Help me diagnose this engine knock before I pull the pan!

[eviction_party]

The engine in our '71 makes a rattle/tap/knock -- sometimes at idle, sometimes only when returning to idle after being reved up -- and I'm trying to do some tests before pulling the oil pan and inspecting the rod bearings. So far, I've pulled the plug wires one-by-one and couldn't tell a huge difference. Removing the cylinder 1 wire changed the noise some, but it was still there. I poked around with a stethoscope and it sounded the clearest when touching the front of the block, ahead of the passenger side motor mount. Just yesterday, I replaced the old 32/36 with a broken water choke with a manual choke 32/36 and it might be a bit less noticeable, but still there.

 

I've got a video below. You can hear it the clearest between 0:02 - 0:04 and 0:21 - 0:23. I also have a very squeaky distributor!

https://youtu.be/yaRPmtEHzjQ

 

What else would be useful to check before pulling the oil pan? 

 

some history on the car + motor: it was sitting for a very long time, last registered in 1988. I got it running, found a hole in the head that was spraying coolant on the timing chain, replaced the head, and am now trying to diagnose this noise. No real driving on it yet, just some short test drives. 

['76mintgrün'02]

50 minutes ago, eviction_party said:

I also have a very squeaky distributor!

 

Put some grease on the center post!  If you don't keep the points' rubbing block lubed, it will wear out the lobes on the center post and they're not available as separate parts.

 

That noise could be a slapping oil chain, or timing chain.  Mine has made a similar sound since I bought it ten years ago.  I am not telling you to ignore your noise, but I accept mine as a "feature".  It is intermittent on mine and only at idle.

 

Paul Winterton has posted a photo showing where the chain was slapping in one of the engines he had apart.

 

It'd be nice if that's all it is.  I think you might be able to shim the oil pump to tighten the chain.  The noise doesn't bother me enough to go through all that.  Yet.

 

Edit--  grease on the post also keeps the rubbing block from wearing down.  As it wears, the dwell angle increases, which retards the timing.  A nice smooth shiny center post that is well lubricated will help keep your timing in tune.  Hopefully you have a dwell meter for maintaining points.  Feeler gauges are okay for the initial setting, but not good for checking/maintaining dwell.  While you are in there, pull the felt plug out of the center post (under the rotor) and put a few drips of oil inside.

 

Tom

Edited July 25, 2021 by '76mintgrün'02

[eviction_party]

On 7/24/2021 at 6:49 PM, '76mintgrün'02 said:

Put some grease on the center post!  If you don't keep the points' rubbing block lubed, it will wear out the lobes on the center post and they're not available as separate parts.

 

I thought I had greased everything when I partially disassembled the dizzy to free up the vacuum advance -- but I guess not!

 

On 7/24/2021 at 6:49 PM, '76mintgrün'02 said:

That noise could be a slapping oil chain, or timing chain.  Mine has made a similar sound since I bought it ten years ago.  I am not telling you to ignore your noise, but I accept mine as a "feature".  It is intermittent on mine and only at idle.

 

Paul Winterton has posted a photo showing where the chain was slapping in one of the engines he had apart.

 

I've seen at least a similar picture... we'll see what it looks like when I pull the pan.

 

Planning some work today: adjusting the valves again, checking the timing chain, greasing the dizzy, then re-do the ignition timing and poke around some more for noises while running. I've been told it also sounds like it could be a leak at a header flange, so I'll try and look for that. Oh, and measure the oil pressure with a test gauge. Then I'll pull the pan!

 

 

['76mintgrün'02]

All I am suggesting is a little dab of stiff grease under the points' rubbing block.  Let's see if that stops your squeeeek.

 

Have you confirmed that the advance pod is still functional?  I wonder if a ruptured diaphragm could make a high pitched sound.

 

Do you have a fancy light with which to set the timing?  One with variable advance?????  Do you have a dwell meter?

 

You need to lift the engine a bit, to pull the pans in these cars, no?

 

Have fun and take photos!

 

Tom

[jimk]

25 minutes ago, eviction_party said:

I thought I had greased everything when I partially disassembled the dizzy to free up the vacuum advance -- but I guess not!

The center post/advance is to have a drop or 2 of oil too.

[PaulTWinterton]

There are instances where peripheral devices knock or screech if they are defective or loose.  I would do a short test, running the engine without the fanbelt.  That eliminates the alternator and water pump as culprits if the noises persist. 

 

The oil pump chain noise is a rattle usually only audible at idle and on decel.

[Buckeye]

On 7/24/2021 at 9:01 PM, eviction_party said:

replaced the head, and am now trying to diagnose this noise. No real driving on it yet, just some short test drives. 

