Just bought a 66 GMC for my son. Truck runs pretty good, but has a leak at what I think is called the water pump bypass hose. It is a short rubber hose only about 3" long that goes from the top of the water pump to the intake manifold, right in the front of the engine.
It looks like you may have to pull the intake manifold off to change it. Anyone know if you could potentially change it without doing that, and also what the size of this hose is? Looks like about 1.25" or 1.5" in diameter.
Final question--to adjust the valves, from what I have read you adjust the valves "engine hot while running". Would one have the motor running, loosen the valve lash adjuster (I assume a lock nut with a slotted screwdriver threaded adjuster), put the right size feeler gauge in and tighten down until you hit the gauge. Sound about right? I can't quite comprehend doing this with the engine runnning, I would think you would do engine hot, then turn it off, then rotate by hand one cyl at a time by rotating until there was no pressure from the valve springs and setting to the gauge then...
Last edited by R-Bo; 09/02/201010:01 PM.
R-Bo
1959 Apache 1/2 ton Big Window, Short bed Fleetside (under reconstruction) 1966 GMC 305V6 in the family
I have the 305 V-6 also and YES will will need to remove the water bridge to replace the hose. The hose size is standard and most FLAPS have it. You can make the gaskets from the off the shelf material. (Trace copies).
On the valve adjustment, Do you have the factory setting or do you need them? I adjusted mine first cold, then warmed her up and rechecked them. All you need is a GOOD closed end wrench, THEY will be hard to turn, use at least an 10-12" GOOD quality wrench, NOT "Harbor Freight quality stuff".
Do you have a shop manual? IF not I can copy the needed pages for tune up, but the book will also tell you all sorts of needed stiff.
Here is one on ebay. THIS IS CHEAP TOO, I had to pay 50.00 when I found mine. The years differance will not be any problems for the engine just the body style.
