73 C10 short bed with lots of issues, mostly solved

[markolson]

I'm new to the forum.  This is my first post.

My son just bought a pretty messed up 73 C10 fleetside short bed.  He wanted a beater he could drive into the ground.  The cab is kind of rusty and the seat bottom is very ripped up.  It has some rust on the passenger floor, right front fender and behind both lower door corners.  The box and frame look good.  It has a fairly new looking 350 crate motor with an Edelbrock intake and carb.  It has long-tube headers with Cherry Bomb glasspacks and downturns behind them, so it is LOUD.  It idles like it has a cam.  It has an Accel 140003 coil on top of the distributor.

The wiring was a mess.  It was full of twist and tape joints, missing wiring and fuses.  There were not interior lights, and the speedometer and oil pressure gauge were the only gauges that worked.  The worst thing was a major ATF leak from the TH350.

We spent the weekend working on the truck  First we cleaned up the engine bay and undercarrage.  Then we tested the gauges and figured out that the temperature gauge was bad.  We replaced it with a junkyard gauge that did work.  We noticed that the fuel gauge was from a different kind of truck.  It had a window at the bottom for something that this truck doesn't have, so we also replaced it with a correct junkyard fuel gauge.  We soldered all of the twist and tape joints, and used DR-25 shrink tubing on all of the exterior joints and regular tubing inside the cab.  We protected the wiring in the engine compartment with plastic conduit.

We had to add temp sender wiring and the connector to the harness, and we had to install a temp sender in the intake manifold.  We had to replace the fuseholder in the ammeter wire next to the terminal block on the firewall.  The fuse was broken the the fuse ends were stuck in the stock holder, so it now has a modern .  I bench tested the ammeter, and it moved to the D and the C marks when about 1.5A was flowing through the gauge.  But in the truck, the gauge is not moving as it should.  I am still trying to figure out how the gauge is supposed to work, so any hints for getting it working would be greatly appreciated.

There is a TCS solenoid shown in the schematics, and it is gone, although the TCS relay is still there.  I have no clue what the TCS solenoid does, so any explanation would also be appreciated.

The dash brake light switch is stuck closed.  We still need to replace it.

Lots of bulbs, interior and exterior needed replacing.  The radio wiring was a total kludge, so we just pulled it all out.

We flushed the radiator and replaced it with Dex Cool.  The degas bottle was cracked across the bottom so it got a functional junkyard replacement as well.

We then tried to tackle the major transmission leak.  We replaced the O-rings at the speedometer cable, modulator and the dipstick.  We replaced the seal at the detent cable.  We replaced the filter and put new pan gasket on, and filled it with ATF.  It did not have a significant leak overnight, but when we started it, ATF started nearly running out.  After all of our research, we felt that the most likely culprit was the front seal or the pump seal.

We were getting ready to pull the transmission out tonight, when my son noticed that there was ATF under a sensor near the detent cable.  I told him there was no sensor there, and he pointed it out to me.  It appears that a PO had installed a pressure sender in the 2-3 Clutch Pressure Tap hole. 

We cleaned up that area and put foot powder all over the area.  We started the truck with the wheels chocked, put it in gear and ATF started running out from under the sensor. 



We replaced the sensor with a 1/8" NPT plug and the major leak went away.  I figured this was a new way to cause a TH350 oil leak, because with all of my research, I had never seen where anyone had hooked a pressure sender into a pressure tap.



There is still a very minor ATF leak, but it is just an occasional drip.  We'll be working on that next.

If you have any hints or input about the TCS solenoid and the ammeter, I'd sure appreciate hearing from you.

Thanks in advance.

[VileZambonie]

I would just eliminate it as you already have it. The ammeter is useless, swap it out for a voltage gauge.

[markolson]

I would just eliminate it as you already have it. The ammeter is useless, swap it out for a voltage gauge.

I appreciate the advice.

Is there a voltmeter from a different year/truck that fits in that cluster so I can rewire the harness to get voltmeter functionality in that spot?

[bd]

Welcome to the Forum from Central California!

TCS is Transmission Controlled Spark.  It was engineered to control distributor vacuum advance based on the gear the transmission was in.  TCS was controlled in part by the pressure switch you removed from the TH350.  I agree with Vile, just eliminate it. 

The factory ammeter is a shunt type.  It registers a small proportional current flow through wiring that is connected in parallel with the main power bus.  There is a fuse on both sides of the ammeter.  Again, I agree with Vile, a voltmeter is a worthy upgrade.  However, the factory voltmeter is not a direct plug-and-play conversion.  Instrument cluster wiring has to be altered a bit to supply 12-volt ignition and ground directly to the volt gauge.

[markolson]

Rich,

Thanks for the welcome and the information.

