What did you do with your GMT400 today...or yesterday....

[Husker6.5]

Could be the turbo oil feed line is leaking and dribbling down onto the exhaust manifold, too. Possible that the turbo to upper intake hose clamp(s) is/are a bit loose and blowing oil mist onto the passenger exhaust manifold. There could be a lot of small things causing this, don't get discouraged, @MrMarty51!

 

[dbrannon79]

for what it's worth, on these engines I have always thought of the sealing surfaces like a good seasoned cast iron skillet where anything we try to stick to it to seal a gasket, it won't stick due to the surface impregnated with oil. I know there isn't any room to do this while the engine is in the truck, but maybe using something like those 3m roloc disks to scratch up the surface for some fresh bare metal might help the gasket and sealant bite and hold.

 

[Will L.]

On severely oiled engines, Usually brake clean everything first and make sure that all dried up, use a roloc if needed, then if the oil is still bad- i have used a small propane torch to cook the oil out of pores.
Obviously huge fire risk so have to take all the precautions.
Then after it is cooled down some brake clean as a finish.

The crc pro can of brake cleaner is my favorite in a can.

 

[MrMarty51]

When I had the RCs off to seal them, I used mineral spirits and Scotch Brite and thoroughly cleaned the head surfaces and the RCs. Then followed that up with scotch brite liberally soaked with Oreillys brand B&P cleaner. All surfaces were totally clean and dry.
I’m taking a short break from the truck. Now that that new propane powered fridge is moved from the garage and hauled to the cabin, it has made a nice opening that I can move some stuff from between the vehicles to ahead of the wifeys car. Give a bunch more room between vehicles and room on the RH side of the truck.
The wifey once again is going to be unhappy with my decision. Installed that new set of rocker arm covers onto my credit card.

 

[MrMarty51]

Not the truck.
The cabin has a 2” gasoline powered pump to pump lake water to the 1500 gallon poly tank on the hill above the cabin.
Someone before my son and I got reckless with the suction side hose and busted the fitting flange on the pump. The foot valve fits under this fitting. Someone packed off the flange to get it welded, shop said they couldnt weld it so he tossed the flange.
I took the foot valve and hope it is not distorted so that the home made flange wont fit.
Got it all put together but then the torch is out of oxygen so today will be another reason for the wife to bitch me out some more. An exchange bottle of oxygen onto the CC.
The flange drawn out on the flat, bolt holes drilled and the pipe nipple welded to it.

 

[Paveltolz]

2015 to Present. HVAC Blower Motor only moves air on low or high not position 2 or 3. Been that way for years. I checked over the schematics and it looked like it was possibly the Blower Motor Resistor that sits on top of the air box assy behind the glove box but, could be the HVAC Control Unit, could be the Blower Motor or, maybe the High Blower Relay (doubtful).

I went for the resistor. Schematics indicate that the HIGH setting circuit doesn't go through the resistor. Nope, with the new resistor the High function was dead too. I swapped out the HVAC Control Unit in the dash and that didn't solve things either.

With a short term ownership of a1995 Tahoe, I had the same issue and I just handed it over to my favorite 'Shade Tree' Mechanic and he said, yup, its the blower motor. We talked about schematics and all and he laughed, kinda pointed at all his ASA certs (he was also an instructor at the Tech College) and I gave him my $$. New Blower Motor solved it on the Tahoe.

Yesterday, I replaced the Blower Motor...NOPE. Not it. My mechanic has since passed away (cancer) so I'm on my own for a bit. I don't have the replacement HVAC controller I tried, not sure where I sourced it or if I disposed of it.
So, I'll work my way backwards and try the resistor again 'since I'm in there' and can't remember if I tried the resistor before or after swapping Control Units (not unlike me to compound an issue with a bad 'new' part). I did buy just a replacement Blower Motor Switch for the controller though so, guess I'll try that next and then beat my head on the dash and the Shop Manuals again.

