Knocking after radiator flush
November 1st, 2018, 05:18 AM
#1
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Knocking after radiator flush
Hello everyone, my wife and I just purchased a 1964 dynamic 88 a couple days ago. The motor runs fine and purred like a kitten when we bought it, and drove it an hour and a half back home the day we got it. The car was low on antifreeze before we drove it home so we filled it up and drove home, we took a couple pit stops and no problems. When we got home the drain hose from the radiator was spitting steam so we let it cool. I figured it was the thermostat, so I flushed the system and removed the the thermostat. Now there is a knock? I don’t know from where, but it sounds like the front of the motor. The knocking sound gets faster with rpm. Can air pockets cause knocking? Can someone point me in a direction to start. I’m not a mechanic by trade, but I do enjoy working on cars.
November 1st, 2018, 11:19 AM
#4
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I’ll try that. I put a half tank of the highest octane chevron had, but I wasn’t knocking until I did the flush. I’m going to try and flush it again and make sure I don’t have any air in the system. There was a lot of foam in the radiator, I’m assuming from the flush solution.
November 1st, 2018, 11:31 AM
#5
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If the noise increases with RPM I would be sure to check fan/water pump/pulleys?
While no one else has offered an opinion, I will go out on a limb and speculate that an "air pocket" in the cooling system should not produce an engine knock.
While no one else has offered an opinion, I will go out on a limb and speculate that an "air pocket" in the cooling system should not produce an engine knock.
November 1st, 2018, 11:59 AM
#6
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As Dave stated above, an air pocket will not cause a knock. Generally you would see wide instantaneous swings in temps from normal to way over boiling. Air pockets create steam and the sensor goes from being in a pocket with steam to then being covered in coolant.
November 1st, 2018, 03:10 PM
#8
Oldsdruid
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Before you start throwing tools...
There's a notch on the harmonic balancer. You will need to index this notch to access the water pump bolt on the bottom of the pump. You will also need a THIN WALL DEEP SOCKET to get in there.
Take the fan belt off and spin the w/p by hand and see if you feel any roughness. These are a 2-year only (1963-64) water pump and may not be easy to find.
Also check the temperature sending unit by grounding both wires and observing dash warning lights. You may nave been overheating and the idjit light didn't warn you.
There's a notch on the harmonic balancer. You will need to index this notch to access the water pump bolt on the bottom of the pump. You will also need a THIN WALL DEEP SOCKET to get in there.
Take the fan belt off and spin the w/p by hand and see if you feel any roughness. These are a 2-year only (1963-64) water pump and may not be easy to find.
Also check the temperature sending unit by grounding both wires and observing dash warning lights. You may nave been overheating and the idjit light didn't warn you.
November 1st, 2018, 03:50 PM
#9
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From your description of overflow spitting steam, car was overheating, not good, means engine got very hot. Check the oil and refill radiator with water, bubbles in the water would indicate bad head gasket. Bad news if the knock increases with RPM.
November 1st, 2018, 04:44 PM
#10
Hookers under Hood
Join Date: Nov 2013
Location: Ontario, Canada
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Hopefully its the water pump, however an internal knock is never good after an overheating condition. I had a bent rod in my 350 several years back, the knock increased with RPM , got very loud at 30MPH driving it across town to my buddies garage. I would pull the plugs out and have a looksie at them.
I will never forget the sound a bent rod makes.
All the best with your findings !
Eric
I will never forget the sound a bent rod makes.
All the best with your findings !
Eric
November 2nd, 2018, 05:21 AM
#11
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Thanks for all the help. The knocking sound went away, after we flushed the coolant 6 times. I don’t know what is was but it’s not there now. I will keep an ear out for it to return. Now I need to track down an oil leak on the drivers side near the oil dip stick. Thanks again.
November 5th, 2018, 03:32 PM
#16
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Oil out of dipstick doesn't sound good, water pump issue would be unusual, seems like pump would lock up before a vane would break completely loose. Do you feel a vacuum at pvc with engine running? Engine running okay?
November 5th, 2018, 04:14 PM
#17
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You have blowby if oil is coming out the dipstick. Check the pcv and on the opposite side run a hose from the VC to the air filter housing this will help relieve pressure under low vacuum situations.
November 6th, 2018, 01:32 PM
#18
Oldsdruid
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Which PCV system does the car have? There are two: open system which has a weird flapper valve on passenger valve cover and a hose from that to the aircleaner snout, with the standard big oil fill cap, or a closed system which was required in California and often retrofitted to 49-state cars. That one has a PCV valve in passenger valve cover with hose running from it to back side of the carb throttle plate. It uses the 65-67 "top hat" style oil filler cap and has a fresh air hose from aircleaner to driver side valve cover.
Servicing the closed system is as simple as installing a new PCV valve and washing the breather filter (same as 65-90 Olds V8s). To service the open system remove the flapper valve and wash it in kerosene or parts washer solvent till the flap moves freely. If the fill cap still has its foam filter, wash in kerosene, reoil with engine oil and squeeze out the excess. If it's gone any piece of foam rubber can be cut to fit it and installed as above.
But be warned blowby is a common condition on 394's.
Servicing the closed system is as simple as installing a new PCV valve and washing the breather filter (same as 65-90 Olds V8s). To service the open system remove the flapper valve and wash it in kerosene or parts washer solvent till the flap moves freely. If the fill cap still has its foam filter, wash in kerosene, reoil with engine oil and squeeze out the excess. If it's gone any piece of foam rubber can be cut to fit it and installed as above.
But be warned blowby is a common condition on 394's.
November 6th, 2018, 08:03 PM
#21
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The car runs fine, no smoke out the tail pipe. I’m not sure we’re the oil is coming from. I cannot replicate the problem in the driveway, so I plugged the dipstick tube and no leak. The PCV system is the one with the vacuum line from the carb. I removed the PCV from the valve cover and covered the hole with my hand and there is a build up of crankcase pressure, but when I do the same to the “snorkel” to the air filter cover I don’t feel it. I don’t know how the car was taken care of before me, but the motor sounds great and runs strong.
November 7th, 2018, 10:19 AM
#22
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The 1965 early Cutlass 442 did not have PVC, late in production year they changed from the four barrel four jet to Q-jet and PVC. Most manuals do not show the change until 1966.
November 7th, 2018, 11:37 AM
#23
Old(s) Fart
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From the 1964 CSM:
November 12th, 2018, 10:14 AM
#25
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