Crossroads for 258 I6 tapping noise

[Hillarie]

I am a new owner of an 84 CJ7 with a AMC 258 i6 / 4.2l I6. It was rebuilt in 2013 (I have the receipt) but then the jeep sat for 3 years. I bought it with 309 miles on it.
I did not know that sitting can cause issues but now I have them.
I have driven it 600 miles and in that time there has been a noise that sounds like tapping.
I removed the valve cover and checked the rocker arms. I also checked to see if the rod ends had broken off. All ok there. I took it to a cert. mechanic and compression is good. I was told they cannot tell me what is going on unless they take the top off but it sounds like rod bearings to them.

So now what? I do not know what to do. Any suggestions would be great. Thanks a bunch.


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[Torxhead]

First guess would be sludge in the lubrication system from poor oil choices or not changing oil when necessary. I would recommend using a high detergent oil like a Shell Rotella 15w-40 and change a regular intervals. It might take awhile to clean it all out.

 

[Hillarie]

Thanks Torxhead. So driveable? I don't want to cause damage and the $ to check it is out of my budget right now. The shop recommended a remanufactured new engine which is way beyond what I can manage at the moment.


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[hole]

X2 on Torxhead's advice. I cant think of too many I6 engines that didn't have an inherent "ticking noise". In fact, I can only say that I've ever heard one that didn't. Not sure if it is still something people do, but running a quart of ATF with your oil change used to be the suggestion for "cleaning out" an engine with a sludge issue. Although, sludge really shouldnt be an issue with only 1000 miles on a rebuild

 

[Hillarie]

Would an engine rebuilt with only 900 miles on it have sludge?


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[hole]

I cant imagine how really, but I'm sure there are circumstances that make it a possibility.

 

[Torxhead]

A poor grade of engine oil installed plus the fact that it has been sitting awhile could do it. I remember using Pennzoil years ago and my engine started sludging up with that. You can also do stuff just to see what shape your engine is in like a compression check, spark plug burn inspect, what shape the carb is in, and complete tune up. I always like to record dates or mileage just to see when what was done as I am too old to remember that stuff.

 

[Hillarie]

It is at a shop now getting a compression test and an overall assessment so I will keep everyone posted. Thanks!


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[Lumpy Grits]

Your first comp test was good-Why do you feel a 2nd test is needed then?
What weight oil do you run?
I run Castrol 20W-50.
LG

 

[Hillarie]

I have gotten different diagnosis from different shops and it is driving me crazy and difficult to know who to trust.
One said lifter
One said rocker bearing

So now I am not going to do anything except change the oil myself and see if that does anything. I am just hoping to not destroy the engine. I am going to try the suggestions here.

It was also suggested it could be piston slap. So I have learned a lot but no real diagnosis without pulling the top of the engine off.

I wanna drive!![emoji41]


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[Belizean]

Another cause of sludge is if the engine never gets to the correct operational temperature because of the wrong thermostat and continued short trips. I have only used Castrol 10-30 and have over 235K miles and the engine is doing well. Knock on wood

 

[Lumpy Grits]

I have gotten different diagnosis from different shops and it is driving me crazy and difficult to know who to trust.
One said lifter
One said rocker bearing

So now I am not going to do anything except change the oil myself and see if that does anything. I am just hoping to not destroy the engine. I am going to try the suggestions here.

It was also suggested it could be piston slap. So I have learned a lot but no real diagnosis without pulling the top of the engine off.

I wanna drive!![emoji41]


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AGAIN I ask, what is the oil weight you are using in the engine?
What oil filter are you using?
What did the last comp test give you for readings?
LG

 

[Hillarie]

I am not trying to frustrate you LG-
I don't know the oil or filter. I have only driven 600 miles on it and the receipt from the oil change just before I bought it doesn't say the weight.
The compression from the last shop is
1-142
2-135
3-148
4-AMC 150
5-148
6-142
The shop recommended 5-30w now and additive and in the summer 10w-30 or straight 30.
So now I am going to change it and try what you suggested.


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[Lumpy Grits]

Your readouts are great.
You're using to 'lite' an oil.
Go to a High-Mileage 20W-50 and see what that does. Go to NAPA and get a NAPA Gold 1522(Wix, that is the OEM filter, BTW)oil filter.
Get that oil changed ASAP, like this weekend.
We both live in the desert, the 20W-50 is great year around. I've run that oil in my Jeep since my first oil change in 1985.
LG

 

[Torxhead]

Thanks for the update. With as few miles as you have on that engine, I would suggest an oil/filter change fairly soon to as to clean the engine out as there might still be just in the lifters that could making that lifter noise. Using a high detergent 10w-30 oil an a Wix filter could help here. Keep those compression #s in your maintaince records.

 

[Lumpy Grits]

Keep a full maintenance log book on everydangthing you do to the Jeep. Be sure to include date, mileage and PN's of the parts involved, along with any torque settings used.
LG

 

[Hillarie]

Great advice. I will start the journal now. Thanks both of you! I will get this thing on the road - there is a run this coming weekend and I am gearing for that. I will change the oil/ filter before I go.


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[Posi]

If it were me, I would add 1quart Mavel Merstery oil to 4 quarts of oil and new filter. Run it about 50-100 miles and dump it. Most plane mechanics know this fix.

 

[Hillarie]

Update:
The tapping graduated to knocking. So I replaced the oil/filter (used the heavy weight oil/filter LG suggested. Pressure was better but the noise wasn't. So rod bearing replacement happened on Wednesday. The sound is so much better but still there :/




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[Lumpy Grits]

What did you use to confirm the clearance of these new bearings is correct?
FWIW: Try replacing the mains.
LG