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Topic: More airflow over the radiator (Read 551 times) previous topic - next topic

More airflow over the radiator

During my big trip out west this year, my poor bus was having a hard time keeping up when the ambient temps got too high and the hills got too steep.  Been pondering this for a while and had an idea for scoops into the side mounted radiator.  I've read several posts about the pros and cons of these side mounted radiator setups.  I've learned alot but not really been able to see any definitive ways to improve the situation.  While pondering I came across some scoops designed for VW buses that cover the intake for the cooling air and look pretty cool.  They were cheap so I ordered a pair.  Just wondering if anyone has put a scoop on the radiator with any results, good or bad?  See pics below for my two mockups.

Anyone tried this? 
You can call me Hunter.  It's my name.
1994 U240 36'
Cat 3116, 6-Speed
CR-V TOAD

Re: More airflow over the radiator

Reply #1 –
Hang some yarn in the area . Take pics and vids.

Re: More airflow over the radiator

Reply #2 –
At the speed a coach normally moves, I doubt much benefit.  Air flow over the grill would have to be very smooth and laminar to be "captured" by such a small scoop.

Where is (are) the radiator fan(s) on your engine.  The fan(s) should be sucking air into the intake, through the radiator, and out the back grill.  Any improvement in air flow past through radiator would probably need to come from bigger or more efficient fan(s).

Just my armchair opinion.  I am NOT a engineer.  8)

1993 U280 SE 40' WTBI, Build: 4359
C8.3 300hp, 6-Speed, Exhaust Brake
960 watts on the roof (6 x 160)
Sorento (or BOLT) on a Kar Kaddy SS
"Nature abhors a vacuum"

Re: More airflow over the radiator

Reply #3 –
Always another option for additional coolant temperature reduction is to fit an inexpensive radiator UP FRONT.

Install valves in hoses to/from dash heater core to select "additional cooling" vs coolant to dash heater core. No need to add fans-- even 40 MPH generates a lot of CFM through the front grill.
Brett Wolfe
EX: 1993 U240
Moderator, ForeForum 2001-
Moderator Diesel RV Club 2002-
Moderator, FMCA Forum 2009-2020
Chairman FMCA Technical Advisory Committee 2011-2020

Re: More airflow over the radiator

Reply #4 –
Quote from: Chuck & Jeannie –
Where is (are) the radiator fan(s) on your engine.  The fan(s) should be sucking air into the intake, through the radiator, and out the back grill.  Any improvement in air flow past through radiator would probably need to come from bigger/more efficient fan(s).

Just my armchair opinion.  I am NOT a engineer.  8)



Yes, on his coach, two hydraulically driven fans such air from the outside, through the CAC, then the radiator and it exits into the engine compartment.
Brett Wolfe
EX: 1993 U240
Moderator, ForeForum 2001-
Moderator Diesel RV Club 2002-
Moderator, FMCA Forum 2009-2020
Chairman FMCA Technical Advisory Committee 2011-2020

Re: More airflow over the radiator

Reply #5 –
Other things to try:

1.  Clean out the radiator and CAC.  They can both accumulate a lot of dirt that degrades thermal transfer.

2.  Change oil and filters in the reservoir feeding the cooling fan hydraulic pump.  Might improve pump/motor efficiency.

3.  If the engine coolant thermostat has never been changed (not uncommon) then it might be time.  A thermostat stuck partially closed will not allow proper circulation of coolant through the radiator.

4.  Don't lug the engine in high gear.  Drop down a gear - keep the engine revs up to increase cooling fan speed and engine water pump RPM.  On my coach (Cummins C8.3) the cooling fan motor RPM is directly tied to engine RPM.  The faster my engine turns, the faster the hydraulic pump turns, and the faster the cooling fans turn.  Your coach (different engine) may operate differently.


