Strange Valve Lash "Problem"

[dorcom]

Here's an odd problem:

Engine cold: fairly quiet running
Engine warming up: Valve lash [clearance] becomes audible
clack-de-tack-clack-clack-tack-clack-de-tack....
Engine warm: still doing it but a little quieter but still sounding like a diesel under load... trak-trak-trak..
Engine thoroughly hot (~1/2 hour freeway @ 65 mph+
Quiet with occasional faint tack-tack"

Now comes the really funny part:

A couple of weeks ago I chased a hit and run driver with my FJ60... Yeah I know, helluva acclereation and cornering....
During the chase I reved yeh ol' 2F several times well above
4,000 into 5,000. My left foot was eternally on the floor putting the "pedal to the metal" to accelerate and catch up before dawn...

Now, believe it or not, the engine runs much quieter and most of the valve lash "clack-de-tack-clack" disappeared!

Even odder:
In the last week the initial symptoms are gradually coming back!

So, one shall "race" this "Mountain-Ferrari-Tractor" of clunky chunky pushrod fuel waster from time to time?

I shall be delighted you sharing your insights and knowledge with me!

D

 

[D'Animal]

Sounds like you blew some carbon out of the engine and a few other places.



Congrats!

 

[2mbb]

Engine warm: still doing it but a little quieter but still sounding like a diesel under load... trak-trak-trak..


D

If your engine is under load and and sounding like a diesel, this is probably not valve noise but pre-detonation known as pinging. This happens when the ignition is too far advanced, fuel mixtureis too lean or when there is excessive carbon build up inside the combustion chamber. You should not get pinging at idle, it usually happens under load.

 

[dorcom]

2mbb

It's not the pre ignition knock for sure.
As for too lean... well at 11 mpg....
Odd is that is only in the lukewarm to warm temp range.
After a lenghty free way drive it runs very smooth and quiet.

 

[Mace]

takes a while for the oil to reach the rocker arms..


Good old itallian tuneup

 

[lehiguy]

You might try a Sea Foam tune up (run some in the oil) or run a quart of ATF in your oil for a while to clean the oil passages inside the engine. What does your oil pressure show?

 

[dorcom]

assume oil pressure is good, gauge goes to top of 2nd 3rd a little higher on the freeway.

 

[cruiser88]

Sounds like you blew some carbon out of the engine and a few other places.



Congrats!

yep

takes a while for the oil to reach the rocker arms..


Good old itallian tuneup

lolz

Adjust the valves...... hot

 

[Pin_Head]

Valve lash isn't going to change like that: disappear and then come back.

Another possibility is an exhaust leak. This is load related, like pinging.

 

[grant5127]

Now comes the really funny part:

A couple of weeks ago I chased a hit and run driver with my FJ60... Yeah I know, helluva acclereation and cornering....
During the chase I reved yeh ol' 2F several times well above
4,000 into 5,000. My left foot was eternally on the floor putting the "pedal to the metal" to accelerate and catch up before dawn...

left foot was eternally on the floor putting the "pedal to the metal???...Left foot??? anyway.....whats the rest of the story?? Did you catch the bitch??