Is it possible

[steve from staten island]

That the knocking noise that sounds exactly like a rod knock is something else? The noise starts shortly after the engines warms and is only heard as RPM increases. Others have listened and they say it sounds consistent with a rod.
Yesterday i had it running and i thought there was more condensation steam then usual. In fact it was steaming away. I looked in the radiator and it was lower then it had been before. So I'm wondering a slight leak in the intake manifold let coolant in and giving me this knock sound? Is that remotely possible? Thanks

 

[68383GTS]

Check your flex plates bolts. I have had them come loose. Then they hit the block as the crank rotates. Sounds like a rod knock.

 

[1967coronet]

Heck Steve, I have near the reverse situation, after warmed up I have a rattle / light knock at idle, rev it up and it goes away. Ive checked the top end for loose rockers, checked / replaced the fuel pump & rod. good compression , good oil pressure hot and at idle or road speed. I have had the same noise for 6yrs at least. The old 383 runs up to 5,500 rpm over and over,
noise never changes.
wrist pin ? , skirt ? same as you I prob will never know unless I tear it down.

 

[Scatpack]

My 440 did the same thing. Ended up being a wrist pin. And also checked your flex plate bolts, mine were loose when I thought it was those that made that noise.

 

[khryslerkid]

If you want to check for coolant in any cylinder, pull your plugs. Coolant in a cylinder will clean a plug like brand new. If you find one like that, then a leak down test would be in store.

 

[Kern Dog]

You can isolate where the knock is coming from by pulling a plug wire while the engine is running. The engine will shake a bit but when the bad cylinder is found, the knock stops.
I did this to a worn out slant six. It had 2 bad rod bearings. One was REALLY bad. It went from KNOCK KNOCK KNOCK to knock knock knock when the plug wire was pulled.

 

[Mike67]

Converter bolts hitting inspection cover?

 

[69L48Z27]

Sounds like two issues. Coolant leak is usually not related to any noise. I had the same thing happen on an original engine that started destroying the timing chain cam gear. It was one that had nylon on it and it was crumbling apart. It made a knock noise, I ended up pulling the engine thinking it was a bearing noise.

Get yourself one of those stethoscope things at the parts store and start listening to different parts of the engine.

 

[Jcharger]

If you decide to check the cylinders, this can be done with one of those inspection cameras ($10-$20) from various sources. I think you will see if one is very different than the others. I don't believe coolant flows into the manifold where it would be drawn in under vacuum, instead, I expect if you have a coolant leak at the cylinder head, that you are likely to get exhaust also into the coolant system. Why the knock starts after things have warmed up may be an important observation. It might mean a thicker oil would mask it, but that would not get to the root of the problem. I would do as KD suggests and pull plug wires. I would also look into a stethoscope (or anything else that lets you locate sound like a tube or a long screwdriver pressed against your ear and various parts of the engine).

 

[PurpleBeeper]

In my opinion, you need to be SURE of the general area where the knock is coming from. Top/bottom and left/right and front/back. That can be a little hard to do, but can be done with patience. Torque converter bolt, rod bearing, main bearing, rocker/lifter/pushrod could all be the cause.

I had what I "thought" was a wrist pin knock, but turned out to be a rocker arm clearance issue with the valve covers (knock up top). I had a knock in a brand-x motor that turned out to be a flywheel (flexplate if a Mopar) had a crack near the attaching bolts which would do the same thing as a loose torque converter/flex plate bolt. (knock down low)

 

[HEMI-ITIS]

Check your flex plates bolts. I have had them come loose. Then they hit the block as the crank rotates. Sounds like a rod knock.

I also had a flex plate bolt work its way out 'till it was hitting the block.Sounded EXACTLY like a rod knock.........
Back in the day I had a max wedge,the piston slap drove me nuts 'till it warmed up and went away!!

 

[tomlin]

On Chevy's the fuel pump rod will knock like a rod when the return spring breaks in the fuel pump. Don't know if this can happen on a Mopar but assume it could?

 

[bearman]

Pull plugs and run a scope and see if you cyn walls have some heavy scratching going on could be wrist pin problem

 

[mopar 3 B]

Steve you should know by now anything is possible. If this is the engine you had rebuilt the question is why now?

 

[steve from staten island]

I took it out to actually drive it. I went up the street a slight incline, the trans sounds like its slipping. I gave it a little gas and it sounds like ****. It idles decent and no noise, under the slightest load when i gave it some gas, were talking 20 mph tops it knocked like crazy. When i turned around and went down the slight incline it did the same thing and i even heard the noise when i was off the gas. Im totally disgusted.... My wife goes for her 6 month scan next week so its the usual tense time, as long as we get past that its the only thing that matters. Im not letting the F-ing car beat me. Im going out there in a little while and checking out a few things. I really dont think what i heard was engine ping. It was a steady knock consistent with the rpm of the engine.

 

[Ranger16]

Have you had the distributor out? I once installed a distributor one tooth off and it sounded like a bad lifter.

 

[Sixpactogo]

On Chevy's the fuel pump rod will knock like a rod when the return spring breaks in the fuel pump. Don't know if this can happen on a Mopar but assume it could?

I have reported this before on another thread....I had the same issue with my 383 Plymouth with what sounded like a rod knocking when the engine warmed up. It was relative to rpm also. It ended up being the fuel pump. What happens is the spring on the fuel pump arm gets weak and doesn't stay tight against the fuel pump rod as it pushes up and down. This causes a rattle that sounded just like a piston rod. I found it with a stethoscope when I put the scope on the fuel pump. Before I even pull the valve covers, I would verify that the pump is not the culprit.
I believe that any mechanical fuel pump could have this issue.

 

[steve from staten island]

Thanks i will listen to the fuel pump tomorrow with my stethoscope. I checked the converter bolts and they were ok. The transmission was a quart and a half low and after i filled it, the trans seemed ok. I think the trans stick is reading wrong. I went under the car and found #8 plug wire off so it sounds better. This mourning i warmed it up and it did not make that knocking noise. I swear if you heard it yesterday it sounded like a rod was ready to break. Im going to check the timing tomorrow and try driving it again. This car will not beat me!

 

[bearman]

Man over machine that's why we do what we do to overcome the machine

 

[HEMI-ITIS]

Don't make me come over there!