Strange Engine Noise...?

[gblawson]

I have a '57 2.6 (early 2 port head)...Since I purchased the car, although it runs smoothly, I have a funny sound which at its best is a metallic 'ting' on deceleration! At its worst it sounds like a tin can full of ball bearings being shaken?
We pulled the rocker assembly today and pulled out the pushrods and lifters...all were fine.
The car has been slowly rebuilt so I haven't put a lot of miles on it... just a few 5 mile drives... perhaps 100 miles total.
I would swear the sound is some hollow metal tube hitting an equally thin metal surface as opposed to a deep knocking.
Broken piston skirts, wrist pins among other things have been speculated on?
The really bad sound is not consistant...comes and goes...the 'ting ting ting' is always there on deceleration and idle, but goes away on acceleration...comes back on even speed ....
We are going to pull the pan tomorrow and see what we can see.....?

 

[nevets]

Before you do anything too labor intensive, you may want to get one of those engine stethoscopes to find out whether the noise is actually eminating from inside the engine...just a thought

 

[gblawson]

I bought one when I first got the engine...listened to every part of the engine and the only thing I could hear was when I put it against the block under the rear carb?

 

[Genos2]

Many years ago, I had a very similar noise on my BJ7. Just asked my wife & we both remember it being something in the bellhousing. It was much more pronounced on acceleration. Can't remember for sure, but it was either part of a clutch spring or a clip off the end of the starter bendix, (c-clip). hope this helps, Genos2

 

[GregW]

Check your radiator to see if the fan blades are hitting it. If it is, there is a tie-rod under the transmission that connects to the frame. The rubber bushings may have melted from an oil leak (how rare on a British car!) and or the nut for the tie-rod may need tightening.

 

[Patrick67BJ8]

I have a '57 2.6 (early 2 port head)...Since I purchased the car, although it runs smoothly, I have a funny sound which at its best is a metallic 'ting' on deceleration! At its worst it sounds like a tin can full of ball bearings being shaken?
We pulled the rocker assembly today and pulled out the pushrods and lifters...all were fine.
The car has been slowly rebuilt so I haven't put a lot of miles on it... just a few 5 mile drives... perhaps 100 miles total.
I would swear the sound is some hollow metal tube hitting an equally thin metal surface as opposed to a deep knocking.
Broken piston skirts, wrist pins among other things have been speculated on?
The really bad sound is not consistant...comes and goes...the 'ting ting ting' is always there on deceleration and idle, but goes away on acceleration...comes back on even speed ....
We are going to pull the pan tomorrow and see what we can see.....?

I had a similar sound for several years and the piston ring finally let go in several pieces turning it into a very loud clacking sound. See if you can get get a look inside each cylinder to see the tops of the pistons. Look for a small piece on top. If you find a piston like this it will be the cause of the noise. I think the instrument you want to use is called a "bores cope" which I used to inspect stuff with when I was in the Service. My #6 piston ring failed, but the noise was coming from the #1 area. I used a stethoscope made for car engines to check out the noise which didn't do me any good.
Patrick

 

[TimK]

Greg and I think alike. I'd check for the fan hitting something. I had disintegrated bushings in the steady bracket on the back of the transmission/OD that holds the engine/trans in place under decel/accel. I replaced them with polyurethane bushings (solid plastic). The lack of the noise on acceleration is what fits this theory best -- the engine moving backward. See if there is any signs of fan hitting on the radiator rear face.

 

[bgbassplyr]

After the steady bracket/fan, if cause of noise not found there, check for throttle return spring, choke cable (or any cables, wires) hitting heat shield or other sheet metal. Maybe exhaust system hitting, muffler baffles loose, muffler heat shield or broken weld (I don't recall, but exhaust system used to have a length of flex pipe before the muffler). Cracked carb heat shield or any cracked sheet metal, loose bonnet support. Broken body spot weld.

You see where this is going.

I would look in all these places next before pulling the engine apart.

 

[gblawson]

Ok...we pulled the valve cover and checked the upper end...all well... in fact the lifters looked brand new....Dropped the pan and nothing down there...bearings looked great.....'Gulp'...pulled the head off and looked at the pistons...one had a half inch break on the outside top....popped them all up....another was almost gone in the same place and every top ring of all 6 pistons was broken!
Happened to have a friend with 6 std NOS pistons and liners that we hope will fit with just honing (without the liners)...machinist is coming in the morning to check the cylinders...

(The piston 'kit' still had the original invoice in the box....21 pounds sterling for the 6)

 

[Patrick67BJ8]

Ok...we pulled the valve cover and checked the upper end...all well... in fact the lifters looked brand new....Dropped the pan and nothing down there...bearings looked great.....'Gulp'...pulled the head off and looked at the pistons...one had a half inch break on the outside top....popped them all up....another was almost gone in the same place and every top ring of all 6 pistons was broken!
Happened to have a friend with 6 std NOS pistons and liners that we hope will fit with just honing (without the liners)...machinist is coming in the morning to check the cylinders...

(The piston 'kit' still had the original invoice in the box....21 pounds sterling for the 6)

Usually the #6 piston is the only one to break the top ring. I'm not sure why and would guess that it has something to do with "heat" in that location. I can count about a dozen #6 piston top ring failures that I know of personally including two with my engines. I think you may have other problems for so many piston ring failures and maybe then again you may have bad pistons??
Patrick

 

[glemon]

Did you push the pistons up through the top of the block? because of the lip or ridge that appears as the liners wear many times rings can be broken on worn engines when removed that way.

 

[gblawson]

Good point about breaking them on removal...the #6 had the broken piece...#5 was not far from breaking....the others were not worn as much.

 

[gblawson]

I was wrong, it was #3 that was broken and #4 almost gone...the mechanic said he was able to push all but two out with his hands and didn't think the rings broke at that point?

 

[gblawson]

...oh, and the NOS pistons/sleeves came with full set of rings plus an extra oil ring down low...I have been told with MGs not to use that lower oil ring?

 

[Johnny]

While your that far along remove the timing chain cover and replace the chain and tensioner. A loose timing chain will make a similar noise on deceleration. Also, seems to simple but check around the driveshaft inside the tunnel. I had a battery hold down rod rubbing against the driveshaft that drove me nuts until it finally lodged up against the driveshaft so bad it sounded like the engine blew up.

 

[gblawson]

 

[gblawson]

Quick update...we have the new standard pistons installed, the cylinders were 'ridge reamed' and lightly honed. One cylinder was 8 thou out, the others between 6 and 7. Although the old pistons could be pushed out by hand, the new ones were tight enough that they had to be tapped in. The head went to the machine shop and spent some time in the tank. The exhaust valves were well pitted and will be replaced along with new seats...the intakes were fine. Guides looked good. Should have it back on the road/ on the road first of next week....



Bit of History

The BMC 'C' series engine (used in the 100/6) was first introduced in the Wolseley 6/90 in the 1954 Series I model. It never shared the new head design and retained the 2 port, 2 sidedraft SU's...

 

[gblawson]

Coming along.....

 

[Johnny]

You never mentioned it but did you replace the crank bearings and rod bushings as well?

 

[dougie]

I discovered broken top rings on #6 and #3 pistons in my race motor when I broke it down for a rebuild last winter. It may have been making a similar sound, but with the racing side exit exhaust you really can't hear a whole lot. I just knew I was low on power and torque. In fact I had these broken rings during this race.

https://www.youtube.com/watch?v=cS6sqyTfNfs

Dougie