Did you fill the pocket near chain tensioner piston and depress the cutout end of piston? Basically, that piston needs to bleed to remove air. 

Confirm piston cutout end is engaged to the chain rail

Confirm chain tensioner ball (check valve) is free and rattles when is shaken.

 

Edited July 26, 2021 by Buckeye
.

[eviction_party]

2 hours ago, Buckeye said:

Did you fill the pocket near chain tensioner piston and depress the cutout end of piston? Basically, that piston needs to bleed to remove air. 

Confirm piston cutout end is engaged to the chain rail

Confirm chain tensioner ball (check valve) is free and rattles when is shaken.

 

Yep -- i did all this when I replaced the head. The chain tension is good. But I didn't have the lower timing cover off, so maybe the guide is damaged.

 

3 hours ago, '76mintgrün'02 said:

Have you confirmed that the advance pod is still functional?  I wonder if a ruptured diaphragm could make a high pitched sound.

 

Do you have a fancy light with which to set the timing?  One with variable advance?????  Do you have a dwell meter?

 

I just greased the dizzy cam and dropped some oil down the center where the rotor goes. I don't have a felt pad there. It does look like the pod isn't holding vacuum though! Once I finish adjusting the valves and start the engine, I'll see if the squeaking still exists from the dizzy, with the advance vacuum line both connected to the intake manifold and then plugged off.

 

Just a plain timing light at the moment! I still need to pick up a dwell meter.

[eviction_party]

4 hours ago, '76mintgrün'02 said:

All I am suggesting is a little dab of stiff grease under the points' rubbing block.  Let's see if that stops your squeeeek.

 

Squeeeek is gone -- thanks Tom! 

 

Even though the vacuum advance pod isn't holding vacuum, it doesn't seem to be causing a vacuum leak... pulling off the hose at the manifold makes the idle rise (running rich at the moment, engine not fully up to temp). And then Idling the engine with the vacuum advance connected sounds the same as idling with the vacuum advance disconnected with the port plugged. 

 

Adjusted the valves -- 3 intake valves were too loose, 1 exhaust valve was too tight.

 

With the squeak out of the way, I poked around again with my stethoscope. I got one that has both a mechanical probe and a funnel sound probe. Found an exhaust leak down at the collector flange right away but couldn't hear anything up around the flanges connecting to the head. Using the mechanical probe, the noise was most noticeable when poking the upper timing cover. Sounds as if the timing chain guide is damaged maybe? Like a chain link is smacking against something, but the timing suggests it's not every link, so maybe the master link? I'm going to pull the valve cover again and see if the master link is damaged at all.

 

 

['76mintgrün'02]

You're welcome.

 

Which distributor do you have?  Is it vacuum advance, or retard?  Is it connected to ported, or manifold vacuum?

 

I may have mentioned this in a post or two previously, but I highly recommend the INNOVA 5568 timing light with a built in dwell meter/volt meter/tachometer/and variable advance.  They were $110 delivered from Summit Racing last I looked.  That is money well spent! 

 

Tom

 

[Buckeye]

15 hours ago, eviction_party said:

Using the mechanical probe, the noise was most noticeable when poking the upper timing cover. Sounds as if the timing chain guide is damaged maybe? Like a chain link is smacking against something, but the timing suggests it's not every link, so maybe the master link? I'm going to pull the valve cover again and see if the master link is damaged at all.

From I witnessed here, it is usually the left chain rail gets worn out. While you have valve cover off try to pinch timing chain at the bottom of sprocket and pull the chain at top of sprocket to see how much chain is stretched.

 

Oh BTW, pictures would be a + for us to help diagnose. 

[eviction_party]

4 hours ago, '76mintgrün'02 said:

Which distributor do you have?  Is it vacuum advance, or retard?  Is it connected to ported, or manifold vacuum?

 

 

The car currently has a 0 231 115 081 distributor with vacuum advance (that doesn't look to be holding vacuum). The old carb that came on the car had a broken nipple for ported vacuum, so the dizzy was connected to intake manifold. With my new 32/36 I now have both options.

 

I borrowed a spare 0 231 115 071 dizzy from my neighbor -- this one has a working vacuum advance. 

 

 

Here's the play in my timing chain, too.

Edited July 27, 2021 by eviction_party

[eviction_party]

OK, I pulled the pan! Wasn't too hard after figuring out how to support the engine. Found some bearing material stuck to the oil pump -- bad sign. I snuck out after dinner to pull the rod cap for cylinder one... not looking great!

 

I should have time to check the other bearings tomorrow, but from this it looks like the PO must've drove this with coolant in the oil for longer than they should've.