from about 2k to 3.5k theres a clicking noise, or nocking noise when under load. normal acceleration. i have octane boosted it, checked valve tolerances, retarted-advanced and everything in between timing at the distributor. whats the deal, anyone have any ideas?

 

exhaust manifold/header leak?

 

how would that cause it? jus curious

 

Clicking under load is usually bad axles, unless you've pinpointed the sound to your engine.

 

if its an exhaust leak it just sounds like valve noise, but isn't

 

i went out with an engine stethascope and i could only find it in the injectors.

 

no ideas? nothing at all?

 

Here are my bets in the order that I think they might be.

1. Bad CV joint (u-joint) right by each of the front wheels. Ussually, clicking will occur most during a hard turn one direction, and may not even be present when turning the other way. This is due to the stress caused by the differential. This is normal wear and tear, but if they are clicking, then there is play and you should have them checked.

2. Exhaust manifold leak. If there is a leak in the gasket againt the head, when that cylinder exhaust valve opens, there will be a puff of high pressure air. It sounds exactly like a clicking. The reason it does this under load is that the engine shifts (rotates) a bit and can stress the gasket if the exhaust header is loose or damaged.

3. Knocking under moderate acceleration can also be just as you suggested - pre-ignition. Normally, the knock sensor will cause the ECU to retard the timing, but the amount of control depends on what year your car is. Mine is 94 and can control some, but I can still move the timing manually (via the rotating the distrib) and get it advanced too far and the ecu cannot back the timing down enough to prevent knocking. Knocking is also more prevalent in the spring and fall when gas companies are shifting to/from summer and winter gas. I can't remember which is which, but the formulation is changed (in winter, I think) to oxygenated gas to help reduce pollution. Anyway, one of the two is much worse about knocking. This should be looked at more closely and this item moved to number 1 if you have made any recent timing, distributor or valve adjustments or if you have an older vehicle that is ODB-I or earlier.

PS - Yep - Winter gas is oxygenated and has lower performance - http://en.wikipedia.org/wiki/Oxygenate

 

my vehicle is obd1 and there hasnt been an ignition timing light on it. i need to get ahold of one. i appritiate the help. i will be changing my exhause gasket after christmas when my head comes off to replace piston 3. i'm assuming that a mechanic could look at the cv joints and tell if they are worn

 

CV joints are just like U-joints. There should be no play in them or the axle can get out of balance. Result is vibration and accelerated wear and eventual failure of the cv joint.

Ussually, a mechanic can look at it. The raise the front end and push, pull and twist looking for play. There will be some in the differential, but there should be none in the cv joints, nor any of the bushings and ball joints.