JBNeal

I had a smoking problem on the '48 a couple of years ago...I drove it into town to run some errands, and I keep it under 40 because of the roads & the traffic. The first hard right I make into a business driveway brought a li'l smoke into the cab, and the stench of gear oil. Upon further inspection, it looks like I forgot to tighten that li'l screw to the air cleaner:

I reckon if the carb was running rich, you'd have black smoke out the tailpipe and there'd be soot in that area too, as well as the spark plugs being a li'l dry carbon fouled. I ain't seen bearings do that before, but it sure looks like the bearing materials are delaminating. The oxidation you cleaned off with steel wool might have been an indication that there had been some chemical damage to the bearings, but that's just a guess. Another thing to consider is the placement of the rings on the piston. I remember reading somewhere that the oil ring gap should be in one location, and the other rings should be located 90° from each other. If the ring gaps were too close, then I reckon some oil burning took place, although that would show up on the spark plugs. Check the pistons & rings thoroughly for any pits, cracks or pitting. My guess is that some of the rings will show some damage from contacting loose material from the bearings, if they got up that far. If the cylinder walls are undamaged, then clean up the pistons and re-use.

a few questions: what kind of assembly lube didja use? didja have the rod #s facing the valve side? were the bearing holes aligned with the holes in the rods? were the holes cleaned out with a small stiff wire? were the clearance specs noted within tolerance? whut kind of break-in procedure didja use once the engine was assembled? but then again, I don't see much streaking or discoloration of the bearings, they appear to be hammered & spalling. I'm curious what the pistons look like for any signs of detonation...anyhow, good luck with the repairs

Good shocks also help with braking. When brakes are applied, the shocks absorb the inertia of the frame + body as it wants to continue in the same direction as it had been travelling. Poor shocks will allow the frame + body to lurch about as the springs travel unfettered, increasing braking distance. This is a similar to hauling a large liquid container that is half full; the sloshing of the liquid has a pulsating effect on braking.

Thanks GTK for this forum...it gives me an opportunity to learn what I need to know & share what I have learned over the years. I'm glad to see that li'l story I sent ya about 'road timing' is on the P-15/D-24 site...it came up at my grandfather's funeral a couple of years ago, and everyone there got a good laugh, those that had heard the story the first time as well as those who were present for such exhilaration.

I don't recall the price, but it was up thar, something like $700 for the whole truck...this was back in '98 and I didn't have a lot of choices available, just what I could find in the Hemmings ads. The advantage I bit on was that the brass sleeving was not as apt to corrode as cast iron would. My cores were ravaged with pitting from sitting so long in a humid environment, and Roberts & Bernbaum & NAPA cost about the same for new. They cleaned them up, sleeved them & replaced all the innerds, good as new.

That's the thing with old hydraulic brakes: you fix one leak, another one pops up somewhar else if'n ya don't replace everything with new. I replaced lines on the '48 after honing the master & wheel cylinders and still had a spongy pedal. Finally bit the bullet and had all the cylinders sleeved by White Post. They told me that the master cylinder & the rear half cylinders were all out of tolerance for the piston cups to seal properly, so fluid was slowly leaking past the sealing lip when pressure was applied. It cost a purty penny, but I had addressed the entire brake system (except the pedal itself) and now it's worry-free braking. When I did the '49, I didn't even bother honing anything, just sent every cylinder to White Post. On both trucks, I went with DOT5 since all the rubber was new; so far, so good...if it weren't for a weeping line on both trucks, I probably wouldn't have to top the MC off at all. Anyhow, I reckon since ya fixed that one leaky fitting that the tolerance issue may have been amplified. I reckon I spent more $$$ on brakes than on the fuel tank & engine compartment combined...Dad told me to focus on the stopping before the going, and the going before the showing. It was a tough pill to swallow when I was 15, but patience paid off as every time I stomp on the brakes, I can do it with confidence.

