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Discussion Starter #1
When engine has been off for a few days, it makes a slight knocking noise for about 15 to 30 seconds until getting warmed up (summer now). Someone mentioned it's maybe a fuel pump noise, lifter noise, but not a rod. Should I add something to my 5 W 30 oil to correct this. It's only done this since the hotter summer months are here and noticed it after car has been not driven. Thanks, Nick
PS=Happy Memorial Day to all.
 

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A better choice (for many reasons) would be 10W40 diesel truck oil. For one thing, it's better for your cam.

And the guy I know who used to run Volvo's engine plant in Hagerstown, MD, says the best of that lot is Mobil Delvac 1300.
 

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Discussion Starter #4
Thanks, does this sound like a mechanical fuel pump noise (realizing U did not hear it), but was initially concerned it was a rod knocking. If so, I suppose it would be continuous not just for 30 seconds. Other than that, lifter or cam, right? Oil change to suggested Mobil Delvan might solve this. N
 

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we in the field call it death rattle.its one of two things .either its piston clearance but that usually lasts a few minutes until the piston warms up and expands into the bore or the more likely cause is worn rod bearings making noise until oil gets to them. i in 40 yrs working on cars and trucks have seen maybe a dozen fuel pumps make noise and the ones that did made it all of the time. try a bottle of lucas oil treatment ,if it quiets it down then its the rod bearings and will only get worse
 

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OMG People ! You know,what i don't understand is,when some one has a engine noise,you guys tell them to add 20 /50 or some heavy weight oil,fist that does not Fix the concern it ,might cover it up,just my 2 cents,also i see no mention of engine size if it was a LT1 or a late model engine you would say through in some 50 weight , better not, if its a old school Chevy / than maybe ok . come on guys,we can give better advice than that ...:texas:
 

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I would like to hear it. The classic tap on startup is a leaking or sticky lifter, if it goes away when it gets warm. If it's really loud on startup, gets a little little lighter when warmed up, but never goes away, that's more likely a rod bearing or piston wrist pin. Chevys aren't very prone to the "rattle of death" that has plagued the Ford 4.6 L engines; that's piston skirt collapse.

If it's a lifter, heavier oil (and a few changes to be sure it's really clean) can help a lot.
 

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OMG People ! You know,what i don't understand is,when some one has a engine noise,you guys tell them to add 20 /50 or some heavy weight oil,fist that does not Fix the concern it ,might cover it up,just my 2 cents,also i see no mention of engine size if it was a LT1 or a late model engine you would say through in some 50 weight , better not, if its a old school Chevy / than maybe ok . come on guys,we can give better advice than that ...:texas:
OK, just rip the motor out first, rebuild it, to make sure you fix it right, when all you have is a daily driver, that can run perfectly for another 50,000 miles by just using a heavier, more protective, oil. It's a hell of lot cheaper to just put in heavier oil and drive it normally. The damage is already done. That's why it rattles on start-up.


When engine has been off for a few days, it makes a slight knocking noise for about 15 to 30 seconds until getting warmed up
 

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As an engine goes over 100,000 Miles the Bearings and Rings are all out going of Spec. Heavy oil, and letting it run twice the mileage between changes will help build up varnishes that will actually help close up the gap...
About now everyone is ready to have a stroke...But a Clean High Mileage engine will rattle like a bucket of chains...Burn oil, and loose power.
Just retired a car with 250,000 miles...the 3800 V6 was perfect...Transmission gave up the ghost. Third time I have pulled this kind of mileage, before that were 2 Jeep Grands with over $250K on the V8's
The older they get, the dirtier the need to be...Hate me all you want on this one...But it works!
Had an uncle that was a chemest with Chrysler back in the day teach me that one...
 

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Discussion Starter #11
This an 86 305 with auto/od transmission; has 95,000 Miles and just started this noise since summer heat. Noise is not "deep' or heavy in sound, but just sounded serious enough to want some advice. Have only owned for 3,000 miles, changed oil to 5W30 Valvoline, new plugs, air filter, thermostat, hoses, exhaust pipe, muffler, so nothing really major repairs. Not been hot rodded that I know of and with noise going away in a matter of seconds, some say not to worry. If I knew it was ONLY a mechanical fuel pump rattle, why would it go away so soon? I'm kinda thinking it's a bearing, but not really ready to do a tear down if that's what it's really going to take. What kind of diagnositic can be performed to really pinpoint? Thanks to all for you answers. Nick
 

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fixitman it was to be used as a tool not a repair or bandaid.it will tell him where he needs to focus his attension and decide its repair urgency. i dont advacate bandaids just proper repair.
 

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never run that thin an oil in a old engine.10/30 is more like what should be in it.5/30 and 0/30 is for the newer cars designed to run it not our older cars
 

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This an 86 305 with auto/od transmission; has 95,000 Miles and just started this noise since summer heat. Noise is not "deep' or heavy in sound, but just sounded serious enough to want some advice. Have only owned for 3,000 miles, changed oil to 5W30 Valvoline, new plugs, air filter, thermostat, hoses, exhaust pipe, muffler, so nothing really major repairs. Not been hot rodded that I know of and with noise going away in a matter of seconds, some say not to worry. If I knew it was ONLY a mechanical fuel pump rattle, why would it go away so soon? I'm kinda thinking it's a bearing, but not really ready to do a tear down if that's what it's really going to take. What kind of diagnositic can be performed to really pinpoint? Thanks to all for you answers. Nick
Again, what you have to do is just run heavier oil, at least through the summer months. The start-up noise/rattle will most probably disappear with the addition of heavier oil. There is no downside to running 20W50. It's not going to hurt anything, and on the other hand, will most probably eliminate your minor problem and concerns.
 

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Discussion Starter #15
Thanks, this may be the real reason for noise of any kind, so I will do the oil change now to the heavier 20W/30 for at least the summer. If this thinner 5W30 is it, must be diagnosed as a rod? Appreciate the help and this noise developed since the change of oil weight as well as higher 80 plus ambient temps. Should go away when changed. Any better brand oil as a suggestion? Go on suggestion Exxon Mobil Delvan 1300. Nick
 

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Thanks, this may be the real reason for noise of any kind, so I will do the oil change now to the heavier 20W/30 for at least the summer. If this thinner 5W30 is it, must be diagnosed as a rod? Appreciate the help and this noise developed since the change of oil weight as well as higher 80 plus ambient temps. Should go away when changed. Any better brand oil as a suggestion? Go on suggestion Exxon Mobil Delvan 1300. Nick
If it quiets down, which I would expect, it only means you have increased bearing clearances caused by wear. It's no big deal. As far as what oil to use, I know this guy who has some kind of big-block (427, 454???) in his pristine 53 shortbed chevy pickup. His oil pump went out and I found out he uses Royal Purple that costs him about $13 a qt. He's nuts, and I told him so. He doesn't race it. He just goes to cruises. I told him he was wasting his money. As a former Advance Auto parts generic oil user, I switched to Walmart oil, because it's cheaper. $12=5qts. Oil is oil. Of course, I change oil about every 1500 miles. Works for me!
 

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Crank the engine for a few seconds or until the oil light goes out then set the choke and start. Oil is draining off the mains and you're hearing them rattle until pressure builds. I concur on the 5w-30 it's too light and is probably draining off quicker than what you previously used.

I have a Chrysler NY with a 440 that has 20,000 miles on it and it will rattle a bit if it lights off right away. not good for the engine but it doesn't mean you have a problem. Worry when you hear the same rattle when the car is fully warmed up!

ErnieR
 
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