LarrBeard
06-04-2020, 09:28 AM
Things are going almost too smoothly for a change.
After a flurry of things that needed to be looked at or worked on, the truck has settled down to a point that seems eerie. The differential vent leak is fixed and for the first time in several years there are no significant piddles under the back end of the truck.
I had new boots put on the U-joints (and all of the needle bearings installed in the trunnions), then I had the driveshaft straightened and balanced; that reduced vibrations a bit. The last step in the vibration project was to have all four wheels dynamically balanced.
After a first spin, the balance tech asked me if it would be OK to use external clamp-on weights, inside glue-ons weren't going to cut it for those tires and rims. I answered “Sure – clamp-on weights are absolutely correct for a 1948 truck”. It took a lot of big weights, but all four wheels are as good as they are going to be. The old guy in the shop made the comment that 72-year old rims usually are not as true as modern rims so there is some unbalance due to the rims themselves. But, I am pleased with how the project ended up. There is a bit of a shudder at 30 MPH – I tell folks it’s like we’re breaking the sound barrier. Once we get through it, it’s a smooth ride!
The last major annoyance was the oil pressure anomaly. You folks with mechanical or crossed coil gauges just don’t have the thrill factor associated with the bi-metal Stewart-Warner gauges. At ignition turn-on, it will take about 15 seconds for the oil pressure gauge to move from pegged below zero up to its no pressure point. Then, at engine start the needle starts to casually move upscale. It can take a good 30 to 45 seconds to move up to idle pressure. I don’t know about you guys, but I’d like to know immediately if I have good oil pressure. During that minute, you use your ears to listen for the low oil noises.
But – my problem was that after about five or ten minutes on the road, oil pressure would start to slowly drop off, then return to normal fairly quickly. Once you see oil pressure dropping, you get gauge fixation; you watch that gauge as much as you watch the road. Then it would move back up, maybe drop again a couple of times and then settle down. This is unnerving to say the least.
But, one quarantine day I got serious with the ohmmeter and crawled up under the dash and after a while, it turned out that the oil pressure sensor was intermittent. It should be about 50-ohms at zero pressure, and 25-ohms at 30 PSI, but it would intermittently go open then go back to normal. The slow response time of the gauge made it look like I was slowly losing oil pressure - not the case at all. WHEW!
Mike at KWAS had a replacement sensor and after about 30-minutes under the truck, things were back together. The new sensor reads a bit differently that the old one, but it stays steady while I’m going down the road.
Over the last week I’ve probably made two road trips and several putter-abouts and everything is good. I’ll do an oil change, then I take the truck back to the body shop for a touch-up next week. We have a spot in the July 4th Parade, so some sort of normal is resuming.
After a flurry of things that needed to be looked at or worked on, the truck has settled down to a point that seems eerie. The differential vent leak is fixed and for the first time in several years there are no significant piddles under the back end of the truck.
I had new boots put on the U-joints (and all of the needle bearings installed in the trunnions), then I had the driveshaft straightened and balanced; that reduced vibrations a bit. The last step in the vibration project was to have all four wheels dynamically balanced.
After a first spin, the balance tech asked me if it would be OK to use external clamp-on weights, inside glue-ons weren't going to cut it for those tires and rims. I answered “Sure – clamp-on weights are absolutely correct for a 1948 truck”. It took a lot of big weights, but all four wheels are as good as they are going to be. The old guy in the shop made the comment that 72-year old rims usually are not as true as modern rims so there is some unbalance due to the rims themselves. But, I am pleased with how the project ended up. There is a bit of a shudder at 30 MPH – I tell folks it’s like we’re breaking the sound barrier. Once we get through it, it’s a smooth ride!
The last major annoyance was the oil pressure anomaly. You folks with mechanical or crossed coil gauges just don’t have the thrill factor associated with the bi-metal Stewart-Warner gauges. At ignition turn-on, it will take about 15 seconds for the oil pressure gauge to move from pegged below zero up to its no pressure point. Then, at engine start the needle starts to casually move upscale. It can take a good 30 to 45 seconds to move up to idle pressure. I don’t know about you guys, but I’d like to know immediately if I have good oil pressure. During that minute, you use your ears to listen for the low oil noises.
But – my problem was that after about five or ten minutes on the road, oil pressure would start to slowly drop off, then return to normal fairly quickly. Once you see oil pressure dropping, you get gauge fixation; you watch that gauge as much as you watch the road. Then it would move back up, maybe drop again a couple of times and then settle down. This is unnerving to say the least.
But, one quarantine day I got serious with the ohmmeter and crawled up under the dash and after a while, it turned out that the oil pressure sensor was intermittent. It should be about 50-ohms at zero pressure, and 25-ohms at 30 PSI, but it would intermittently go open then go back to normal. The slow response time of the gauge made it look like I was slowly losing oil pressure - not the case at all. WHEW!
Mike at KWAS had a replacement sensor and after about 30-minutes under the truck, things were back together. The new sensor reads a bit differently that the old one, but it stays steady while I’m going down the road.
Over the last week I’ve probably made two road trips and several putter-abouts and everything is good. I’ll do an oil change, then I take the truck back to the body shop for a touch-up next week. We have a spot in the July 4th Parade, so some sort of normal is resuming.