 

[dbrannon79]

2015 to Present. HVAC Blower Motor only moves air on low or high not position 2 or 3. Been that way for years. I checked over the schematics and it looked like it was possibly the Blower Motor Resistor that sits on top of the air box assy behind the glove box but, could be the HVAC Control Unit, could be the Blower Motor or, maybe the High Blower Relay (doubtful).

I went for the resistor. Schematics indicate that the HIGH setting circuit doesn't go through the resistor. Nope, with the new resistor the High function was dead too. I swapped out the HVAC Control Unit in the dash and that didn't solve things either.

With a short term ownership of a1995 Tahoe, I had the same issue and I just handed it over to my favorite 'Shade Tree' Mechanic and he said, yup, its the blower motor. We talked about schematics and all and he laughed, kinda pointed at all his ASA certs (he was also an instructor at the Tech College) and I gave him my $$. New Blower Motor solved it on the Tahoe.

Yesterday, I replaced the Blower Motor...NOPE. Not it. My mechanic has since passed away (cancer) so I'm on my own for a bit. I don't have the replacement HVAC controller I tried, not sure where I sourced it or if I disposed of it.
So, I'll work my way backwards and try the resistor again 'since I'm in there' and can't remember if I tried the resistor before or after swapping Control Units (not unlike me to compound an issue with a bad 'new' part). I did buy just a replacement Blower Motor Switch for the controller though so, guess I'll try that next and then beat my head on the dash and the Shop Manuals again.

when you swapped the controls, did you check the connectors to the blower fan switch or replace the switch? with only low and high working, and no med speeds, if the resistor didn't do it, it would have to be the blower fan switch or one of the connectors has a bad or melted contact.

nowadays even the new switches seem to be junk. cheaply made. my 95 has issues with the low and med speeds just suddenly stop working, with a quick turn of the switch off and back on makes it work again. I'm sure the switch contacts are giving up again, I have been wanting to incorporate some extra relays under the dash to help keep the blower switch from burning up. the only speed that has a relay is the high speed, but if you check the amp draw at the blower switch, it's the same for all speeds due to the resistor that pulls power making the blower spin slower.

GM started using separate relays for all fan speeds on the newer 2000+ year models to help this issue.

 

[Paveltolz]

when you swapped the controls, did you check the connectors to the blower fan switch or replace the switch? with only low and high working, and no med speeds, if the resistor didn't do it, it would have to be the blower fan switch or one of the connectors has a bad or melted contact.

nowadays even the new switches seem to be junk. cheaply made. my 95 has issues with the low and med speeds just suddenly stop working, with a quick turn of the switch off and back on makes it work again. I'm sure the switch contacts are giving up again, I have been wanting to incorporate some extra relays under the dash to help keep the blower switch from burning up. the only speed that has a relay is the high speed, but if you check the amp draw at the blower switch, it's the same for all speeds due to the resistor that pulls power making the blower spin slower.

GM started using separate relays for all fan speeds on the newer 2000+ year models to help this issue.

No, I didn't check connectors. Shortsighted. When I swapped Control Units, I'm not even positive the 'new' unit was actually a new one or one I pulled from a yard or e-bay. I didn't know the blower switch was a replaceable unit until a couple of weeks ago when it came up while trying to find a newer control unit.

Yesterday I noted that when I did a couple of rapid switch position changes I had position 3 back briefly but, NFL (not for long). So, I'm leaning more towards the blower switch itself.

I don't have a lot of confidence in the longevity of the new switch either. Some of the comments for other suppliers give one pause. I may even take the old switch apart and clean it up. Worked with the under hood reel lamps so it can't hurt to try as long as everything is disconnected from power, right?
I'm planning on checking continuities between contacts on the switches, resistor and motor as well as resistances on the resistor positions itself today or tomorrow. Mostly to confirm things and partly to educate myself.

 

[SnowDrift]

Something burned up in mine a few years back that was right around the blower motor and ECM. I'll see if I can dig up what it was. My fan quit altogether one day when I was pulling a trailer in a parade in August which was really awesome since it was in the 90s out that day.

