620 1974 L18 Crank Bolt LOOSE & Fan/Pulley Bolts not clamping tightly

[Cardinal Grammeter]

CRANK BOLT:

 

Why did bolt come loose?

 

Obviously torque it to spec BUT should I use Loctite???   Which color???

 

FAN/PULLEY/WATER PUMP BOLTS:

 

Fan/pulley Bolts were installed w/safety bolt head lock tabs and NO torque wrench.  Now with the belt adjusted, I can grab the fan and see it move relative to the pulley - this should not happen. 

 

Previous Failure:  Last time I didn't use the lock tabs and used Loctite and also NO torque wrench, the bolts came loose, pulley started hammering against the bolts, the bolts elongated the pulley holes and finally, the pulley SHEARED OFF ALL FOUR BOLTS and Destroyed the Radiator.  I had tightened them w/o a torque wrench and was confident they were right enough.

 

The only thing I can think of is to use a torque wrench since the bolts "clearly" did not spin out of the lock tabs.

 

 

[datzenmike]

Crank bolt is 90 -120 ft lbs 'nuff said.

 

 

[Cardinal Grammeter]

Thanks Mike, I'll go with 120 on the wrench.

 

I checked the FSM and there is no torque spec for the fan bolts.  When I tightened those bolts, I went as far as I thought I could w/o damaging the plastic due to clamping force - and yet, I could with not much effort cause the fan to slide back and forth on the pulley face, the bolts still as originally installed.  NOTE:  maybe this is how things should be, but if yes, then it's really a crappy design - so I'm not buying it - there must be a way to keep the fan from sliding around.

 

FAN/PULLEY CONTACT SURFACE:

 

I was thinking of some way to bond the plastic fan to the steel pulley but not much sticks to plastic (I think the fan is nylon or a plastic that is "oily" and doesn't bond well.)

 

Epoxy

Aviation Form a Gasket

RTV Gasket Maker

Contact Adhesive

 

Roughening up the steel surface might work but I don't like the idea of "defacing" the pulley:

 

Radially scoring with extremely coarse sand paper or grinding disk

Upsetting/dimpling with a center punch on the contact face

 

PULLEY/WATER PUMP FLANGE SURFACE:

 

The previous failure where the bolts loosened and then hammered out the pulley slots was a result of relative motion between the Pulley and the Pump Flange.

 

Epoxy there would probably eliminate that relative motion and eliminate another similar failure.  The fan bolts would then only have to keep the fan attached and if there was a little sliding on the pulley face, it wouldn't matter.

 

Stud Bolts would solve the problem - especially these with the thin, large diameter head that would have nice contact area with the fan:

 

 

Edited May 5, 2022 by Cardinal Grammeter

[datzenmike]

Are the bolts bottoming out?

 

I did have the crank pulley off on my 521, it was an L20B. No torque wrench when I put it back on. One afternoon of ultra high RPM hill climbing and on the way home the pulley detached. I walked back an picked up the pieces off the highway and put it back on with vice grips and got there.

[Cardinal Grammeter]

So the crank bolt fell out and then the pulley actually came off?   If YES, did it miss the radiator?  You had vise grips on the crank snout??? (!)

 

The fan bolts are not bottoming (but I will be sure to checked when I remove and redo them.)  I just can't see that big, thick plastic fan in the parts stack NOT creeping under the clamping force resulting in looseness.  The FSM sure isn't worried about their assembly so perhaps as long as the safety tabs are engaged, the bit of slippage I can make between my 2 hands is OK???

 

After my rad destruction, I don't want to take any chances (especially since I scored a #481 Eagle brass OE rad that's on the truck now.

[datzenmike]

Bolt and washer were on the highway. Pulley was off the woodruf keys but stayed with the belt and alternator. I pushed it back on and then saw that the bolt was gone. Really surprised the bolt was a hundred feet behind the truck about where the red charge light came on. I had had a few, and was climbing a hill to get out of a depression in the woods. Took at least a dozen tries to get out. I'm not surprised it shook loose. Again it was not torqued to speck just back yard ratchet with pipe on handle.

 

Maybe time for an electric fan. You'll never hear them unless stopped idling long enough or maybe at lights. All vehicles today, maybe not trucks, have electric fans. Long as vehicle is moving, hardly need the fan at all, and never during warm up.  A much more efficient use.

 

I have a set of them on my 710 and wired on at all times. They will even come on after shut down during the heat soak period. If idles long enough they come on for 10 seconds and off for 30 or more. They don't come on at all when driving.

[Cardinal Grammeter]

Electric fan isn't on the table.  The "theme" for my 620 is everything OE - it's my Personal War Against Entropy.

 

I'm considering NOT disturbing the still correctly safety tabbed fan bolts since there was no torque spec for them (I don't think even tighter will change things so the amount of "fan slippage" I'm seeing is probably acceptable.)

[Stoffregen Motorsports]

13 hours ago, Cardinal Grammeter said:

CRANK BOLT:

 

Why did bolt come loose?

