Knock

C

cheese1

Member
Engine: 69' 304 89,000 miles. Sat for 10 years, heavy sludge
compression: dry 110 -120, wet 110 - 135
oil pressure: cold start 45psi, hot 7psi
parts replaced: plugs, wires, cap, rotor, points, condenser, rebuilt carb; timed 8* advanced.

I bought this Scout last February. Primed the oil pump before starting. Not the detailed Mike mayben way but a novice with a drill and old screwdriver.(I'm learning) put a rebuilt carb on it due to cracked base plate. The truck started right up. Not 2 seconds into running I heard knock, knock, knock. Turned it off scratched my head and thought stuck valve. I poured tranny oil down the carb and it did quiet down but the knock came back. I then started to check lifters. The second from the front (#2 intake) lifter was cupped. Put in a new lifter, cleaned up the rockers, shaft and valve covers as best I could. Fired it back up and still knocking.

Now February 09. After getting dejected with the knock I moved onto other items on the truck. Brakes, electrical, front and rear wheel bearings, differentials etc. Now I'm getting real close to putting this truck back on the road and I want to get rid of the knock. I do plan on pulling the rocker shafts again for a more thorough cleaning. After the cleaning what do I start to look for?

The truck is 80 miles from my house at the inlaws farm. I start working on it at 8am until midnight. Naturally parts are scarce for these trucks in the city much less in flatonia, tx. I need to plan ahead for diagnostics and repair. The advice on this site is invaluable. Any advice would be appreciated.
 
The answer you are seeking is contained in the links in this thread:

http://www.forums.IHPartsAmerica.com/gas-engine-tech/1589-ic-392-valve-train-issues.html

All those links are contained in this sub-forum.

The issues regarding valve train noise are all linked to the same root cause. No matter which IH sv engine variation or which I-4 variation, the lubrication systems and valve train anomalies are all exactly the same, what works for one...works for all.

Don't automatically assume "cam bearings"...the diagnostics must lead to that conclusion. However...a "cupped" lifter is hollerin' flat cam lobe. Look down tha hole and ya can see the cam lobes after poppin' the lifters out, a "worn"/flat one is real obvious.

With the motor runnin', take a hammer handle and press down hard on the push rod end of the rocker and that will make the "noisey" rocker/lifter more noisey. Don't be surprised to find that more than one are possibles.

I swap flatonia for leaburg any time ya wanna vacation dude!
 
It's a shame, the motor runs great. I'll check for a flat cam the next trip out. If it is a flat cam I can only assume it's time for a rebuild. Which leads me to another question.

I picked up a rebuilt 304 from a guy in bryan, tx. The motor was rebuilt sometime in the early to mid 90's. The guy picked up the motor, put it on a pallet and never installed it. The motor has never been run. I have it on a stand and have pulled the oil pan and valve covers for a look see and the motor is spotless. It is a later 70's motor with emission tubes in the exhaust ports and boat style rockers. Any advice on how to proceed?
 
If the motor runs ok (except for noise) and a compression test shows ok, then a cam lobe that is "down" is not a concern. Just proceed with the rocker shaft oiling diagnosis. At the same time rip into the rocker assembly involved and purge it!

As for the other motor...since it's onna stand, then simply perform the operation I developed for pre-lubing any IH I-4 or sv engine found in this thread:

http://www.forums.IHPartsAmerica.co...I-4-sv-engine-non-oiling-rocker-assembly.html

Download and print the procedure in the attachment in posts #2 and #3 and do the deal. Otherwise, if ya even rotate the motor by hand just a touch right now to see if it's "free", ya run the risk of having the cam bearings adhered to the journals, new bearings/used bearings, it doesn't matter. You must create an oil wedge between all journals and bearings before attempting rotation. Same for rods and mains.

Don't despair regarding the engine with the current noise issue, ya just haven't completed the diagnostic process, the solution May be real simple!
 
Thanks for the advice Mike. Out of curiosity if the rockers are distributing oil and the cam lobe is down what is the next step? Do I just get used to the noise?

On the new unused motor I'm afraid the motor has turned a bit. The guy I bought it from did bump the crankshaft to show the motor wasn't seized. When I took the oil pan off there is evidense of assembly lube. But no telling how much or how effective after 10 - 15 years.

By the way. The advice on the Holley 2300 list 2977 rebuild was spot on. The rebuild totally changed how the motor was running.
 
If ya have a "flat" or "semi-flat" (it'll only get flatter!) cam lobe, then that cylinder simply won't carry it's share of the load...like a pair of horses inna hitch and one of 'em's lame! Basically a dead (or nearly dead) cylinder.

"flat" is a relative term, really just slang us old farts throw around so we can laff instead of cry about these dead ducks!

After ya got it back running and have verified oiling...then I'd replace whichever lifter is rattlin' with new (if it's still noisy). We can also source push rods in o.010", 0.020", and 0.030" over-length as another form of band aid. But let's work our way up to that point and not rush to judgement yet. The overlength push rod is a method of compensating for incorrect overall valve geometry.

Regarding the "fresher" motor, I had already figgrd that it had been rotated...but I'm obligated to throw out the company line here! Inna perfect world...IH motors never shit cam bearings! In the real world...they do! So the best thang ya can do now is simply go through the pre-oil procedure, do that with the valve covers off so ya can watch all the rockers oil while the drill motor spins. And do that for at least 30 minutes once ya see oil ooze from all the nooks and crannies.

Great to hear ya had success with the carb! It's all in the attention to detail when doing that kinda work...and being clean!
 
It's time to follow up on the last post. I did verify that it is a flat cam. I pulled the suspect lifter and pushrod and ran the motor without them and no knock. I then replaced the lifter and installed a new one and it still knocks. I cut up an old valve cover and inspected the oiling from the rockers and all is okay. Could be better but they all drip a fair amount. Mike you had mentioned an option of using a longer pushod to take up some slack, any ideas on where to locate some. The rockers are the stamped type.
 
If the cam lobe is "going flat"...it will continue to do so as the motor runs on a fresh lifter. The "hard surface" is most likely gone...May take some time but gradually the valve timing for that cylinder will become more and more out of sync and compression will start to subside.

Metal is of course being removed but should be landing in either the sump or the filter.

If you can give me an accurate measurement on the current push rod length (ball/ball end push rod is for the boat rockers), I'll check availability for the "+ length" push rods from our supplier. Iirc, they are available in +0.020" and +0.040" but I May be wrong on the + dimensions. I know what the oem push rods are "supposed" to measure, let's see how close you can get!

The boat-type rockers/push rods were not original to a '69 era 304! The motor has obviously been into before...most likely for the same issue! It could not be "corrected" so it was parked????

To make certain the cam lobe is down..I'd rig a dial indicator over each rocker at the same point and quantify how much the lobe is down. You'd be much better off replacing the cam with the engine in the rig now, than continuing to bandaid it as the lobe gradually goes away.
 
I will start prepping the new motor to be installed. Replacing the cam in the heavily sludged motor just doesn't seem worth it.
 
Do you have a part number for the pushrod for a 304 that has the ball ends on both ends and is 8 7/8 inches long??
 
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