Ever heard of this happening?

I posted a few days ago to get suggestions for what people might have thought happened to my 87 TC. I was having an intermittent stuttering problem, but the power was good..sometimes and occasionally the stutter would be accompanied by a knock. The timing belt was loose as hell on the drivers side (longer side) and extremely tight on the passenger side. Took it to the mechanic to have the timing belt changed (since I don't have the tools to retime it), he took the spout out to set it to 10 degrees and hooked it back up afterward just like he was supposed to after he put the new belt on. The car idled really rough, and it still had a slight knock that increased with engine rpm. After checking a few things, he discovered that the little pin (or key) that holds the cam sprocket to the end of the cam had broken! So the cam was just free spinning and sometimes hitting in the right spot to keep the car running. He put a pin back in it and got it timed right, and it will idle fine but the knock is still there. Now I don't know how much damage is caused, I should know by tomorrow...this sucks, what do you think could possible have happened? Is the knock a broken rod from the piston coming up on the firing stroke? Damn, I hope not, what do you think?

These engines are "non-interference" which means the pistons can't hit the valves, even if the belt brakes or the cam sprocket comes loose. There are a lot of things that can knock. Try using the big end of a screw driver stuck in your ear, while you put the other end at various places on the running engine and see if you can narrow down the location some (poor man's stethoscope). How 'heavy" a knock is it?
Let use know what you find.

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NATO Member. it's not a vice, it's an obsession
"The nice thing about each new day is nobody ever used it before" Barnaby Jones
88 TC X 2, 86 SVO, mods list at
http://www.turbotbird.com/showroom/pd_88tc.htm

[This message has been edited by Pete D (edited 12-13-2002).]

The knock is slight, but noticeable, not in the bottom end though. But it does increase in speed with rpm. I realized that these engines have clearance for a free spinning crank against the valves, I've popped a timing belt off of my 88 before. I'm gonna have a couple more people look at it and see what they think because I have no idea unless the cam is indexed wrong according to the cam gear. I might end up getting a new head for this one too. Damn.

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Kev
88 TC 5spd
Black body, red leather
K&N in front of the radiator, bypassed BCS at around 17 psi, polished throttle body, 2 1/2 dynomax ultraflow mandrel bent duals. 255 lph fuel pump.
87 TC 5spd
Gun metal gray body, blue/gray cloth
K&N
Bypassed BCS

Could be that you have a Hyd. Lash Adjuster that is partially collapsed (won't fill with oil). I have one that takes a few minutes to pump up and clicks during that time...after that it's fine.

Also note that the injectors on these are fairly loud and make a clicking sound.

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Dan Eaves
88TC 5spd, Crower 5.5" Sportsman Rods, Short Wiseco Pistons bored .030" Over, Ported Head with Polished Combustion Chambers, Gutted & Polished Upper, Ported & Polished Lower, Polished T/B, Ported E6, SVO T3 .63AR Turbo, Bosch Bypass Valve, 3" DP w/No Cat, 2 1/2" DynoMax single cat back w/DynoMax Super Turbo Muffler, RR Cam, K&N in Fenderwell, Gillis Boost Valve, Centerforce I Clutch, Removed A/C, Polished Wheels, Polished Valve Cover, Polished Crank and W/P Pulleys, Walbro 255LPH HP Pump, Kirban Adj FPR, and the DAMN Heater Core is new too !

http://www.geocities.com/wot_turbo/WOT.html

NATO MEMBER (Vice Chairman...if it's a vice...I deal with it)

Originally posted by Kev:
Is the knock a broken rod from the piston coming up on the firing stroke?

No, that's not possible. The cam just controls the intake and exhaust valves, even with the cam not doing what its supposed to the distributor (and thus ignition) is run by the auxiliary shaft, so the spark plugs are still going to fire at the right time.

Yeah shiftless, that makes sense. I still can't figure out what the damn knocking sound might be. Unless the hydraulic lifter not loading up sounds like a rod knock, then that can't be it. I know what clicking injectors sound like too, but this isn't a click, it's a knock but it's in the top end. And the car idles fine, man, this is weird. The knock isn't loud, but it's definitely a knock, not a click. hmmmmm

I would guess it's a lifter....but check the easy stuff first.

Seems that if it was a lifter, then it wouldn't idle smooth, but it does. I'll know more on Monday.