Did some research on The HAMB and found some interesting observations regarding PCV systems on hot rods. An explanation was made that I reckon has filled in some information gaps for me with regards to the PCV valve. As y'all know, vacuum varies with throttle; low throttle = high vacuum & vice versa. The PCV valve's function is two-fold: not only is it a check valve to prevent backfire into the crankcase, but as vacuum varies, so does the PCV valve opening, controlling the source of crankcase gas extraction, something I had not thought about. With the PCV valve installed between the intake manifold & the draft tube port, crankcase gases are removed at idle but not under loading because the vacuum drops & the PCV valve closes. Under loading, crankcase gases are drawn from the tube mounted from the base of the oil filler tube to the base of the air filter housing, since vacuum is higher at the air filter during loading. I reckon if the road draft tube is replaced with a tube & PCV valve to the intake and no tube is located from the oil filler to the air filter, crankcase gases would be scavenged mainly at idle speeds. Under loading, crankcase gases would filter out through the filler cap breather as pressure builds in the crankcase. If this pressure is high enough, the crankcase gases will "f@rt" through the PCV valve, which might affect performance, albeit intermittently. Filtration of crankcase gases would not be necessary since they do not normally contain particulates that could damage the engine; only outside air requires filtration. Modern V-blocks have some filtration of the crankcase gases for emission regulations, something that I had overlooked. One thing I noticed in the vacuumatic crankcase ventilator instructions was the replacement of the idle orifice tube. I assume this replacement affects the air/fuel ratio at the carburetor at idle to compensate for the added air being drawn from the crankcase into the intake manifoldat idle. Without this replacement orifice, the carburetor needs to be adjusted at idle with the new PCV system installed to account for this added air source. Now I fully understand why Chrysler specifies the road draft tube replaced with a tube & PCV valve to the intake manifold (no load at idle) AND the tube from the base of the oil filler tube to the air filter housing (full load at speed). These are two separate scavenging sources for two separate loading situations, with a PCV valve to regulate variations in between. Mystery solved, now to get to work on the real deal...

looks good...have ya thought about adding gussets below your fabricated brackets to spread the engine loading across the web of the frame? I'm thinking that if ya drew a straight line from the top bottom of the engine heads through the motor mount bolts that it might pass very near the bottom of the frame.

SHHHHH!!! We're not supposed to know this yet.

The problem is the path to ground from the sending unit. With a ground stud, you can ground directly to the battery. The original design doesn't take into account the resistance that builds from corrosion at the locking ring, the tank mounting bolts, the bracket mounting bolts, or the frame rivets. With a 6V system, all of this resistance is detrimental to adequate circuit continuity. I reckon when folks go to 12V, they are attempting to overcome all of this small resistance, kinda like burning through rusty scale when welding. I have found that once circuit resistance is minimized, that the 6V electrical system works just fine, with the exception of maybe dimmer headlights/taillights.

Yet another reason I'll be tearing down the '48 in the coming months. When I rebuilt the motor in high school, #6 had a stuck ring that I managed to remove after taking a chunk out of the piston itself. I replaced the piston with a new one, but I didn't weigh any of them. The engine has a vibration at 45mph that I suspect is rooted in the piston area, so I self-governed my speeds to 40 and it ran decent. But the long-term effects of an unbalanced engine ain't too pleasin', so I'm gonna try to nip it in the bud.

Yep, I added a ground stud similarly to get a consistent ground. It cured my inconsistent fuel gauge readings immediately. I also adjusted the float arm so that the gauge shows "E" when it's about 2" from the tank bottom. When it reads "E" without bouncing around, I've got about 2 gallons left before it's time to do the walk of shame along the side of the road with gas can in hand.

I've wondered about the placement of rear shocks after seeing different locations & directions on different axles. I reckon the simple physics is that with the shocks next to the springs, they see similar loading as the springs receive. With them moved further away from the springs towards the driveshaft, they help to spread the load over the frame to assist in stability under heavy loading. I don't recall how far away the next crossmember is on the Pilot-House frame, so maybe it's a good idea to mount the shocks in the same place as the originals. That way, if ya ever load the back end up to the gills with taters or whutnot, the frame won't get tweaked.

I agree, that sounds normal. I have deduced that the '49 1ton has a sticking oil pressure relief valve, as my oil pressure is 40psi at cold startup, but after letting off the throttle after driving it around for 10 minutes, the gauge hangs at about 20psi. Doesn't smoke, no crud in the oil, just a low gauge reading...another thing to get to on the to-do list.

