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Old 11-22-2019, 12:43 PM   #1
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Engine temperature?

New here and to motor home. 1997 Itasca Sunrise with Chevrolet L29 454 cid consistently runs at 210 degrees. Warm or cold weather. Seems high to me. Thinking 180 degrees more like it. 88,700mi, runs like a Swiss watch. Any input appreciated.
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Old 11-22-2019, 01:41 PM   #2
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That is not that old and that engine was a good one but it is always true that things fail. So my move would be to first check some specs to see what is normal as well as what thermostat is the normal. One thing to watch on any used item is how the previous owners may have "improved" things to the point that they don't work!! Possible the thermostat changed out and the correct one, might be the easy fix. They do fail, but then there are loads of other things which might also need a look. Fans working and not any problems with airflow? Bent damaged or clogged radiators, is not uncommon as well as simple things like leaking radiator caps, so it will take a bit of checking but several of the checks are pretty easy DIY stuff. That temp does sound pretty high but I'm not into watching/knowing those specs.
But while doing some thinking/checking, how is the coolant? Right stuff in the right portions? Folks often think of it as anti-freeze but it can also be anti-BOIL!
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Old 11-28-2019, 08:29 AM   #3
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Everything Morich added, but make sure the radiator cap is the correct one for that system. Good luck.
2008 Voyage 35L, Allison 6 speed auto and GM Workhorse 8.1 gas
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Old 11-28-2019, 01:25 PM   #4
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‘44, BEFORE you get too involved here spending a lot of time and money chasing what appears to be a non-problem. ..... maybe this will help.

Your engine’s operating temperature sounds right. A”cooking” engine will run about 212F or 100C at least. Maybe a little more on an extremely hot day, hill climbing or a heavy tow. 100C is the optimal minimum temperature. The engine systems are designed that way.

Thermostats come in several ratings reflecting their “opening” temperature, usually 190F (90.5:C). They will be fully open about 210F (98.8 C). So, if the cooling system is in good condition, you will see about 212F/100C on the gauge.

Note that your “needle” should be about centered in the gauge or with in a bracket or described NORMAL range. Above that on the HOT side is usually a red mark, bar or range. That red mark is usually around 240F (115C). If the needle gets up to the end of normal and starts bumping the red range, you need to stop and figure out what is what. DO NOT OPEN radiator cap on a hot engine!

Rad caps. Cooling systems operate under pressure, usually about 14 psi. Pressurization and use of a glycol, or similar, coolant raises the boiling point of the coolant well above 212F/100C boiling point of water.

So, you are OK from the sounds of it.
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Old 12-01-2019, 07:05 PM   #5
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454 temp

IMHO your engine is running hotter than it should. My 2000 Workhorse 454 ran about 160-170 degrees F. My mechanic said it was in the right range. I would check the temperature spec for the 1997 454 engine. Someone may have installed the wrong thermostat, or you may have a bad gauge.
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Old 12-01-2019, 08:49 PM   #6
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Working on cars and light trucks for 35 years, I have not seen any since the 90s that run a lower temp thermostat than 190 deg. This is where todays vehicles are designed to run for best fuel and emissions. You can give your local parts store your VIN number and they can verify what temp thermostat goes in your chassis. You can also verify what your temperature is measured on a scan tool plugged in under the dash and compare to what you are reading on the dash. That said 210 does not seem too high to me if that's as high as normally gets. You are still okay at higher temps under extreme conditions.
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Old 12-01-2019, 08:56 PM   #7
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First of all, the factory gauge is designed to stay in the middle unless the motor really overheats. My 8.1 (2004) usually ran in the 200-206 range with the standard 195° thermostat. So yours is probably in the ball park.
A radiator flush, new cap and thermostat wouldn't be a bad idea along with a new belt and idler...just to be safe.
Good luck.
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Old 12-01-2019, 09:10 PM   #8
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I think you are reading way more accuracy into a factory gauge than anyone ever thought it would have, unless you've added a calibrated sensor somewhere. Factory gauges are just not that precise. I wouldn't believe the numbers within 10 degrees.
If that's what it's been reading consistently and you have no coolant loss, you're not overheating. Engines that run "too hot" ALWAYS lose coolant.
Keep an eye on the gauge when you're under a big load - towing or a hot day, and notice if there's movement going up a steep hill. It's OK to have a little, but it shouldn't get nervously close to being out of range.
If that's all good, you're good. Trust reality, and your instruments when you don't have any choice
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Old 12-01-2019, 11:11 PM   #9
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First thing you need to do when getting a used vehicle is level set the maintenance items especially the services that must be done every 2 years such as brake fluid flushes and coolant flushes which appear to be the ones most often skipped over. By Default a motor home is considered to be under the Severe Service Schedule.

You can use a commercial prepackaged flush or just drain and refill the cooling system with a rough 50/50 mix of distilled water and white vinegar letting the engine run until warm and allowing it to sit for 15 to 30 minutes before flushing it out with distilled water a few times. If the prior owner has been skipping the coolant flushes for a long time you could have a lot of buildup in the cooling system which could clog the radiator or heater core however it still needs to be done.

Be sure to install a verified correct thermostat or take the time to test the operation of the existing thermostat by boiling it and observing the temperatures at which it starts to open and is fully opened using an accurate wet immersion thermometer.

Afterwards consider adding some Water Wetter or Lucas Super Coolant to the cooling system when you refill with coolant.

