6.9 in a bus needs radiator. Upgrades?

Luke_IDI

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Gotcha, thanks for posting those. Mine is probably the same as well--it looks like we have a similar amount of clearance. For some reason I was imagining an obvious notch as opposed to a smooth narrowing. I'll have to check it out. I'm still thinking there might be enough room there to flip the passenger side exhaust manifold, but it looks like it will probably wind up with less than 3/4" of clearance, which sounds a bit tight to me. I think I would enjoy the project of fabricating a manifold for it, especially seeing as R&D sells a flange kit.

Glad to hear of a nice cold start for your rig. And hope it made for a good camping trip! Mine also starts very well, especially after the head job last year. Cranked it up a couple of weeks ago after it sat for a couple of months. I have the glow plugs unplugged as most of them are no good, and I seem to have misplaced the set of Berus I bought months ago, so no glow plugs. Cranks for maybe 2 seconds, then fires. Granted, I'm in the South, so a cold start is 70+ degrees most of the year. But I don't think the glow plug system has ever been functional since we've owned the bus, and we've definitely fired it up cold in temperatures right around freezing. Those old plugs are bugging me--I wish I had replaced them when I had the heads off, but I didn't know about the swelling issues at the time. It does run rough for the first 30 seconds or so, though. I'm guessing I am losing some prime in the injector lines over time and it has to burp out a couple of small air bubbles. When the bus sat for a year, I had to crack the lines and crank until I saw fuel. Then it started right up.

I should also update that over the last several weeks some more stuff has gotten done. After installing the new radiator, the next time I went to crank up the bus, I had coolant pouring from the water pump weep hole. So, new water pump from Gates. The system is finally filled with 8 gallons of Fleet Charge and leak-free. I think I can say that I have as much faith now in the cooling system as I will ever have. New radiator, new oil cooler o-rings, new water pump, new thermostat, block very heavily flushed with Cascade countless times, and a coolant filter plumbed in to the heater core loop. To celebrate, I will post a pic of what the original radiator looked like inside when I pulled the tanks off:

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It looked like someone grabbed a handful of potting soil and dropped it on top of the core! Ol' Baby Blue has come a long way in terms of staying cool.

Ah, but I do still need a definitive test on the fan clutch. Did you have to replace your fan clutch? Where did you source a replacement? I know it mounts to the water pump differently from the pickup version.

The AT545 also got refilled with new Dex/Merc. I'm working on plumbing in a temperature gauge following your idea on location of the sender. It sounded like you had a hard time flaring the steel tubing, though, so instead of teeing into the hard line, I'm replacing the elbow coming out of the transmission with a 3/8" Male NPT - 1/2" Male JIC - 1/2" Male JIC fitting, which I found at a hydraulic supply store. (I think those are the correct nominal dimensions. And I think it should fit right where the elbow did.) As you observed, there's enough meat in the unused JIC fitting to drill and tap for 1/4" NPT. I think I'm going to have to tap farther than I already have, and maybe cut off the end of the tapped JIC fitting, to get the end of the sender down into the fluid stream. Should work nicely.

The last couple of things that are nagging me slightly about the bus are some noises coming from the rear half of the vehicle, which I've begun to think more about now that things in the engine bay have been taken care of. It has a pretty significant driveline whine at 40mph+ that sounds consistent with a worn ring and pinion. The rear differential is definitely full of oil. I'm wondering if I should change it. The back of the bus is also very bouncy at some narrow range of speeds around 35-40 mph--as in a bounce turns into a slow harmonic vibration (maybe 3 bounces per second?) and won't stop until I change speed. I'm thinking new rear shocks will cure this. There is another vibration that seems to have developed recently. This one feels like it's coming from the rear as well, only at speeds above probably 40 mph. I would describe it as a short pattern of several pulses that repeats rapidly a few times a second. Not something I've ever felt in a light duty vehicle. I'm hoping shocks will take care of that issue as well, but the fact that there is a discernable pattern makes me think it's not a harmonic vibration. Still, everything feels perfectly smooth back there are lower speeds, so maybe it is harmonic.
 

Booyah45828

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Ah, but I do still need a definitive test on the fan clutch. Did you have to replace your fan clutch? Where did you source a replacement? I know it mounts to the water pump differently from the pickup version.

