AMC 360 valve noise

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Grand_Wag_85
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AMC 360 valve noise

Post by Grand_Wag_85 »

I have an 88 GW that I woke up after a very long time in storage. Drove it 600 miles home and it made it but after the first few hundred miles started to get some valve noises. After I got it home it got parked and hasn’t run in more or less a year.

Fired it up yesterday and the valve noise is VERY noticeable. Runs healthy otherwise. What should I check? Could the pushrods be clogged? Has plenty of oil and always has. One of the first things I did was an oil change.
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88 GW

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Dr.Bob
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Re: AMC 360 valve noise

Post by Dr.Bob »

Valve-noise is from excess clearance.

Hydraulic lifters ordinary take up any extra clearance; you get that noise when the clearances exceed the lifter's ability to take up the slack.

There are any number of possible wear-points that can increase that clearance:

* Worn cam lobes (likely)
* Worn lifter faces (likely)
* Worn pushrod ends (unlikely)
* Worn Rocker-arm at tip and trunnion-pivot (most certainly)
* Work Rocker pivot (possible, but the rocker arm wears quicker)
* Worn valvestem (unlikely)

I'm guessing the engine is in the 150,000 mile range, give or take a few dozen thousand miles; that's about the time these things have worn to the point of causing the noise you hear.

You can start by checking the rocker-arms for wear; replacing them if they're worn might take up enough slack to put the clearances back within the range that the lifters can automatically adjust to.

If not, a cam and lifter change is likely in your future. Just note that if the cam is worn, the cam bearings are likely worn, so you might be heading toward an engine rebuild, for if the cam-bearings are worn, so too might be the rod and main bearings. And if you're pulling the motor apart to do those, you may as well do pistons and rings, and freshen up the valve-seats, and boom, you've got a rebuilt engine.
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tgreese
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Re: AMC 360 valve noise

Post by tgreese »

Exhaust leaks can be mistaken for a valve tick.

Dr. Bob skips over the lifters themselves. Sometimes they gum up - which intuitively seems likely if the engine sat for a long time. The lifters are supposed to be pumped up by the oil pressure - taking up the slack - then the oil leaks out slower than the speed of the valve action. I believe they also simply wear out and then leak down too fast.

Just my experience - engines that sit a long time without running develop valve ticks. I don't have a big sample, but I've seen a few examples of this. Before you take things apart, you might try an oil additive with a lot of detergent. Automatic transmission fluid is sometimes suggested. Maybe Marvel Mystery Oil? Motor oil made for diesel engines also has a lot of detergent.
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rocklaurence
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Re: AMC 360 valve noise

Post by rocklaurence »

Id run some engine flush though it until hot. Then add Diesel oil in the 40W with a bottle of zinc additive. The additive is required for Flat Tappet lifters because they dont add the zinc anymore to oil due to roller lifters. Did you add zinc on the first oil change? Does it sound like more than one lifter?
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carnuck
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Re: AMC 360 valve noise

Post by carnuck »

Make absolutely sure the oil filter isn’t Orange because “Orange filter bad, M’Kay?”
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