Piston slap... I'm lost

[Austin O.]

Its been a while since I've posted on here... A couple months ago I started hearing a knocking coming from my 4.0. It was pretty quiet initially and could only really hear it while idling but now it has gotten louder and is sometimes concerningly loud when accelerating in lower gears (so I am going slow enough to hear it). I am very confident it is piston slap based on all the reading that I have done recently. And it doesnt seem to go away very quickly even once the engine has been warm for a while, sometimes it does. I'm at about 176k on the engine. What are my next steps? What are my options? I'm pretty frustrated and not sure what to do. Thanks

 

[macleanflood]

Pull the head and the oil pan...new crank and rod bearings...new pistons, rings, Felpro head gasket kit.

A solid weekend of work but only about $500-$600.

If you don't have access to a press DeXJs.com will sell you assembled rods and pistons.

These engines are very simple.

I just built my own stroker with a Clegg Stage 2 kit. Lot priceier.

-Mac

 

[Mud Mixer]

Try Valvoline VR1 20w-50
See if that works.
If it doesn't, see above.

 

[B1Toad]

Pull the head and the oil pan...new crank and rod bearings...new pistons, rings, Felpro head gasket kit.

A solid weekend of work but only about $500-$600.

If you don't have access to a press DeXJs.com will sell you assembled rods and pistons.

These engines are very simple.

I just built my own stroker with a Clegg Stage 2 kit. Lot priceier.

-Mac

Mac are you saying you can just pop in new standard size pistons with new rings and don't need to measure/bore?

 

[macleanflood]

Mac are you saying you can just pop in new standard size pistons with new rings and don't need to measure/bore?

Good point... usually aftermarket pistons are marked up and stamped...but definitely a good thing to check!

DeXJs has some great YouTube videos on down and dirty 4.0 refreshes. I'd check those out, make your own decisions and battle plan.

-Mac

 

[GoldenGorilla]

DeXJs has some great YouTube videos on down and dirty 4.0 refreshes. I'd check those out, make your own decisions and battle plan.

X2 - mad lad

 

[Zorba]

"In place rebuild". I've never heard tell of it being possible in a typical automotive situation, but thinking about it makes me think its indeed possible. If @macleanflood has done it, it obviously is! Wow, that's really cool actually...

 

[macleanflood]

"In place rebuild". I've never heard tell of it being possible in a typical automotive situation, but thinking about it makes me think its indeed possible. If @macleanflood has done it, it obviously is! Wow, that's really cool actually...

I haven't done it. I chickened out. I shouldn't have. I spent way more money on a stroker.

-Mac

 

[rweathers2001]

I decided to do this one with mine when the #3 piston skirt broke. I figured it couldn't hurt and to give it a try. Mine is a 2000 so I also put a new head from Clearwater on it. I ordered the pistons and rods from DeXj. It wasn't that bad of a job and could easily be done in a weekend if you have the parts.

One thing I did while I was doing the job was replace the lifters. I shouldn't have done this since one lifter didn't like the cam and it put a hole in the bottom of it. Took it back apart and put in a new cam, timing chain, and balancer. Also changed the oil pump while I was there. This isn't a hard job if you have some basic mechanical skills.

 

[Austin O.]

Pull the head and the oil pan...new crank and rod bearings...new pistons, rings, Felpro head gasket kit.

A solid weekend of work but only about $500-$600.

If you don't have access to a press DeXJs.com will sell you assembled rods and pistons.

These engines are very simple.

I just built my own stroker with a Clegg Stage 2 kit. Lot priceier.

-Mac

Ill look I to this, thanks for your help.

At what point is this solution not going to fix the issue and I’ll actually have to fully rebuild? Meaning, will doing this fully fix my problem, or is it possible the engine is too far gone right now to be fixed in this way and it would just make sense to look into a full rebuild instead?

Thanks!

 

[macleanflood]

At what point is this solution not going to fix the issue

Scored cylinder bores. Cracked block. Broken valves that damaged the head.

Happens but not often according to Dex.

-Mac

 

[GoldenGorilla]

The difference is in the condition of the motor. Know it lived a life of neglect and abuse? Like no oil change for 30,000 miles? Probably better to take the block to the machine shop for a good cleaning as oil galleys could be clogged.

Or if you send an oil sample to test and it shows high copper content or other material out of the bearings. Main bearings and rod bearings are made of the same materials, but if mains are going you need to take the crank out to replace.

 

[GoldenGorilla]

And note above about lifters. Uncle Tony's Garage has a good video explaining good cam wear patterns, which you can see clearly in our motors when the oil pan is removed.. If your pattern looks good, even if the lifter isn't pumping up instantly, I'd say swapping the lifter is a bigger roll of the dice in today's world. The cam and lifter are married after break in.

 

[GoldenGorilla]

The DeXJs video referenced

View: https://www.youtube.com/watch?v=MLE2b6btTIo

 

[LJBean]

I bought a doner 4.0 from a Grand Cherokee and built a stroker for more $ than I originally planned, cuz I couldn't resist a ported performance head and port matched intake from Russ. No regrets there, but when I disassembled the original engine with 300k+ miles on it I was amazed at the condition of the engine. The only material defect I found was a broken compression ring on piston 3 - and even that cylinder looked pretty clean. I haven't measured the cam, but it did not show material wear, nor did the lifters. In retrospect I think I may have been able to refresh it quickly and cost-efficiently with mac's approach. Not sure how much longer it would have lasted with the original cam bearings, though.

These AMC strait six engines are amazing.

 

[macleanflood]

In retrospect I think I may have been able to refresh it quickly and cost-efficiently with mac's approach.

I spent way more than I planned on my stroker. Did the exact same thing with the XJ block. Ceramic coated the intake, had to replace the oil pan and radiator...bunch of little things along the way that added up.

-Mac

 

[GoldenGorilla]

No regrets there, but when I disassembled the original engine with 300k+ miles on it I was amazed at the condition of the engine.

These AMC strait six engines are amazing.

The cast iron blocks certainly are. It seems to take some crazy neglect and abuse before a block is destroyed. And capable of taking some serious abuse when stroked and boosted. Very different from the construction of most of today's sleeved motors.

 

[Austin O.]

I drove it about 200 miles home from school a few days ago. I didn’t hear noise anymore but thought it may be because I had the doors on and was driving on the highway. I just now took the doors off and drove it and still do not hear the knocking. I can hear a ticking sound now… Any ideas with what’s going on here?