Top 20 1991 GMC K1500 Questions & Answers

Wiring, schematic, electrical diagrams, fuse diag, error codes, torque settings etc are basic contents of these online books they have here on this website www.reliable-store.com I have attached. Must check it out

You should be able to readjust the aiming screws to reset them to the way you want. Remove the head light bezel and you should see the aiming screws.

Should be Dexron, you should be able to tell by removing the side plug. You see red it is Dex.

Check for spark/fuel??

NO, but if in question replace it, not difficult. I replaced mine on my 1988 gmc k2500, but thats me, I did a total rebuild, like to make things run perfect, run good, these trucks last like they should.

You also have no carburetor on a 1991 vehicleNo one on the internet would know either withouta picture of the problem

Yes, by any chance you know your transmission ratio and your differential. If they are very different then you have to change the rear ratio. By changing the ring and pinion. Now you play there is a bolt with a screw head and a nut around it. Loosen the nut but do not let the screw turn with it as you loosen the nut. Turn the screw bolt 1/4 to 1/2 a turn clockwise and keep checking it for your satisfaction, but do not take it all the way off.

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If this vehicle has high miles, the camshaft timing gear nylon teeth may be breaking off and going into the lower part of the oil pan, blocking off the oil pickup tube screen. Oil starvation.

Hope it helps.

as long as it is a 5.0 or 5.7 and still a vortec series they will intechange fine

As you've already realised, this is serious. The engine is more than likely totally shot. Maybe a broken valve and punched a hole in a piston. Broken piston rod maybe. It's been overheated and also probably blown the head gasket and warped a head. You're looking at a complete engine re-build already. I think I'd just buy a rebuilt long block and start fresh.

They must be loose.

Should just pull off,if it is plastic
Got rubber gaskets, all that's holding it

CLUTCH ON COOLING FAN FREEWHEELING. COOLING FAN SHOULD HAVE RESISTANCE WHEN TURN WITH HAND WHEN ENGINE HOT.IF NOT FAN FREE WHEEL FAN CLUTCH NEEDS TO BE REPLACED.IF COOLING FAN OKAY.YOU COULD HAVE BLOWN HEAD GASKET.YOUR RADIATOR AND ENGINE BLOCK NEED FLUSHING OUT.CHECK WATER PUMP FOR LEAKING WEEP HOLE IF LEAKING REPLACE WATER PUMP.

yes you do have to knock shims out if you go get it alined they charge you alot more to do that becouse they cant aline the frontend with them in there they are in there in to keep the front end alined from the factory

The thermostat probably just needs to be replaced they are only like five to en dollars.

mark the direction rotor is pointing and then dont turn motor after removal

adjust the rear brakes up manually ,and grind the lip down on the edge of the brake drum so you can adjust brakes right up before you refit the drum

Sounds like you have a bad connection at the light housing. If you have a volt meter check the voltage at the bulb connector when the brakes are applied. You may have a bad wire coming in at the housing. If you do, the connector can be changed.