg.... I had it go up some then come back down fairly fast. He was saying the engine would run more efficiently.