AMC 360 ate cylinder 1 exhaust lifter... twice! - JeepForum.com
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post #1 of 33 Old 10-10-2021, 10:34 PM Thread Starter
Aaroneous
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AMC 360 ate cylinder 1 exhaust lifter... twice!

I'm hoping someone in the group has some experience solving this issue. I purchased a 360 from a friend and fellow Jeep enthusiast with the plan of having it rebuilt to start fresh in my CJ. I took it to a reputable engine builder in Denver and paid $2800 for a full long block rebuild. Got it back about a year ago and have many (many) hours into installing accessories, cleaning, painting, dressing, installing, wiring, breaking-in, etc.

I ran through the initial break-in (20min @ 2k rpm, 10 min fluctuating between 1k and 2500 rpm), changed the oil/filter and took it around the block. The engine made 100lbs of oil pressure per the gauge. Less than a mile in, I developed a pretty noticeable tick that almost immediately turned into a violent pop through the throttle body. I stopped and towed it home. Cylinder 1 exhaust rocker wasn't moving at all when running and rod was spongey when pressed on.


I reached out to the previous owner to let him know what was going on, and he immediately sent me video of the same rocker failed in the same way and a picture of the same cylinder/valve lifter that had failed when the cam wore a hole through the friction surface.




I pulled the rod and it was straight, so I removed the intake and the lifter in question. Sure enough, it was completely ground through. Unlike the first failure, it was ground through in a straight line, so it wasn't spinning at all. The intake lifter for the same cylinder was perfectly fine. The cam shows heat markers, but I can't tell if it has been damaged.




This is all within an hour of runtime. I can't help but think that there must be an oil passage plugged that is keeping that cam lobe / lifter from getting oil. I'm working with the engine builder to figure out how to warranty this, but I wanted to see if anyone had experienced this and come up with a solution. Needless to say, the idea of taking this all apart immediately after finishing it makes me nauseous... but I don't know if there's a way around it.

Can anyone think of anything that can be done in place to learn more about what the root cause might be? Thanks in advance!

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CJ7, AMC 360 Howell TBI, T-18a, d300, D44 front and rear, Stock YJ rear springs all around SOA and outboarded, BFG 33x12.50s, Warn XD9000i
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post #2 of 33 Old 10-10-2021, 10:49 PM
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post #3 of 33 Old 10-11-2021, 05:22 AM
Matt1981CJ7
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Did the rocker arm for that lifter show any evidence of oil coming up thru the pushrod? There should be a small pool of oil in the rocker arm, if it’s oiling correctly.

Also, did you check for any burrs or obstructions in the lifter bore that would prevent the lifter from spinning?

Is the valve stuck closed?

Sorry for your troubles, man.

Matt
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post #4 of 33 Old 10-11-2021, 05:50 AM
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I'd also be very suspect of 100 psi of oil pressure.

The oil pump has a relief valve that is calibrated for a maximum of 75 psi of oil pressure

If your oil pressure is truly 100 psi, there's a blockage somewhere.

Matt


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post #5 of 33 Old 10-11-2021, 08:44 AM
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More history on this engine might help to understand this situation.

Matt hit on some good points. I suspect an oil feed issue like Matt mentions.

Since you hired a shop to do the work, and you seem to be trying to work it out with the shop, the ball is in their court so to speak. I guess you are going to find out how reputable the shop is.

I know some people will prime the oil pump prior to the initial startup on a fresh engine. They will turn the oil pump with a drill until oil pressure is indicated. If you have the valve covers off while you are priming the oil pump, you will see oil coming out of each push rod, lubing the rocker arms. Is this something you did prior to the initial startup?

If that particular lifter has a blocked oil feed passage, the method mentioned above might catch the issue.

It sounds like this particular lifter is a problem child, that’s where more history comes in.

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post #6 of 33 Old 10-11-2021, 08:54 AM
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This image may help to understand how the oil system is suppose to operate on a AMC V8.

