TR4/4A Engine Noise--Advice Please

[KVH]

I know; I'm hearing things again. My '66 4A

It's real. I just hope my questions make sense.

There's a distinct sound, like tappets, a slight knocking, and it gets louder and more persistent around 2000 RPMs. I'd hoped it would just go away, but today it was almost constant.

I got out my stethoscope and checked all over the engine. I can't seem to find it.

I adjusted the tappets last month, and they're right on. The rocker shaft seemed good, and the tappets didn't seem bent or cupped. It's not my fan belt, generator or fan--I don't think.

But: My stethoscope really knocked my eardrums when I put it on the distributor cap. Very loud, and that would be an easy fix I'd hope. When I rebuilt the engine 3 years ago I shimmed that gear in the distributor housing, and I hope I did it correctly. Could I just have a bad cap or rotor flopping around in there? The rotor looks fine "by eye."

One last question on this. While I'm fairly sure my timing is correct by static method, I'm puzzled by something I'd not noticed before. The vacuum unit (distributor alignment) is pointed "more in" toward the engine, rather than slightly out, away from the engine as I recall being the case for years in my old TR4, and as shown in most pictures of TR4 and TR3 engine bays. In other words, if the angle of the advance unit is a guide, it's off from the usual angel.

Is it possible I've got things way off in the way my distributor is set, and turned one lobe too far?

 

[sammyb]

I wonder if one of the weights in the distributor has come loose and is banging around? You could always mark and pull the dizzy and spin it by hand to see if anything (like the centrifugal weights) are flying around and bonking into the housing.

 

[TomMull]

Check the distributor / oil pump drive shaft. Mentioned in Roger Williams TR3 resto guide, don't know about the Tr4. Tom

 

[Geo Hahn]

..The vacuum unit (distributor alignment) is pointed "more in" toward the engine, rather than slightly out, away from the engine...

That position sounds right & is how I set mine based on the pic in the TR3A Practical Hints:

Certainly makes sense to open up the dizzy, check the cap for any signs of trauma or contact, wiggle the rotor/shaft looking for slop & removing the base plate to see if the weights move & return freely.

 

[TR3driver]

But: My stethoscope really knocked my eardrums when I put it on the distributor cap. Very loud, and that would be an easy fix I'd hope.

FWIW, I've seen one where apparently someone dropped the nut from the points into the works and left it there. Had to have made a lot of noise, but apparently no one heard it (or maybe the noise was the reason my buddy got a "good deal"). The nut had gotten jammed between the spring posts and body, pretty well ruining all concerned. Just something to look for, if the problem isn't obvious with the cap off.

Is it possible I've got things way off in the way my distributor is set, and turned one lobe too far?

I don't think there is enough room to turn it a full lobe (1/4 turn) in that direction before the vacuum unit hits the head. More likely I think, the cam gear is off by a tooth (or perhaps two). But it shouldn't be a problem as long as the timing is right and the vacuum unit isn't actually touching the head. If it ain't broke ...

 

[KVH]

Thanks for the advice.

I don't want to chase down one issue to the exclusion of something obvious. After all, the knocking last night at regular driving speeds was quite disturbing. Oil pressure and drivetrain seem perfect.

So, before I get into that distributor, I want to ask whether anything about the fan or pulley might be causing this. Or even the chain tensioner?

The sound has the rhythmic rattle of loose sheet metal, like a wobbling screw at the front grill; but it's not that. And, as I mentioned, it seems have worsened in recent days. That seems to tell me it could be something deteriorating or relating to the fan, pulley or chain. Would a broken chain tensioner cause these kinds of symptoms?

Also, I had the starter recently repaired. It works great, but could the drive gear in any way be interfering with the flywheel?

Anything about the front dog-bolt? I torqued it only to about 85 pounds three years ago--before someone here said 100.

 

[sammyb]

The most important thing in diagnosis is to identify the general area. If it is happening at idle and you can pinpoint it to the dizzy -- start there. If you rev it to 2000 and a different noise appears somewhere else, then you have two problems! Could it be the timing chain? It could - it's one of those "possible but not probable" things...and should be easy to isolate with your stethoscope on the timing cover. (Chains are not quiet -- even less so with slack on 'em!)

You might also just take five minutes to take off the valve cover, do a look-see of the health all the rocker arms/pushrods/springs and put the cover back on.

A lot of diagnosing noises that are repetitive is in determining the frequency. Calculate if it is the frequency of one cylinder/dizzy rotation vs a fan or wheel rotation. If it gets faster in relation to engine speed vs staying the same... Again, you could have multiple sounds competing, but do your best to isolate.

 

[sp53]

Have you ran it without the fan belt to see if it is the generator? Or just loosened the belt enough to feel the pulley and the fan dealie behind it for wear.

 

[DanB]

Timing chain tensioner will make a noise like that if it's broken.

