Top end engine tapping

[RDKeysor]

At the risk of becoming the biggest blabber on this forum--I was a writer/editor in real life--I will offer still another issue on my car. This is a Series 1 BN7 that has had an extensive restoration, including, I have been told, an engine rebuild (and a Toyota gear box, etc). The car runs great, and I drove it to Florida from Virginia after its purchase in Virginia However, it has a pronounced tapping sound upon start up and at idle. It sounds like it is in the rocker/valve train. This sound goes away under load and isn't audible driving down the road. Initially, I thought (hoped) it was possibly a very loose rocker, but I've checked the valve settings and listened to the sound with the valve cover removed and engine running. The screwdriver-to-ear test, holding the screwdriver at various points around the head, didn't help me locate the source of the sound. I also had two of the leading lights of the local Healey club listen to it--they were at the time kind of focused on a brake bleeding problem on a 100M--and neither of them offered an opinion. I thought perhaps it was a tappet, but I don't think there is much that can go wrong there, and a friend thought it might be the water pump. That doesn't ring true to me. I think the important clue is that the sound seems to go away when the car is in gear and the engine is at work.

 

[57_BN4]

One cause of tapping on reconditioned engines I read about a while back is if one of the rebushed rockers doesn't get its oil hole drilled and therefore runs dry at times. If you are getting an even drip from each rocker around the bushing and also a little oil coming out of the spit holes on the top then all is probably ok.

You could also try inserting a feeler blade (or a piece of cereal box cardboard) into each valve clearance gap when the engine is running which will find any incorrectly set tappet. Sometimes on a well used engine the valve stem wears a divot into the rocker arm tip which makes setting the tappets impossible with a feeler blade and this problem occurs- hopefully not an issue on your engine.

Look at the rocker movement compared to each other, are the valves all opening approximately the same amount at idle? If the cam didn't bed in properly and has lost a lobe then it will clack. Your oil filter will also be full of magnetic trash too at that stage so you could pull the filter and strip out the paper element to see if it is unusually dirty.

Can you make a YouTube video of it idling? Often a video camera will pick up high pitched sounds far better than ears can and if you move it around and point at different areas you may be able to pinpoint the location better.

Andy.

 

[tahoe healey]

pitted tappets.

 

[Genos2]

Check rocker arm bushes..

 

[Johnny]

Hi Andy, sounds like your not getting enough oil on the tappets at start up. Since the motor smooths out on acceleration could be the oil pump. When cold started check the oil pressure, should be high.

 

[Patrick67BJ8]

At the risk of becoming the biggest blabber on this forum--I was a writer/editor in real life--I will offer still another issue on my car. This is a Series 1 BN7 that has had an extensive restoration, including, I have been told, an engine rebuild (and a Toyota gear box, etc). The car runs great, and I drove it to Florida from Virginia after its purchase in Virginia However, it has a pronounced tapping sound upon start up and at idle. It sounds like it is in the rocker/valve train. This sound goes away under load and isn't audible driving down the road. Initially, I thought (hoped) it was possibly a very loose rocker, but I've checked the valve settings and listened to the sound with the valve cover removed and engine running. The screwdriver-to-ear test, holding the screwdriver at various points around the head, didn't help me locate the source of the sound. I also had two of the leading lights of the local Healey club listen to it--they were at the time kind of focused on a brake bleeding problem on a 100M--and neither of them offered an opinion. I thought perhaps it was a tappet, but I don't think there is much that can go wrong there, and a friend thought it might be the water pump. That doesn't ring true to me. I think the important clue is that the sound seems to go away when the car is in gear and the engine is at work.

I had a simliar noise...broken piston ring and part of the ring took a piece of the piston with it and the ring piece was being hit by the valve. Compression was consistent on all pistons.