Matt
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post #7 of 33 Old 10-11-2021, 09:54 AM Thread Starter
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Quote:
Originally Posted by Matt1981CJ7 View Post
Did the rocker arm for that lifter show any evidence of oil coming up thru the pushrod? There should be a small pool of oil in the rocker arm, if it’s oiling correctly.
The shop that built the engine asked me to drain the tank and fill with fresh 10 gallons of 91 octane w/ 1 cup of ATF mixed in and run for 2 minutes to see if it would un-stick a potentially varnished valve. It did nothing, but I video'd it. The first rocker is, in fact, filling with oil!

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Also, did you check for any burrs or obstructions in the lifter bore that would prevent the lifter from spinning?
This is a good question, I will have to look closely and report back. I did notice that the intake lifter pulled out with no resistance with a small magnet pen, but the exhaust valve (collapsed) needed to be grabbed and pulled lightly once it poked out of the bore.

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Originally Posted by Matt1981CJ7 View Post
Is the valve stuck closed?
Cylinder 1 is showing 145psi and Cylinder 3 150psi of compression, so I'm assuming yes.

Quote:
Originally Posted by Matt1981CJ7 View Post
I'd also be very suspect of 100 psi of oil pressure.

The oil pump has a relief valve that is calibrated for a maximum of 75 psi of oil pressure

If your oil pressure is truly 100 psi, there's a blockage somewhere.
When I re-assembled the oil pump I carefully checked the oil filter housing pressure release plunger bore to make sure the plunger would slide without binding and bottom out. It is a Bulltear unit.

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Originally Posted by Axhammer View Post
I know some people will prime the oil pump prior to the initial startup on a fresh engine. They will turn the oil pump with a drill until oil pressure is indicated. If you have the valve covers off while you are priming the oil pump, you will see oil coming out of each push rod, lubing the rocker arms. Is this something you did prior to the initial startup?.
I packed the oil pump with vaseline and primed the system with a screwdriver until the oil pressure gauge registered significantly. I did not have the valve covers off during that process, so I can't confirm how much oil was pumped up onto the rocker arms. If you see the video above, though, that rocker is getting lubed.

Per the diagram you posted Matt, it seems like that lobe would be the first to get oiled, no? A blockage affecting that lobe would affect all lobes on that bank, getting worse as you move to the rear of the block. Am I interpreting that correctly?

CJ7, AMC 360 Howell TBI, T-18a, d300, D44 front and rear, Stock YJ rear springs all around SOA and outboarded, BFG 33x12.50s, Warn XD9000i
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post #8 of 33 Old 10-11-2021, 11:32 AM
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By the looks of the lifter it wasn't spinning, check the bore. Also there could be a slight misalignment between the lifter and cam. Do not reuse that cam, that exh. lobe is shot. I wouldn't think the valve is the hanging up unless the shop didn't redo the heads. A quick check is to tap the valve with a rubber mallet to see if the valve is moving up and down without hanging up.
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post #9 of 33 Old 10-11-2021, 11:45 AM
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Aaroneous,

I think you are interpreting the diagram correctly. Any oil blockage to the #1 lifters would surely result in blockage further down the line.

So, it appears that lifter is getting oil. The question is, why is it not spinning in the bore, as it should. You may have answered that question, when you observed that it was more difficult to remove than the other lifters.

That still doesn't address the excessively high oil pressure. What type of gauge are you using? The factory gauges are notorious for failing, or being inaccurate.

Matt


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post #10 of 33 Old 10-11-2021, 11:54 AM
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I’m curious as to the history of this engine. At one time this engine ran like it should I would guess.

It has experienced a failed lifter twice according to the thread title.

What has happened to this engine between when it ran correctly, and when the lifter failed?

Why do I own a CJ? I like to “Balance the wrench and the steering wheel”
1985 CJ-7 Sebring Red, White hardtop, 284 CID inline six (4.7) TF 999 auto
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post #11 of 33 Old 10-11-2021, 12:57 PM Thread Starter
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Quote:
Originally Posted by RiverandSand View Post
By the looks of the lifter it wasn't spinning, check the bore. ... A quick check is to tap the valve with a rubber mallet to see if the valve is moving up and down without hanging up.
I will inspect the bore more closely. The angle is really awkward, so I need to get out there with the dental tools tonight. The valve passed the mallet test.