 

[SnowDrift]

No Blower Motor at any speed.

I posted this in the electrical section, but also realize it's specific to the model years/makes with the 6.5 ('95, in particular), so I'm posting here, too. The link to the other post is below in case someone needs to look through it in a future search. My blower motor spins when I hook 12v...

www.thetruckstop.us

Try here - I'm not sure if it applies to yours but maybe

 

[Paveltolz]

No Blower Motor at any speed.

I posted this in the electrical section, but also realize it's specific to the model years/makes with the 6.5 ('95, in particular), so I'm posting here, too. The link to the other post is below in case someone needs to look through it in a future search. My blower motor spins when I hook 12v...

www.thetruckstop.us

Try here - I'm not sure if it applies to yours but maybe

Thanks, I'll check it out but, I've got low and high speeds...for now. We'll see how it goes after I try to 'fix' things.
At least I know my old blower motor is good. Tryin' to stay positive.

 

[Husker6.5]

You might want to try an aftermarket multi-pole switch with like a 15-25 amp contact rating. It may not fit exactly (but aren't we always modifying something to fit on our beasties b/c OEM is either unavailable or inadequate) but I bet it's rated for a lot higher load than the GM-engineered "just enough to satisfy the bean-counters" switch is. Just like the infamous melting ground connector for the fan!

 

[dbrannon79]

There is a insulated single spade connector inline from the blower motors main power lead up in the harness by the back side of the glove box. mine had melted. I ended up just cutting it out and soldering the wires together. not long after that my blower motor burned up. I guess all the years of not getting it's full power through crappy GM connections made it give up the ghost.

 

[Paveltolz]

Blower switch connector is a bit cooked. The "Light Blue" wire isn't so much for a bit back from the connector.

Still, there’s no short between the A and B connections so that’s good news.
Checking continuity of the wires between the Blower Switch (Lt Bl, Yel, Tan) and the Resistor Connection test good despite the burned Switch connector.
Checking the resistor’s resistance values and connectivity for both the old and new gave me mixed results and had a bit confused because connectivity at the pins on the front and resistance values for the coils were different. Which one correct? Not knowing (photo’s courtesy of RockAuto).


So I set the new resistor in place and hooked things up just for grins and giggles. Confidence was not high and I wasn’t disappointed because just as I remembered from before, there was absolutely no voltage getting to the blower motor. FWIW, my new resistor was out of the box from AC Delco.
I put the old one on and it was as before, only low and high. I did some further inspection of the old unit which is original to the truck and, honestly, looked cheaper. I noticed that it appeared two of the resistance coils were in contact which, given the nature of construction, didn’t seem like a big deal but, I separated them and tried things again.
SUCCESS! All speeds work. Even after reassembly everything is working fine. So, my original diagnostics were correct, I just had a bad out of the box part. I’m not even going to speculate how the OEM resistor went south with two coils coming in contact unless it was during the repair of the leaking Heater Coil and I bumped the resistor which is about 1/2. I don’t recall the blower motor’s issues showing up at that time but, who the $%^&* knows.
It is now working and I can move on to diagnosing and repairing the 4x4 actuator failure.
NEXT!

 

[dbrannon79]

that melted connector is the reason I want to add additional relays for each fan speed. with only the high speed relay, the high speed is the only speed setting at which the current the blower is drawing is not being pulled through the fan switch. all the other speeds get loaded through the fan switch. the resistor is like a heating element that only reduces the current at the blower but together still pull a great deal through the contacts of the switch. I'm not positive but I think that one melted contact is the power in to the switch supplied from the ignition.

one other thing to note is watching the voltage gauge in the dash as you turn the blower on the different speeds. The gauge will drop even though if you put a meter on the battery and you'll see the voltage stays constant when running. this is due to the poor too small of wire used in the harness to supply the cab electronics and inside fuse box with power. to help this issue, I want to run a heavy power lead from the battery with a 60 amp main breaker into the cab like you do for installing a boom box amp. Having this power lead go to a distribution fuse panel and use this to supply all of the fan speed relays (the ones that get added) including re-routing the power to the high blower relay.

I have learned over the years that not just GM, but most all vehicle makes don't have adequate main power wires going in to supply the cab.

 

[Will L.]

Those melt because as you point out, full power to those coils- and they are like the wires in your toaster. They cook. But it is open so when the nice cold a/c air blows across it, they cool down and just make your ac perform worse.

But what if you use your heater you ask? Oh, well they help produce heat. And they sit there and cook and cook and cook. And the more you use the lower settings the sooner they will fail, especially in the winter time.

Why do it that way? Because they save a buck a truck. And 20 million trucks later, that is a bonus for an executive. So what is the smart way to do it? A rheostat at the knob. A wire large enough to handle the power when on full. And eliminate those other wires for the different levels. GM reaaaaalllllyyyyy sucks sometimes. This is one of them.
But don’t worry, gm tricked AM General into using them also. So they same sucky thing is in my 95 hummer with the control system that was in the 93 truck. Until I get rich and famous enough to rip the whole system out and put in something good, Like an ice cube and a fan. Haha
If i end up keeping my stock blower fan, it will have one wire going to a rheostat.

 

[MrMarty51]

Warmed the engine some before heading into the garage.
Decided to do a short video clip.

Seems to run quite well, now to get the oil leaks plugged.

 

[jrsavoie]

that melted connector is the reason I want to add additional relays for each fan speed. with only the high speed relay, the high speed is the only speed setting at which the current the blower is drawing is not being pulled through the fan switch. all the other speeds get loaded through the fan switch. the resistor is like a heating element that only reduces the current at the blower but together still pull a great deal through the contacts of the switch. I'm not positive but I think that one melted contact is the power in to the switch supplied from the ignition.

one other thing to note is watching the voltage gauge in the dash as you turn the blower on the different speeds. The gauge will drop even though if you put a meter on the battery and you'll see the voltage stays constant when running. this is due to the poor too small of wire used in the harness to supply the cab electronics and inside fuse box with power. to help this issue, I want to run a heavy power lead from the battery with a 60 amp main breaker into the cab like you do for installing a boom box amp. Having this power lead go to a distribution fuse panel and use this to supply all of the fan speed relays (the ones that get added) including re-routing the power to the high blower relay.

I have learned over the years that not just GM, but most all vehicle makes don't have adequate main power wires going in to supply the cab.

Or grounds

 

[Paveltolz]

Had a "Spin, no start" for the second time in a few days. Motor not spinning fast enough. Load Test batteries at O'Reilly's and the 13 year old Optima's both test bad. O'Reilly doesn't sell 'em. Schlep the batteries back to the T-Reg and over to Auto Zone. They sell 'em, don't have them in stock but can order them. Ok, schlep the old batts into the store and, Oh, the store up the road has two in stock. Schelp the old ones out to the car again. After dealing with Utard driver's for 10 more eternal miles I finally arrive a little less sane at the second AZ. They don't open the door like O'Reilly's or the other AZ store and, as I walk in with both batts the kid masquerading as an Auto Parts sales person asks, 'what can we do for you today?" Tongue bitten off I manage to politely state I need the two Optima 34-78 Red Tops they have on the shelf. "I'll see if they are here?"
Then the 20 questions to see if the computer agrees with me on what I need. "What vehicle?"
"96 Chevy K1500, 6.5 Diesel"
"Is that 4-Wheel Drive?"
"That's what the 'K' is for."
"What motor?"
"Diesel"
"Which one (he's only paying attention to the displacement options)?"
"The only diesel on your list cause it damn sure isn't the 5.7."
And on it went to include another 10 miles of Utardian drivers.
Anyway, two new Optima's standing by to go in tomorrow morning.

 

[MrMarty51]

Ten miles to get to the next AZ parts store. WOW.
Ten miles here, in any direction, puts You a good distance from anything besides farm or ranch land.
Three parts stores in town. All three maybe a mile and a half, two at the most, and all three within a 1/4 mile of each other.