454 getting too hot

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seilerbird

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I got a set of gauges installed on my motorhome and I have an engine temperature problem with my 85 Allegro 454. The temperature runs about 210. First thing I replaced was the radiator cap and that didn't help. There is no fluid leaks and the fluid is at the proper level. I believe my engine has a clutch fan and I never hear it run even when it climbs to 220. So I am guessing that I will need to replace the thermostat and the clutch fan. Any one have any other ideas?
 
No, all was not fine. I could tell the engine was getting hotter than it should. Occasionally it would run on after I shut off the engine. The dog house was getting a bit warm to the touch.
 
You may want to verify that your engine has a 195 degree t-stat which I believe is the OE temp stat.  According to the Stant website an alternative temp t-stat of 205 degrees is available. 
 
seilerbird said:
I got a set of gauges installed on my motorhome and I have an engine temperature problem with my 85 Allegro 454. The temperature runs about 210. First thing I replaced was the radiator cap and that didn't help. There is no fluid leaks and the fluid is at the proper level. I believe my engine has a clutch fan and I never hear it run even when it climbs to 220. So I am guessing that I will need to replace the thermostat and the clutch fan. Any one have any other ideas?
I would not consider a steady 210 as being too  hot if it doesn't increase. If it makes you feel better to run at a lower temp, but in a lower temp thermostat. The thermostat is what sets your minimum temperature on a warmed up engine.

-Don- Reno. NV
 
DonTom said:
I would not consider a steady 210 as being too  hot if it doesn't increase. If it makes you feel better to run at a lower temp, but in a lower temp thermostat. The thermostat is what sets your minimum temperature on a warmed up engine.

-Don- Reno. NV
That's an interesting observation, I thought that it would have a 190 degree thermostat and that it should run at 190. It does tend to go up to 220 if it idles for a bit.
 
I Googled normal temperature 454 and came up with this link:

http://snippets.com/what-is-a-normal-engine-temperature-for-my-454.htm

The answers are all over the map, but many agree with DonTom that 210 isn't abnormal.
 
To check the fan clutch, do two things. With everything off, spin it by hand as fast as you can. It should stop instantly when you let go. If it keeps on spinning, you have a bad fan clutch.

Also make sure there is no free-play in the fan.  Grab each end of the fan and check for forward and back free play.

I have noticed that I can always hear my fan run at full speed when climbing up a very long hill on a warm day.

If your fan is not working, it will easily get above 220F in no time at slow speeds, even on a fairly cool day.  And it will pin your temperature gauge in a short period of time.

If it only climbs up to 220F max, you don't have anything to worry about, IMO.
-Don-
 
210 is an ok running temp and an occasional heat up to 220 is ok but if it stays there something needs to be done. I had an 89' 454 and when that fan clutch locked up it sounded like a fighter jet was flying over the cab, if you don't here it come on by 220 degrees it's probably bad. Keeping the engine rpm a little higher than idle (say 1200) helps to keep more air flow across the radiator when sitting. Most t-stats today run a 10 degree band, 180-190, 190-200, 195-205 etc... A 190-200 t-stat will start to open at 190 and is fully open at 200. Being an 1985 it might just be time for some cooling system maintenance, system flush, possibly a water pump $$$, who knows. You definitely can't live with a coolant system problem though or it will do a lot more damage than the coolant system maintenance would cost.
 
seilerbird said:
That's an interesting observation, I thought that it would have a 190 degree thermostat and that it should run at 190. It does tend to go up to 220 if it idles for a bit.
I have noticed many thermostats open slowly when from a cold start. This means that it can go above it's rating for a half minute or so and then come back down to around it's rating.

A thermostat only has a real effect on your minimum temperature.  You're  not running too warm until around 250F or above. You know you're too hot when your coolant is boiling out to the ground.

210 should give you better MPG and better performance than 190F.  210 is an efficient temperature for most gasoline engines. I would worry more if mine ran at 180F than 210F as a 454 is not designed to run that cool.
-Don-Reno, NV
 
My 454 runs at 195-205, above 210 the fan will run until I'm back under 205. I have never hit 220, even in the summer.
J
 
Sounds like a classic bad fan clutch. As someone noted above, the fan on an older 454 should sound like a 747 when the clutch is engaged (my 96 engaged at about 215-220F). I'd also note that the air flow around the radiator is critical. MY 96 Flair was not well designed and so ran hot enough to make me nervous. Some people have used sheet metal or similar to close in the sides of the fan and increase air flow through it.
Final note; if the engine runs hot, it doesn't really hurt until its very hot, however transmissions (the cooler is in the radiator) are very sensitive to high temperatures.
Ernie
 
Also check the radiator fins for dirt, dust, insects, etc.  The fan clutch is triggered mostly by the temperature of the air surrounding it and partially by the temperature of the shaft coming from the water pump.  If the radiator is partially plugged it's not as efficient at transferring the engine heat to the surrounding air, so the fan won't engage until a higher water temperature.

