Rocker arm failure
I had the engine in my 48 Commodore Six rebuilt when I first bought the car 15 years ago. About two weeks ago I started hearing a noise coming from the engine. I took it for a ride of about 20 miles today and it got worse. I stopped by my old car guru's garage and he told me that I have a rocker arm that is about to let go. What causes that? Is it something that naturally happens over a period of time with these old engines or did the guy not build it right? I've never let the oil get low and I just installed an oil filter about a month or two ago. What am I looking at as far as whether it's worth it to build it again? I've been told I'd be better off installing a Chevy crate engine, but I'd like to keep it as original as possible.
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Rocker arm?0
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Hudson flat had engines (and all flat head engines) Do not have rocker arms. The noise you hear could be any number of things. The first thing on my list would be,,, DO NOT GO BACK TO THAT "MECHANIC". Perhaps something has happened to the oil supply due to the oil filter installation. By any chance was the filter installed by the guy that says you have bad rocker arm? Sorry If I sound sarcastic, but JEEZ!
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Nothing like installing a "seldom seen" small block Chevy in your car. That'll really make it stand out at the next cruise night. I agree with SuperDave, don't go back to that "mechanic".0
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My mistake. The mechanic said connecting rod.0
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Why did he tell you to install a chevy crate engine? Rocker arm?
Please take it to a competent mechanic that actually knows something about flathead engines. You'll be far better off.
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Ok guys, in defense of my mechanic, he did NOT say Rocker Arm, that was my mistake. He didn't suggest the Chevy crate engine either. That was another buddy that puts small block Chevy engines in everything. My mechanic works on all the antique cars in the area. If it weren't for him, a lot of the old cars wouldn't be running. He knows what he's doing, I just misspoke what he told me. Bottom line, the engine is getting ready to fail and he just told me the likely cause based on the sound the car is making. And don't give me a rash about rocker arms (I'm a lawyer by trade, not a mechanic) but I know that flatheads don't have rocker arms. Don't know why I said that....0
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Bottom end problems on the 48 and up six cylinder engines is rare. The rod bearing s in this engine have more surface than a small block Chevrolet mains ! It can be fixed, but first.. Find out why before proceeding... it's got to have something to do with the oiling system.0
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Okay, I installed the oil filter canister pictured below and I started noticing the noise shortly thereafter. When I first put it on, I didn't tighten the top as much as I should and oil just poured out the top which indicated to me that the oil pressure was good. Now the oil is a lot cleaner and the idiot light goes out when it's running, so I don't know if putting the filter on created the problem or if it existed before I installed it. I have noticed a small amount of oil on the block in front of the starter where line from the engine goes to the bottom of the filter as shown in the second picture.0
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What oil did you put in the engine? Id think they would run best on a straight weight 30 detergent oil. If you drained out 50 year old nondetergent oil, and just started to use a detergent oil, the detergents in the oil are going to break down some of the sludge, which can clog the screen on the oil pump in a short period of time. A clogged oil pump screen will starve the bearings for oil, which will make noise, but it wont be immediate like your describing. How hard is it to pull the oil pan and check the main/large end rod bearings? I havent worked on any Hudson engines, but have a hundred plus small flat head engines. I always pull the pans off every engine I pick up and give it a thorough cleaning before running. Ive pulled apart some engines which have sat so long the paraffin oil turned into a sheet of wax! As others have said, there are no rockers, but how about the lifters, could a lifter be marred from sitting. Ive seen water cavitate lifters in other engines and when run, make a horrid noise. With the engine running, you should be able to hear where the noise is coming from. If the noise is spark related, it will change with rpm and the way you set the timing. Id definitely be cautious of running it much if you have a rod/main bearing issue.
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"Now the oil is a lot cleaner and the idiot light goes out when it's running......"
Does this mean that you ran it with the idiot light on?? If you meant for a few moments, then no matter, but if you drove it that way, I'd expect serious damage.
A bypass type filter will not affect oil pressure if it's plugged. It will have a slight effect on pressure when in operation but is inconsequential. By design, the system "waits" until the pressure is up to ~20 psi before allowing oil to pass to the filter. I'd never thought of it as an indicator of oil pressure, but the flow of oil from under the canister lid would indicate at least 20 psi since the system dis-allows flow below that pressure.
If it's knocking, deadline it! It won't heal.
F
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A deep knock tends to be lower end. A tap tends to be valve train. Please describe the noise and its source a bit more.
Get an underhood oil pressure gauge and install in place of the oil pressure sender, start it, and make sure youre getting decent pressure, ~40 psi when revving. If not shut it down immediately and investigate: pump, pickup, etc. But it won't be due to the oil filter system per se, unless you messed with the large diameter flat nut on the driver side near the oil filter, and removed the spring or piston, did not reinstall, therefore oil just leaves the pump and squirts back in the pan.0 -
Sounds like your mechanic knows engines. Sorry to say, but if he's right, the pan has to come off to check things. If it's a bearing, it's probably a rod. A new set is only $84 at Dale Cooper's. It's almost easier to pull the whole engine with tranny. Then it's out where you can get at it.
I'd check the main and rod bearings for scoring and clearance.
Once you get this engine clean and adjusted, it will outlast a Chivvy, and leave it in the dust as well.