Regarding the TCS, thanks for the explanation.  It makes sense just to leave it out.

I forgot to check the second fuse in the ammeter circuit.  Good reminder.  I will do that.

But I agree that a voltage gauge would be a better gauge to have.  Modifying the harness at the cluster to convert it to a voltage gauge would be no problem for me.   My only question is where to find a voltage gauge that would bolt into the cluster and look right.   A newer GM truck?  A GM car from a similar vintage?

I really appreciate the advice.

Mark

[bd]

...My only question is where to find a voltage gauge that would bolt into the cluster and look right.  A newer GM truck?  A GM car from a similar vintage?

'76 - '90 Chevy/GMC used factory voltmeters.  The gauge needles changed color from fluorescent red to orange at some point, but otherwise I think are interchangeable(?).

[Irish_Alley]

welcome from maryland. its not what you have, but what you take care of.

[markolson]

Thanks for the welcomes and the advice.

My son brought his C10 home again last night so we could work on the final transmission leak.  With more foot powder, we proved that it was the dip-stick tube that was leaking.  The tube had a pretty loose fit in the hole in the case.  After two new O-rings with the same results, we bought a fancy RPC chrome dip stick and tube for the TH350.

We found the RPC tube nearly impossible to install.  The guy at the local parts store asked us if and old tube had been broken off inside the transmission case.  We could not tell, so we pulled the pan.  There was no boken off tube in there, so we used a block of wood and a hammer and installed the tube.  24 hours later, there is no dip stick leak (but there is a minor leak at the back of the pan).  We think a simple retorque of the pan bolts will fix that.

We did find that the tab that you use to bolt the RPC tube to the engine was about 1.5" too high for our engine.  So we fabbed a 2" long bracket to ensure the dipstick tube would stay in place.  We were a little surprised that it did not fit.  How many dipstick tube variations are there?

Now it is on to finding the junkyard volt gauge.  And we need to go through the brakes and suspension to make sure the truck is safe. 

We are now trying to decide if we should give it a complete tune-up or convert it to EFI.  My son is having a bit of sticker shock at the gas pump...

[Irish_Alley]

i've ran into problems with dip sticks before some want to drive slow in the fast lane. but anyway are you sure it was all the way down in the pan? but i was for real i have had the same problem. even on my 94 when i replaced the trans neither the stick that came with the trans or my old one fit. it was only a little off so i was able to bend it a tad but you have to be careful cause you can rip the tab off and leave a couple hole in the tube

[markolson]

Ha!  There were a bunch of those dipsticks on the road around here today.   

Both dipstick tubes went all the way in to the flared spot.  The old leaky dipstick tube was pretty loose fitting, and the mounting tab was long, maybe 2".  The new tube fit very tight, and is not leaking so far.  But the mounting tab was about half as long as the one on the old tube, and located 1-1/2" too high.  With the bracket I made, it will be fine, but it seems funny that it did not fit.  There was no way it could have been bent to fit.

Go figure...

[markolson]

Update:

The truck ran for a couple of days without any transmission leaks, but then yesterday my son parked it with the nose up the slightly sloped driveway, and after a couple of hours, it started leaking from the weep hole in the driveshaft yoke.  When he backed it into the driveway, the leak stopped.  So today he bought the output shaft O-ring from Chevy.  He also bought a new tail extension squared O-ring and a new rear seal, just to freshen them up while we have things apart.

I think it would be a good idea to check the transmission vent pipe to ensure it isn't clogged, too, but I am not sure exactly how to do that.

His left front fender was pretty badly rusted. We found the leak while we were replacing his fender with a clean junkyard fender.  It looks a lot better.

We also bought a junkyard volt gauge from a 77 truck, and have figured out how to rewire the cluster harness to make it work.  I'll do a writeup when we are done.

[markolson]

The writeup about the ammeter to volt gauge conversion is in the interior & equipment forum.  http://forum.73-87chevytrucks.com/smforum/index.php/topic,26734.0.html  It works very well.

We pulled the tailshaft housing off of the TH350 to try to fix the leak out of the weep hole.  We put a new rear main seal and a new tailshaft housing to main case seal.  We had also bought the O-ring that goes in the cup that goes around the output shaft, but we had no cup so we had nowhere to install the seal.  So we loaded up the splines with grease and are hoping for the best.  After several days, no more transmission leaks, knock on wood.

The brake fault light was on and the brakes were obviously not very good.  When we pulled the wheels to check all of the brake pads and shoes, we noticed a little leakage around the right rear slave cylinder.  We also noticed that pressing on the brakes only moved the disk brakes up front, but not the drums in back.  The good news was the pads, shoes, disks and drums were all good.  When we tried bleeding the brakes, we pressed the pedal with the cover off, and brake fluid blew out of the master cylinder.  We blew compressed air into the rear brake line and the brakes worked so we knew we did not have a clogged line.  So it was off to the parts store for a new master cylinder and two new rear slave cylinders.   We had to return the slaves to get ones for a 76 truck because the ones for the 73 truck (which is what we have) would not fit.  The hard brake lines on the 73 went straight into the slave cylinder.  The 73 slave cylinders came in from an angle.  We are wondering what kind of swapping had been done by one of the POs.

There was a missing spring (the one what holds the bottoms of the shoes together) on the right side, and the star adjuster was installed backwards on the left side, so that side would not have automatic brake adjustment.  We had also bought a spring kit, so we  replaced all of the springs.

We bench bled the master cylinder and installed it, and then flushed the fronts and then bled and flushed the rears.  It took a lot of brake fluid.  The brakes firmed up nicely but the brake fault light did not go out until we did a bit of spirited braking.  The truck stops very well now.  It feels a lot safer.

We replaced all of the shocks.  The fronts weren't too bad, but the rears had some of the bushings completely gone.  The truck rides an lot better.  It will be even better when the new suspension bushings arrive and are installed.  Some of the old bushings are in pretty bad shape too. 

With the new volt gauge installed, we noticed that the voltage was kind of low at idle, and the battery started dying on us.  Since the battery was 10 years old, we took it down to the parts store for load testing, but the battery showed it was ok.  So we replaced the alternator and the thing runs at 14.5V at idle.

The truck was only getting up to about the 1/4 mark on the temperature gauge during the day, and wouldn't even make it to the C mark at night.  I suspected a PO had removed the thermostat, so we checked that today.  Sure enough, no T-stat, so it got a new 195* unit.  So tonight we went to adjust the headlights, and noticed that the heater is always on.  We now need to find out where the heater valve is and hook that up.

The headlight adjusters are completely non-functional, so that's a job for tomorrow.  The windshield washer motor was starting to smoke when we tested it, too.  we are cueing things up for another trip to Pick N Pull.

We are gradually getting this truck into good working condition. 

[markolson]

One of the previous owners had installed the plastic headlight adjustment nuts into the truck from the rear, and a couple were broken.  When we pushed on the adjuster screws to turn them, two simply popped out.  The passenger side headlight bucket adjuster screw slot was completely bent up and widened, so the adjuster screw kept falling out.  One of the spot welded tabs on the passenger side headlight retainer ring had broken, so there was nothing to keep the headlights steady or aimed in any one direction for long.  We replaced the plastic adjuster nuts, the passenger side bucket and we repaired the headlight retainer ring with a pop rivet.  Now the headlights are firmly in place and fully adjustable.

We also replaced the headlight switch with a good unit, so the instrument cluster lights can now be dimmed.

He finally changed the oil.  It was very black.  We wonder how long it has been since it was changed last.  The nylon drain plug washer was split, so we are pretty sure we found the source of one of the engine oil leaks.

We are now waiting on a whole bunch of bushings and power steering parts.  It will be really convenient to get the power steering working. 

We are slowly getting this truck into good working order. 

[markolson]

Time for another update.

We spent part of Saturday figuring out how the   power steering mount kit was supposed to go together, and installing a new power steering pump and lines. Then we tried to bleed the power steering system.

The battery kept dying on us, so we threw an ammeter between the battery and the truck and learned that we had a 750mA drain on the battery. After pulling all the fuses and not finding the drain, we unplugged the alternator connector, and the battery drain stopped. So we replaced the newly rebuilt alternator with another one. But it had a stripped bolt hole, so we finally gave up on the rebuilt alternators, and threw a bit more money in and upgraded to a new alternator. But then we tried to start the truck, and the starter wouldn't even turn.

We were seeing 13V on the battery, but when we turned the key on, we saw the voltage drop to 0.5V. We checked the current draw at 0/5 and it was only about 300mA. We took the battery down and had it tested, and it showed it was good on two testers, even though the battery was 10 years old. We took it home and tried it again, with the same results. We we went back to the store and bought a new battery. I also didn't like the look of the ground cable terminal, so we replaced it too. That make the truck start like a champ, and the new alternator was charging the battery at 14.3V and not draining the battery when not running.

So we were finally able to finish bleeding the power steering system, and it is now working like a champ, no leaks so far, knock on wood.

We replaced the shredded seat belts after that.

Next weekend, we'll get started on replacing the cab mount bushings, and rebuilding the front end. We also plan to replace the fuel filler hoses and seals too, since they are a bit leaky.

The truck is slowly getting whipped back into shape.

[Irish_Alley]

a bad ground will cause all sorts of problems