I recently rebuilt the 390 in my 1966 Ford Thunderbird (note for the police, the basic body style and mechanicals date to 1964 or earlier) and had it running. We had a very intermittent knock at first, which then went away. It came back today, and knocks pretty consistently. I originally thought that it may be a wrist pin, but since it got worse I am unsure. Help?
Knock, knock, knock. Used to tick before rebuild, did after rebuild too. Has probably 3-4 hours, 12 miles run time on it. Oil pressure was a higher than before rebuild.
There are a few things that will cause a knock and none of them are good. Make SURE the flywheel, torque converter and bellhousing bolts are tight. If all that stuff is good, drain the oil and look at a sample in the sunlight. Good luck, I hope it is something simple. -Abone.
More likely rod , drop pan and check , might be able to get away with Emery cloth the journal and oversize bearing, A lot of things can be done but someone with a know how experience ,hands on
When you say rebuilt , was it built by a machine shop , all new everything etc? Or refurbished at home? New rings bearings and cleaned up? Makes a difference. A low slow constant bang like a hammer on an anvil is bottom end More of a quick hammer hit on steel is piston or wrist pin A “ rattle” type noise that speeds up is usually valve train. I had a torque converter that was loose sound like a bottom end knock, have seen crank pulleys and balances come loose and make noise Get a automotive stethoscope ( cheap) and see if you can pin point where the noise is coming from before a full tear down Really hope it’s something stupid Keep us posted
@VANDENPLAS can you expound a bit on the loose torque converter? Ours popped out when intalling the engine, we just pushed it back in. The rebuild was machined at a shop, and we ***embled it there under supervision.
I mean, the flywheel had 2 nuts on the converter when someone helping me let up slightly on the hoist. The engine swung towards the front of the car and pulled the torque converter out of the bellhousing with it. It’s at idle, but we do idle high.
Hi Clay- I had a similar issue on a Big block Chevy and it turned out the 1968 harmonic balancer was wore out. You couldn't tell by looking but the outer ring delaminates from the inner ring and the firing pulses at idle would create a knock sound. Put a new balancer on and it cured it. Good luck, and let us know what you find! Matt
Retightened torque converter bolts. Not as deep now, back to intermittent. Suspecting top end, probably push rod
I had a rebuilt 400 turbo on a 472 Cadillac engine with a new aftermarket torque converter. When the car first started, like the first 20 seconds or so it would knock. Turned out that the stock converter to flex plate bolts bottomed out against the converter just before they were tight. So the bolts were tight, but were not clamping the converter to the flex plate. I put in shorter bolts and that stopped the knock.
Clay it’s kinda hard to diagnose a sound with out actually hearing it... but I will tell you of an experience we had with my buddies ot car back in the sixties. He overhauled his 289, under a tree, rings bearings, hone, ground the valves, new oil pump. When he started it it sounded like a rod knocking. Pulled the pan again, checked everything. Asked a bunch of people.... everybody said it’s a rod, even drove it to shops. Then he found out if he tighten this piticular rocker arm the noise would go away , but come back. It also would kinda come and go. Still everyone he asked ***ured him it was a rod and he problaly wouldn’t make it home....... So we drink some beer.... he has an idea...... we take the car to the highway, he puts in in low gear (289-2 V-3 speed) and puts it on the floor for about 4 miles. He pulls over, noise is the same.... he says” I guess it’s not a rod”. He drove it that way till he traded it. No recommending you do this, but sometimes sounds can be misleading. Bones
We had that intermittent noise in a 390 after the trans and engine were rebuilt. I lived with it for 5 years. I pulled the engine and trans after I wrecked the car. There was a hairline crack that connected all of the flex plate bolt holes. I got another plate. Noise was gone. If you use a broom handle against your ear and touch it to different spots on the engine, you can isolate the noise. Sent from my LG-H830 using The H.A.M.B. mobile app
With me the torque converter bolts were looses on the flywheel You saying the torque converter came out and you pushed it in It may have come off the splines and you could of crushed it back into the pump The first thing I would do it unbolt the converter from the flywheel and then run the engine and see if the noise goes away
Just listened to your video, had some International trucks back in the day with Allison’s in them, the flexplate that connect the crank to the torque converter was cracked. Sounded kinda like that. Bones
I have seen this happen 3 times in all the time I’ve been around cars 1st time on an 80’s auto 5.0 L mustang, torque converter not in all the way, forced trans together broke broke the mains in the engine and pushed the fan into the rad ( tech noticed a coolant leak from upfront) 2nd at jaguar same thing torque converter not in “ all 3 notches” tech somehowfirced it together, car ran and drove but had codes and engine light on. On removal found the torque converter snub bent and looking in the pump could see not niceness 3rd time on a ford pickup mid 80’s F150 tech forced it together and went to start it, making all kinds of horrible noise Pull your inspection cover and unbolt the torque converter it’s quick work and will eliminates all that stuff. Then go to harbour freight and buy a stethoscope for listening to engines to pinpoint noise The video is good but sound is different over a phone,the internets and then back through a phone. Sorry clay
One of these guys, heck even a long screwdriver or prybat held to your ear and at different spots on the engine will work, the stethoscope is just easier
A simple piece of hose works well to isolate sounds. Hold one end to your ear and place the other ends at different places around the engine/bell housing, find where the noise is loudest.
I agree that either the TC is not totally into the pump or the flex plate is cracked. It may have cracked from the TC being too far forward when it was tightened up. The noise does not sound engine related.
Hard to tell when you are not standing there in person, but that does not sound like a rod knock. A rod knock is usually easiest to hear when you lightly rev the engine and let off the throttle. Kind of a vroom, knockknockknock. Unbolt the torque converter from the flywheel and see what happens. -Abone.
By the sound of video , automotive stethoscope is going to be a big help / start to narrow down location of the sound , then go from there , put on a jackstand chalk the wheels use a creeper start probing
Whan I was a young lad,bout 45 years ago, i cheap built a 250 chevy 6 that i both overhoned one cylinder and wire brushed the carbon off the pistons with a bench grinder wire brush. Long story short, ended up with piston slap that caused a constant and steady knock. Bad juju
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