I hadn't driven by 91 305 tbi in a while and after getting quite cold I start it up and it is making a horrible ticking (not really a knock)sound that fluctuates with the rpm's. It seems to have the same power and everything looks fine on the guages so I don't know whats wrong. its not in the fan and i don't see any metal touching metal anywhere. The car has just over 100k. ANy ideas?

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Kramedogg
91 305 TBI

 

If I were you I'd check the bearings in the engine accessories...I just had to replace my smog pump, a/c, and tensioner pully which kinda sucked. Take off the belt and jiggle the pulleys to see if they're bad. If you end up having to replace some of that stuff, let me know I might be able to save you some headaches...

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89 Iroc-Z LB9 305 TPI auto 2.73 posi:
3" Dynomax "cat" back,K&N filters, TB bypass, 3" pipe in place of cat, cleaned and flow-matched injectors, 170' thermo, mild ignition mods, synthetic oil, kicker sound system, soon to have 3.73 posi...

 

does it go away after a while, or does it stay for as long as the car is running? just thinking that if it goes away as the car warms up, it could be an oil problem (tapping rocker arm) or something. but i'm no engine master, so take it for what it's worth...

 

l realize its a TBI, but on an MPFI, you can sometimes hear the ticking of injectors opening. Wonder if it would be possible for TBI injectors to make a similar noise?

Just a thought.

 

E-mail me at FTA84@hotmail.com and I can send you a wav file of the rod knock my L69 had, my website won't let me currently upload it.

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1984 WS6 Trans Am Hartop
Former L69 Car under restoration
1984 WS6 Trans Am T-top car
4-bolt main 350, headers, Holley 650, T-5 and 3.23's.
Daily driver and restoration

 

Dogg,

Well, here goes another armchair diagnosis -

I'll take a guess at a sticky lifter plunger.

After sitting for an extended period, the varnishes that accumulate in and around lifters can harden and become troublesome. The $5 cure is a can of "CD-2".

Or, any other reputable product (name branded) that says "frees sticky lifters".

I've used CD-2 with success in several old beater cars that did not get frequent oil changes.

OBTW - make sure that noise is not a belt - sometimes belts make a loud TAPPING noise instead of the traditional squeal. a shot of WD-40 on the belts will quiet them.

And no, it will not cause a properly adjusted belt to slip. It actually serves to dress the rubber in the belts, keeping it pliable as well as quiet.

Let us know. Good luck.

BOR

 

My car does the exact same thing. After it warms up, the ticking goes away. I always thought its an exhaust problem cause i took out my smog pump and all the hoses so the air tubes are left open right now. (Getting headers very soon). I hope the problem goes away after i put the headers on.

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Mods:Hooker Aerochamber 3" exhaust, gutted kitty,
March 2 piece underdrive pullies, smog pump gone,
14x4 K&N, 3.42 gears,
Eibach springs with KYB's all around.
Appearance: Harwood cowl hood, Z-28 wing, painted black(7/20/00)-original color was light blue
*All these mods were made this year
Stock Options:120,000 miles on motor, 5spd, TBI, 305, T-tops
Run a best of 16.7 @85mph before gears

 

Also, when you take off your air cleaner assembly, you will see that the injectors can actually make that sound when they spray the fuel against the throttle flaps. Maybe when its cold, the fuel sprays in a thin line (kind of like taking a ****) instead of in a cone shape, which might be causing the loud sound.

 

i like the thought of the injectors since it is tbi, every throttle body motor i had i could clearly hear the damn thing tick.. with your motor running, listen around, take off the lid of the air cleaner as mentioned and see if it gets louder.. if thats not it, id definatly agree with BOR as far as sticking lifter..

 

An exhaust leak at the head or the collector is famous for that ticking sound until it warms up. My 89RS TBI was doing that, and I found the back bolts on the exhaust manifold were loose. Your manifold or collector will expand enough when it heats up to make the leak go away. Tightening those bolts back up cured mine.



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89RS w/350 TPI; 69RS/SS w/450 HP 350/Muncie 4-Speed "Too weird to live, too rare to die."