MGA mga engine [sounds like a deisel when idling??

[bear2468]

hello!...i have a mga engine that sounds like a deisel when idling!...when i rev the engine up it goes away, the valves are adjusted correctly @ .015.....the sound seems to be coming from the lifters....it sounds like a heavy marble rolling sound, similiar to a deisel engine...any help would be appreciated....thanks, dale

 

[WA1KWA]

Check your oil level.

Later B series engines have their oil passage to the rockers offset This has to be matched to the oil passage on the head (rear pedistal of the rockers). If not, the rockers will be starved of oil & eventually fail. This happened to me. The converse could also be true, I inagine someone could have put an offset oil passage head with straight passage rocker arms.

Hope this helps.

Colin

 

[bob67bgt]

check the crank pulley. on MGA's they are rivited together. When the rivits come loose it could make the sound you are discribing. PS check it with the engine OFF...Remove the fan belt and see what the pulley feels like. bob

 

[bear2468]

thanks for the reply!...the oil passages line up...the crank pulley is solid, no looseness!

 

[WA1KWA]

Hmmmmmmmm................

Thinking out loud here:

Is it the same sound with the clutch depressed? Throw out bearing?

Water pump? Generator?

Anything loose on the engine/transmission?

Can you isolate the general area?

Timing chain/tensioner?

I assume all settings are reasonably close; i. e. valve lash, points, timing, stuff like that.

Colin

 

[Terry_Geiger]

Probably a long shot here but it could be worn piston skirts causing piston slap. The pistons will "rock" inside the engine bore and cause the noise as they go up and down. I had a high compression chevy v8 as a kid that had one cylinder doing this. I pulled the one piston and had the piston skirt knurled and this solved the problem. Sounded just like a diesel at idle.

 

[bob67bgt]

If its not something simple like the air filters loose i would remove the valve cover and start the engine. insert a junk old feeler guage around 10 or 12 thou. where you adjust the valves. See what that does and if the noise goes away. A buddy had a noise something like you discribed and when he did that the noise went away. All the valve clearances checked good. It ended up being a loose nut on the front of the camshaft.Odd but the noise went away when he put the feeler guage in while running. This would be a real stab in the dark if all else fails. Also more info would help. Was it fine then went funky? Is it a fresh rebuild? Bob