| wattagan | -- 02-07-2010 @ 1:32 AM |
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Hi all, Just joined your forum in the hope someone can help me decide whether to replace bigends or not. 38 Ford truck engine (21 stud) runs nicely and pulls well. Bit of blowby and not much oil pressure when hot. Has 50psi cold though. As revs rise at say over 2000 there is a clicking/ticking/clacking sort of noise and it gets worse are revs rise more. If it's a conrod then it's only one because there is only one noise per rev. Some time ago I had the sump off and wiggled all the bigends and could find no perceptible movement in any of them. Especially not one bad one. So, the question is. 1/. How long is it going to hold together if it's a bigend 2/. Could it be something else ? I did just replace front universal which was worn in the hope it was that as it sounds a bit like one but it's actually at engine speed not road speed as it happens over 2000 even in 3rd gear. I don't use it much and don't plan to so hoping I can just live with it ???
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| supereal | -- 02-07-2010 @ 12:07 PM |
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A loose rod will be evident as a hard knock, not a clicking noise, particularly before the engine is warmed up, and at much lower revs than 2,000. If it is a drive line noise, it should disappear, or at least quiet down when the clutch pedal is pushed down. The only way to know if you are headed for bearing failure is to pull the pan and check bearing clearances with PlastiGage. I suspect your noise is not a rod, but something else, such as a valve, valve spring, or keeper, from your description. If it is actually a bad lower end bearing, it will get worse soon, and must be fixed to avoid the possibility of destroying the engine. A quick check for a loose rod is to pull the spark plug wires one at a time and listen for the noise to quiet or quit as you rev the engine.
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| 37RAGTOPMAN | -- 02-07-2010 @ 2:51 PM |
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hi have the engine running raise the RPM till you hear the noise,have a friend, hold the engine at a steady RPM with the engine running, disconnect one plug at a time, if the noise goes away, this might tell you which cylinder CONNETING ROD is making the noise, if the noise is still there, it is something else,the ticking noise could be a timing gear,or in the valve train, also if you drive up a steep hill in high gear, does in make more noise or less ? let us know what you find, the more info we have, will help us and you, hope this helps 37RAAGTOPMAN
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| trjford8 | -- 02-07-2010 @ 7:31 PM |
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I suspect it's the fuel pump push rod.
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| wattagan | -- 02-08-2010 @ 2:03 AM |
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Wow thanks for all the responses. Now let's see. The noise is not evident when just running the engine in the shed. I have a hand throttle and can set it at anything up to 3000 and can't notice the noise. When driving it's ONLY on light throttle. Noise disappears on accelleration or climbing a hill and also on overrun ie with the pedal lifted going down hill. Noise returns when travelling on level at light throttle just to maintain speed. I have just replaced the timing gear so had all the valve train out then so doubt it's valve related. Cam bearings were very good as were followers and springs etc. Also it's not a half engine speed noise it's pretty well once per engine rev. As trjford8 suggests it's not the fuel pump pushrod because I use an electric pump and have removed the pushrod and blanked off the hole to retain oil pressure. In response to supereal, it's not a hard knock like is normally associated with bigends but then its not a light ticking like from valves (and not at half speed) Hard to describe. More like a rattle really.
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| TomO | -- 02-08-2010 @ 6:33 AM |
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The noise could be pre-ignition. Try turning in the screw on the vacuum brake. Count your turns, so you can return it to the original setting if it doesn't cure the problem. If it doesn't go away within 3 turns, go back to the original setting. I would also try removing the fan as that can be a source of noise. Look around the engine compartment in the area of the water pumps and radiator for signs of interference between parts. Tom
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| 37RAGTOPMAN | -- 02-08-2010 @ 6:38 AM |
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HI wattagan Try taking the ignition wires off one at a time,if knock is less or cannot hear it,that is the one making the noise, low oil pressure could cause this,maybe the oil pump is worn,? causing the rattle in the rods, drain the oil look for silver particles,this might give a indication that the rods are loose,also check the pistons from down below looking up , see if any cracks in them,,use a good flash light, now you can pull the oil pan base, and check the rod bearing on that cylinder.INSPECT Try moving the rods on the crank before removing them,do one at a time and mark them,before removing, I use a center punch, 1 mark is number one,do top and bottom, on rod,on the cap and on the rod, 2 punch is number 2 and so on,make the marks all on the same side of the rods, SO YOU KNOW were they GO, let us know what you find, remember if it is a rod and it lets loose it could take out the block,when it does, hope this helps, 37RAGTOPMAN
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| supereal | -- 02-08-2010 @ 10:23 AM |
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Before you tear down the engine, it is important to locate the source of the sound. As it appears when the car is coasting, or with little power applied, but not just running in your shed, it could be in the drive line. Diagnosing problems without "hands on" access is mostly just guesswork under the best of circumstances. Most of us "old timers" try to relate the description of the problem with our own experience to suggest a "cure", and many times it isn't helpful. If you have a sturdy, reliable set of jack stands, I'd put the car on them with all wheels off the ground, and run it while checking for the noise. A stethoscope or long rod held to the ear as you probe various sections can often isolate a noise while a helper varies the speed of the engine and driveline. Noises "telegraph" through the metal, and often are found in odd places. Just be careful while you have the car elevated.
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| supereal | -- 02-09-2010 @ 11:23 AM |
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Also, check the exhaust system to see it it interferes with the frame when the system is hot. We had one that knocked when it was hot and the pipe expanded. As the engine shifted on its mounts, the noise changed. It did mimic engine noise, and was tough to find.
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