If the front of the radiator is obscured by a transmission cooler or air conditioning condenser it's a good bet it hasn't been cleaned for a while.
 
There are two coolers in front of the radiator and they look relatively dirty. Can I just go to a 25 cent car wash and hose away the dirt? Or should I just use a garden hose hooked up to city water with a nozzle?
 
DonTom said:
To check the fan clutch, do two things. With everything off, spin it by hand as fast as you can. It should stop instantly when you let go. If it keeps on spinning, you have a bad fan clutch.

Also make sure there is no free-play in the fan.  Grab each end of the fan and check for forward and back free play.

I have noticed that I can always hear my fan run at full speed when climbing up a very long hill on a warm day.


-Don-
The engine finally cooled off enough to check the fan clutch. It stops spinning immediately and there is no free play, so I am going to assume the fan clutch is ok. It would kick in and sound like a jet engine when I was climbing hills when I was out west but currently I am in the east where there is no hills and I don't remember hearing it come on recently.
 
34footer said:
My 454 runs at 195-205, above 210 the fan will run until I'm back under 205. I have never hit 220, even in the summer.
J
I guess you never climbed up a steep hill, towing,  in Death Valley during a mid July day at 125F outside. ;D

But a bad fan will not just get to a temperature below 250 and stay steady. It will cause temperature  to raise until the temperature meter is pinned, under slow driving conditions.

BTW, perhaps not all years of the 454 are to operate at the same temperature. The first step is to see what temperature thermostat is stock for your engine year and then see what your manual considers the normal operating range. In fact, most temperature scales have red color right on the scale exactly where  they consider it too hot under any conditions. That's usually around 240F.

Let me look mine up, I have all the manuals for the 2000 454, both shop and owner's manuals.

Page 2-56 of the owner's manual shows 210F as mid scale on my temperature gauge. It shows as 240F as the very start of the red range. So at 240F, is where  to worry about overheating. 210 is considered exactly where it should be under normal running conditions for a year 2000 454 engine. It should increase from there when climbing up hills on a hot day, but should never get to 240F. And 240F only means you should stop to let it cool down, it's not proof of a cooling  problem according to the manual. For an example, I assume that means if you're towing slowly up a hill in Death Valley on a hot mid summer day, 240F means you should stop the engine and let it cool for a while. It does not mean there is anything malfunctioning with the cooling system.

-Don- Reno, NV
 
seilerbird said:
There are two coolers in front of the radiator and they look relatively dirty. Can I just go to a 25 cent car wash and hose away the dirt? Or should I just use a garden hose hooked up to city water with a nozzle?
I would just use a garden hose with no more pressure than necessary.

But don't expect it to fix a problem that you do not have.

-Don- Reno, NV
 
My last coach was a 1995 P30 with a 454 and the service manual had a procedure for checking the fan clutch. They said to measure the temp of the AIR coming out of the radiator. I used a metal meat thermometer. I had to drill a small hole in the plastic shroud around the fan so I could get the thermometer between the fan and the radiator.
They said to block the radiator with cardboard and run the engine at about 2000 RPM to get the engine to heat up.
The fan will spin before it's fully engaged, but it's obvious when it engages because of the noise.
It should engage at an air temp between 165'F and 195'F. If it doesn't it should be replaced.

With everything in good shape my 454 ran right at the top of the OEM gauge just before the red area.

When it's warmed up and running down the road My 8.1 L Chevy engine runs from 195 t0 210. The fan clutch kicks in at about the 210 temp and rapidly falls to 206 or so.
 
DonTom said:
BTW, perhaps not all years of the 454 are to operate at the same temperature. The first step is to see what temperature thermostat is stock for your engine year and then see what your manual considers the normal operating range. In fact, most temperature scales have red color right on the scale exactly where  they consider it too hot under any conditions. That's usually around 240F.


-Don- Reno, NV

The problem is that no manual came with the motorhome. Tiffin has not been very helpful with customer service in the past, but I will email them and see if I can get the info.
 
DonTom said:
I guess you never climbed up a steep hill, towing,  in Death Valley during a mid July day at 125F outside. ;D
-Don- Reno, NV
I live near Pasadena, Ca, I've pulled my '89 Mitsubishi Galant many times to Las Vegas, Northern Ca, in the summer. I take I15 to Vegas, have to pull the Cajon Pass and the hills through Baker. When I had my '85 Pace Arrow it never saw 230, nor did my '76 Eldorado Class C that was on the Dodge chassis. I carry full fuel, full propane, and a half tank of fresh water along with all of my goodies. In the winter the fan hardly ever engages.
 
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