Heavy Tapping low in the Engine

[Patrick67BJ8]

Can I assume that you checked the harmonic balancer? The woodruff key can be worn causing some play. Also check to see the rubber seal on it hasn’t delaminated. Loose crank nut?

 

[RAC68]

Hi Patrick,

No, thank you for bringing up that possibility. As mentioned, the tapping is regualr and seems singular and has not been deminished when disconnecting the spark plug wires, one by one. Although pulling the engine and doing a full rebuild would probably eliminate the problem. However, this would be an extended expense I don't feel would be needed on an engine performing so well. Although the tapping appears low in the engine, we all are aware that sounds emitted from the engine are not always located from where they appear and, as Patrick's suggestion indicates, could be caused homed somewhere different. This is a regular tapping, not to different from a valve tapping but the sound appears to be coming from lower on the engine and not the valve train. So, what else could this be causing this tapping?

We appreciate all the comments as this issue has stopped the use of a recently completed Healey by its owner for his fear of having a catastrophic engine development.

Ray(64BJ8P1)

 

[Patrick67BJ8]

Hi Patrick,

No, thank you for bringing up that possibility. As mentioned, the tapping is regualr and seems singular and has not been deminished when disconnecting the spark plug wires, one by one. Although pulling the engine and doing a full rebuild would probably eliminate the problem. However, this would be an extended expense I don't feel would be needed on an engine performing so well. Although the tapping appears low in the engine, we all are aware that sounds emitted from the engine are not always located from where they appear and, as Patrick's suggestion indicates, could be caused homed somewhere different. This is a regular tapping, not to different from a valve tapping but the sound appears to be coming from lower on the engine and not the valve train. So, what else could this be causing this tapping?

We appreciate all the comments as this issue has stopped the use of a recently completed Healey by its owner for his fear of having a catastrophic engine development.

Ray(64BJ8P1)

In the 70’s I used to overhaul big Healey engines and on tear downs on a couple of engines I found a timing chain tensioner that the piston part of it was almost out of its socket. The chain was very stretched and loose. The engine made a noise, it also burned oil too so an overhaul was in order. And on another engine the generator was making a ticking noise. Disconnect the fan belt to eliminate this possible cause too.

 

[steveg]

Ray - There are YouTube videos with rod bearing sounds. Suggest those for comparison to yours.

 

[RAC68]

Hi Patrick/Steve,

When rebuilding my Healey in the mid to late 1980s, I pulled the engine apart to the extend of exposing critical components by removing pans and covers. Pulling the front cover, I found my chain tensioner in the bottom of the space and wondered how it never got caught on the front crank gear. I did replace the timing chain and tensioner but did not need to change anything else and the engine ran quite well when finally installed in the car. Oil pressure was quite good and my compression was quite high due to replacing a blown head gasket and requesting (incorrectly) the machine shop shave the head 0.060" rather then the intended 0.006". Well, that was in the late 1980s and the engine is still running well with good oil pressure.

Steve,
I will definitely look for the YouTube to get an idea of the sound and, hopefully, how they addressed it. It would be great if it was a Healey 6 in the YouTube.

Thanks guys,
I really appreciate the input,
Ray(64BJ8P1)

 

[Michael Oritt]

I recently replaced the timing chain and tensioner belt on my 100. Though i know the tensioner on the 6 cylinder engine is different than the belt on the 4 the noise that the loose chain made (which disappeared after the R & R) was similar to a rattle and bore no relationship to engine speed, etc. I doubt that is his issue.

 

[RAC68]

Steve,

I listened to the sounds made when by the bearing slip and other connecting rod noised in the YouTube films and find them less like a tapping as the noise made by my friend's Healey engine. The Healey engine is making more of a tapping sound, not too different from a valve tapping only low on the engine. If I remember correctly, tapping increases in rate as RPMs increase but diminishes in volume when the engine is momentarily raced and returns to be heard when the RPMs diminish toward idle.

Purchasing this car a few years ago, what's frustrating, he had completed the installation of a new interior and top as well as addressed many issues leading to good concourse judgements. Additionally, even with these good presentation efforts, he really drives his car more then many and only suspected that the tapping was from the valve train.

He became aware of the NON-Valve-train possibility when, at a gathering of a number of Healey-owner assembled to test the condition of a stored OD/transmission, he happened to start his Healey and drew attention by the tapping. That is when we pulled the spark plugs one-by-one to look for the tapping to disappear at a specific cylinder. However, no change in tapping was found from any cylinder.

Hope this helps,
Ray(64BJ8P1)

 

[steveg]

Ray -
Before anything else, why not try Marvel Mystery Oil?

