The dreaded Knock Knock Knock

[jd52cranbrook]

Approximately 17,500 on my rebuilt motor, and I started hearing a knock during acceleration after warm up. Very slight, but kept my ear to it. Over time I could hear at stead speeds under load. Very hard to duplicate while just sitting and toying with the RPMS. At idle it ran smooth as a swiss clock.

Anyway, went to the engine builder, sounded to him like a loose flywheel bolt, not from the engine itself.

Finally got so I could reproduce it out of gear in the garage. Had a friend move the throttle as I crawled underneath, yep, crankcase. Although it was still very slight, I want to nip it in the bud.

Pulled the plug wires one by one, number 5 seemed to be the culprit.

Dropped the pan, pulled the bearing cap off number 5 rod.

Kind of hard to pick up with the camera, but in the center there is deterioration of the bearing, like a spider web was indented into the bearing, plus some weird worn spots.

Same on the upper bearing.

So I pulled the head, popped the piston out and back to the builder, who took them to a race engine builder.

Told it was too much fuel in the oil, or carbs running to rich. I was pretty sure I got them as lean as I could, but will have to check when new bearings are put back in.

Then I pulled the main bearing next to number 5 cylinder. If you look, there is a hair line crack in the bearing itself just above the oil galley. Sorry the cam does not show it that great, but you can feel it with you fingernail.

So, new bearings, and a good carb and timing adjustment is in order.

At least the crank seemed in good order still. I don't have a micrometer, but used a caliber, plus no wear on the crank itself.

Have to wait a week for Kanters to get to me, so time for cleaning I guess.

[Normspeed]

Darn, that is bad news. Were you noticing a lot of flooding or did the oil smell like gasoline when oil change time came around? I hope the new bearings hold up better.

[Don Coatney]

Told it was too much fuel in the oil, or carbs running to rich.

Say what? I dont buy that. Best get a micrometer and do some more measuring of your crankshaft.

[Heavy Flat Head]

If it is as they say, why not all the bearings looking like that. You would also need to have a lot of fuel in the oil for that to happen. I do not see it happening either. Like Don says check the crank and it might not hurt to have the rod end look at also.

Ed.

[John Moran]

I cann't tell by the picture but dose the oil whole in the bearing line up? John M.

[jd52cranbrook]

Was hoping somebody would jump in., Thank you

As for the rod bearings, I have numbers 4 5 6 out so far, and they all have a bit of the spider web deal embedded in them.

I have time to get micrometer and check now anyway. I really don't want to pull the motor again, but will if need be.

The bearings are all .020 so the crank was worked on during the rebuild.

The pics don't really show, but none of the bearings are worn down to copper (I think thats right). But the main bearing defiantly had a hair line mark/crack, or something in it.

I think I'm going to take up the builders offer to come out and look underneath.

Also keep in the mind the engine never skipped a beat. Purred at idle or 3,000 RPM. It was I who first heard the knock, sometimes I wish I was deaf.

[jd52cranbrook]

I cann't tell by the picture but dose the oil whole in the bearing line up? John M.

Hi John, yes the holes were right. Like I said engine has about 17,500 on the build.

[jd52cranbrook]

I have changed oil many times since the build. But this could have been the longest I waited, maybe 4-5 thousand miles, it was black.

[Normspeed]

4 or 5 thousand on an oil change is nothing to these motors, shouldn't have caused any problems. I'd sure take the builder up on his offer to come over and inspect it. If you have the 46-54 Plymouth manual, take a look under inspection of bearing halves.

I've never used Plastigage but maybe you could also do some checking on the old and replacement bearings and journals with some of that. Hope it goes well.

I'm no expert on bearings, but I did find this article and photos about bearing wear.

http://www.babcox.com/editorial/us/us90126.htm

[jd52cranbrook]

Thanks Norm, I will be checking the link, and the books for sure.

To be honest, this is new territory for me. I'm a wrencher, I can unbolt and tighten things, and not afraid to try something new. But I am not sure how bad is bad, or what to look for or not to be concerned about. But I do want to learn as much as I can on this car, and the 48 I just bought. Over the last three years I have learned a lot through trial and error, and with the help of the board members, plus good car guys locally. I didn't do the guts to the car during the rebuild, as in cam, valve, pistons, crank install, but I did do all the rest.