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No. I didn't run it with the idiot light on.. Just because I mistakenly called a connecting rod a rocker arm doesn't make me that big of an idiot. Thanks for all the responses. I will check the oil pressure first chance I get and go from there.0
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Short out each plug in turn and see if you make the noise go away. That would be a start. it could be anything - a stuck valve, a piston collapsing, a bearing gone. a broken valve spring. You need to diagnose the problem. does it knock all the time, or only when accelerating, is it a heavy knock, a thumping, a tapping, a hollow knock? If it is in the valve train you will not bale to eliminate the knock, but most others can be detected by shorting out the plug on that cylinder. Just to be silly - I know one guy thought he had a bad knock, and it turned out to be the exhuast gasket gone on one flange. Good luck,Geoff0
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My take is it definitely needs some more troubleshooting. I can't hear it so I'm going with your mechanics take that it is a connecting rod. With the engine running I'd pull the plug wires one at a time(and replace) and listen for a change in the sound. This will narrow down your issue to a specific cylinder. If it does have a rod bearing in distress it should show up in the oil as metallic glitter. Also you should be able to disassemble the filter cartridge for a close inspection for metal. If you want to get really forensic you can easily send a sample of oil to a lab that will be able to detect specific bearing material. For my money the oil analysis is cheaper than a mechanics hourly labor rate and will tell you more than what he can troubleshoot/inspect in that time. Your problem could also be on the piston end of the rod or be a piston noise too. Neither of these issues would put any significant metal in the oil though. Just my take, I would narrow it down to a specific cylinder and do an oil analysis before I start paying to drop the oil pan or pull the engine. Also I would stick with the Hudson engine. There is value there when it comes time to sell and nobody is going to do a GOOD chevy swap for the money it will take to repair the Hudson motor. This coming from a guy that has hot rodded everything for the last 40 years. My 49 Commodore runs the later Hornet 308 but it is still basically the same motor as yours.
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OK.....I apologize for insulting you with the idiot light question but you must admit, you set me up with the "rocker arm" thing and the filter snafu. It's difficult to tell from here just how much you know.
Frank
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Hudson flat had engines (and all flat head engines) Do not have rocker arms. ........
A bit of side valve trivia. The Packard side valve sixes and eights of the 20s actually did have rocker arms down in the block. The valves were not directly above the camshaft, they were offset somewhat, and because of that there were rocker arms to transfer the vertical motion of the cam follower to the valve.
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Same with Rover and Land Rover F-head motors - the side valves were angled about 45 degrees, and had rocker arms.0
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Jason,I'm curious to know whether or not you have overdrive, and what speed you drive when taking trips. As Super Dave said, these cars don't have a reputation for loosening connecting rods. Perhaps the problem is related to high engine speed.Walt says that the oil pan can be removed, after removing the bolts and the clutch cover, by positioning the engine so cylinders #1 and #2 have their pistons fairly high up. The pan can then be pulled backwards until the front of it clears the cross member of the frame. If the loose rod is on the cylinders towards the rear of the engine, the crankshaft throw can be checked easily, and if OK, a new bearing insert installed.Per0
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Per,The car does have overdrive and the noise increases the faster the engine is run. I wouldn't even call the noise a knock, but more like a roaring sound when the car is being pushed.0
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Oh yeah, I forgot to mention that before the noise started, I would drive 60 to 65 mph on the interstate and did the speed limit (mostly 55) the rest of the time per my GPS. The car did great for two long trips of 1200 and 800 miles this summer and fall. It started making that noise and not pulling as well up hills about three weeks ago.0
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So Ken what is the cure? Will replacing the distributor fix it or is more involved than that?0
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Have you checked out my suggestion that it could be the exhaust gasket?0
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Agreed, crank-related problems do not roar. Get the sound isolated elsewhere if you cannot isolate it yourself. Will it do it at idle? If so a mechanic's stethoscope may be of help. Heck, a vacuum leak can affect performance and cause a hiss or other sounds of air movement. I'm feeling better about the motor as a whole, but you or a mechanic HAS to isolate the sound0
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Thanks guys. Not yet, Geoff, but I hope to have it checked out thoroughly in the next couple of weeks.0
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Ok, I just checked the oil pressure and it barely got over 25 lbs. even when the engine was revved up. When I told another old mechanic friend of mine about the oil pressure over the phone, he immediately mentioned the rod bearings as the culprit. I hope to get one more opinion from a guy on site that used to work on Hudsons in his much younger days. The irony of my situation is that the mechanic who rebuilt the engine nearly sixteen years ago said it would last a lifetime. It did...his. He died about three weeks ago at the age of 70....just before the noises started.0
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I don't believe we've determined if, in fact, that it's a rod knocking, but if you have pressure that low, I'd remove the pressure regulator bore plug (behind and below the distributor) and check to see that the spring hasn't broken. If it previously had reasonable O/P but dropped quickly, the spring may be the culprit. If, in fact the sound is a rod, then the damage is already done.
My opinion is that if it isn't knocking loudly on numerous rods, the low pressure isn't caused by excessive bearing clearance. The pump should put out a high enough volume at elevated rpms to keep up with bearing clearances that are not yet "talking to you". That leads me back to the spring being either broken or just very tired.
Question: Does it come up to the ~25psi fairly quickly but just not go any higher? or does it slowly progress to 25 over the entire rising rpm range. The former says "spring", the latter says "big leak", like wide bearing clearances.
Frank
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Goes quickly to the ~25 psi and stays there. Query: How hard is it to get a replacement spring?0
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Ok. in case I installed it improperly, I took the oil filter canister shown above off and cranked the car. It went to ~40 psi. However, the longer the car ran, the lower the oil pressure became and finally rested at ~25 psi. Is that normal? Somebody mentioned that I should be running 30W oil in that engine, but I've been running 10W40 oil in that car ever since I bought it.0
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Could be piston slap, if it was just re-ringed 15 years ago0
This discussion has been closed.
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