440 whines at idle

I have a 1973 motorhome 440 with low miles. I opened it up and checked all clearances and all was well within specs.

At idle, it has a whine like a turbine or blower like sound. As soon as its off idle (700 rpm) it goes away. I removed all the belts to confirm its not alternator, water pump or power steering pump.

Anyone have this experience and what was causing it?

Thanks in advance, Mike

You have your idle set at 700RPM , raise it to 800 and see if it goes away ?

It might be the transmission ?

pcv valve noise?

JohnRR thats exactly what I did, set it to 800 and dont really hear it anymore. Transmission could def be a possibility, its an unknown unit I bought many years ago. It does operate and shift normally from idle on upwards. How to test if its the noise?

PCV is new, but I can def look at that. I can try another one.

Good suggestions so far, thanks, keep them coming.

Mike

It sounds like it could be the front pump in the transmission. Cant think of an engine noise that sounds like a whine- unless you put a gear drive or blower on your motorhome.

It sounds like a pump whine, and I was convinced it was power steering pump until I disconnected it.

If it is the front pump, how long before the trans needs to be pulled?

I do have a second 727 trans but has short tail stock. I should be able to swap that out for the long tail stock?

Mike

Does the whine go away when you drop in in gear?

Curb idle at 800 you barely hear the whine, when in gear and rpm drops to 700 you can hear the whine. As you drive away and rpm increases the whine goes away very quickly, I would say by 900 you can't hear it at all.

While it is whining slowly push the throttle linkage back for the trans - not the engine throttle.
If the noise goes away it’s likely the regulator valve in the valve body, assuming the trans filter is ok and the fluid level is correctly set in neutral and not Park.

Transman great suggestion i would never thought of that. However it made no difference in park or neutral and part pressure slowly to full pressure while idling at 700 rpm. Transbhas new oil and filter and proper level hot in neutral.
So it looks like front pump could be problem?. What about torque convertor could it make a whine at idle and go away as idle increases? Remember the whine happens in gear too.

There is no throttle pressure in Park and Neutral, try cycling the linkage with the shifter in Drive.

John i did as you suggested still no difference at any pressure while in drive idling at 700 rpm.

Don't go crazy trying to figure it out until you check one thing. My 73 Winnebego with 440 had a gear drive cam. It would whine at idle but would also whine a little when revved up.

Mrbill69 thanks for your suggestion. I took this motor apart and it has the chain drive.

Does anyone think the distributor could make a noise like this?

Mike

Look for a blower up top...

If the whine was consistent id know the current location of my ex wife.

Sure its not some sort of vac leak sounding like a whine?

Sunroofcuda, it would be awesome if it did have a blower on top lol.

EV2Bird, I can double check for vacuum leak, but it runs very well and have no reason to suspect a leak.

I keep thinking the Distributor, as the sound is at the front of the motor. I don't have a second one to swap out, and tried a little wd40 on upper bushing area, no change. I will take it out and see if there is anything I can do to lubricate it to see if its the cause of the whine.

Appears to be coming from the carb. New Eddy 800 with spacer, new gaskets and bolts are tight. As you shut it down the whine goes down in pitch, so its more like a whistle is what we are hearing.

Thoughts?

Spray Wd40 or similar around the carb and or intake to head area and see if it changes/goes away

Spray some starting fluid around the carb while it idles. You have a vacuum leak of some kind. Idle will increase when the ether is sucked in.

Do you have PCV on one valve cover and a breather on the other? If not, add a breather to the other valve cover. I had a 360 do that one time and the issue was excess crankcase pressure trying to escape. Added a breather and it solved the mystery.

Yes i have pcv on one valve cover and breather on the other. Did the wd40 and no change, i changed the gaskets between spacer and manifold and spacer to carb. No change either....its def motor speed related.