Obsessed with a knock - pics, vids. (1 Viewer)

Joined
Mar 21, 2011
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West GA
disclosure: I obsess about my fj40, ask my wife, and I am by no stretch of the imagination a mechanic. I can't help it, I want to know what sound is where, why; and how, if needed, i should fix it. What I know about my truck is from what I've read, what I've watched others do, and the occasional light weight tinkering in the garage. With that being said, thank you for any advice. The purpose of this thread is to document, however long it takes, the process in which i will locate and hopefully resolve my fj40s engine noise.

I've been reading everything here about knocks, ticks, oil pressure, maintenance, etc. ever since I started hearing a slight knocking sound from my 40. I've owned her for 5 months or so and can not remember a time when I did not hear what originally sounded like to me, well, what I thought most old engines probably sound like. I didn't think that it was an issue until a mechanic friend of mine mentioned it.

Background:

  • My 40 is my DD, currently drive her 20 miles a day on average. Few weekends a month I make a 100 mile round trip to a handful of parks where I moderately wheel with the family. I'm that guy that looks forward to going to work every morning because he gets to drive a fj40.
  • '77 original 2f, 75k on the odometer but I'm guessing it's 175k
  • Bought her in Calif and drove her back to GA (hell of a trip).
  • Recently performed complete de-smog, new headers (had a good exhaust leak or two) and cleaned up the carb (not rebuilt). I also added the petronix ignition system. Did all this at once and I'm guessing a 25-30% increase in power: take-off, pull, etc. It still amazes me how many ponies I was missing; no more down shifting going up hills. In short, the truck runs great.
  • She leaks more than I'm comfortable with. The obvious is from the e-brake drum, the not so obvious could be oil pan gasket or somewhere below the oil cooler thingy.
In an attempt to locate the sound, to date, I've purchased the probe and audible cone stethoscope. After lots of listening, I am still not certain but the sound is loudest around the oil pan and between the oil pump and the starter.

Thinking the first step would be to verify the oil pressure, I just installed an autometer oil gauge, t-d off to run both new and old sending units. Here is what I got after finishing an hour ago:

first pic is at cold start idle autometer:


http://imageshack.us/a/img854/9787/coldstartidle.jpg

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second pic is cold start idle oem gauge:


http://imageshack.us/a/img825/5174/coldstartidleoemgauge.jpg

Uploaded with ImageShack.us


third pic is warm idle autometer


http://imageshack.us/a/img543/2029/warmidle.jpg

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fourth pic warm idle oem gauge


http://imageshack.us/a/img13/7971/warmidleoemgauge.jpg

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The warm pic oem is what scared me. The tack will drop a hair below the first hash mark when running at cruising speed - 55mps 2700 rpm. But I actually feel better about the pressure now after seeing the autometer's readings.

What you guys think? Is this pressure acceptable? Or is it low?

Lastly, the video was from warm idle as well.

http://www.youtube.com/watch?v=24GKK37kYnk&feature=share&list=UL24GKK37kYnk

I now have the e-brake kit, shoes, speedy sleeve, gaskets, etc., so the next steps will be to diagnose and fix all the oil leaks and see if that has any measurable impacts to pressure. I'll start this weekend.

Next will be....? Oil pump? Fuel pump? Remove pan and take a look? Not sure I know what I'm looking for.....hell, maybe I'm over thinking all of this and should stop spending money, drive and enjoy.

Thanks for reading.
 
Joined
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Oil pressure looks good. Don't worry about the stock gauge, they suck. Have you tried removing the fan belt and running it for a minute? I would do that just to remove any possibility that it could be a water pump, fan clutch, alternator, smog pump etc. Next would be a valve adjustment. only after all that checks out would I start getting worried. If you hit that point, I'd drop the pan and inspect the rod bearings. Also, I have heard of, but not personally experienced, a clacking noise coming from the timing gear. Maybe someone else will step in on that. Good luck!
 
Joined
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thanks for the comment, I have not thought about temporary running the engine minus the fan belt, but I'm going to give it a try.


side note: Not sure its an indicator, but I forgot to add that I do not hear the knocking sound until after she warms up.
 
Joined
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dose the "knocking" get louder as u rev it? if so dose it sound like a "crank speed knock" or more of a "cam speed knocking"?


BTW a cam knock will be slightly slower then crank
 
Joined
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Your oil pressure looks fine. Oil pressure a little higher when cold and thick.

You should start by adjusting your valves, though.
There is no better way to become one with the sounds of your engine.
This may or may not be the source of the sound you hear but nothing but good can come of it.
It will run better and sound better.
 
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Joined
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Thanks for reading guys, this helps.

I do not hear a knocking at higher rpms or when revving the engine. The additional engine noise either blocks the sound or it goes away.

I'll read up on how to adjust valves. I was just about to buy an oil pan gasket, guess the valve cover has one too? I'll search.
 
