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Discussion Starter · #1 ·
Hi all, I’ll make it brief. 1981 280zx turbo. Installed megasquirt 2 plug n play. Had to get a 82/83 turbo dizzy. When I installed it, had to get TDC, did that by turning the crankshaft bolt. Thinking back, it wasn’t real hard to turn. Anyway, I got it all installed and hooked up to computer and tried to start it. It started right up but ran very rough like the timing was off or something. I then used a timing gun and had my wife start the car and I kept it running with the throttle linkage so I could point the timing light. The car was only running about 30 seconds when I saw the belts start to wobble so I cut it off. Upon closer inspection, I saw that the crankshaft pulley bolt was almost all the way out and the pulley was loose and a little oil was leaking out. I then took the pulley off and saw that the shaft portion of the pulley, that fit onto the crankshaft, was cracked a a piece fell off. Also, the oil seal was chewed up and the oil thrower was chewed up around the edges. I think that pulley must have wobbled hard enough to tangle up with the oil seal and thrower. The car only run about 30 seconds and I didn’t hear it break and I didn’t hear any motor klinking.
So, my question is, is it likely that I only need to replace the pulley, seal, and thrower and all will be good? Also, is it common for the pulley bolt to back out like that? I know I turned the crankshaft with a ratchet, but I don’t think I turned it counterclockwise, and it wasn’t hard to turn.
One more question, anyone have any leads on a crankshaft pulley with the crank plate and 3 pulleys on it?
Thanks guys
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Ouch! Can't help with the bolt backing out but this might help:
 

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Hooo Doagies. That's one ugly kettle of fish; my sympathies.

The clues provided suggest, forensically speaking, a plausible guess about this scenario of woe.

First, the amount of dirt/crud in the bolt socket suggest that this problem might have begun some time ago with a pulley bolt that lost/never had sufficient torque to keep the pulley firmly fixed. This would have allowed the pulley walk up and back in ever larger steps, that would induce the bolt to unwind and produce sufficient wear (abetted by the invasion of crud) to increase the inside diameter of the hub and vex the seal, as evidenced by the copious amount of oil-saturated crud deposits everywhere.

The degree of wear of the thrust side of the keyway (a look at the key would be interesting, if it was present during the autopsy) indicates that the key had begun to rotate axially until the contact of the rising corner finally broke the sleeve of the pulley hub.

Meanwhile, the seal was exposed to abrasive contamination, unaccustomed movements, and finally, a broken hub sleeve, and succumbed to the abuse some time ago.

From the look at the back of the pulley, it would seem the only thing turning your belts was the jambed key against the thrust side of the broken hub.

I suggest that the condition of the keyway would make a cleaning and replacement of parts a temporary solution at best.

I would further speculate that the seal's utter failure may have allowed sufficient contamination to endanger the condition of the dist. drive gear and even the #1 bearing behind it. At any rate, I would think more disassembly will be required to reach an informed assessment of the damage.

Of course, this is just one interpretation of the clues provided, and other, more learned minds, might draw different conclusions.

Again, just $.02 worth from the cheap seats.

I wish you good luck in dealing with this.
 

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The woodruf key is for allignment purpose only. I have seen much worse damage done by people not paying attention when they reassemble the front of the engine after removing the damper. The large center bolt is what holds the damper from moving but proper torque specs need to be applied. Tap out the center hole in the crank to clean out the crap. Buy a new key off ebay. Its metric and may be hard to find locally. Buy a new oil slinger and seal. I have a turbo damper that someone put on my N/A car (why!!!!! who knows) I have replace it with the proper damper and I do not own a turbo car so I am not in need of it, just can't remember where I put it, but I will find it.
Text me at seven, zero, one 471 fifteen, thirty four with your contact info and I will let you know when I find it and we can talkl about getting it to you. Name is Craig.
 

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Discussion Starter · #8 ·
The woodruf key is for allignment purpose only. I have seen much worse damage done by people not paying attention when they reassemble the front of the engine after removing the damper. The large center bolt is what holds the damper from moving but proper torque specs need to be applied. Tap out the center hole in the crank to clean out the crap. Buy a new key off ebay. Its metric and may be hard to find locally. Buy a new oil slinger and seal. I have a turbo damper that someone put on my N/A car (why!!!!! who knows) I have replace it with the proper damper and I do not own a turbo car so I am not in need of it, just can't remember where I put it, but I will find it.
Text me at seven, zero, one 471 fifteen, thirty four with your contact info and I will let you know when I find it and we can talkl about getting it to you. Name is Craig.
 

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Discussion Starter · #9 ·
Craig, Thanks for the info. Yes, I would certainly be interested in the damper. It’s late tonite so I will text you tomorrow.
 

