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'89 R3500 Crew Cab 2wd to 4wd conversion & beyond

Started out with 2wd TBI350 with SM465 to current 4wd with 454, 700r4, NP241
Overview Gallery Discussion
skunked said:
I need something like this too. I’ve been using a heavy duty trash bag with clamps when the truck isn’t in use.
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This is my second one. I haven't had any trouble with it staying on the bumper. However when I had to trailer the truck when the coil driver failed I left the cover on the hood and it blew off. It fits the bumper so the wind can't get under it, but that's not the case on the hood.
 
Truckman4life said:
Yeah that liquid crap they spray on the roads is rough on everything.
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I didn't drive it the winter before the last to avoid it. I wasn't as careful this past winter and now I'm regretting it. I keep trying to tell myself it's adding character along with the dents....
 
Gonna be towing the camper up into the mountains tomorrow and I'm worried about engine temps after the last time we pulled the big passes with the camper. Decided that even though I have the bypass holes in the thermostat, I would go ahead and put the bypass hose in. Want to make sure I have all the advantages I can get.

2020-07-20 19.18.37-1.jpg

I used a pre-curved hose, but I could have just about used a straight hose. For anyone that ever needs to know, they are 1/2"NPT with 3/4" hose barb.
 
Some say just having the holes in the thermostat works fine. Others I found still had to use the bypass hose. I was thinking that the (3) 3/16" diameter holes in the thermostat is a lot less opening than a 3/4" hose.
 
my vortec L31 sbc 5.7 i swapped in my k30 has to have a bypass hose like this or it will girggle / and burp non stop . it gets to pushing air bubbles up in the rad and then past the cap to the over flow tank and that makes the coolant smell out the vented open cap to the blower motor and in to the cabin making you think you have a bad heater core or popped head gasket .

i did this from a tech at gm warranty department on the phone after i got the engine . he said it happens on a few some need it some dont . he told me to install the bypass hose and i wouldnt need to call back again . . . he was right .

reason for it on the L31 vortec engines is the vortec heads do not have the air bleed holes cast in them or the block . so the vortec uses a water pump with the bypass hose port and it takes care of it .
 
I used regular heater core hose and it partially collapsed. May or may not have effected anything but I changed it out when I had the engine tore down.
 
skunked said:
I used regular heater core hose and it partially collapsed. May or may not have effected anything but I changed it out when I had the engine tore down.
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I would have used the molded one for it too. but I didn`t have it at the time and this has been ok.
I remember it being a bit of a bitch to get on the fittings cause the hose is so short.
 
max 02 said:
I would have used the molded one for it too. but I didn`t have it at the time and this has been ok.
I remember it being a bit of a bitch to get on the fittings cause the hose is so short.
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agreed, I couldn’t find the damn part number the first time I needed one. Some of your favorite lube makes them slide on easier.
 
hot rod magazine tech artical Q & A section i found .

Q:

I have a question about the small hose going from the front of the intake manifold to the water pump on a big-block Chevy. I have a Dart manifold that has no provision for that water hose. I've heard different opinions about this hose: Some say plug off the hole on the top of the water pump and forget it. Others say Chevy put it there for a reason and it should be there. I've also seen manifolds with water lines running from front to rear on both sides of the manifold. I'd like to get your opinion.

A:

All engines that run a thermostat need to have some type of bypass provision to avoid localized hot spots, minimize the chance of steam pockets developing, promote even and rapid warm-up, and prevent water-pump cavitation. On some engines, such as classic Chevy small-blocks, the bypass is internal; on others, such as your big-block Chevy, the bypass is external.

You have a number of options that run the gamut from simple to complex:

  • Don't run a thermostat (not recommended for street-driven engines).
  • Drill two 316-inch holes in the thermostat flange area. This simple fix should provide sufficient bypass and in most cases the thermostat will respond as well or better than using a separate bypass.
  • A car heating system utilizing full-time circulation through the core (no heater-control valve), will perform adequately as a bypass even when the heater isn't on.
  • Use an existing -NPT boss that's located in the top of the intake coolant runners on each side of the thermostat housing. These outlets are normally used for the outlet hose to the heater or for a coolant-temperature sensor, but they'll work just fine for plumbing a bypass hose.
  • Drill and tap the front of the intake below the thermostat housing to add the bypass at the original location. A blank pad is still present at this location on Dart single-plane intakes.
 
sweetk30 said:
my vortec L31 sbc 5.7 i swapped in my k30 has to have a bypass hose like this or it will girggle / and burp non stop . it gets to pushing air bubbles up in the rad and then past the cap to the over flow tank and that makes the coolant smell out the vented open cap to the blower motor and in to the cabin making you think you have a bad heater core or popped head gasket .

i did this from a tech at gm warranty department on the phone after i got the engine . he said it happens on a few some need it some dont . he told me to install the bypass hose and i wouldnt need to call back again . . . he was right .

reason for it on the L31 vortec engines is the vortec heads do not have the air bleed holes cast in them or the block . so the vortec uses a water pump with the bypass hose port and it takes care of it .
Click to expand...

It's the block. The classic small block has that extra hole on the passenger side leg of the water pump mounting surface, the hole below the bottom bolt. The water pump bypass port meets up with that bypass hole in the block. The L31 block does not have that bypass port in the block, which is why the water pump has the dedicated bypass hose that goes to the intake.
 
Kay86K5 said:
What degree thermostat do you have in that thing?
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Its 180°F.

Little update while we're in town to wash the clothes and sleeping bag our son puked in. :eek:

Made up the big hill over the divide. The last pull the tunnel is the toughest. Engine got up to 200 and trans 190. That's about 20° better than the last time pulling the camper in the mountains.

I need more regular driving to say for sure, but I felt like the coolant temperature ran much steadier at 180 after putting the bypass hose in.

We'll see how it does on the drive back home Monday.
 
Had a successful run on Holy Cross, only scratched the rear driveshaft.

2020-07-25 15.49.02.jpg

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We also camped near Leadville. This was the first time hauling the camper over the Continental Divide in a couple of years. Last time I did this I had cooling issues and ended up with big oil leaks at the front an rear mains. I have since installed larger electric fans, replaced the high volume oil pump with a standard, replaced the 7qt pan with a 5qt pan, and replaced the main seals. This time around I didn't end the trip with any oil leaks.

However, I'm still having the cooling issue. I have enough power I can pull the steeper grades at about 40mph. The longest steep climb is east bound on I-70 climbing up to the Eisenhower/Johnson Tunnels from the west side. IMO it's the hardest highway climb in the state. It's not uncommon to see the car manufacturers running their test vehicles on it all covered with the plastic that disguises the model. Anyway, I had to stop and cool off the engine about halfway up.

When I pulled over, the engine was running 212F. FWIW, the trans was around 200F. I sat for about 10 minutes for the engine to cool back down to 180F, and made the rest of the climb hitting about 200F at the tunnels. I think it's time to ditch the electric fans and go with a mechanical fan with a heavy duty fan clutch. I've come across several posts on various forums of people saying it's really the best way to cool a big block towing.

I believe @Kay86K5 and @ZooMad75 are using 6.2L radiators and mechanical fans; if you guys have any incite. I have the 6.2L radiator in the truck now so all I need is a shroud, fan, and clutch.

Also verified that when towing the camper, which weighs about 4600lbs, I'm about 2000lbs over the GVWR for the truck. Luckily no school buses full of nuns were driving down I-70 in the past 6 days.

2020-07-27 15.36.07.jpg

If you recall from my past posts, the truck ways 8100lbs on this same scale. I guess I can't bee too disappointed. I decided I need to put this sticker on the back of the camper:

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