Next thing to do is verify that the fuel injection system is clean and not running a touch lean since lean means hotter. Adding a good fuel system cleaner on par with Berrymans B12 will be a good start. Note that Seafoam is a step below the Berrymans and very good for maintenance however for a remediation on a used 21 year old motor home you want the better product.

Also check the fuel injection hoses for any signs of seepage and replace any that are showing any signs of age since a lot of engine fires are due to old hoses and higher pressures of a fuel injected system. An engine that is running slightly lean and hot may still run smoothly.

Even when a fuel stabilizer is used that is only good for a maximum of 2 years when added to fresh fuel so it may be a good idea to check the condition of the fuel in the tank. Ethanol is highly prone to phase separation and developing white or pink algae as it sits especially if your in a warm humid area so there may even be a need to have the fuel polished or possibly drained and replaced depending on how the prior owner cared for it. I see a lot of issues from Ethanol in old used vehicles and boats here and have had on numerous occasions had to either drain and clean out the tanks or call in a fuel polisher to run the fuel through their system. Saving the 80 gallons of fuel alone can make up for the cost of polishing never mind the cost of dropping and cleaning out an 80 gallon fuel tank. With the engine running well still you probably won't be in need of this yet however you should top off the tank, treat it with a fuel system cleaner and use up that old fuel before too many months go by, Add a good stabilizer once you have ensured that the fuel in the tank is fresh.

This is pretty much best practice when dealing with a 21 year old seldom used vehicle from 1997 where you are not 100% certain of its service and maintenance history..
Neil V
2001 Winnebago Adventurer WFG35U
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Old 12-02-2019, 10:27 AM   #10
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First thing I do is add a temp gage for the transmission. That gives me double input to work with. The transmission oil goes thru the radiator for pre conditioning. If the engine is running too hot it will show right away in the new gage.
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Old 12-03-2019, 06:59 AM   #11
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As a supplement:
The coolant, such as engine oil and transmission oil, brake fluid, etc., should always be changed every year, at the latest every two years. Do it only with a cold engine, otherwise there is a big risk of serious injuries.
As it seems, not only the coolant has to be replaced, but also the thermostat. 210F are too much, 195F are correct.
The fact that the temperature fluctuates strongly, for example when driving downhill becomes cooler and in cities hotter, serves as a hint for a defective fan. If this is the case, the entire radiator must be checked for leaks too and the fan replaced.

By the way: The fact that the engine seems to run without any problems is not proof that everything is ok. An engine always runs without any problems, until there are different causes together that cause a problem. Sometimes sooner, sometimes later.

As a tip:
It doesn't cost too much to have this done by a GM service partner (if the entire cooling system has to be replaced, you get rid of a maximum of $800). But you are on the safe side and don't have to mix any coolants etc. yourself. Calculate once your own time which you need to save perhaps a hundred bucks.... Personally, I prefer to spend money on the Garage than stand somewhere in the middle of nowhere and working on the vehicle instead of enjoying the holidays. A motorhome costs money. Saving in maintenance is definitely the wrong way to save money.
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Old 12-03-2019, 09:01 AM   #12
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OK.... trying to not get my feathers in a ruffle! Or be a grumpy Crow.

Guys! The OP said: "New here and to motor home. 1997 Itasca Sunrise with Chevrolet L29 454 cid consistently runs at 210 degrees. Warm or cold weather. Seems high to me. Thinking 180 degrees more like it. 88,700mi, runs like a Swiss watch. Any input appreciated."

Absent a mechanical or maintenance issue (the OP didn't mention either one or both), we take his question at face value.... 12 Y.O. RV witha 454 CID Chebby big block pulling about 15K lbs on a good day. Warm weather or cold.... it runs about 210F. Probably a bit more sometimes.

That is NORMAL OPERATING TEMPERATURE for a working engine hauling around 15 THOUSAND pounds of high aero-drag barn at highway speeds. If you look at several temperature gauges used in a variety of modern vehicles (some don't even have them....) The operating range is about 212F/100C to about 240F/~115C.

The full article is here:

It would be helpful to review it as there is a complete semi-technical discussion of the effects of using glycol coolants and pressure caps on operating temperatures.

I'd also disagree with using a transmission oil temperature value to determine the operating temperature of the engine coolant. Here's why..... in a hot... like stinking hot system ..... think of hauling that 15 thousand pound slab side barn at highway speeds..... the coolant temperature AND the transmission temperature will very closely matched. A bit higher than 212F (100C), Everything is equilibrium. Now here's the catch. The temperature 'delta' of the transmission fluid always lags behind the 'delta' of the engine coolant. (Sparing details to avoid confusion here...) It may take several dozen miles and many minutes of driving to get trans coolant up from the ambient to it's full operating temperature AFTER the coolant is at it's operating temperature. Also, the engine coolant will cool faster than the trans fluid (like after climbing a long hill). So, to use the trans temperature as reliable reference for the engine coolant isn't really a great idea.

OTH, 'most' of the time the trans temp is at 'equilibrium' with the coolant or 212F (about). Co-inky-dinkly.... the design specification/preferred operating temperature for engine oil AND trans oils is.... amazingly, 212F or 100C.

Look, not trying to be a PITA here but the OP doesn't need to do an expensive SNIPE HUNT looking for what appears to be a NON-PROBLEM. Should you always perform PM on your RV... yes. Always a great idea to fully check out a purchase.... new or old. Then you know what you have. AND.... always a great idea to keep an eye on all aspects of RV operation.

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