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Your keyway is definitely in need of repair. You can replace the crank, or short of having the keyway welded closed and remachined which is a two fold problem. First it will be expensive and second you have to find a place that can do the crank work. Very few and far between. Anyhow, stuff a rag in the hole in the timing cover to keep more contamination from going in the engine. Then sterilize the keyway as best as you can with brake kleen or lacquer thinner. Dry it out thoroughly with compressed air or time. Use a product like Quicksteel and fill the worn side of the keyway with that product. Facing the crank that will be on the left side of the keyway. Then take a piece of Saran wrap and place it loosely over the hole, take a good woodruff key, preferably a new one and push the key into the slot all the way. Using a popsicle stick you can lightly push down on the Quicksteel, making sure that it is tight against the key. Fill in any imperfections on the crank as well. Let it sit for 24 hours then pull the key out, and remove the Saran wrap. You'll probably have to lightly file the crank smooth again where the Quicksteel has created a high spot. Once that is done pull out the rag, clean out that area from filings, install your new oil slinger, then front seal. A light coat of oil on the end of the crank and you can install the replacement harmonic balancer. Then install the bolt and torque it to 125 psi. If you're not using the CAS from an 81 turbo then you don't necessarily need the turbo crank pulley. Any ZX crank pulley will work in that case. Don't expect this repair to last forever. It should last a considerable amount of time if you sterilize it thoroughly but it's definitely not a permanent fix. I've had them last for quite a few years before although the best fix is still to replace or repair the crank properly.
What usually causes this scenario is either the bolt was never torqued properly, OR the rear pulley which is pressed on with rubber has rotted and slips on the hub. This throws the pulley out of balance which causes a vibration. That wears out the ID of the pulley which causes it to wobble on the crank until the bolt backs out. The third reason that this can happen is from a static electricity build up in the rear pulley from a slipping belt. Once the charge builds up to a certain point it will be enough for the electric charge to jump between the rear pulley and the hub which will usually fry the rubber and bonding agent that is used to glue the rear pulley to the hub. Once it fries then it's just a matter of time until the pulley starts to slip and failure is inevitable. Next time you hear a vehicle start up and there is a squeal from a loose belt you'll know it's much worse than just another squealing belt.
Before installing any used crank pulley, always inspect the rubber bonding the pulley and the hub together. If the rubber is starting to crack then the pulley needs to be replaced or rebuilt. I do sell rebuilt pulleys (with a trade in) or I can rebuild yours as long as there is no metal damage to it. When the pulley is being rebuilt there are 3 beryllium wires that get soldered to the 2 pulley pieces to make sure that they're grounded to each other. This will eliminate any chance of a larger static discharge due to slipping belts.
When I build a Z engine, I usually rebuild the pulley automatically, especially if I"m getting the engine balanced which is VERY necessary, especially if it's an L28. The balance job on them is terrible.
Z man of Washington
 

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Discussion Starter · #12 ·
ZMan, you said, “Use a product like and fill the worn side of the keyway with that product.”
What product are you referring to? Thanks
 

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There is nothing on the market that is cheap that will hold with the exception of Belzona 1111. Its very expensive! dont worry about the damage, get the center bolt tight!
 

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Discussion Starter · #14 ·
Ok, I have a new pulley, oil seal, bolt and washer, and oil thrower. I will install them when I get time from work (busy season). Maybe next weekend. Let you guys know how she runs. Thanks for all of the advice.
 

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Yellowbone, I know I have already told you this but I wanted to share this with the rest of the members.


Just a small dab of superglue to hold the key it in place. The key does not have any tortional strength to prevent the balancer from spinning If the balancer would stop and the crank kept spinning the key would just shear off. It’s the friction from the center bolt holding the balancer to the oil pump drive gear up against the bottom chain gear that is up against the crankshaft. Get it tight! glad you got the parts!

BTW I have had a keyway repaired when I sent my 1981 crank in to be crack checked and cut 10/10. I had to send it to Minneapolis, MN.

I also have a 1983 that has a badly damaged keyway form a previous owner not paying attention when they re-assembled the front of the engine. I actually tac welded the key in place. I did have the front cover off the engine and was able to make sue the key was in the correct place by sliding the oil drive gear and bottom timing gear off and on the end of the crank. Is this the "correct" way of repairing this, not really.
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The alternative is to pull the crank and send it for repair, over 300.00 repair, for what? I was able to get the proper alignment of the key to get the gears on and off and that’s ALL / the ONLY thing, nothing more, is the reason that key is there. Alignment. Even if it was off 1/32 of an inch, what is that 1/2 degree or less of timing? Get the bolt tight! And if anyone didn't know, superglue is highly resistant to petroleum products including gasoline.

I'm sure I will get a keyboard lashing over this, but I'm sure I am not the first to re-assemble a damper with a damaged keyway, it seems to be a common issue?

Good luck yellowbone and please remember to finish your story so we know how it all turns out!
 

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I corrected my original post. I use a product called Quicksteel. I have used JB weld in the past as well. I couldn't remember the name of the products as it was getting late that night. I meant to correct it the next day and forgot all about it. My apologies.
Kickstand, there is another reason for the keyways besides being a proper alignment locator. It's called shear strength, and it's basic engineering, especially on a rotating object like a crankshaft. It's every bit as important as stress strength. It takes both of them working together to make things work and stay together. ZMOW
 
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