I'm gonna be going through the axles soon, when I did this 10 years ago I don't remember needing a puller. The driver side shaft I used the brake drum to pull the shaft with the backing plate removed. The passenger side shaft just walked on out, wasn't tight at all. I recall at the time that didn't seem right, but I didn't see any damage, no scoring or rust was present, and I've put 10k on it in the meantime. This will be an area of concern if the bearing cup just falls out, I don't know for certain how this can be repaired readily. I'll have to take plenty of measurements to see if something is out of whack. Does the loose bearing cup sound like an indication of a looming problem, such as axle shaft failure? YIKES

screwdrivers (big, little, std. & phillips) pliers (slip joint & needle nose) crescent wrenches (6" & 10") baling wire (or coat hangers) half-used roll of duct tape starting fluid a couple of shop rags piece of 3/4" plywood (24" x 36") gallon of H2O a small collection of business cards from area wrecker services (stuff happens)

PCV systems aren't required, they are an engine improvement, much like putting in a 180 thermostat, modern detergent oils or ethylene glycol coolant. Chrysler put out several service bulletins for their vacuumatic crankcase ventilators to replace the draft tube on the flatheads. Evidently, Chrysler engineers recognized a benefit to crankcase ventilation of blow-by gases, but I don't think Chrysler management deemed it important enough to implement this as a design change as the road draft tube system was maintained for years (not including Power Wagon applications). There should be two vacuum ports on the intake manifold, one for windshield wipers, the other a test port for setting the carburetor. Early PCV systems appear to route crankcase blow-by from the draft tube port through a vacuum check valve (PCV valve) into the intake manifold via the test port. Another tube was routed from the oil filler tube directly to the air cleaner. What's puzzling to me is that the draft tube ventilation appears to bypass the air/fuel ratio metering done by the carburetor. I would think this would affect the carburetor settings as this represents a controlled vacuum leak. I am considering routing both PCV tubes to the air cleaner so that the air cleaner can trap any particulates as well as the carburetor to correctly meter the air/fuel ratio for maximized performance & efficiency. I have studied other forum members' PCV installations and noted their performance gains, i.e. cleaner engine oil per mile & reduced sludge in the valve lifter area. But the nagging question remains: does feeding the intake manifold the crankcase blow-by gases adversely affect engine performance? if so, is this negligible? I am inclined to think there is a negligible effect on engine performance, but I haven't done any calculations or performance testing to verify this...I'll put that on my to-do list.

How'bout providing Bunns' books as sources for the info...mention that gas tanks were in between the frame rails instead of in the cab behind the seat, an industry first.

Does the DPETCA have a registry by serial number? Just curious I reckon...

I reckon information from Wikipedia should always be taken with a grain of salt since anyone can sign up and contribute, no matter how correct that information is. The whole notion of 'notorious blind spot' kinda irks me as purt'near all trucks of that era were built about the same with regards to aft visibility and optional corner glass. As most research goes, it's good practice to find multiple sources that verify particular information. But with the advent of the internet, it's becoming more common that multiple information sources are repetitions from the same source. At any rate, allpar seems to do a decent job referencing historical documents as Don Bunn has done in the past with his publications (IMO).

The axle shafts are bolted to the hubs, the hubs are retained by the large axle nut. The axle shaft splines are not held in place at the differential. Feel free to remove the axle cover to see how much sludge is in thar and maybe give it a good rinsing out with parts cleaner. I recall draining the gear oil out of the '49 & refilling with diesel. I let it sit for a week, then put the rear axle on jack stands, fired up the motor, put it in 1st, and let the differential gears slosh the diesel around in the case for about 15-20 minutes or so to agitate like a clothes washer. When I drained it out & pulled the rear cover, it got almost all of the crud out, so rebuilding the differential was a snap afterwards.

I agree, the hidden condition can be a real stinker. Dad told me that it was always cheaper to inspect beforehand in the barn rather than pick up the pieces in the ditch afterwards. My brake linings were stuck to the drum, wheel cylinder rubber was hard as a rock, and one of the shoe return springs was broke. I ended up rebuilding the whole axle: seals, bearings, wheel cylinders, shoes & springs...relatively cheap insurance knowing what all has been done and not guessing as to what might need doing.

I'm kinda thinkin' that the '48-'49, maybe '50, had a different crossmember when the fuel tank changed shape so that it mounted directly to the frame without mounting brackets.

here's a few