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Trust me. Start with the valve job (and valve cover gasket).
It's easy and can be the source of a lot of knocking noises in engines.
Doing it and seeing the results may motivate you to move on.

Oil pan gasket can be the fix for a lot of leaks but it is messy and time consuming to get it right. If you've got noises coming from your bearings down there, it's probably not something you're going to fix yourself as a noob, Valves, alternator, water pump, fan clutch...hope your noise is one of these as these are simple fixes.
 
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bonehead of me but I forgot to mention another symptom that may or may not have to do with the knocking.

My 40 has a hum vibration that pulses in and out in rhythm that can be felt in the floorboard and heard when driving or revving between 2k and 2500 rpms. It is not loud, it's a hum.

This sound/vibration does not occur during idle. I can duplicate this vibration when she's cold or warm, clutch depressed or not. My reading leans me towards the harmonic balancer.
 

kurtnkegger

Running Topless and Dirty
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Trust me. Start with the valve job (and valve cover gasket).
It's easy and can be the source of a lot of knocking noises in engines.
Doing it and seeing the results may motivate you to move on.

Oil pan gasket can be the fix for a lot of leaks but it is messy and time consuming to get it right. If you've got noises coming from your bearings down there, it's probably not something you're going to fix yourself as a noob, Valves, alternator, water pump, fan clutch...hope your noise is one of these as these are simple fixes.

^^ This ^^

Also check your rocker supports and see they're tight. You will get a decent knock from a loose support.
 
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i think i can hear the lifters in your video, and they sound normal, or maybe slightly loose, so adjusting them would be a good thing.
your oil pressure is good, but what is it when the engine is at 170 plus degrees?
removing the fan belt is ok, BUT!, don't run it for more than a minute, or less! without the water pump working, else you could cause very severe damage to the engine.
you said the knock sounds loudest noise comes from the oil pan...well, hate to say it but that sounds like it could be a rod or main bearing... if it is, and it isn't promptly replaced, it won't be long before the crankshaft might break. anytime i have to replace mains and rod bearings, it's usually time to go ahead and overhaul the engine.
 
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One more option it could be - mechanical fuel pump. As the lobe on the cam gets worn, a space develops between the arm of the fuel pump and the cam. It can make a slight knocking sound. Its hard to tell from your video. However, since you say you can't hear it as you rev your engine, that tells me it is not a rod knock as a rod knock will get louder and faster as the engine revs. If you end up dropping the oil pan to check bearings, you can check the fuel pump / cam as well.

Good luck!

:cheers:
 
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As mentioned above, the first and easiest thing to do is determine whether the knock is running at the cam or crank frequency. Put a chalk mark on the crank pulley so you can watch the crank revs while listening. The cam runs at half the speed of the crank. That will narrow down the possibilities a bunch.
 
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West GA
Thanks for all the comments.

i think i can hear the lifters in your video, and they sound normal, or maybe slightly loose, so adjusting them would be a good thing.
your oil pressure is good, but what is it when the engine is at 170 plus degrees?
removing the fan belt is ok, BUT!, don't run it for more than a minute, or less! without the water pump working, else you could cause very severe damage to the engine.
you said the knock sounds loudest noise comes from the oil pan...well, hate to say it but that sounds like it could be a rod or main bearing... if it is, and it isn't promptly replaced, it won't be long before the crankshaft might break. anytime i have to replace mains and rod bearings, it's usually time to go ahead and overhaul the engine.

The second set of pics in the OP were after running up and down the highway for 20mins, I was idle at running temp.

And the Main/rod bearings is my biggest fear and I’ll start picking away at the obvious, first. Tomorrow will include dropping the fan belt for a quick listen, e-brake rebuild (unrelated), and a valve adjustment. Local ATL crew will do the adjustment so I’m looking forward to the experienced advice.

One more option it could be - mechanical fuel pump. As the lobe on the cam gets worn, a space develops between the arm of the fuel pump and the cam. It can make a slight knocking sound. Its hard to tell from your video. However, since you say you can't hear it as you rev your engine, that tells me it is not a rod knock as a rod knock will get louder and faster as the engine revs. If you end up dropping the oil pan to check bearings, you can check the fuel pump / cam as well.

Good luck!

:cheers:

If the sound doesn't stop after the valve adjustment, I was thinking of replacing both the oil and fuel pumps. I won't be able to afford this immediately, but it does seem the logical next step.

What about the dizzy? Can it knock? The sound does come from that general area.
 
Joined
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As mentioned above, the first and easiest thing to do is determine whether the knock is running at the cam or crank frequency. Put a chalk mark on the crank pulley so you can watch the crank revs while listening. The cam runs at half the speed of the crank. That will narrow down the possibilities a bunch.

Will make sure this is measured tomorrow.

And thanks for the input, a lot of what I've learned here on MUD about knocks has come from your prior posts (years of it).
 

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