454 overheating/hi temp

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454 overheating/hi temp

Home > Discussion Forum > Mechanic's Corner - Engines

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All Messages in Thread	Author	Date
454 overheating/hi temp	karl schneider	8-16-03
I have a 90 suburban with a 454. When the clutch fan started making noises I changed it. That's when the problem started. The new clutch won't disengage until around 60mph.I put in a 180 thermostat which doesn't sound like a good idea.but with that it runs good until I hit a hill. The fan being engaged takes away my power and makes alot of noise.Temp goes up past half.Temp also goes up at idle to over 210.Will putting the 195 thermo help the temp at Idle?What is up with the thermo clutch fan?
Re: 454 overheating/hi temp	Gary CC NV	8-16-03
A 195 degree thermostat will help beyond a shadow of a dough. The reason being is, with the 180 deg. thermo, the water circulates to fast, thats why the temp. goes up at an idle, as soon you hit a hill, or try to tow something. Does the fan clutch have a spring in the middle of it? If so, it's a Thermo Type. If not, it's a Centrifugal type.
Re: 454 overheating/hi temp	Gary CC NV	8-17-03
Are you sure it is a Thermo Type Fan Clutch? Does it have the Spring in front, "Radiator side of fan clutch, Center" Sure sounds like the way a Centrifugal Type Fan Clutch acts. Or, it could be the wrong fan clutch for that engine, to Heavy a Duty, and not the right number of Fan Blades for it to work right, when ordered, Standard or Heavy Duty? As far as the temperature goes, does it feel hot, smell hot? Feel the bottom radiator hose "engine to normal temp.,engine not running", should just be Warm, top radiator hose will be a little hotter. Are you going by the Factory Installed temperature Gage? or an added on Electrical type Temp. gage? You might consider replacing the Temperature Sending units. If you want an Accurate Temp. reading, get the Hard Line type, the one that reads all the time, "Mechanical Type" But use Plenty of gasket sealer at the end that connects into the Cylinder head, they have a tendency to leak, just because of the poor fittings used. Be careful bending the tube, once it brakes, throw it away, because its no good, and won't work. Flex Fan, there should all ready be a Factory Installed Steel Flex Fan, you can't do any better than that, check it for cracks, just to be safe. Only trust a Fiberglass Flex Fan as far as you can throw it.
Re: 454 overheating/hi temp	Sam Watson	8-20-03
The fan, although noisy, shouldn't drop your power to the degree you indicate. A sudden onset of reduced power bears investigating, starting with engine base ignition timing and advance. Have the timing checked, if it is retarded by 7 1/2 degrees, or any multiple there of, then the camshaft timing has "jumped timing", that is, the timing chain has jumped a tooth or so on the sprockets. If initial timing is OK, then check spark advance against specs. While you're at it, check the air cleaner's heated air intake for proper operation, overheated intake air will cause a drop in power output.
Re: 454 overheating/hi temp	jack dunn	10-29-03
A major problem with the p-30 based m/h is the a/c condenser is only about 1/2 inch from the rad this gets pluged with what looks like lint and cuts down airflow you have to seperate the two to clean properly -good luck
Re: 454 overheating/hi temp	karl schneider	8-16-03
I put a thermo clutch in to replace the one that froze up. It stays engaged until I reach 65-70 mph.Once it disengages it won't engage until I stop or slow RPM's is this the way it is supose to work?Is it supose to disengage earlier, The fan makes alot of noise would a flex fan work better. My temp gage reads 210 constant during normal operation with a 195 stat, is this normal operating temp?
Re: 454 overheating/hi temp	John Ogletree	8-16-03
Help me out with something here. What does vehicle speed have to do with the engagement/disengagement of a thermo fan? I thought it responded to temperature.
Re: 454 overheating/hi temp	barbara holmes	3-7-04
96 suburban overheats going up hill.overheats at stop light
Re: 454 overheating/hi temp	KARL	8-17-03
That's why the questions.If the thermo fan clutch is supose to engage at 220 degrees why is it engaging? there should be enough air flow at 25 to 30 mph to desengage the clutch my temp is running normal but I don't have power with the fan constantly running.
Re: 454 overheating/hi temp	John Ogletree	8-17-03
