Loud Fan - 454 TBI

[Revco]

I've been working on the new house alot. I drive the Suburban 454 TBI up there in the afternoons, 100+ degree heat, about 48 miles on the interstate one way. The fan clutch is engaged pretty much the entire trip. On the way home at night...little or no engagement, even at 90-degree temps at night. This is highway speeds of 65-70mph the entire time...no steep grades, no elevation change, no real traffic. Temps never change, never runs over 200-degrees regardless of fan clutch engagement. Doesn't run hot when idling or pulling the trailer either. I changed the fan clutch with a new Severe Duty clutch and it didn't change anything. If it wouldn't run for so damn long I wouldn't care as much, but it just engages too often and for too long.

I'm sick of the noise, but more sick of the robbed power and MPG loss by this fan clutch. Electric fans are not an option. Not only are they ridiculously expensive ($700), they are prone to too many failures and have been shown that they can't supply the CFM that the stock fan pulls. I don't use flex fans on anything after having to replace a $550 radiator and $400 fiberglass hood when one came apart on the highway. I've read about an 11-blade replacement fan that reduces noise, but have yet to see any real experiences with them.

I've had tons of vehicles of all types and have always lived in the same climate and have never heard a fan as loud as this one, nor have I ever had one that was engaged so often.

Ive got the old fan clutch, which is still good I'm thinking of tweaking the spring to change the engagement temp and seeing if that does anything beneficial. I also considered taking the hood off for a trip up there and back to see what happens, maybe it just has a hard time expelling the heat built up in the engine bay. If that's the case I'll have to find a cowl-induction hood or run some cooling ducts or something.

Any ideas?

 

[xpndbl3]

spray off the radiator/condensor with a hose and clear out all the mud/dirt/bugs that are probably clogging it up.

 

[rxm6]

I wonder if your fan clutch engaging so often is covering up a problem with your cooling system; i.e. partially clogged radiator, head gasket, etc?

 

[Revco]

It has a new radiator, water pump, hoses, thermostat, etc. Engine warms up like it should and operating temperature is always perfect. I took the grille off and pressure washed the radiator. Maybe the aux cooler and fan are blocking some airflow to the radiator, but not enough for it to affect anything. With the engine at idle and the clutch fan engaged, the suction created can easily hold a shop rag to the grille, so blockage isn't really a concern.

 

[rxm6]

Do you still have your fan shroud on your radiator?
Is this with the AC on that the clutch is engaging?
Are you running without AC at night?
What year is your truck?

 

[Revco]

Yep, factory fan shroud intact.

Clutch isn't engaged as long if turn the AC off.

Yes AC is running at night.

1993.


I know its perfectly normal. It's hot as hell here in Texas. I'll fart around with the spring wind on the other clutch and see what happens. I also found the part number for the lighter plastic 11-blade replacement fan, it's only $35, might be worth a shot.

 

[FellowTraveler]

There should be a baffle about 27" wide x 20" deep under truck from lower radiator support then sloping to bottom of front cross-member it stops high pressure air from getting into engine bay after the radiator support which stalls air flow through radiator, condenser, p/s, oil coolers etc................."if missing its more likely than not your issue"!

It appears, at idle or slow speed there are no effects of high pressure restricting air flow through radiator. Another consideration would be internal restriction in radiator if 10 years old and especially if that orange crap GM put in em was there for any amount of time.

 

[Revco]

Ahh, that might be the issue. Not sure if mine has it, I'll pull it in the shop in a little bit and crawl under and see.

 

[FellowTraveler]

Just lean over and look

Ahh, that might be the issue. Not sure if mine has it, I'll pull it in the shop in a little bit and crawl under and see.

The cover can be seen just by walking away from vehicle then leaning over and looking under front bumper to bottom of cross-member its very obvious the panel/cover.

 

[Revco]

There is no cover on mine. There is a plastic piece behind the bumper, under the core support, and that's it. It's the width of the frame rails and only about 8" deep. In the LMC catalog it only shows that same plastic piece I have and they call it an "air baffle". The aluminum skid plate goes from the frame horns to the crossmember if that's what you're talking about...and mine had the skid plate until a few weeks ago when I fabricated a front receiver hitch and haven't got around to re-forming the skid plate to clear the new hitch. Even with the skid plate intact, it acts the same.

Yesterday morning I removed the grille, lights, etc. Turns out the auxillary electric pusher fan mine has isn't working even with direct power to it, so I'm going to find another one soon and see if that helps. I moved the aux trans cooler and the AC condenser out of the way and pressure washed the radiator fins, along with the trans cooler, power steering fluid cooler, and the AC condenser. There wasn't any blockage except for a small pile of dead bugs and leaves that were in the bottom center of the radiator. Drove today with no difference from before the cleaning. I'll swap that fan out soon and see how that affects it. I think I have a couple electric fans somewhere, but I'm too busy to go hunting for them right now.

 

[FellowTraveler]

Electric fan or?

There is no cover on mine. There is a plastic piece behind the bumper, under the core support, and that's it. It's the width of the frame rails and only about 8" deep. In the LMC catalog it only shows that same plastic piece I have and they call it an "air baffle". The aluminum skid plate goes from the frame horns to the crossmember if that's what you're talking about...and mine had the skid plate until a few weeks ago when I fabricated a front receiver hitch and haven't got around to re-forming the skid plate to clear the new hitch. Even with the skid plate intact, it acts the same.

Yesterday morning I removed the grille, lights, etc. Turns out the auxillary electric pusher fan mine has isn't working even with direct power to it, so I'm going to find another one soon and see if that helps. I moved the aux trans cooler and the AC condenser out of the way and pressure washed the radiator fins, along with the trans cooler, power steering fluid cooler, and the AC condenser. There wasn't any blockage except for a small pile of dead bugs and leaves that were in the bottom center of the radiator. Drove today with no difference from before the cleaning. I'll swap that fan out soon and see how that affects it. I think I have a couple electric fans somewhere, but I'm too busy to go hunting for them right now.

That's the proper cover, wheel well covers in place?

Doubtful an electric aux fan will do anything other than help at slow stop/go speeds at speed the air pressure hitting the blades render the fan pretty much ineffective.

Your operating temp is not critical however be sure to check the fan clutch calibration and that it is not a tropical clutch which would engage at lower rpms and temps.

All else being equal the radiator if more than 10 years old could be clogged internally for various reasons and not shedding the heat, perhaps someone put a stop leak product in or air entered the cooling system causing the "orange coolant" to corrode the tubes, etc..

 

[Revco]

I met a guy at a gas station the other night. He had the same Suburban as mine, same year, same engine/tonnage/drive, same everything except his was a plain trim model and mine's the fully loaded conversion. He asked me about my tires and then we got to talking about fuel mileage, issues, etc. I mentioned how loud the fan was during the day and he said his does the same thing, and it has done it since he bought it brand new in 1993. He said that he ran a $650 dual electric fan for about a month before going back to the loud clutch fan because the electric fans wouldn't cool while sitting in traffic. He had 310k miles on the original 454 and 4L80E and this thing looked like it was brand new, save for some faded paint on the roof. Anyway, after talking to him, it just confirms what I've been thinking...it's just how this thing is built, this is normal operation, and nothing is wrong with my rig.

Thanks to those who replied.