The AT545 also got refilled with new Dex/Merc. I'm working on plumbing in a temperature gauge following your idea on location of the sender. It sounded like you had a hard time flaring the steel tubing, though, so instead of teeing into the hard line, I'm replacing the elbow coming out of the transmission with a 3/8" Male NPT - 1/2" Male JIC - 1/2" Male JIC fitting, which I found at a hydraulic supply store. (I think those are the correct nominal dimensions. And I think it should fit right where the elbow did.) As you observed, there's enough meat in the unused JIC fitting to drill and tap for 1/4" NPT. I think I'm going to have to tap farther than I already have, and maybe cut off the end of the tapped JIC fitting, to get the end of the sender down into the fluid stream. Should work nicely.

The last couple of things that are nagging me slightly about the bus are some noises coming from the rear half of the vehicle, which I've begun to think more about now that things in the engine bay have been taken care of. It has a pretty significant driveline whine at 40mph+ that sounds consistent with a worn ring and pinion. The rear differential is definitely full of oil. I'm wondering if I should change it. The back of the bus is also very bouncy at some narrow range of speeds around 35-40 mph--as in a bounce turns into a slow harmonic vibration (maybe 3 bounces per second?) and won't stop until I change speed. I'm thinking new rear shocks will cure this. There is another vibration that seems to have developed recently. This one feels like it's coming from the rear as well, only at speeds above probably 40 mph. I would describe it as a short pattern of several pulses that repeats rapidly a few times a second. Not something I've ever felt in a light duty vehicle. I'm hoping shocks will take care of that issue as well, but the fact that there is a discernable pattern makes me think it's not a harmonic vibration. Still, everything feels perfectly smooth back there are lower speeds, so maybe it is harmonic.
I did change my clutch. I'm not going to call it an exact nightmare, but after searching and cross referencing for hours I found that anything new off the shelf was going to cost close to $1k. Whether new(rare) clutch with my current fan, or new(common) with a compatible new fan.

After a bunch of part number searching on google, I found a NOS unit at a truck recycler in Michigan that I installed. After install, I was confident it was working, but after running it this past weekend, I don't/didn't hear it engaged at startup like I should have, so I'm not certain that it's working anymore.

IDK what to suggest to you. You can pull numbers off your old clutch/fan and look for something like I did. I had at one time all the numbers that I found on a paper, but IDK what happened to that. Even with the numbers, parts store clutches are abysmally unreliable it seems. And it's not like they're cheap or common either. I thought about making an adapter to use a more common ford clutch, but like I said, parts store clutches aren't what I'd consider reliable. I've read about guys adding new silicone fluid into old clutches, and am really thinking about modifying one of my old clutches with a screw plug to do just that. I've also considered retrofitting an air clutch to this, so long as I can find one cheap/used that would fit. Or I still might just run a pair of self tappers through it making it so it's always on.........

Flaring the steel tubing was hard. The cheap flare tool I bought from summit wouldn't have flared paper. A good flare tool would work, but those aren't cheap, and I didn't have one. I'd say an elbow would work so long as you get the right dimensions threads to line up, I used what I had available locally. I probably should have just used new hydraulic lines when I did mine, as the steel ones are rusted and it wouldn't hurt to replace them.

Check all your u-joints and tires for the vibration. These heavy rear ends are whiney by default compared to anything on a passenger car or light truck. Mine has a definite whine to it when riding in the back. Most of the time, if your rear end is failing, the noise/vibration will come and go based off of load by power being applied vs coasting. If it's there all the time, check wheel bearings/u-joints. It occurring around 30mph or so indicates to me that it's more pinion/drive shaft speed vs axle/wheel speed related.

Moral of the story is that you can disconnect the drive shaft and check u-joints/carrier bearings for dry/sticky/wear issues a lot easier then it is to check for any rear differential issues.
 

Luke_IDI

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I thought about adding silicone to the fan clutch too, but couldn’t find any evidence of it having leaked, nor could I figure out how much to add. Also didn’t want to go messing up my only fan clutch. At this point it has already run cool in the Alabama summer heat, so I’m inclined to leave it alone unless I’m unhappy with coolant temps at some point.

I crawled under the bus today to poke around at the driveline. I did find some noticeable play in one of the u joints. Maybe that explains the vibration. Looks like I should be able to disconnect the driveshaft at the ends and spin it to look for any other issues. I’m going to be taking the bus for some drives the next few days. I’ll take some more detailed notes on when the whine happens, but last time I drove it, I observed the volume to be definitely related to load. Hmm. At 57,000 miles, that’s not much of a service life. Perhaps it was set up incorrectly from the factory? I wonder how many more miles I might be able to squeeze out of it? Draining and inspecting the oil might give some clues. Maybe the regear will be moving up the list of priorities.
 

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