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Wes's Burb build/update/maintance

Wes Harden said:
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One thing i need to get on is sliders. Gonna have to play footman all weekend sovthe little woman can get in and out of the truck:doah:
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My partner is also vertically challenged. For her rig, we angled some sliders a few degrees away from the body and they serve really well as a step without looking to much like one IMO, anti slip tape gives it away though. lol.

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Temperature is up here in Az, ac is being used.
With ac use engine temps are up at idle and low speeds, not even that Hot yet. Didn't have this issue last year.

Things that have changed since last September.
Fan clutch failed.
Bigger tires 37 from 33s
Timing is more advanced at Idle.
Carb is just a touch leaner at idle and cruise.
No Ac temps run normal, ac at 45mph + temp are only up a small bit.
This appears to be an air fliw issue. Probably caused by the tire up size.
Things I have tried.
New propper size alt belt. Tighten belts.
Switched 6 blade 19" Derale fan blade for factory 19.5" 5 blade fan, with used GM clutch.
Switch used fan clutch with laster September's Duralast replacement. 5 blade
New Haden Severe duty clutch, on Derale 6 blade.
None of these combos made any difference.
My electric condenser 10" pusher fan is @5 years old, probably not best quality when purchased. I did check it. It is moving air and will hold a rag up.
Have a 12" Derale pusher coming.
Should I try a 7 blade 19.5" gm fan? Maybe a smaller water pump pulley? Engine never really sees over 3800rpm.
If I lock the trans to 2nd gear at 25mph the temperature does improve. That is @2k rpm. I notice 2250 + seems to be the sweet spot.
 
It's been a long thread, apologies as I don't remember the specifics. But I do seem to recall this has been a long standing issue. Didn't you even add louvers on the hood?

Was the pusher installed to help with the overheating, or to help with the AC?

Depending on what you've seen prior as you've dealt with this issue, I'd be concerned that at cruising speeds the pusher is just getting in the way. The GM fans by all accounts are very effective, and from everything I've seen through the years, aftermarket fans generally don't hold a candle to OEM, whether that's mechanical or electrical OEM.

I've said it for awhile, the cutouts in the core support only allow so much air through. They arent nearly as large as the radiator. I would therefore expect anything forward of the core support that disrupts airflow, to potentially cause issues.

Overheating is one of these weird topics where seemingly similar vehicles have completely different results. From memory, I can't recall seeing overheating issues with non-ac trucks using essentially all stock components, small or big block. I go to my dad's 454 as an example pretty regularly, as it was used to tow a 10k travel trailer frequently, and it never had a cooling problem, using the BBC radiator.

Of course I have to caveat that by saying most of the time (not always however) it was not used for towing in ambient temps over maybe 80-85*. It was used to tow over fairly steep mountain passes, but that isn't apples to apples.

I never worry about my K5's engine temps, it has no problem holding within the limits set by the cooling system components, but again, no AC and manual trans. As temps do climb, say towing uphill in 90* weather, the OEM electric fan (only one for primary, secondary is a 240* backup) at highway speeds visibly drops the engine temp back to the fan "off" temp. I'd venture we are talking total combined weight of 8000lbs or so when towing, so not massively heavy, but decent I figure. The L31 definitely struggles on the hills towing unless I run the RPM's ridiculously high (I don't) so I know the cooling system is having to shed a large amount of heat. 465/3.42/33's.

At this stage I'm running the standard 19" Small Block radiator (parts store cheapy) and high flow water pump, but other than *maybe* longer warmup at idle, I can't tell that the high flow pump is doing significantly better than the stock one I had prior.

While the electric fan(s) in my application work exceedingly well, I don't think they are a solution to an overheating issue. Far too many are successful with the clutch fans.
 
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Thanks for the reply. So it runs warmer with AC on, over 85° F ambient. Warmer not overheating. I have miss placed my IR temp gun(think I left it in the motor home in CA).
Dash gauge reads 1/4 no ac, and doesn't move much higher with ac on at 45mph +. Even 35mph in 3rd with ac on am 3/8ths on gauge. it is at 25mph and stops the needle will creep to 1/2 or 9/16ths which iirc is @210° at the t stat with Ir temp gun. 160° high flow thermostat.
I have switched between the 2 blades I have available atm, the 19" Derale 6 and GM factory 5 blade. Ea one has had all 3 clutches I currently have, no real difference.

In Moab last year it never went to 1/2, 90°+ AC on all trails esp afternoons. That was on the 33 inch tires, Rpm range was much higher. Now on 37's. Also this truck is heavy. Over 6k if not around 7k. No trans cooler in rad. Only item in front of rad is the condenser, and the one electric fan which is on when ac clutch is on. Also the big ass winch. BJ lights are outside of core support opening. AC works good am getting down in the 40s even at lower mph.

My current thinking is air flow at stops and low speeds. Not a problem with out AC. I did shut the ac off to see if temps would go down at 25mph up hill, third selected which is @1800 rpm, and they do.

