|
|
|
Your donations help keep this valuable resource free and growing. Thank you.
|
AMC 360 - Bad sound after overheating (VIDEO) |
Post Reply 
|
Page <1234 6> |
| Author | |
Sonic Silver 
Supporter of TheAMCForum 
Joined: Nov/23/2011 Location: East Tennessee Status: Offline Points: 7950 |
 Post Options
 Thanks(1)
 Quote Reply
 Posted: Oct/11/2022 at 2:27pm |
|
|
 |
|
|
SC397
AMC Addicted 
Joined: Apr/30/2009 Location: Michigan Status: Offline Points: 5476 |
Post Options
Thanks(0)
Quote Reply
Posted: Oct/11/2022 at 2:41pm |
|
A little JB Weld would fix that..
|
|
|
|
|
J10_Shorty
AMC Apprentice 
Joined: Oct/16/2009 Location: Boston, MA Status: Offline Points: 71 |
Post Options
Thanks(0)
Quote Reply
Posted: Oct/11/2022 at 4:37pm |
|
Thank you all so much for the suggestions. I was planning on dumping the oil and checking the filter tonight and then pulling the pan tomorrow to see if there was any movement of the rods but the test light to ground the ignition sounds like a great idea.
Too much timing could be a factor and again, on me but I don't recall the total advance I had it set to. Just know know I've never heard a ping in 5 years and I've run it pretty hard at times. TH400 with shift kit and 2000 stall. Didn't think pulling a light boat for 20 min would even make it sweat. Either way rod bearing damage or piston slap seems extreme for what I'm assuming was a simple overheat. The engine may have been cursing me for the last 10 mins of the tow and finallly said enough if this guy isn't smart enough to have a temp gauge. Again, can't thank the group for the suggestions. I'll report back as I always make it a point to close out a thread so others can learn (in this case from my mistakes:(.
|
|
|
|
|
sweatlock
AMC Addicted
Joined: Apr/28/2014 Location: Largo, FL Status: Offline Points: 3315 |
Post Options
Thanks(0)
Quote Reply
Posted: Oct/11/2022 at 4:57pm |
|
Beautiful truck and I’m really hoping for the best for you - situations like this suck. Do you have any idea as to why it may have overheated in the first place? I think you stated in your first post that it had never overheated prior to this and, as you say, towing a small (although define small) boat shouldn’t be too taxing for a stockish 360. Overheating, like steam/coolant gushing out?
Edited by sweatlock - Oct/11/2022 at 8:06pm |
|
|
|
|
bigbad69
Supporter of TheAMCForum
Joined: Jul/02/2007 Location: Ottawa, Ont. Status: Offline Points: 6668 |
Post Options
Thanks(0)
Quote Reply
Posted: Oct/11/2022 at 6:11pm |
|
I had a Mopar 383 that sounded like that - quiet at idle, knock as you rev'ed it up. It turned out to be a worn thrust bearing. The knock was the crank eating its way into the block. Since this started after an overheating incident, it's probably not a trust bearing, but crank travel is easy to check with a pry on the dampener.
|
|
|
69 Javelin SST BBO 390 T10
|
|
|
|
|
J10_Shorty
AMC Apprentice
Joined: Oct/16/2009 Location: Boston, MA Status: Offline Points: 71 |
Post Options
Thanks(0)
Quote Reply
Posted: Oct/11/2022 at 9:20pm |
|
Sweatlock - No idea on the cause of the overheating. I was thinking maybe the water pump went or something.
This engine was a full rebuild and has been great. I actually don't think I've towed anything with this engine yet as we use my wife's truck. I towed a 17' wood runabout 1500-1800 lbs with trailer at most. I saw a little smoke or steam behind me and she shut down as I pulled over. The radiator just pushed coolant back through the expansion tank onto the ground. After 30 min she fired back up but I heard the knocking sound.
|
|
|
|
|
Boris Badanov
AMC Addicted
Joined: Dec/14/2013 Location: NH USA Status: Offline Points: 4209 |
Post Options
Thanks(0)
Quote Reply
Posted: Oct/12/2022 at 5:21am |
|
Ring end gap closed up the took off a piece of piston when it got warm.
