Can't catch a break?!

[Orpedcrow]

Man that looks nice!!! What type of intake is that? I like the timing cover! Did you have any "special" work done to it, cylinders bored over, port & polish the intake/head runners, cam?! Is that already installed or are you in the process of doing it now?

It’s just a stock vortec intake I painted. Timing cover is a Holley. Nothing special, bored .20 over I think he said, one of the cylinders had grooves in it. GM Marine cam. The first intake got a little bit of cleaning up with a dremel but I broke the egr port so the second intake just got cleaned and painted. It is installed! About 2000 miles on it I guess.


Here’s my build thread if you’re interested in the intake drama lol
There’s several “can’t catch a break” moments.

Thread 'Teal daily driven farm truck.'
https://www.gmt400.com/threads/teal-daily-driven-farm-truck.59676/

 

[Schurkey]

There's not much to "rebuild" on a TBI unit.

The throttle shafts may have worn the casting that supports it from a round hole to oblong. The casting gets drilled-out and a bushing crammed in on each side. Exactly the same as throttle-shaft bushings in a carburetor--a real PITA. Don't dick with this if the shaft seems well-supported and doesn't wiggle around in the casting.

Aside from that, you can replace some seals, inspect the screens in the injectors, assure that all the vacuum passages are free of deposits, and--probably most important--install a fresh diaphragm and perhaps a spring in the pressure regulator.

Then make sure the top of the pressure regulator assembly is flat and smooth.

Ordinary sandpaper, and a piece of glass to assure flatness.

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[95OBSMan]

Great build thread Opedcrow!!! Schurkey, thanks for the heads up on the TBI rebuild, throttle shafts seem good with no "play" in them, got a rebuild kit that included the diaphragm gasket and a new spring and all the o-rings and injector screens etc... will be better than rebuilding an old Q-jet carb!

 

[Schurkey]

will be better than rebuilding an old Q-jet carb!

...and about 1/10 the labor 'n' headache.

 

[95OBSMan]

you ain't kidding on that one!!

 

[Schurkey]

Don't get me wrong...I loved (and still do love) doing carb overhauls. That was "good work" at the time...no heavy lifting, no rusted bolts, and like auto-transmission work, it was "clean" work at least on the reassembly.

The overhauled carb could make a massive difference in how the vehicle ran. Carb overhauls could be very satisfying work.

But it did require actual concentration, and a willingness to perform ALL the adjustments listed on the instruction sheet, not merely most of them, or worse--check the float level (close enough!) and throw it back on the car.

Most recent carb work? Dicking with a Tecumseh 8-horse wood-chipper carb with a leaking needle/seat. The seat is rubber, and it's pulled out of, and poked into the carb orifice using the two ends of a glorified crochet hook.

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[95OBSMan]

So after a month in the garage replacing the intake manifold gasket and a whole lot of other items on the engine, which needed to be replaced do to age and some normal wear and tear, pulling a bone head move with the starter, and getting the exhaust done, finally I get to fire it up, runs great, but...

I drive it around the block, close to the house just in case something leaks or comes flying off, all good there, now get her up on the highway and open it up and get it to normal operating temp, now time to turn the HVAC knob to hot and turn the fan on to high, after all the work still "Luke warm" air inside cabin and a "strong smell of coolant" enough to open both windows, pull over and look for a coolant leak, not one leak, outside air temp 42 degree's speed was around 65 to 80 durning test drive, 20 minute drive, arrive back at the house, pop hood still no coolant leak any where, blower motor on high setting as is the knob for temp, engine still running and idle is perfect, smell of anti-freeze still present in cabin, overflow tank did not "puke" any out, and nothing "burning" off the Y-pipe.

I did not replace heater core, just back flushed as advised, did not see any coolant dripping from the tube that is right next to the heater core tubes where the heater hoses attach to, I'm assuming that tube is a drain tube that is for the heater core case that is under the dash, and the carpet is not wet?! Any thoughts on what's happening or not happening?

 

[Schurkey]

turn the HVAC knob to hot and turn the fan on to high, after all the work still "Luke warm" air inside cabin

Put a thermometer on the dash ducts, turn the airflow to "vent", temperature to fully-hot, and blower speed to "low" with the engine FULLY WARM.

You'd want to see 150+ degree temps. My truck has a 205 degree F. thermostat, I'm getting 190+ temp out of the vent under those conditions if the outside air is ~50 degrees F. At -20F, I am still roasted out of the single-cab truck if I drive far enough. Gotta turn the temp down, or the fan speed down, or both.

The issue is that these trucks were built with low-budget foam seals in the HVAC system. When that foam degrades you have an under-dash air leak of cold air. The heater can't throw enough BTUs to warm the cabin when the cold air is pouring in--even if the heater is working properly.

And you don't get a proper temperature reading at the floor-level heat duct again due to the massive cold air coming in under the dash. That's why you set the airflow to "vent", and test there.

and a "strong smell of coolant" enough to open both windows, pull over and look for a coolant leak, not one leak.

Do you have the rubber seal at the rear edge of the hood, that seals the hood to the front of the plenum? If not--or if the hood doesn't close properly so that the seal is effective--maybe you're getting residual coolant fumes from the engine compartment drawn into the HVAC plenum, and then pushed into the cabin via the HVAC blower motor.

I did not replace heater core, just back flushed as advised, did not see any coolant dripping from the tube that is right next to the heater core tubes where the heater hoses attach to, I'm assuming that tube is a drain tube that is for the heater core case that is under the dash, and the carpet is not wet?!

The drain tube is more for the A/C evaporator condensation than the heater core. I suspect there'd have to be a substantial amount of coolant in the heater-box area before it'd flow out of the drain tube.

But I haven't actually looked into that. Maybe I'm wrong.

NOT having wet carpet (well, more the carpet pad than the carpet) by the heater core is a good sign in terms of the heater core not leaking.

 

[95OBSMan]

SchurKey, thanks for the info, I will go outside now and test as you have said and will report back on those findings. I installed a 195 T-stat as outside in the service manual for this engine, and I should be ran out of the cabin do to the temp flowing through the heater core!

The rubber seals just arrived at the house today from LMC, I will install them tonight as well.

I was not positive either if that drain tube was for heater core and or A/C evaporator, I'm thinking that you are correct in that its the A/C evaporator condensation drain tube.

What is involved or how do I confirm that the low-budget HVAC foam is bad, this truck spent it whole life in Az., Vegas, and now in southern Utah, all very, very hot and arid climate, with little to no relative humidity what so ever, which is equal to the salt belt and what that does to all uncoated metal on vehicles in those areas!
Thanks again for the info and what to check for to help solve this problem!

 

[Schurkey]

What is involved or how do I confirm that the low-budget HVAC foam is bad,

Have someone drive the truck when it's cold out. You'll feel cold air coming in the cab from under the dash, you'll probably trace it to somewhere above the HVAC fan.

There's a foam seal between the formed-steel of the cowl, and the molded-plastic air inlet for the HVAC fan.