I haven't started my SBC in my 51 for a couple of months. I took it down to add an electric fan, got distracted with work and life, had a few setbacks with the install, but finally got around to getting it fired back up tonight. During this time, I also replaced a leaky water neck gasket and my persistant leaky ****** puked quite a bit of fluid. I replaced the lost fluid, have decent oil pressure, and checked everything out pretty good. Engine fired real quick and aside burning a little of the ****** fluid off the exhaust pipe and stinking up the garage, it idled down fine and the fan came on and cooled as designed. After running it for about 20 minutes the motor started to make a persistant whine kind of like one of those hand held compressed air horns or a tea kettle. I checked the ****** fluid and was good, engine oil looks good, seem to have good flow in the radiator. Whine seems to back off a little with acceleration then promtly returns when I let off the gas. I let the car cool for about 30 minutes and tried it again, same scenario after about ten minutes it returned. The car originally had a fan on the water pump that is now removed in lieu of the electric pusher fan. Other than that, not much has changed. Any one have an idea what might be going on? I have several theories but can't seem to prove/disprove them. Thanks in advance...
Fan pulley bolts rubbing the main casting? Water pump bearing going out, and now it rides 1% differently without the pulling load of the fan blade? Transmission pump going out?
A couple of things I have seen in the past are.... A leak between the warped carb base and gasket,allowing a screaming squeal of a vacuum leak. Also on some engines[ that are not adequately vented]- the cranckcase pressures are released or alsothe same [as suction] causes the squeal of air escaping or entering the engine thru a tight opening such as the gasket on an oil breather /cap or twist on oil fill cap/plug.....
yeah, that's a good way to find the problem. We gotta throw out a few random suggestions of what to take apart first, though, it's proper internet troubleshooting etiquette
Shifty - One of my theories, what can I do to diagnose or is it trial and error with a new waterpump? Squirrel/Choprods - If it was a vacuum leak, wouldn't it be there from the start? Why after the engine warms up? Thomas - Good idea, I will try that for sure.
It's impossible for us to know just exactly how everything is on your engine, the best we can do is offer some different possibilities, and maybe even some ways to point you to which is most likely. Wierd noises behave in strange ways, so it's best not to make any ***umptions about how they should do it all the time instead of just when warmed up, etc. Get some heater or garden hose and CAREFULLY listen around. Take your time, it's easy to be misled, sounds bounce around in strange and mysterious ways, and even normal engines sound wierd thru a hose.
come to think of it...i remember being at a racetrack and hearing a loud whistle..it was a carb gasket like squirrel suggested. The thing about the hose is at least you can locate the general area to start troubleshooting
maybe you alternator or belt slipping from the added load of the electric fan running? those thing draw a lot of juice....
First thing I'd do is warm it up till the noise starts, as quick as you can loosen, remove, or cut your belts if they are due for replacement anyway. This is a quick easy way to eliminate the alternater, water pump, power steering pump and any other belt driven accesories. My first guess without hearing it myself would be mabye the bearings in the alternator. That's happened to me before. Good Luck
Thank you everyone... I have traded the cursing and puzzled looks for a hot shower and some almonds. Very good suggestions, I will look at it and let you all know what I find out. Got to find it though the car has got a date with Thomas and Tim up at Bodylines next week and I'll be damned if it's not going to make it....
Just went through this and like these guys said, check the carb/gasket for a vac leak... I didnt belive it but thats what it was for me anyway.
I'll check that first, but I'm still curious from a diagnostic standpoint why it would wait until the engine warmed to make the noise. Wouldn't it howl from the start? On the other hand, why ask why if it eliminates the problem.
Warm it up,run it through the gears,and check the ****** fluid level. Just a wag,but my Ford and my Mopar ******s will both whine and buzz from the valve body,(I am guessing),when they are a little low on fluid,as they both leak when sitting for a while.
Don't know if the car has a standard GM alt or p/s pump on it, but could be either of those. If it does it as soon as you start it, you could take the belt off and run it for a minute to see if the sound is still there. Would rule out any accessories making that noise.
For those of you keeping score.... Bad vacuum advance. Cheers to Von Wrench for diagnosing in it like 20 seconds. Thanks for all the ideas on the possible culprits...
The Jalopy Journal