Several years ago I had a very loud tapping - like someone was rapping on the engine with a hammer. It was a dry rocker arm socket.

Am wondering how difficult it would be to pull the valve cover, move the car around in gear and look for a loose pushrod. That would indicate a sticking lifter.

 

[RAC68]

Steve,

Its worth a try. When we were initially looking for the tapping, we put a stethoscope on the valve cover and could not hear anything and the engine revved without an issue with an increase in oil pressure reading. My initial thought was that a lifter had hung up or even a broken push rod but others suggested it was more likely a warn connecting rod bearing and we went on to test for that issue by pulling each spark plug wire one-by-one without a validating result.

I will suggest he place the stethoscope on each side plate and listen for banging/tapping. Once locating the sound, pull the side plate and examine the lifters to make sure they are seated on the cam. If they are all resting on the cam, I will suggest pulling the valve cover rocker arms and push rods of the associated valves.

Thanks Steve,
Ray(64BJ8P1)
​

 

[Dandare]

One thing that tricked me when using the shorting out a cylinder method to diagnose (what turned out to be) a con rod bearing-little end was; If there is more than one bad one then killing one cylinder won't stop the noise!

Danny

 

[Legal Bill]

1. Please buy a workshop manual. (If you don't know the torque settings for the rod bolts, you don't have a workshop manual)
2. An engine with a "stuck" tappet does not run strong, period. A valve is either stuck open or closed. If you still think this is possible, try a compression check and see if any of the cylinders show poor compression.
3. Buy a valve cover gasket and remove the valve cover. Rotate the engine and check the operation of each pushrod, rocker, spring and valve. Each assembly should go up and down. Make sure the valve keepers are in place and check the valve clearance. Adjust as necessary. Valves with excessive adjustment make a tap.
4. If the top end is all good and the engine compression is good, you can look to the bottom end, but an engine with a rod bearing so badly worn that it demonstrates a constant knocking requires a tear down. If you only hear it on first start and it goes away when oil pressure builds, then perhaps you can replace the rod bearings and buy a bit more time for the engine. You will know immediately if a rod bearing is bad. The soft gray babbet material will be worn away and you will see the bronze or copper color showing, usually in the middle of the bearing half.
5. If you have never done this sort of work before, get some professional help. A professional will know at a glance if one of the rod bearings is worn. He will know with a touch if the rod journal needs to be polished or cut undersize. Removal and reassembly must be done correctly to prevent damage of the rod and end caps and the new bearings. You want everything to be perfectly cleaned and the rod journal surface must be inspected to insure that it is suitable for reuse. You need to be sure you have ordered the correct bearings and the engine may have been rebuilt once and the bearings may be oversized. You don't replace just the bad one. While you have it opened up, you replace them all. You want to lubricate the journal before replacing the bearing.
6. A professional who hears this noise will know pretty quickly if it is a rod rap or some other problem.

 

[RAC68]

Hi Bill,

First, thank you for your comprehensive response. I will be at our "Positive Earth Drivers Club" meeting with my friend tonight and we are scheduled to take his car to another club member who builds LBC Racing engines next Tuesday. We have a workshop manual and have tested compression with good results. There is no miss in the engine and the engine seems to be performing quite well with the exception of the low end ticking. Although I would do all the tests prior to deciding on a full rebuild (if for no other reason but to save money), I must admit I am not a proponent of a full rebuild as so many taking this corrective action seem to report disappointment and additional problems after.

I respect your suggestion of pulling a local expert into the discussion, if for no other reason but to validate any conclusion and action plan. In this situation, and since it is not my car, any conclusion I would come to should be validated by another, and that other person should have great credibility (expertise) in this area. Whether my friend does some or all the work required or farms it out to our expert is a decision he will need to make. However, I must say that our expert is someone I would go to if I had a major issue I could not rectify.

I really respect the suggestions of this group and I can truly state that this respect was earned by the many suggestions I have followed to correct my issues and keep my unrebuilt engine performing quite well.

Thank you to all and I will keep you informed on what we find and the corrective actions taken.
All the best to all,
Ray(64BJ8P1)

 

[Patrick67BJ8]

Hi Bill,

First, thank you for your comprehensive response. I will be at our "Positive Earth Drivers Club" meeting with my friend tonight and we are scheduled to take his car to another club member who builds LBC Racing engines next Tuesday. We have a workshop manual and have tested compression with good results. There is no miss in the engine and the engine seems to be performing quite well with the exception of the low end ticking. Although I would do all the tests prior to deciding on a full rebuild (if for no other reason but to save money), I must admit I am not a proponent of a full rebuild as so many taking this corrective action seem to report disappointment and additional problems after.