I can not decide if a 7 blade GM fan is good idea. The big fan may block more air flow at speed than the 5. I am also thinking blade pitch may need to addressed. The 6.2 diesel fan has a higher pitched blade to move more air at slower speeds. Believe gas engine pitch is 2.25° and the 6.2 diesel is 2.5°. The 6.2 is a 5 blade as well.
Anyone have both fan blades we can compare pitch?
 
Wes Harden said:
Temperature is up here in Az, ac is being used.
With ac use engine temps are up at idle and low speeds, not even that Hot yet. Didn't have this issue last year.

Things that have changed since last September.
Fan clutch failed.
Bigger tires 37 from 33s
Timing is more advanced at Idle.
Carb is just a touch leaner at idle and cruise.
No Ac temps run normal, ac at 45mph + temp are only up a small bit.
This appears to be an air fliw issue. Probably caused by the tire up size.
Things I have tried.
New propper size alt belt. Tighten belts.
Switched 6 blade 19" Derale fan blade for factory 19.5" 5 blade fan, with used GM clutch.
Switch used fan clutch with laster September's Duralast replacement. 5 blade
New Haden Severe duty clutch, on Derale 6 blade.
None of these combos made any difference.
My electric condenser 10" pusher fan is @5 years old, probably not best quality when purchased. I did check it. It is moving air and will hold a rag up.
Have a 12" Derale pusher coming.
Should I try a 7 blade 19.5" gm fan? Maybe a smaller water pump pulley? Engine never really sees over 3800rpm.
If I lock the trans to 2nd gear at 25mph the temperature does improve. That is @2k rpm. I notice 2250 + seems to be the sweet spot.
Click to expand...
Your bigger tires definitely don't help but I think your biggest issue is running lean, that always overheats in the hot summer
 
I can change that, though my mileage has dropped, with jet/rod combo I have in the carb right now. original idle area 0.0027214, current Idle area 0.00273319. Rods lifted stock 0.00320835, current 0.00365446. The metering rod spring is softer so it doesn't lift as soon. I could try a stronger spring.
 
I agree about that the more aggressive fan blade pitch is better as is the heavy pitched GM seven blade fans in conjunction with the SD clutch.
But, as you said I think your problem is deeper because it very much gives signs of lack of airflow or blockage of some kind.

Might be a dumb question but sometimes going back to the basics helps with problems like this - is there any hidden debris between the bottom portion of the condenser and radiator ?
I ask this because you mentioned the rig has been wheeling a few times over the past year and could have easily sucked up enough crap to impede low RPM airflow. I’ve found this to be the culprit a few times on cases of troublesome airflow issues - it’s easy to miss and difficult to spot.

As a side note - every GM square truck that was in our wheeling group ( which was eleven rigs ) had a four core radiator and the SD clutch with the GM 19.5” seven blade heavy pitch ( 2.5 IIRC ) fan with no added electric pushers and none of the trucks ever had any cooling issues - even running the motors really hard on long runs in the soft sand ( very hard on the motors ).
That’s how every truck came to have that setup - guys with the big three core radiators and five blade fans would wonder why our trucks never had concerns of running too warm in the Florida summer temps and once they upgraded most reverted back and used a 195* instead of the previous 160* thermostats.
In addition most of these trucks were modified big blocks and were worked very hard and cooling was never an issue even with other coolers stacked in front and most had WARN 8274’s up front blocking even more airflow - that combo just plain works even when temps are over a 100* plus.
 
Since it's a low speed issue, it's either airflow or the cooling system IMO.

Google running lean vs heat generation and I think you'll be surprised. Apparently that is an incorrect assumption. I haven't watched all the videos or read the articles, but the consensus seems to be running lean isn't a heat concern.

I have a feeling if timing is a factor, it's because the cooling system already has issues. The amount of heat combustion generates is probably so great that timing is only going to be a minimal factor.

How's the radiator itself? Internally clearly good condition and one of the larger designs?

If you are only getting to 210* I don't know as there is concern to be had. I run a 195* thermostat and to keep the fan cycle rate down, I don't turn the fan on until 212*. I think GM originally spec'd 220* for the primary fan "on" temp, but commanded one or both (can't remember) on with AC regardless of engine temp, so they clearly weren't concerned with the SBC's regularly hitting 220*.

Only concern I might have with the 160* thermostat is that if I were trying to tune a carb and dial timing in while running a consistent 50* temp spread. It's probably more difficult to do so vs. a ~15* temp swing. What starts to ping and/or run lean at 210 probably won't at 160*, and clearly you have been to that level of tuning where it could be noticed.

Really never seen good rationale for running a 160* thermostat as a control for overheating problems. If the thermostat is open, that's all it can do. Once temp goes past it's rated temp (assuming it's fully open) it's no longer a factor in managing heat. Thermostat is only to establish the minimum running temp, after the full open value is exceeded, it's up to the fan/water pump/radiator to stop it from going higher.

Using a 160* thermostat, if the cooling system wants to run 210*, it sounds like that's where the components are designed to most effectively limit upward temp movement. That being apparently 210* is probably not a coincidence.
 
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Have checked for debre. Will do so.

Big 4 row brass radiator,high fin count, new in 19. Engine and rad flushed in 22? New coolant with new wp and timing chain 23. Block checked last summer.
 
dyeager535 said:
Since it's a low speed issue, it's either airflow or the cooling system IMO.