 

[Geo Hahn]

I will be having an espresso at the Starbucks on the NW corner of Speedway & Wilmot tomorrow morning at 5:15 if you want to bring it by for a 2nd (and 3rd) opinion.

 

[KVH]

I will be having an espresso at the Starbucks on the NW corner of Speedway & Wilmot tomorrow morning at 5:15 if you want to bring it by for a 2nd (and 3rd) opinion.

I'd love to, but I'm afraid to drive it after the last rattling drive I had.

I'm going to pull the distributor and look at the oil pump shaft drive rod. Any idea what I should be looking for there? I remember carefully checking the end float, but who knows.

 

[mt10flyer]

Here is a link to my tensioner issues. It basically sounds like a light rattling when the tensioner has failed. It gets flopped around by the timing chain and can wear a hole in the cover or even through the front plate. But, all things beings equal it is an easy fix. The tensioner I ran from TRW is hanging in there so far, but I went through 3 from Moss in short order.


https://www.britishcarforum.com/bcf/showthread.php?91745-Timing-Chain-Tensioner-1959-TR3

 

[TR3driver]

I'm going to pull the distributor and look at the oil pump shaft drive rod. Any idea what I should be looking for there? I remember carefully checking the end float, but who knows.

The end float would be for the gear that drive the oil pump, distributor and tach. Although I doubt the shaft is the problem, I would check the tab at the oil pump end for damage. I had one break there, lotta years ago. You could also check that it is a reasonably snug fit in the bushing through the block, and inspect the bushing for damage (perhaps from insufficient end float on the gear )

 

[KVH]

The end float would be for the gear that drive the oil pump, distributor and tach. Although I doubt the shaft is the problem, I would check the tab at the oil pump end for damage. I had one break there, lotta years ago. You could also check that it is a reasonably snug fit in the bushing through the block, and inspect the bushing for damage (perhaps from insufficient end float on the gear )

All measured. I've got about .007 end float. I have to say, that method in the Manual is crude because when the pedestal is put back in over a washer, the fit is a bit imprecise and by tightening the nuts on the distributor pedestal I was able to get different clearances between the pedestal and the block--in fact, leading up to .009 end float, but I don't know what I can do about that. My oil pump/distributor shaft does not seem worn, not does the bushing face. Also, there's no side play in the bushing. It's tight. Anyway, I'm living with it unless someone knows of great peril.

 

[KVH]

Just an update. Runs and starts great with my new distributor cap, plug wires, and rotor, but I'm hearing that clack every second or so, then it stops and starts again. Sounds like under the valve cover, so I'm pulling that one more time. There's got to be something there.

The generator, fan belt and pulley all look fine, and my handy Harbor Freight stethoscope (recommend by Dr. Hahn) tells me there's nothing wrong inside the timing cover.

I'm having fun, though; that's for sure.

 

[karls59tr]

I had a similar tappet like knocking sound on my TR3 years ago. It turned out to the " keyway" in the fan pulley having worn to the point where it was over an inch wide and that was creating the knocking. Have a good look and see if that pulley is moving back and forth creating the noise.

 

[KVH]

Have a good look and see if that pulley is moving back and forth creating the noise.

I'm stumped. As best I can tell, it knocks most at about 2000 rpm. Sounds like rapping a spoon on a hollow porcelain cup. It's also not unlike "pinging" from poor timing or bad gasoline. I actually gets quite loud.

I'm going to remove the fan belt and check both the water pump pulley and the crank pulley. I do definitely recall that the key way on my new water pump (1 year old) was not snug. I figured the locknut on the pulley face would be good enough.

If I pull the valve cover, any harm in running the engine without the cover so I might see if something's wrong there?

I'll report back my findings, and if any of the above brings any thoughts to mind, I'm all ears.

 

[glemon]

If I pull the valve cover, any harm in running the engine without the cover so I might see if something's wrong there?

Should not do any harm running with the valve cover off, it will usually throw little droplets of oil around, you can either throw out some towels around the engine compartment or wipe things off after, friend recently had a sticky lifter (in a Sunbeam Alpine) that made a godawful knocking noise, ran with some engine flush then changed the oil and it went away. Doesn't sound exactly like your problem, but who knows?

 

[Geo Hahn]

As noted awhile back here -- if it is a valve or valve train noise it will occur and half the beat of other noises.

Did you ever remove the base plate from the distributor and inspect the weights? Just 2 small screws to take the plate off -- but don't let them drop in (voice of experience).

Sure you can run it with the valve cover off -- fun to watch all the action. I recall seeing someone fix a stuck valve by smacking it with a hammer while watching the valve train operate. Some even adjust the valves (by ear) with the cover off but they're just showing off.

 

[TR3driver]

Sure you can run it with the valve cover off -- fun to watch all the action.

I make it a part of my regular PM routine, but generally I only run long enough to see that oil does flow to all the rockers. It takes a surprisingly long time for that to happen though, several minutes. Although it's never happened to me, I've seen other TR engines where the rocker shaft got plugged with oil sludge.