Thrust Bearing Help Please

FastBird91

Registered User
Can someone please help me out here. Apparently is sounds like my crank is walking. My engine rebuild guy says i need to definately take the crank out to do this. According to some of your expertice here i can simply do it from underneath by pulling the oil pan and replacing the bearing on the crank.
 
looking at you post makes me ask two questions;

1. what year of S/C do you have / is it the original engine?

2. are you sure he did not say that the "camshaft" not "crankshaft" is walking?

as i am looking at my ford service manual on the exploded view for the V6 engine, the only item in the short block that has a thrust plate to stop walking( which is what a thrust plate is designed for ) is the camshaft.

if you "misremembered" about what he said and it's the camshaft, the hardest thing you'll have to take off to replace the thrust-plate is gonna be the harmonic damper/balancer. you should have enough room with just the fan and shroud removed to accomplish this. pretty much after you get the balancer off, pull the timing cover and remove the chain and cam-sprocket. after that, pretty much pull the 2 bolts off and the plate will be the thrust-plate.

if it is your crank that's walking you have HUGE problems. that means that the main journals on either the block or the crank is TOAST!!!

if I'm off on this or you have a V8, gasp!, sorry to waste your time:D
 
Thanks for the info Cmill. Its a 91 SC (supercharged) and its got the original motor in it though i did have the top end of the motor redone when the head gasket went about a year ago. Its does sound like the bottom end. and the motor guy said "thrust bearing" and definately said "the crank is walking. maybe he doesnt know. Can we replace the crank bearings from under the car. Its worth ashot maybe is there room?
 
Doesnt exactly sound like the rod bearings but apparently is. Makes a knocking sound and cuts in and out at throttle unless i give it enough gas. Also at that certain rpm i here the octane knock.
 
rod knock and octane knock are usually different sounds, usually. rod knock can be figured out by draining some oil(2 or more quarts) and replacing it with 50+wt oil. that will take up the slack in the rod bearings so you know thats what's making that sound. I've done this before in a 72 charger w/a 318 that i scraped a hole in the oil pan and ran it inadvertently dry. the heavy-weight oil stopped the rod-knock for about a week and a half to where we could put a rebuilt short block in it. if you've spun a bearing this probably wont work, but the crankshaft wouldn't "walk". although just like the English language, there's always an exception to the rule.
something to rule out octane knock would be put octane booster in it and fill it up with premium unleaded. i had old gas in my 95 and after putting 15% total overdrive on the blower it rattled like it was gonna fall apart. i did the new gas w/the premium and it goes like a blended frog!!
 
I think what his engine guy is saying is his crankshaft thrust bearing is worn out.Which is located on the second maincap counting from the rear of the engine going forward.I also think the "walking" he is talking about is from the thrust bearing being excessivley worn causing excessive crankshaft endplay/movement of the crank back and forth in the main caps.Which if this is the case replacing the main bearings with the engine still in the car would be a huge pain.I think it'd be easier to just pull the engine and change them on the engine stand plus this would give you a better viewing point to throughly inspect everything.



Jay
 
Yeah .. not very easy to do underneath the car, thats for sure. And chances are that if its wearing the Thrust bearing, it may be wearing on the crankshaft also.

This is more typical of a 5 speed vehicle - is yours auto, or manual ?? The manual transmission's put alot more pressure against the flywheel / crankshaft when the clutch is engaged which could cause the thrust bearing to wear out.

- Dan
 
Generally if the crank is walking on an early model SC, you'll lose your PIP signal as the damper vanes move outside the crank sensor. Of course this maybe only happens in extreme cases. Mine had walked .125" and wouldn't start b/c of the PIP loss. Take your belts off and push in and pull out on the crank pulley. Does it move any?
 
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i will say that when i try to start the SC it acts like it has no compression. Almost drains the battery everytime. Drives like it has compression havent floored it though because of the noise. I can here octane ping alot when im driving it.

So where is the best bang for the buck on a stock/mildly modified engine rebuild kit.
 
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