"If the thermo fan clutch is supose to engage at 220 degrees why is it engaging?" Did you mean to say 'if the clutch is supposed to DISENGAGE at 220...'? My understanding is that when cold it is engaged and will have friction power for about 2 minutes or less after starting, at which time it should disenage, as evidenced by a lessening of the fan roar. At this time it will still be turning but just idling. Then when the thermostatic spring in the clutch senses about 220 degrees air temp after the air has come through the radiator, it starts driving the fan again, as evidenced by an increased roar. Then it just disengages and engages at the direction of the thermostatic spring. I hope I haven't clouded the issue even more.
Re: 454 overheating/hi temp	karl	8-18-03
Exactly that john! in my case with a new water pump,thermo clutch fan,radiator cap,195degree thermostat, it's not working like that it just roars almost all the time untill i drive at 60mph for about 2 min. what else should I check? I still reach over 220 while idleing and climbing grades,and don't have much power.
Re: 454 overheating/hi temp	John Ogletree	8-18-03
In the words of Dr. Henry Lee in the Simpson murder trial, or should I say mistrial, "Something wrong." If you have to drive 60 to get that fan to shut off, and if you're hitting over 220 idling, I'd bet that somehow the shop has managed to partially block your cooling system. Why not propose that in strong terms to that shop? I think you got disservice, not service. Maybe they installed the thermostat backwards. It's happened before.
Re: 454 overheating/hi temp	karl schneider	8-18-03
Here is how things were explained to me today. When purchasing a thermo clutch fan for $60.00 from autozone it seems that the stock on the shelf has been sitting for long periods of time in the Palmdale desert heat causing the internal jelly substance to settle in a lopsided fashion(if part sat on its side).So I was told to go to the dealer and pay the extra dollars for a new properly stored clutch. Does that make any since??
Re: 454 overheating/hi temp	John Ogletree	8-19-03
OOPS! I jumped to a conclusion that you had the work done. On re-reading the thread you didn't say that so I guess you did it yourself. Sorry about that. I don't know about improper storage. If that's true you have a beef with A.Z. for not taking proper care of their inventory. I can add nothing further to this.
Re: 454 overheating/hi temp	Sam Watson	8-20-03
Thermo fan clutch 101. The material in the clutch is a viscous silicone compound. When you cold start the vehicle, this material is free to move through passages in the clutch, centifugal force circulates it through these passages. Until the compound has done this, there is enough fluid friction to cause the clutch to drive the fan at a higher speed. After the engine has been operating for about 2 minutes from a cold start, the fluid has mostly quit driving the fan so that the sound of rapidly moving air lessens as the air flow from the fan drops off. This condition continues until air passing through the radiator reaches a temp of around 220. This temp causes the bimetal spiral spring to unwind. This spring is fastened to a shaft which bears shutters to block certain fluid passages in the fan clutch, causing the fluid to once again drag the member bearing the fan around with it. In order to have the clutch re-engage, it is necessary that the heated air impinge upon the spiral spring. For this reason, any aux. radiater,(cooler) added to the radiator core must have a bit of a gap between its fins and that of the radiator. A flex fan is a definite no-no on a heavy duty chassis. Just think about it, the flex fan's blades are designed to "feather" at high RPM. How about this scenario; You start up a hill, vehicle speed decreases, you downshift, engine revs, fan blades feather, air flow through the radiator decreases as vehicle slows and fan quits moving air, vehicle coolant temperature starts climbing, overheat!
Re: 454 overheating/hi temp	John Ogletree	8-20-03
Sam, what a great description of the fan clutch! So is the part about improper storage just hogwash? Is a flex fan one that has soft blades, and is it necessarily engine-driven? Is it easily recognizable?
Re: 454 overheating/hi temp	Sam Watson	8-20-03
John, kind words, indeed. The only thing about storing fan clutches is not to have the shaft pointing downwards. During long periods of storage leakage may occur at the shaft seal.The flex fan will have the thin, flexible blades, and will be engine driven.
Re: 454 overheating/hi temp	Larry B.	8-22-03
Thank you all for this info. about 454s.I just went thru this with a "77" 440 Dodge in a 21 ft American Clipper. Finnally got it to stay cool.Now to cold.170 degrees.Should run about 180.Every thing new from the water pump out.Including about changing the 50/50 anti freeze and water ratio.More water per the directions on a product called water wetter. Bought at an auto parts store. Now I'm tradeing the rig in on a 24 ft.1995 Winnebago Warrior,with a 454.Looks like I might have to start over again.