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Originally Posted by Matt1981CJ7 View Post
The question is, why is it not spinning in the bore, as it should. You may have answered that question, when you observed that it was more difficult to remove than the other lifters. ... That still doesn't address the excessively high oil pressure. What type of gauge are you using? The factory gauges are notorious for failing, or being inaccurate.
I will try to oil and insert the intake lifter in the exhaust bore to rule out burs from the grinding on the lifter itself causing the binding on the way out.

I checked with the helper that was reading the gauge (Speedhut) and confirmed that when it read 100lbs it was fluctuating rapidly between 50-100 and then stabilized in the 70lbs range. I'm guessing the fluctuations were actually the plunger moving up and down in the bypass bore while the idle was choppy because of the crippled cylinder.

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What has happened to this engine between when it ran correctly, and when the lifter failed?
I'm not ignoring your note re: history, I just don't have much to share. The best I know is that the first failure looked like it happened over a very long period of time (by the conical wear pattern). My understanding is that the engine had never been rebuilt, so that took ~100k+ miles to fail, and spun correctly for the majority of that time.

CJ7, AMC 360 Howell TBI, T-18a, d300, D44 front and rear, Stock YJ rear springs all around SOA and outboarded, BFG 33x12.50s, Warn XD9000i
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post #12 of 33 Old 10-11-2021, 01:51 PM
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My 360 had unknown miles on it when I rebuilt it. It, too, had one lifter that appeared it wasn't spinning properly, but the wear pattern was very slight, and the lifter was still functional. I don't recall which cylinder it was in, but I made sure that bore got thoroughly cleaned out and the new lifter slid up and down in the bore easily.

Your worn lifter looks like it was sticking in the bore pretty badly, especially to wear like that in such a short time frame.

As someone else said, I fear your cam is toast, unfortunately.

Matt
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post #13 of 33 Old 10-11-2021, 02:15 PM
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The oil pressure is high, but if the motor was built with tight clearances, it is going to somewhat high. If the pressures don't come down it's a problem. I would expect to see around 60 to 70 psi on a tight motor, after the break-in period. It will decrease some over time as the the clearances open up. One problem with high pressures is the filter, most common filters don't like high pressures and will usually blow the seal out. Frams HP line are designed to take higher pressures, may want to use one until the pressures come down.

If there is a weird issue with the bore, it may have to be sleeved.
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post #14 of 33 Old 10-11-2021, 03:00 PM
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Which failure was this one pictured below?

Why is there a hole in the center of the lifter?

I have heard of Crower Cool Face SFT lifters with an oil orifice in the face of the lifter, but they are generally used in race engines. The size of the orifice seems too large as well, I have to ask, why is there a hole in the face of your lifter?
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D416CFCD-4F4D-4896-BE39-7E1A54D82A6C.jpg   A46C36A9-769D-4E96-B68A-0B79830364AE.jpg  

Why do I own a CJ? I like to “Balance the wrench and the steering wheel”
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post #15 of 33 Old 10-11-2021, 03:37 PM Thread Starter
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Quote:
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Which failure was this one pictured below? Why is there a hole in the center of the lifter?
The picture you are referencing was the first failure (pre-rebuild), and the lifter on the right with the hole in it was the one that failed being compared to a "new" lifter of the same type on the left. Prior to wearing all the way through the friction surface, the symptom was a tapping sound, and once it wore deep enough to create the hole, the lifter collapsed and the tap became a violent pop (see the video I posted above in the context of rocker oiling) because the plunger no longer offered resistance to push the rod up when the cam lobe came around.

The hole in the lifter is the same ultimate failure that was observed pre-rebuild and post-rebuild as you can see from the image here that has identical age and model (Melling 2011) lifters, one that got worn through.


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