Google running lean vs heat generation and I think you'll be surprised. Apparently that is an incorrect assumption. I haven't watched all the videos or read the articles, but the consensus seems to be running lean isn't a heat concern.

I have a feeling if timing is a factor, it's because the cooling system already has issues. The amount of heat combustion generates is probably so great that timing is only going to be a minimal factor.

How's the radiator itself? Internally clearly good condition and one of the larger designs?

If you are only getting to 210* I don't know as there is concern to be had. I run a 195* thermostat and to keep the fan cycle rate down, I don't turn the fan on until 212*. I think GM originally spec'd 220* for the primary fan "on" temp, but commanded one or both (can't remember) on with AC regardless of engine temp, so they clearly weren't concerned with the SBC's regularly hitting 220*.

Only concern I might have with the 160* thermostat is that if I were trying to tune a carb and dial timing in while running a consistent 50* temp spread. It's probably more difficult to do so vs. a ~15* temp swing. What starts to ping and/or run lean at 210 probably won't at 160*, and clearly you have been to that level of tuning where it could be noticed.

Really never seen good rationale for running a 160* thermostat as a control for overheating problems. If the thermostat is open, that's all it can do. Once temp goes past it's rated temp (assuming it's fully open) it's no longer a factor in managing heat. Thermostat is only to establish the minimum running temp, after the full open value is exceeded, it's up to the fan/water pump/radiator to stop it from going higher.

Using a 160* thermostat, if the cooling system wants to run 210*, it sounds like that's where the components are designed to most effectively limit upward temp movement. That being apparently 210* is probably not a coincidence.
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I agree on the thermostat, I don't change from the 193- 195 stock in every car.
And most of my cars run at 200-210.
When I got my 2012 freightliner I first freaked out because it was always running at 220, but it was steady at 220 winter or summer, learned later it needs to be hotter to keep the dpf filter hot.
 
Yes. Many if not all emissions control engines come with 190°+ t stat.
in the early 70s 180° was the hot t stat for temperate areas. Could get 190 in cold areas.
160 was a common alternative temp available easily in any part store.
This truck was built with a sbc 400 no cat, no egr. Only air injection system, which i will admit if it were still functional might cool the combustion temps.
Coolant flow has been on my mind. If I could find my dam ir gun it would help fugure it out. Is not in the couch,brother checked yesterday.
 
Wes, I’d take a look at Larry’s setup in his K10 as I’ve never known it to run the slightest bit hot in triple digit heat, ac on and creeping around in the desert in low range at slow speed.

He doesn’t have any electric fan on the either. Just. Severe duty fan clutch, big fan (I’ll check what he got it from) and the big 4 core radiator from a 6.2d/big block truck. I’ve always been amazed at how well it keeps that thing cool with the ac on.
 
Just texted Larry. The k10 and burb are both running the same L29 RV blade, but the K5 project is running a 9 blade from a gmt400 truck with a 6.5 oil burner.

I’m running a plastic blade from a 6.0ls and hd clutch and I’m lucky if it gets to 200 degrees on a 100 degree day. But I’m lacking ac too.

Here is the 9 blade unit. I’ve seen it at Larry’s place and it is huge. Might rob some HP spinning it but I bet it never runs hot either. Though keep in mind these are serp drive blades so they don’t spin the right way for v belts. I can’t remember if you still have v belts or went to a serp drive.
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I went from a factory 5 blade fan and clutch on my old ‘88 Bronco ( 5.8/351 ) to a F-350 ambulance SD fan clutch and a metal 10 blade fan from a 5.4 Expedition and it was an incredible difference in cooling - even with the OEM three core radiator.
It sounded like a Freight Liner when the clutch engaged but it worked great.

I’ve never needed more than the GM seven blade standard rotation fan but if anyone has ever found an application for a 19” 7+ blade conventional rotation fan I’d like to know what it is ?
 
Since none of mine is overheating, you should do like I do and run the heater while driving. If it gets warm in the cab, just roll down the window and smell the snow melting. :dunno:
 
tarussell said:
I went from a factory 5 blade fan and clutch on my old ‘88 Bronco ( 5.8/351 ) to a F-350 ambulance SD fan clutch and a metal 10 blade fan from a 5.4 Expedition and it was an incredible difference in cooling - even with the OEM three core radiator.
It sounded like a Freight Liner when the clutch engaged but it worked great.

I’ve never needed more than the GM seven blade standard rotation fan but if anyone has ever found an application for a 19” 7+ blade conventional rotation fan I’d like to know what it is ?
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It's funny you like a freightliner, when the fan comes on in my freightliner you know it did, it's a direct drive with an electric clutch.
 
Thanks Rob that fan is huge, to bad it is turning the opposite direction for my use. I am leaning on the 7 blade gas engine fan or the 5 blade oil burner, haven't found a 7 blade oil burner yet.

Further testing mid to hi 80's this afternoon ran 1/3rd at 25mph flat, and level ac on, turn up hill and starts climbing. 25 mph in 3rd is less than 1500 rpm with the 37's
 
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