I don't know what else could be making the knock. This is a bad time of the year to have the car apart. Summertime is the time to have this thing on the road, listening to tunes through the amps and stereo, and to be cruising in comfort with that AC making nice.

[Normspeed]

Here's another. Bigger photos but quality not so great.

http://www.thirskauto.net/BearingPics.html

[jd52cranbrook]

Both Norms,

The thinking behind the builder's theory is that I am running the Langdons dual two barrel set up. And just dumping to much fuel for the motor to handle at times.

I'm open to other suggestions, but one thing I will do for sure after getting it back together is to really look at the mixture.

Thanks for the other link. This is great forum for advice and fact finding.

[jd52cranbrook]

Good point Norm,

But as I was reading over the articles I printed out, one thing popped in my head.

About 1000 miles ago I blew a head gasket. These finned composite heads don't like to get hot, or overly warm even. It came apart between 5 and 6 cylinders.

Anyway, the article I was reading says.

A good set of bearings can be wiped out if antifreeze finds its way into the crankcase. Coolant is a lousy bearing lubricant, and it dosen't take much contamination to cause problems. If the oil shows signs of coolant contamination, pressure test the cooling system for internal leaks. A leaky head gasket, cracked block or head may be allowing coolant to mix with the oil.

When I replaced the gasket, I did not change oil. Coolant could easily have gotten down to the crank case when I pulled the head. It says it doesn't take much. Could this have happened because of my own stupid mistake???????

[jd52cranbrook]

Man,

Live and learn.

I'm afraid to ask this but, is there a way replace the upper main bearings without pulling the motor?

[Don Coatney]

that was due to the idiot salesman who let his oil run dry and blew the engine.

Norm;

I hope you learned to check your oil after you blew that engine:D

Both Norms' date='

The thinking behind the builder's theory is that I am running the Langdons dual two barrel set up. And just dumping to much fuel for the motor to handle at times.

[/quote']

The first sign of too much fuel is fouled plugs. With fouled plugs your engine would misfire.

A good set of bearings can be wiped out if antifreeze finds its way into the crankcase. Coolant is a lousy bearing lubricant, and it dosen't take much contamination to cause problems. If the oil shows signs of coolant contamination, pressure test the cooling system for internal leaks. A leaky head gasket, cracked block or head may be allowing coolant to mix with the oil.

You should read the book "THE CALL ME MISTER 500" written by Andy Granatilli. During a Indy 500 race one of his engines lost almost all of its oil. Rules stated no oil could be added during the race. In despiration Andy filled the crankcase with water and sent the car back out on the track. The car completed another 150 miles at race speed before the engine died.

If you had water or antifreeze in your oil your dipstick would look milky and you would know right away assuming you checked your oil on a regular basis.

Man,

Live and learn.

I'm afraid to ask this but, is there a way replace the upper main bearings without pulling the motor?

Yes it can be done

[james curl]

most books show what they call a key, which is a cotter pin which has had the head flattened in a vice to form a T shapped key. The leg on the T will have to be angled to fit in the oil hole and have the cross bar flat on the crank. The cross on the T cannot be any thicker than the bearing shell. You insert the T in the oil hole and rotate the crankshaft to roll the old shell out. Because the bearing is keyed to the block it will only roll out in one direction. You start the new bearing into the block and use the key to roll it in place, be sure that the shell you put in the block has an oil hole in it. Even after thinking about it I put the shell without the hole in it in my #1 main last year.

[Jim Saraceno]

That's a shame. It does look like the picture of "Cavitation"

Here's a good article on Bearings, hope it helps.

http://www.imperialclub.com/Repair/Lit/Master/004/cover.htm

[kevinanderson]

I've never done this, but I remember my Dad changing bearings in engines that were in place. He would loosen the main caps a bit and then either rotate the crank slowly or carefully tap the end of the bearing with a small pocket screw driver around. Patience and Caution. That man can fix anything. I don't remember the details, so don't blast me with improbabilities.

[jd52cranbrook]

Well shoot, after reading Don's post I'm back to being confused again. The oil looked dark, not milky. The plugs didn't foul. I did check the oil regularly.

The head gasket blew between compression chambers.