1993 U280 SE 40' WTBI, Build: 4359
C8.3 300hp, 6-Speed, Exhaust Brake
960 watts on the roof (6 x 160)
Sorento (or BOLT) on a Kar Kaddy SS
"Nature abhors a vacuum"

Re: More airflow over the radiator

Reply #6 –
Something seems not quite right, fan shroud missing or damaged. Seal leaks between shroud and radiator with foil duct tape, any gap will bypass air (remember air seeks the path of least resistance). How hot is she getting?
Old Phart Phred, EIEIO
89 GV ored 36' #3405 300 hp cat 3208 ATAAC side radiator, mountain tamer exhaust brake

Re: More airflow over the radiator

Reply #7 –
Brett and several others put a radiator up front. Aluminum radiators off ebay are available in many dimensions and are not expensive. A pick-n-pull yard is even less expensive radiators and will come with one or two electric fans. The heater hoses will have a lot of friction loss but should move enough coolant to drop the temps. Our U300 is also not happy on grades in summer. You could also put a photo tach on the fans to make sure they are up to speed. An IR gun can be useful for checking temps across the radiator to check for blockages.

I've used a 50/50 mix of water and vinegar into hoses in and out of radiators and then used a 5 gallon pail with a sump pump to circulate the mix for 45 minutes. Lots of deposits come flying out of the discharge hose. Tankless water heaters do this on a routine basis if the water is hard.

Pierce

Pierce and Gaylie Stewart
'93 U300/36 WTBI
Detroit 6V-92TA Jake
1140 watts on the roof
SBFD (ret)

Re: More airflow over the radiator

Reply #8 –
Thank you all for the tips.  I've looked at the fans and they move alot of air, but I haven't test beyond that.  I also agree on the scoops likely being too shallow.  I'm sure air isn't moving smoothly along the side, but I do wonder if it would move more air at speed. 

I haven't changed out the thermostat, but that is definitely on the list of things to change.  I haven't had any other reason to suspect it, but that's cheap insurance either way.

Love the radiator upfront idea.  That's something I can do easily that would likely make the biggest impact...

One big mitigating factor early in the trip was a crack in my coolant overflow tank.  I ran low on coolant because it was all leaking out of the overflow once it warmed up in the morning.  I've since replaced the tank but I had to JB weld it to get it home.  I never let water temp get over 215.  At Yosemite, I was up and down several passes and she performed fine, but I was slow rolling up some of those grades and the ambient temp was 80 or so.  Water temp settles in around 185-190.  It was just when the ambient temps got over 90 that it became a struggle.  I pulled over to cool down 5 or 6 times total on the trip including the coolant bottle fiasco.

As far as the radiator goes, all hoses look good, the coolant's been changed, all of the shroud is there.


Quote from: Old phart phred –
Something seems not quite right, fan shroud missing or damaged. Seal leaks between shroud and radiator with foil duct tape, any gap will bypass air (remember air seeks the path of least resistance). How hot is she getting?
You can call me Hunter.  It's my name.
1994 U240 36'
Cat 3116, 6-Speed
CR-V TOAD

Re: More airflow over the radiator

Reply #9 –
I recommend you verify that it is really getting hot.  Are you deciding this based on the dash gauge?
I have found my dash gauge to very inaccurate with more error at higher temperatures.  I have a Silverleaf so I can compare the dash reading with the engine computer reading.  At lower temperatures (170F to 180F) there's only a few degrees of difference; at 205F it's closer to 15 degrees of difference.
I'm guessing the CAT 3116 is an all mechanical engine so no option for using a Silverleaf.  A IR gun is very handy but you will need a second person with the bed up to get readings while it's under load and overheating.  I would point the IR gun right where the dash sensor is threaded into the engine if you can. There must also be an number of gauges, temperature indicating strips (irreversible), or other ways to get the temperature of the engine.  All I'm saying is to try to verify the issue before spending money to fix it.

John Fitzgerald
1991 U300 (SAI) Side Aisle Island Bed 40'
Detroit 6V92 with Allison Retarder
Meridian (Boise), Idaho

Re: More airflow over the radiator

Reply #10 –
Has the coolant system been flushed out,could be a factor,usually the only ones that need the scoops are the ford 460 versions.
96 U270 BUILD 4810
85 380SL
Drummonds TN.
 

Re: More airflow over the radiator

Reply #11 –
Yep, flushed it before we left on our trip. 

Quote from: John44 –
Has the coolant system been flushed out,could be a factor,usually the only ones that need the scoops are the ford 460 versions.
You can call me Hunter.  It's my name.
1994 U240 36'
Cat 3116, 6-Speed
CR-V TOAD