I did it back in my first 390, I gapped it by the recomendation from the ring manufacturer. It was too tight for a forged piston. It sounds the SAME. But wrist pin failure sounds like that as well....
|
|
|
Gremlin Dreams
|
|
|
|
|
merr6267
AMC Apprentice
Joined: Aug/22/2013 Location: Ravenna, MI Status: Offline Points: 69 |
Post Options
Thanks(0)
Quote Reply
Posted: Oct/12/2022 at 9:29am |
I think the same. In fact, in this spitballing exercise I think this might be a likely scenario: Engine was recently rebuilt in a stock-ish fashion (correct any of these assumptions, as they are just assumptions) Truck was never loaded heavily for extended time and possibly had a cold thermostat. I'm assuming being in MA, that you're not running this thing for almost 6 months of the year to keep the salt off of it. Pistons were likely set up for stock type use, and ring gaps may be unadjusted or setup nice and tight. Cylinder bores may even be on the small side for that particular piston. Assuming the tuneup was perfect and there were no cooling issues (still could be a factor, just eliminating that in this thought experiment) the engine had never been allowed to warm up fully to a hot internal temp with a load on it for extended time. When cylinder walls got hot, the rings started butting themselves together. This led to increased heat due to friction, which led to more throttle input to maintain speed, which led to more heat and friction, which led to the ring ends crashing together even harder. At this point something has to give, and the rings upset and buckle, pushing a chunk of piston upward, downward, or any which way it will be allowed to move. Now that the ring is buckled and a chunk of piston is cracked out, you get a piece of piston floating around, whether it's actually loose or retained by the rings, you may have contact being made with the cylinder head. I experienced this on my Jeep like I mentioned above. I also experienced this on a chainsaw rebuild that I didn't pay attention to the ring gaps. It was running really well, then suddenly got really hot and stalled. fortunately on a chainsaw, it's just a single cylinder and when the rings butted it just stalled abruptly. With a v8 you don't have the luxury of that as the other 7 holes might have been working along happily. My 360 on the other hand in the same Jeep was a junkyard mess, that got put back together without replacing anything. It has been beaten so severely and taken everything. The engine has been so hot that the temp gauge was wrapped around to the cold side over a dozen times and it still kicks over. I attribute that to the worn out condition of the pistons and rings not allowing any seizure to happen. |
|
|
|
|
J10_Shorty
AMC Apprentice
Joined: Oct/16/2009 Location: Boston, MA Status: Offline Points: 71 |
Post Options
Thanks(1)
Quote Reply
Posted: Oct/12/2022 at 6:57pm |
|
*** QUICK UPDATE ***
I did the test this morning and everything points to the #3 cylinder. Significantly quieter and no sharp "rap" when I pulled the pug wire and raised it above idle. I did a quick bore scope and from what I can tell the piston looks ok. I could certainly be missing something around the edge and I can really see the cylinder wall. I also brought the #3 up to TDC and then and inch or two back down and used a dowel to push down to see if there was any play. I got the very slightest movement which is making me feel like it could be a rod bearing. Sounds like next step is drop the oil pan unless there are any other suggestions. Thanks for all the guidance so far...
 |
|
|
|
|
SC397
AMC Addicted
Joined: Apr/30/2009 Location: Michigan Status: Offline Points: 5476 |
Post Options
Thanks(0)
Quote Reply
Posted: Oct/12/2022 at 8:50pm |
|
Just pull the engine and find out what is wrong.
If you pull the pan and find out that it is a rod or rod bearing or pretty much anything else you are going to have to pull it apart anyway.
|
|
|
|
|
Post Reply
|
Page <1234 6> |
Tweet
|
| Forum Jump | Forum Permissions You cannot post new topics in this forum You cannot reply to topics in this forum You cannot delete your posts in this forum You cannot edit your posts in this forum You cannot create polls in this forum You cannot vote in polls in this forum |
Click for TheAMCForum Rules
Topic Options
merr6267 wrote: