Need Engine Advice....Again - The 1947 - Present Chevrolet & GMC Truck Message Board Network

WarpathEngineering · 10-07-2017, 05:03 PM

So I'm getting ready to put my K20 into hibernation and am trying to come up with a game plan for winter engine repairs.

I had already planned on replacing the front and rear main seals (leaking) and with them, the oil pump, water pump, timing chain & various gaskets. Then, when I was out driving it the other day, I came off the interstate and one (or more) of my lifters started to really tick. Since I've had the truck it's had a cold start knock & lifter tick until the oil pumps up (reason for the oil pump) and then it goes right away. Haven't thought too much about the knock until now because it only knocks on start up.

So question #1 is what is this knock and how do I correct it?

Since the lifter/s are ticking, lifters & push rods are on the list. I guess now would be a good time to think about replacing the cam.

Question # 2 any suggestions on a mild driver cam for an original 78 350 with 40K miles?

Questions #3 is this just a waste of time because I need an engine?

Dead Parrot · 10-07-2017, 08:04 PM

My first thought is you are low on oil, causing the sudden lifter clatter.

I would do a good compression check before proceeding with any engine repairs. A 40K motor should have near new numbers, assuming no past abuse.

Pull all the belts off and do a cold start. See if the noises are still there. A PS pump knock can sound a lot like an engine knock. A small exhaust leak can sound like a lifter tick. Getting rid of the fan and other accessory noises makes other noises easier to find. Just don't run it more then a few minutes since you won't have any coolant movement.

70K10Hunter · 10-07-2017, 09:56 PM

What is your oil pressure? I believe that truck should have an oil pressure gauge. if not hook up a mechanical gauge and check it, 40yr old lifters (meh) have you ever checked the rockers for proper adjustment? what oil are you using?
If you are going to pull the pan to replace the main seal you might as well check the rod and main bearings. You can do that without hurting anything just do them one at a time and retorque them as you go.

10-07-2017, 08:04 PM	#2
Dead Parrot Registered User Join Date: Aug 2012 Location: Oklahoma City, OK Posts: 2,521	Re: Need Engine Advice....Again My first thought is you are low on oil, causing the sudden lifter clatter. I would do a good compression check before proceeding with any engine repairs. A 40K motor should have near new numbers, assuming no past abuse. Pull all the belts off and do a cold start. See if the noises are still there. A PS pump knock can sound a lot like an engine knock. A small exhaust leak can sound like a lifter tick. Getting rid of the fan and other accessory noises makes other noises easier to find. Just don't run it more then a few minutes since you won't have any coolant movement.

10-07-2017, 05:03 PM	#1
WarpathEngineering Registered User Join Date: May 2007 Location: Erlanger, KY Posts: 99	Need Engine Advice....Again So I'm getting ready to put my K20 into hibernation and am trying to come up with a game plan for winter engine repairs. I had already planned on replacing the front and rear main seals (leaking) and with them, the oil pump, water pump, timing chain & various gaskets. Then, when I was out driving it the other day, I came off the interstate and one (or more) of my lifters started to really tick. Since I've had the truck it's had a cold start knock & lifter tick until the oil pumps up (reason for the oil pump) and then it goes right away. Haven't thought too much about the knock until now because it only knocks on start up. So question #1 is what is this knock and how do I correct it? Since the lifter/s are ticking, lifters & push rods are on the list. I guess now would be a good time to think about replacing the cam. Question # 2 any suggestions on a mild driver cam for an original 78 350 with 40K miles? Questions #3 is this just a waste of time because I need an engine? __________________ 1980 GMC Sierra Grande C15 1987-1992 1988 Chevy Silverado K1500 1992-1996 1978 Chevy K5 Blazer 1998-2002 1998 GMC Sierra SL K2500 2002-2010 2007 GMC Sierra Classic 2500HD LBZ 2010-Present 1978 Chevy Silverado K20 2016-Present

10-07-2017, 09:56 PM	#3
70K10Hunter Registered User Join Date: Jun 2012 Location: Hill Country Posts: 435	Re: Need Engine Advice....Again What is your oil pressure? I believe that truck should have an oil pressure gauge. if not hook up a mechanical gauge and check it, 40yr old lifters (meh) have you ever checked the rockers for proper adjustment? what oil are you using? If you are going to pull the pan to replace the main seal you might as well check the rod and main bearings. You can do that without hurting anything just do them one at a time and retorque them as you go.



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