Have a 1990 Z71 4wd that hasn't been drove very much over the last 12 months. After driving it 4 miles today, I started to hear a loud knocking noise. Thinking its a lifter (?)because it hasn't been drove much. It's a 350 engine and 150K for miles. I would like to fix this myself.
I'd consider some fresh, clean oil & filter change first of all, if it hasn't been done . drive it for a while providing it isn't too bad, & see if it goes away, if not get back to us.
That's a 350 chevy, they never say die ! ha-ha. Mileage is getting up there but I would have oil pressure checked with mechanical gauge & see what you get. If oil pressure is within reasonable specs, I'd pull rocker cover, inspect rocker arms, pivots & pushrods on the noisy side, and replace whats worn if any, then re-install & adjust valves (hydraulic) , replace rocker cover gasket, change oil & filter, and see what happens. It will all depend on oil pressure test. I've had some that all I did was pull rocker cover, adjust the valves that were noisy, put it back together & away they went.
See if you can get a small mirror down in there if need be and shine a flashlight on it to see what exactly is going on there. It has to be a coolant line obviously, but it must slide into the hole with an "O" ring on it, or a bracket holding it in with bolts I would expect. I'll dig a little & see what I can find out.
I'm trying to visualize but my old brain is just about done for the night. Been putting some long hours in at work, as this is busiest time of year for us. Obviously it will need to be replaced, and my guess is that it may very well be a dealer only item. A trip to the dealer, with a picture if you can, may help give you an idea of how it was attached, and what the cost of replacement will be. See how you make out. I'll check back tomorrow night.
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Hi:
A loud engine knock or a clattering at the valve cover? The best way to verify a knock(as in rod knocl) is to drain the oil and check for dull silvery or copper particles. drain to drain the oil into a clean drain pan. Lifters sound more of a clicking or clattering.. If you have a gauge and not an oil light, note your oil pressure. A bad rod does not noticebly affect oil pressureA bad main brg has little effect on oil pressire. Again, note your oil pressure.. Let me know, but do not rev up the engine or you can put a rod through the block. We can go from there if you still want to fix it yourself..-
The water fitting is no big thing. It should be removable and replaceable with a new onefrom the parts store.Now the clattering. These should be hydraulic lifters. If you found an unsually loose rocker you peobably have a collapsed lifter. Tightening it dow won't resolce the problem. A hydrauliclifter is like an oil cushion the adjust itself to the proper stroke travel of the push rod. A motor that is run rarely allows a lifter under pressure to bleed down making it necessary for it to pump itself back up. The lifter is surrounded by oil and the oil pressure assisrs by more or less mainting pressure forcoong oil into the lifter. The lifter has holes in the side to accomodate the in and out of oil. Engines that sit tend to sludge up and moisture turns into little bubbles that are carried with the oil. Lifters don't like this. Draing the oil, replacing the filter and letting the engine run at operating tempature will help vaporize any moisture in the engine. Short runs are not good because they cause condensation. Use a multi viscosity oil, Like 10w 30. quaker state. high detergent. Again, , it would be wise to lighten up on that rocker you tightened.. go by the other rockers setting the adjustment so the stud is the same or near another rocker of the same. Exhaust/exhaust intake/ intake That will give you a safe starting point. Good Luc.
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After changing intake gaskets on a 99 Chevy Express Van 5.7, I have experienced the supports inside the valve cover ( the type that has bolts down through ) coming out of adjustment after fighting to remove the cover from all the hoses and wires that sounds kinda like a knock type noise/sound. It drove me crazy until I removed the cover and noticed the rocker rubbing inside. Once I straitened the support and reinstalled it the noise was gone.
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co7196 and motor1258,
Gave her a good once over.
Took the chance and drove her 3 miles round trip since she hasnt been drove very much. When I got home, I left her run, popped the hood and felt the valve cover. I would describe the noise as chattering, not knocking, and I could feel a slight vibration in the front of the right valve cover. Wasn't as noticable in the back, and the left had none. I shut the vehicle off and crawled underneath. What an oily mess!!!! But I think the oily mess is another problem entirely. The mileage on the engine is almost 200k exactly and its never been rebuilt.
So I took the valve covers off and adjusted the valves on both sides. Drivers side was easy, passenger side I ran into a problem. While taking it off I bumped into a coolant line on the rear of the engine right about the valve cover that goes from the fire wall to the top of the engine block. I broke the piece that goes into the block clean off! Coolant was pooring out, so thats how I know it had to do with the cooling system. The piece that broke off is cast so that leads me to believe its part of the block, but that's just a guess. Any ideas on how to fix this?
It's on top of the block and to the right of an engine "hook" or "mount". There are 2 bolts but they look like they connect the "hook" to the engine. It's also rightin front of and to the left of the distributor.
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