New 196 with a warm knock

[Tom Mandera]

I haven't heard it run - it's ~250 miles away.

I built a 196. Everything spec'd out when assembling it.

It was installed, ran for a while, then knocked when warm.

That's when John Fleck also discovered that V8 and 4cyl bearings are different - the 4cyl bearings have a small bleed hole that matches up with the con-rod and allows hot oil to escape the crank journal.

Pulled the engine, noted two scored rod bearings, turned the crank, installed NOS 4cyl con-rod bearings this time, degreed the cam (IIRC 108 ICL - it is a stock cam reground to stock specs) and re-installed.

Ran fine for a while, got to 180-deg, sounded fine, throttle was applied, and some sort of knock returned.

It has a new oil pump, and a spin-on oil filter.

Stock gauge indicates half scale I'm told. I confirmed it had oil to all of the right places before it left my shop - I prime it and rotate the crank to check for oil leaks (which required the powder-coated aluminum spin-on filter adapter to be planed - this has happened each time I've had one powder coated) and confirm oil to the rocker shafts before it leaves.

The 196 has a one-piece balancer, so it can't spin. The new timing gears are lined up properly.

It has a 4cyl flywheel, and if it didn't, it would knock when cold, too.

Start it up cold, it's fine. Let it warm up, it knocks. Last night and this morning I'm told - both times, it was happy until warm (180F)

If the oil isn't getting out of the bearing, that could explain it - that's why the bearings were replaced in the first place.

I didn't verify that the weep holes in the rods were clear - the rods were resized and cleaned - I didn't think to run a wire (very small one at that) through them or anything until just now. The holes in the bearings did line up with the holes in the rods. The 4cyl rod bearings are also slightly narrower, allowing more oil to seep out the sides around the journal.

Am I going to find rod bearing damage again (and if so, what the heck did I miss), or is there some other possible explanation I should contemplate before it comes back out?

[Jay Tabor]

these are all causes, some can be eliminated by your knowledge of the build.

too much crank end play.
bad wrist pin.
cracked piston.
carbon knock.
since a couple of rod bearings were damaged- maybe dirt in oil journals of main galley or in the crank got to the rods/journals.
loose clearances to begin with.
thin oil.
pull each spark plug wire while engine operating to listen maybe isolate a cylinder.
con rods on backwards.
harmonic balancer bolt could be loose, so its loose on the woodruff key.
manual or automatic trans> loose flex plates or cracked flexplates.
loose flywheel
does noise go away with rpms?

[specfour]

About 25 years ago, My Dad had a Scout with the 4cyl. I can't remember if it was the 196 or the smaller 4cyl. It had the same problem, had a knock when warm. We finally figured out it was the bushing area in the block where the bottom of the distibutor shaft rides was worn. Never did fix it, and as far as I know, that Scout is still running around South Texas somewhere.

Andy

[Tom Mandera]

I finally got the Scout in hand, and I didn't hear any bottom end noises - I hear the fan hitting the shroud and "ting-ing" and such.

What's concerning isn't a "warm knock" as much as valve train noise.

It sounds like I left out an oil gallery plug.. but this is a 196, and I used a mirror to double check - there's a plug behind the distributor.

The lifters are pumping up - removing them I can't depress the plunger since there's still oil pressure in them - but the racket sounds like they're not getting enough oil, or the rocker arms are hitting the valve cover.

I don't see any witness marks from the rocker arms, so I'm doubting that. (these are boat rockers on a 196)

Each rocker had a thimble of oil sitting in it/on it. There are definitely getting oil.

I pulled the oil filter adapter - a Scout II spin-on - to check the block for the extra return passage, and didn't find one (it would've needed plugged otherwise) (you have to remove the engine mounting brackets to pull the filter adapter, BTW)

The stock gauge reads more than half scale of oil pressure, but I don't put much stock in those. Besides, a tight engine will have decent pressure even with that lifter gallery plug removed..

I don't believe the 196 has TWO galleries, since it only has one bank.

The plug behind the timing cover was in place..



It was one of the first things I installed. The one behind the distributor is in place.

The lifters are fed from the the rear of the camshaft - in the bellhousing - and the 196 uses a 4cyl specific gasket and cover, which are installed. Cam end play was good.

Even if the cam bearing stuck out past the edge of the block, there is enough room to let oil past and feed the gallery and lifters..

I need to find my mechanical gauge and check the oil pressure at the block and then at the head ports...

[Jay Tabor]

Correct length pushrods?

[Tom Mandera]

I should check those. I'm also wondering about the condition of the rocker arms.

Both were cleaned and supplied to me, and installed. I didn't double check they were within spec.

It runs boat style rockers.

I'm thinking of grabbing a set of welded rockers and pushrods - while I have a supply of the boat rockers, I don't have any 345/392/196 length pushrods for them - everything I own runs the welded rockers.

I'm having a hard time figuring out why else it would clatter so badly..

[Bill usn-1]

Any intake bolts sticking thru and rubbing a push rod?

Was the head or block shaved to make up for the thicker head gasket?

[Jeff Bade]

Rocker arms / assembly / pushrods all the original ones or was some of this taken off a different engine?

[Tom Mandera]

Originally Posted by Jeff Bade

Rocker arms / assembly / pushrods all the original ones or was some of this taken off a different engine?

Taken from a different engine and supplied to me. (and, turns out, that engine had oiling issues, but this was the "best" set - hrrmm!)

The original engine looked like it was in a boat.. I had to drill and break the pistons only to discover the block was junk, so this is block #2.



Bill - the intake bolts do protrude into the pushrod cavity a bit - enough that I couldn't remove the two center lifters through their own holes, and had to switch to a different hole to get them out.

I may replace those bolts with shorter ones, though there are no marks on the pushrods indicating contact.

Head was minimally shaved to true it. Being a 196, it should have had a composite gasket from the factory IIRC (or is it just the IC392s that all had composite gaskets?)

Cam is the stock cam, reground, so the base circle is smaller than original by some degree.

This is a pretty boring "stock" 196.

[Jay Tabor]

if its still in running condition, then fire it up and push on each pushrod/rocker arm, if it/they quiet up, you found the noisy one[s]>
lifters clacking on the cam make more noise than pushrod to rocker arm do/does /