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12-05-2002, 03:58 PM | #1 |
I miss this truck.
Join Date: Dec 2001
Location: Lexington, KY U.S.A.
Posts: 2,863
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A couple of problem I could use suggestions on
I have 2 problems (beyond the swiss cheese sheet metal).
#1) Everything Electrical works fine at higher RPM; at Idle, the turn signals flash VVVEEEERRRRYYYYYY slowly, the heater fan comes on and off (only when on hi, could be due to a worn out relay) and all the light inside and outside get a little dim. Is this most likely an alternator problem, or is there somewhere else I should check first? #2) Summer: Truck runs hot, new thermostat and water pump, still runs hot. Winter, temp qauge right where it should be, only get hot air out of heater at higher RPM, not very hot at that. Just a radiator that needs to be flushed?
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'07 GMC Acadia SLT. Sweet ride. '08 Crew Cab Z-71 short bed. Really like this truck A LOT. |
12-05-2002, 04:03 PM | #2 |
Registered User
Join Date: Aug 2001
Location: escondido, ca 92026
Posts: 1,222
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check frame, engine, and body grounding for the electrical problem...
heater problem is kinda strange... does your blower motor speed up and slow down with the rpm...?? could also be a grounding problem.... otherwise, your heater core may be toast and need to be replaced...
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'72 short step, 350, 700R4, tilt, ps, pdb, a/c, lowered coils, etc., other work in progress... San Diego, CA 72 Stepside Project Last edited by bigvinnie; 12-05-2002 at 04:06 PM. |
12-05-2002, 04:09 PM | #3 |
Just an Old Mr Goodwrench
Join Date: Feb 2002
Location: Green Ridge, MO USA
Posts: 259
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Also check your regulator - if the points are corroded the unit may not be making contact until you get the RPM's up.
You get Hot air from the heater?? That's novel
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1969 CST 20 Longhorn 1970 CST 20 Fleetside 1991 Jaguar Sovereign 1992 Mazda Miata |
12-05-2002, 04:31 PM | #4 |
Ain't we cute?
Join Date: May 2002
Location: Friendswood, TX
Posts: 700
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my guesses:
voltage reg. or ground problem heater core and/or blockage somewhere
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69 C10 2WD LWB Fleet 350/350 power front disc conversion (6 lug disc kit from gmcpauls) and new engine, PS, A/C, fresh fluids, SHE DRIVES! FOR SALE $3900 |
12-05-2002, 06:24 PM | #5 |
L.E.D. Tail lights, Baby!
Join Date: Jan 2002
Location: Corona, Ca
Posts: 290
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Heater core/blockage very likely...
However, check your mixture % You may need to run more water. It helped me in my truck when it was 100 degrees outside.
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12-05-2002, 07:44 PM | #6 |
I miss this truck.
Join Date: Dec 2001
Location: Lexington, KY U.S.A.
Posts: 2,863
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Well, I guess that solves one problem. I stopped at Auto Zone to have them check the alternator. Sure enough, I'm gettin' plenty o' volts, but only 21 amps. That Alt is rated for 60. I'll put it on tomorrow and hope for the best.
On the heater thing, I checked the hoses. Rad to heater cont. valve is hot, valve to core warm, return to rad. stone cold. Have you ever heard of a year old core plugging up, but not leaking? The cooling system has never seen anything but distilled water and antifreeze. I'll change the valve tomorrow and hope for the best on that too. Thanks for the help.
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'07 GMC Acadia SLT. Sweet ride. '08 Crew Cab Z-71 short bed. Really like this truck A LOT. |
12-05-2002, 10:25 PM | #7 |
"Ochre Ogre"
Join Date: Apr 2000
Location: Springfield, MN
Posts: 3,558
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Do you have factory A/C? I only ask because that is the only valve that would be in-line on the heater hose. If you do then that is your problem. It could be stuck shut or maybe the vacuum hose is connected to the wrong port and it is closing when it should be open.
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Bowtie Truck Stop Inc. Mid-West GM Truck Restoration Parts Supplier Your Key Parts, Auto Metal Direct, Dynacorn, and Goodmark dealer. like us @ www.facebook.com/BowtieTruckStop 1971 C-10 Suburban (Ochre) 1971 K-10 Suburban (Ochre) 1972 C-10 Suburban (Ochre) 1972 K-20 Suburban (Yellow- that just aint right!) Springfield, Minnesota 56087 |
12-06-2002, 12:11 AM | #8 |
My other Love
Join Date: Aug 2001
Location: Castlegar B.C. Canada
Posts: 4,085
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Could you have an airlock in the heater core?
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Castlegar B.C.The great white North (Canada Eh!) Hooter_5@hotmail.com First generation Monte Carlo club pictures of my life |
12-06-2002, 12:47 AM | #9 |
Cantankerous Geezer
Join Date: Aug 2002
Location: Bel Aire, KS
Posts: 6,264
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I think da burb is onto something. Before replacing the valve, check a couple of things. Does the valve have vacuum to it with the engine running and the heater on? Check it with a vacuum gauge if you have one. It should have a strong reading. If the reading is low, check your lines to the control and back to the engine. Also check the valve. Try blowing into it to check for a diaphragm leak. Sucking can get you a mouth full of crap. You could also take the valve out of the hose and see if you get heat that way.
