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Old 08-29-2007, 01:33 PM
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How hot is too hot for a 406?

Currently my 406 is running around 190-215 degrees when driven during the day (usually 85-100+ in the Sacramento area). I have heard that keeping it below the 230 degree mark is the magic number. Is that correct? Hearing how these engines have a tendency to burn themselves up has me a bit worried given the money put into this engine by the original builder. Also, has anyone tried using products like Water Wetter to keep temps down? Do they work?

thanks

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Old 08-29-2007, 01:49 PM
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235 to 240 won't hurt it with the right cap and coolant mixture the key is preventing boil over. 210 is just about perfect.
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Old 08-29-2007, 05:18 PM
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You have to remember that typically oil temps will run 30-40 degrees higher than water temps. Given that 235 to 240 water temps are way too high in my opinion. They are especially too high if you run a thermostat anywhere in the 180 to 195 range.

I don't see anything wrong with 190 to 210/215. It would appear the cooling system is struggling a tad at times but what can you expect with 100 degree temps. Unless you upgrade the radiator and pump and potentially the fan not much is going to help.
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Old 08-30-2007, 07:29 AM
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I was baseing the temp on the fact GM turns on the electric fan at approx.235 degrees in many newer vehicles including the 3rd and 4th gen F- bodies.Again 210 is just about perfect as the oil temp must be over 200 to rid itself of harmful moisture etc.
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Old 08-30-2007, 10:15 AM
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eng oil cooler??

We pulled a 400 SBC 400 th out of a cargo van ... It came from the factory with an engine oil cooler....I plan on using it on a rat chopped and channeled 42 International truck.....I also have a couple of Ford 460 engine coolers for heavy duty trucks and vans. It should be easy to add one using factory parts (Cheap) and new hoses
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Old 08-30-2007, 01:51 PM
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Quote:
Originally Posted by barnym17
I was baseing the temp on the fact GM turns on the electric fan at approx.235 degrees in many newer vehicles including the 3rd and 4th gen F- bodies.Again 210 is just about perfect as the oil temp must be over 200 to rid itself of harmful moisture etc.
The factory runs 220 and up coolant temps and 5W-XX Energy Savings oil strictly to meet EPA/DOT fuel economy standards. These things have no relativity beyond that to the real world. The engines are still principally made of gray iron which isn't anymore friendly to overheat temps today than is was 50 years ago.

Back in the Hyper aircraft engine era of the late 1930s and early 40s the Army Air Corps tried to run up engine temp into the 300s F and it didn't work with motors built from billet chrome moly steels and forged aluminum/magnesium alloys; so why people today think that something magic has happened with the auto-industry's wonder metal, cast iron, and it's limited use of cast aluminum is beyond my reckoning. Physics hasn't changed the limits of these materials that I'm aware of.

I rather think that a 180 thermostat with a hot day coolant temp of 190-200 is plenty high enough. As was stated the oil is running 20 to 40 degrees more which for mineral oil at 220-240 is getting edgy. Plus at those temps, 5W-XX mineral oil has the consistency of hot water. Synthetic oils are more tolerant of these temps, but still that's plenty hot. If the slightest thing goes wrong you can be over the edge in an instant and from the number of toasted engines I see, it happens a lot especially with trucks and SUVs hauling the family on vacation.

One has to be careful about OEM oil coolers, since the 90s the factories have run engine oil into a radiator mounted heat exchanger as they do with auto tranny oil. This however is not done to cool the engine's oil; quite the opposite, it's done to heat it so the engine warms faster so mileage improves sooner and the emissions come down faster by eliminating time it's on cold enrichment (choke). While there are some striking advantages to doing this, there is no way that you can depend upon this system to protect your oil from overheating, especially when the engine is working hard or is running in slow moving traffic on a hot day. To truly cool engine oil you need a stand alone cooler. To take advantage of the OEM system to shorten warm up time and keep the engine oil cool the way to replumb this is take pressure oil into the factory heat exchanger. Coming off the exchanger flow into a thermostatic bypass valve. When under 160 degrees the oil is returned to the pan, when hotter the valve routes the oil to the external cooler. On a hot day this will take 10-20 degrees off the cooalnt temp as well as keeping oil temps around 210-220. Plumbing the automatic transmission the same way will do similar things to the engine coolant and tranny fluid temps as well.

I won't run Energy/Fuel Savings oil in anything whether it's mineral or synthetic base, the thinnest I'll put in an engine is 15-40, for myself 20-40/50 the year around.

Bogie
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Old 08-30-2007, 03:32 PM
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Cool thanks for the info, if I'm understanding ya the factory is running on the ragged edge with no margin for error?
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Old 08-30-2007, 05:17 PM
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oil coolers

the chevy cargo box van and the ford 460 coolers are stand alone systems.... not part of radiator
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Old 08-31-2007, 07:53 AM
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Cooling ?

I believe the answer to your question about Water Wetter ect is yes. I used Motor Max and got a lot less electric cooling fan activity. I have the fan temperature switch set at 200. I can hear them (dual fans) or watch the voltmeter to know they are on.

The 215 is fine in my opinion. If your still concerned, look at a fan driven auxillary oil cooler. Summit has different sizes to mount in the fender wells or under? I plan to add one next Spring. Also I recommend picking up a heat gun about $35. so you can verify your gauge. I found my up-dated gauge was reading 10 degrees high because the sender is a head mount close to exhaust ports and with thin wall headers there's a lot of heat around it. Good luck .
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