I still have the oil in some used bleach jugs for recycling, I will check them.

Then get a good mechanic friend over with a good micrometer.

Thanks for the good input and links everyone.

Although I'm feeling a bit like Homer Simpson.

[jd52cranbrook]

Talked to a guy who builds his own race engines. Every time he tears one apart he drains the oil filter, cuts it open on a lath, then lays out the guts and can tell lots of what is going on in the engine. Think I'll try that.

[martybose]

Good point Norm,

But as I was reading over the articles I printed out, one thing popped in my head.

About 1000 miles ago I blew a head gasket. These finned composite heads don't like to get hot, or overly warm even. It came apart between 5 and 6 cylinders.

I blew a gasket between 5 and 6 once. No water leaks at all, because there aren't any water passages in the area between the two back cylinders where they tend to blow. I seriously doubt that it had anything to do with the bearing issue.

Marty

[jd52cranbrook]

I blew a gasket between 5 and 6 once. No water leaks at all, because there aren't any water passages in the area between the two back cylinders where they tend to blow. I seriously doubt that it had anything to do with the bearing issue.

Marty

I think your right Marty.

I removed the rest of the pistons,,, all bearings have damage. So I took the lot to a guy who races and rebuilds his own engines.

He said heat caused it.

I believe him. Because,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,

I have blown three head gaskets over two years with this finned head. It took me awhile to get the overflow recovery tank to work right. Had a bad radiator cap. It was the correct type, but would not suck water back in. Even after that I blew another gasket and it was running normal when it did.

Now, I admit I drive the car alot, and hard at times. But I don't over rev the motor, and my feeling is the engine should be able to handle it. I cruise at 70 with the OD, and rarely hit 80 when passing or such.

I now am running the stock temp gauge, (which is off), and a auto meter one plugged into the blocked port at the water pump. That has kelped me once when a belt come off the water pump. Read cool at the pump, but the head got hot,and I pulled over.

But, now that I have the safeguards put in, the damage was done to engine over time I believe. I blew a gasket on the drive home from Detroit in the middle of August last year and the cylinders filled with water. I changed the gasket on the side of the road, but did not change oil till I got home.

So anyway, a live, in person inspection by someone who knows is much better than trying to read pictures online. But, I am hoping the damage is to the bearings only, with me there will be no such luck I am sure.

I am going to install the new bearings, run the car with 20-50 oil, and hope for the best. This winter I am building the engine for the 48 and if need be I will put that one in this car, (52). Then pull this one and rebuild it.

The reasoning is it is summertime, time to drive, not have them torn down.

Both are going to be P23 engines.

Anyway, thats it, I know maybe not the best answer for a fix, the engine should probably come out and the crank gone thru at the least. But I am going to cross my fingers and hope for the best.

Thanks again for all the input.

And BTW, I will not be putting a finned head in the 48. Aluminum heads, iron blocks are not made for the long haul IMO.

[Andydodge]

JD, which/whose finned head was it?.......what did you tighten the head bolts at?........curious as blowing 3 gaskets seems overly "lucky".......also what head gaskets did you use?, reason why I ask is that I have an edgy head and whilst I have not installed it yet I chased up a Best brand gasket set with a steel not copper head gasket, i'll also be using ARP head studs & nuts not the original Plymouth head bolts......anyway am sorry to hear of your problems......andyd

[jd52cranbrook]

I am using the Edgy finned head.

Reinz gasket I (not sure of the spelling) with the copper on one side.

Head bolts were torqued at 55 lbs, starting at 50 and working my way up. Earl runs his Bonneville car at 65.

And still using the original head bolts, I was told because of their make up these do get stressed.

I know the car got hot several times over the past two years until I got everything figured out on recovery, etc. Al through it never got above 220, I still have to keep a eye on the gauges in hot weather, climbing, etc.

Once the head blew between cylinders 2 and 3, the between 5 and 6, then between 5 and 6 again and took piece to the near water jacket with it.

Is anybody doing anything with the stock head? I may look into that for the D24.

[jd52cranbrook]

Norm,

Had it checked and machined everytime it needed it. Only when it blew halfway from Detroit did I have to wait till I got home to do it. Even then I had it done and put a new gasket on. Checked the block also at the bolt locations for a raised head.