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Fred There is no such thing as too much cam...just not enough engine. |
12-06-2002, 12:51 AM | #10 |
My other Love
Join Date: Aug 2001
Location: Castlegar B.C. Canada
Posts: 4,085
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Ah you can always spit the crap out.
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Castlegar B.C.The great white North (Canada Eh!) Hooter_5@hotmail.com First generation Monte Carlo club pictures of my life |
12-06-2002, 01:00 AM | #11 |
its all about the +6 inches
Join Date: Jan 2001
Location: Hilliard Ohio
Posts: 2,690
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Bypass the valve.
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12-06-2002, 09:21 AM | #12 |
Senior Member
Join Date: Jun 2001
Location: Shelbyville, KY
Posts: 3,261
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Tynee, know the alt is not putting out but still take the time to check for good grounds---block to firewall, cab to frame, etc. Even a perfect Alt will not give you the results you need with bad grounds. My bet on your heater is that valve. Had to replace mine on every A/C truck I've had due to leaking or just not working. that vacuum line is also critical----I also wind up replacing all the vacuum lines, heater hoses etc. to ward off the deamons!! With everything working perfect it still takes me 4-5 miles before I get heat in either of my trucks~~. Let us know what you find out. Huck
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12-06-2002, 10:21 AM | #13 |
Working on a Nova.
Join Date: Nov 2002
Location: ##
Posts: 506
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Huck
I've found the miles all depend on how fast I'm going!!! HeeHee!!! Sorry you all, just had to throw that in. Da Hound |
12-06-2002, 03:20 PM | #14 |
I miss this truck.
Join Date: Dec 2001
Location: Lexington, KY U.S.A.
Posts: 2,863
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Okay, put the alt. on, seems to have cleared up the electrical issue. Heater blower still a bit suspicious on hi, but I think thats the relay.
Now just the heater thing. I changed the valve and life got worse, nothing but COLD air. Bypassed the valve & can't stay in the cab without breaking a sweat. I've got about 17psi vacuum at that valve, surely that should open in, right? I think I'll go look this up. Maybe the valve is backward, but that shouldn't matter once its open, should it?
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'07 GMC Acadia SLT. Sweet ride. '08 Crew Cab Z-71 short bed. Really like this truck A LOT. |
12-07-2002, 10:16 AM | #15 |
I miss this truck.
Join Date: Dec 2001
Location: Lexington, KY U.S.A.
Posts: 2,863
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How 'bout it, anyone know how many psi I need to open that valve?
ttt
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'07 GMC Acadia SLT. Sweet ride. '08 Crew Cab Z-71 short bed. Really like this truck A LOT. |
12-07-2002, 02:57 PM | #16 |
Registered User
Join Date: Jan 2001
Location: Killingworth, CT. USA
Posts: 3,378
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I believe the valve remains open when there is no vaccum or if it's disconnected. When vaccum is applied it closes the valve. I think anything over 5 inches of vaccum would operate the valve if it's in good condition. Also, is the thermostat working? If it is functioning correctly it helps force the coolant through the heater core during warm up.
To check your ground condition, use a digital volt meter, set it to the 20V DC scale, connect the black lead to the neg post of battery, turn ignition on, engine off, turn on lights, heater on high and with the red lead, touch it to the radiater support, frame, engine and cab. Readings should not eceed 0.10 Volts. If the readings are within the 0.10 V limit, your grounds are fine, if the readings are over that, you need to clean up or add ground straps from neg post of bat to the rad support, engine to frame and engine to cab.
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1971 C10 swb stepside 350/700R4/3.73posi (retired as of 4/22/03) 1998 S10 short bed 2002 S10 Blazer 1942 Oldsmobile 1958 Massey Harris Pony 1951 Wife Killingworth, Connecticut May those who love us, love us, any of those who do not love us, may God turn their hearts. And if God is unable to turn their hearts, may he turn their ankles so we may know them by their limping. A man who works with his hands is a laborer; a man who works with his hands and his brain is a craftsman; but a man who works with his hands and his brain and his heart is an artist. Last edited by Gordo; 12-07-2002 at 03:10 PM. |
12-08-2002, 03:53 PM | #17 |
I miss this truck.
Join Date: Dec 2001
Location: Lexington, KY U.S.A.
Posts: 2,863
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Ohhh, then I have been working on completely the wrong assumption. I must have misunderstood. I was under the impression that the valve opened when pressure was applied. So what do I need to look at to see why their is constant vacuum to the valve? Can someone clear up all of the functions of all three levers on the heat/air controls? I know I've got one that is broken, and is probably stuck at one extreme or the other(top lever). I believe the bottom lever directs the air between feet/defrost vents, corrrect?
Thanks ofr any and all help!!
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'07 GMC Acadia SLT. Sweet ride. '08 Crew Cab Z-71 short bed. Really like this truck A LOT. |
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