I have a difficult problem I would like your thoughts on. I just purchased my
62 TR4, which is really in good overall condition. I have been working off a
long list of mechanical chores and I am almost done.
There has been one high priority problem nagging at me since the day I made the
offer on the car. That is a worrisome noise under the hood under certain
conditions. I have hoped against hope that it does not require a engine
rebuild or a bottom end job.
Here are the symptoms:
Engine starts and idles fine. It is quite strong and peppy. Compression is
175 across all cylinders. Oil pressure 70 lbs. Cold, 50 lbs. warmed up… still
OK at idle. Carbs are balanced and smooth. BUT when I give it lots of gas
pedal I hear a loud banging noise that sounds like the hood "prop up" rod
rattling on the wheel well or something like that. There is some added
vibration that goes with the added power, but not unusual. The noise is not
the bearing noise I have heard before in my life, which sounds like the muted
sound of a hammer on a big anvil.
Work done so far:
I have chased all the obvious things like the "prop up" rod by wrapping it in
cloths. I have searched the under hood area for anything loose. Removed a
Monza header and changed the exhaust system to a stock manifold and all new
stainless steel.
The radiator cap makes contact with the hood when it closed because the neck
was re-soldered by the PO with the wrong angle and it leaks slightly at this
joint. This one of my next things to try… having it re-soldered and
straightened. But this should not be affected by apply the gas.
Since it only happens when I push on the gas pedal, I thought it might be the
vacuum advance system cranking in too much advance and creating monster
pre-ignition. The distributor is very sloppy with lots of twisting play and
end play. It is also in the wrong position compared to the workshop manual.
The vacuum advance is pointing at 7:00 position instead of 9:30 o'clock. I
suspect that the drive gear is off one notch. In order to align the points the
distributor must be turned counter-clockwise to the 7:00 o'clock position.
While doing the exhaust system, I noticed that the engine mounts are very
mushy. I plan to remove the hood and drive the car hoodless to isolate another
possible noise source and at the same time check the amount of movement I am
getting when the engine is under load.
Any ideas are welcome. I want to use the car for some local events and longer
trips. I am reluctant to do so until I can sort out this noise… so I am
getting very frustrated.
Brian Sanborn
62 TR4 CT16260L Groton,MA
sanborn@net1plus.com
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