I respect your suggestion of pulling a local expert into the discussion, if for no other reason but to validate any conclusion and action plan. In this situation, and since it is not my car, any conclusion I would come to should be validated by another, and that other person should have great credibility (expertise) in this area. Whether my friend does some or all the work required or farms it out to our expert is a decision he will need to make. However, I must say that our expert is someone I would go to if I had a major issue I could not rectify.

I really respect the suggestions of this group and I can truly state that this respect was earned by the many suggestions I have followed to correct my issues and keep my unrebuilt engine performing quite well.

Thank you to all and I will keep you informed on what we find and the corrective actions taken.
All the best to all,
Ray(64BJ8P1)

One last thought from me. I had a “ticking” sound that didn’t change with engine revs. I adjusted valves, etc. good compression. It turned out to be broken rings tgatvended up on a piston top. Can you get access to a borescope to look at the piston tops before you remove the head? I’ve had two different engines of my own that #6 piston went bad plus I overhauled a few that also had bad #6 cylinders.

 

[RAC68]

Hi Patrick,

Thanks for the thought. I will bring this up at our meeting with our expert as he probably does have the tool.

Its funny you mention the bad rings as, if I remember correctly, a friend having compression problems, rebuilt his engine and, during teardown, only found the bottom 1 or 2 rings on 5 of his pistons. Since he had purchased the car 3rd hand and finding no evidence of the missing rings, he always wondered if the seller found an engine problem after taking it apart and only put back what he had and quickly sold the car. Since then, and after rebuilding a number of Jaguar E type and Healey engines, this condition had appeared in 2 of the 4 Healey engines worked on. What he has concluded is that the rings broke and were churned within the combustion chamber by the pistons and the bits blown out the open exhaust valves.

Thanks again,
Ray(64BJ8P1)

 

[dancrim]

To find out if you have a sticking valve with solid lifters:

1. Properly adjust all valve clearances.
2. Start motor to be sure you haven't fixed it by proper adjustment. If not proceed to 3.
3. One at a time, set valve clearance to .002"
4. Start motor. If the sound has changed or goes away you found a valve or
camshaft problem. If sound persists, set clearance back and proceed to next
valve. You can do this with the motor running and just setting the clearance down
to zero but NOT more.
5. A rod knock can be diagnosed by bringing motor to a high RPM and then quickly
letting off the gas pedal. The sound will increase for a second when the motor slows.

 

[Bob_Spidell]

Have heard recommended that a ring or two on stock 5-ring pistons can be left off. Advantage is less ring friction, as the top 2 compression rings do most of the work; disadvantage would be perhaps a bit less stability of the piston ('piston slap'). Some aftermarket pistons, like those from DWR, only have 3 rings; 2 compression and one oil-retention (and the skirts are shorter).

re: "... the rings broke and were churned within the combustion chamber by the pistons and the bits blown out the open exhaust valves."

I think, if this happened, you'd have severe damage in the cylinders.

 

[Healey Nut]

Has anyone mentioned or thought about timing chain issues ?

 

[RAC68]

Bob,

I have talked to other Healey owners after my friend told me of his experience and feeling that the rings were never installed. When relating the mystery to other Healey owners, I was told of others who had the same experience and where the installed but missing rings went. Since he intended to replace pistons and rings in his full engine rebuild, it made no difference other then clearing up the mystery. As the engine was run for quite a while in this condition, he also indicated the caked carbon on the top of the pistons.

Is that what happened to his rings? I don't know but it is potential if other also experience a similar condition. With hard brittle fractured rings, it would not take much to fracture them to the point of being able to pass through the open exhaust valve with the hot gasses.

Ray(64BJ8P1)

 

[RAC68]

Hi Healey Nut,

Has anyone mentioned or thought about timing chain issues ?​

This potential is still open. I had thought that if the piston on the hydraulic timing chain tensioner had escaped the cylinder due to a stretched chain, it could be tapping on the front cover. However, although this would reduce oil pressure and been easily identified with a stethoscope, we have not yet tested for it. Also, I would expect the tapping not to be as regular as we are experiencing and don't think the sound would vary with RPM. However, based on these thoughts, I would personally suggest this cause be investigated if other failure potentials prove invalid.

I really appreciate and thought about your suggestion as I found the tensioner piston laying on the bottom of the front cover when taking my engine partially apart and often wondered what would have happened if the piston got court by the low long toothed crank gear.

Thank you,
Ray(64BJ8P1)

 

[Legal Bill]

The sound you describe and the engine running strong negates the likelihood of broken rings. A wrist pin is a possible problem.