knocking noise on cold start-up 99 4cyl.

[shockley]

I have a 99 s10 w/76,000 miles on it ,when you first start it up it is pretty noisey for a couple of minutes.Is this anything to worry about?What can i do to help it?

[sector95]

Originally Posted by shockley

I have a 99 s10 w/76,000 miles on it ,when you first start it up it is pretty noisey for a couple of minutes.Is this anything to worry about?What can i do to help it?

A little more info needed here.... what does the noise sound like? Is it a light clattering or tcking sound or a dull metallic knocking sound.

How long does it last... just a few seconds or is it longer in duration?

It could be something as simple as your valve lifters or a deeper problem with rod bearings.

There is also a knocking caused by piston slap.... typically noticeable on the first cold start of the day and will last for up to a few minutes as the piston(s) warm up and expand. Some GM V-8's have this problem that the factory is want to call "normal"...don't know about the 4 cyl engines...


Mike

[shockley]

It is a light chatter (like a lifter)i just did not think with only 76,000 it would be normal.

[sector95]

Originally Posted by shockley

It is a light chatter (like a lifter)i just did not think with only 76,000 it would be normal.

A couple of ideas:

Oil: What viscosity of oil are you using? Most modern engines require 5w30 under most conditions. If you're of the old school you probably think the "watery" 5w30 isn't the way to go and substitute 10w30 or something higher; don't. The 5w30 is specified because the oil will flow and build pressure quickly, especially on cold starts, reaching the extreme locations (like the valve train and upper cylinder head) of the engine much faster than a heavier weight oil. The oil pumps are supposedly built to tighter tolerances so they can provide adequate oil pressure with the lighter viscosity oil.

Filter: Oil filters have what's called an anti-drain back valve that's built into the filter. What it does is to prevent the oil trapped in the block oil galleys from leaking down back into the crankcase. Some filters have good valves, others not so good. If you're using an 'off brand" or "no-name" brand (like you get at Jiffy Lube, et.al.) or if you're using a Fram filter (which is a big name but very cheaply made these days), consider using another brand of filter. Good filters are AC/Delco, NAPA Gold/WIX and Purolator "PurOne" filters. These all have good anti-drain back valves in addition to being well-made filters. There's a web site run by a fellow who did a lot of research into the various filters.... even opened them up so you can see what's inside.

Partially blocked oil pickup screen: I don't know how you drive or maintain your truck but if there's a lot of sludge that's built up in the crankcase this could be a possibility. Also, if you've fallen for using "Slick 50" in your engine it has been supposedly the cause of clogged pickup screens. Next time you change you oil try using a crankcase flush to loosen the crude and when you refill the oil use a quart of Marvel Mystery Oil. I've used this stuff to clean the sludge out of my old '67 Pontiac and help clean up some noisy lifters. Run the oil for less than your normal change interval, drain and if you think it needs another shot, do the same thing again.

I'm not an expert or professional mechanic, just a hobbiest who likes to work on older cars and trucks. These are some things I'd try if it were my truck.....


Mike

[BlazerLT]

^^^ Good Advice.

Lemme guess, you are using a Fram filter right?