Hey this stumps me and a very weird sound. I picked up a 87 cutlass supreme,new water pump. new alternator and the powersteering works just fine,plus no belt or pulley movement. I started this car when cold around 30 degrees to 40. I have a strange moan only when cold and no other problems with it including charging when warm 0 sounds or warmed up temps it has me stumped any suggestions seriously?

 

I would take the belts off and run it so as to isolate your accessories and see if it goes away first.

 

i removed the belts and they are new and this is not a belt sound to clear that up. i am really stumped and it was not a acessorie by the way i bought this pretty recently would a low ac system or weeping seal make this sound.

 

Does it have manifolds could it be that valve that goes at the ex. manifold . or some sort of valve that is triggered by heat.

 

hey that is a excellent suggestion i could have a erosion problem due to time on the manifold.

 

If it has an A.I.R. pump it is probably the pump operating in "open loop" until it warms up enough for the Computer Command Control System to go into "Closed Loop" and redirect the flow of air through the A.I.R. pump and pipes. Confirm that you do not have any exhaust leaks anywhere so that carbon monoxide does not enter the passenger compartment.

If the noise goes away just into warm-up and it stops rather abruptly this is probably the source. I would describe the noise as a medium to low tone flutter.

 

X2 on the above if it's not accessory related.

 

hey thank you for the suggestions i almost garauntee that it is that it really makes sense also the exhaust seems solid but it is old.

 

hey by the way could this small exhaust leak cause the air pump to go out in time?

 

Had the same problem moaning sound when cold. talked to GM tech the problem was the heater hose routing. The 3/4" hose needs to be wrapped around the accumalator.
If not it traps air in the heater core and makes a moaning sound. Sounds crazy but that fixed my cutlass G body. G body had this problem alot so the factory routed them this way. If you look Oldsmobiles in late 70's-80's. they were all routed like. And they
were olds powered. Something to do with the Olds cooling system. Hope it helps

 

I too am fighting a groan/moan in a 68 442 with A/C. Its RPM sensitive (above 1800). It only occurs when I switch the heater temp to hot, thus opening the valve. I think I may have finally figured it out. I believe my problem is with the restrictor portion of the heater control valve. The old style is larger in the restrictor area vs. the newer yet both have the same part number. The problem occured when I changed them out 10 years ago but never put 2&2 together. I will put the Snap-On hose pinchers on one of the heater lines tomorrow and see if the noise disappears. I also have picture of the two I will post later if needed.

 

My son's 67 442 had the same problem after the balancer lost the outer ring. We tore the engine down but did not find anything. A few months later we had to replace the heater core and the moan went away. No explanation as to why it started after the balancer spun.

 

Here is the pictures of the two different sized restrictors in the two HCVs. I have. The larger one was installed when the engine was rebuilt in 1985 by the PO. When this one went I purchased two, installed one . They are from 4 seasons PN74601