 

Obviously torque it to spec BUT should I use Loctite???   Which color???

 

FAN/PULLEY/WATER PUMP BOLTS:

 

Fan/pulley Bolts were installed w/safety bolt head lock tabs and NO torque wrench.  Now with the belt adjusted, I can grab the fan and see it move relative to the pulley - this should not happen. 

 

Previous Failure:  Last time I didn't use the lock tabs and used Loctite and also NO torque wrench, the bolts came loose, pulley started hammering against the bolts, the bolts elongated the pulley holes and finally, the pulley SHEARED OFF ALL FOUR BOLTS and Destroyed the Radiator.  I had tightened them w/o a torque wrench and was confident they were right enough.

 

The only thing I can think of is to use a torque wrench since the bolts "clearly" did not spin out of the lock tabs.

 

 

I always use red loctite on the crank pulley bolt. You can run the bolt in with a rattle gun, without using a torque wrench.

 

There can be an issue though. If the bolt has been loose for very long, it can wear out the key way in the pulley hub, making it sloppy back and forth. It can also wear the snout of the crank,the key in the crank snout and even the key way in the crank snout. Best to remove it to make sure before you tighten it back up.

 

If the keyway has been worn, it is possible to shim it tight with different materials, depending on how bad the wear is. Sometimes it just need a slice of beer can to make tight again.

[Cardinal Grammeter]

WTF - bolts hammering and slotting pulley AGAIN.

 

Fuck this - I'm drilling and tapping a 5th hole in the pulley and flange so I can install a cap or button head screw to secure the pulley to the flange.

 

Then I'll hog out a little bolt head clearance on the back side of the plastic fan.

 

The loose as fuck safety tabbed fan bolts only have to hold the fan on - NOT secure the pulley to the flange.

 

 

[Cardinal Grammeter]

I wish you wouldn't have said any of that!  LOL

 

Yeah to the keyway, I've seen all the wear you've mentioned in those early Paxton supercharger drive pulleys.

 

There is clearly some rotational slop in the Datsun pulley - maybe 1/16" circumferentially along it's OD.

 

The fact that I could easily rotate/wiggle the pulley with the loose bolt indicates the snout is worn (I assume the pulley is a press fit needing a puller to get off?)

 

Is the wear present on all the components (pulley, key, crank) or do any of the parts wear more than others?  I wonder if replacing the pulley would solve any of the problems?

 

Loctite had that sleeve formulation which was the strongest back in the 70's - I think it might have been green.  That might work on a worn snout/pulley surface. 

[datzenmike]

5 hours ago, Cardinal Grammeter said:

Electric fan isn't on the table.  The "theme" for my 620 is everything OE - it's my Personal War Against Entropy.

 

 

 

Actually an electric fan that is off when an engine is cold or cool enough (most of the time) would be much more efficient at reducing entropy compared to a mechanical one that is on all the time. 

[Cardinal Grammeter]

I was using Entropy conversationally - as a measure of chaos - and when you restore a car, you decrease it's "chaos"

 

QUESTION:  Does the crank pulley have a slight interference fit requiring a puller to remove and bolt to pull on?  or does it slide off and on?  The FSM gives no indication - it simply says "remove."

 

With the crank bolt loosened, the pulley can be turned slightly showing some play in the key - it can be wiggled easily indicating NO interference.

 

[Ooph!]

It sounds like ( No Picture of it ) it may be the fan bolts bottoming out on the shank of the bolt not on the end of the bolt but the unthreaded portion stopping when it meets the threaded hole.

Edited May 6, 2022 by Ooph!

[datzenmike]

28 minutes ago, Cardinal Grammeter said:

I was using Entropy conversationally - as a measure of chaos - and when you restore a car, you decrease it's "chaos"

 

QUESTION:  Does the crank pulley have a slight interference fit requiring a puller to remove and bolt to pull on?  or does it slide off and on?  The FSM gives no indication - it simply says "remove."

 

With the crank bolt loosened, the pulley can be turned slightly showing some play in the key - it can be wiggled easily indicating NO interference.

 

 

A puller is nice but there's no room and I have never used one. I use the 27mm socket for the bolt and tap the pulley forward. 50-60 taps and off she comes. Probably done over a dozen this way.

 

Wiggling isn't right but it's the 120 ft lbs that holds it still once tightened on. It's only spinning the alternator and the water pump. Are the woodruff keys damaged or have they been replaced with a wrong one???

[Cardinal Grammeter]

7 minutes ago, Ooph! said:

It sounds like ( No Picture of it ) it may be the fan bolts bottoming out on the shank of the bolt not on the end of the bolt but the unthreaded portion stopping when it meets the threaded hole.

Here are some pics:

 

See how the bolt w/safety tab strips have dug into the fan?  I think the fan plastic wears away resulting in less clamping force which allows slipping.

 

 

Here are the bolts from the SECOND failure (the FIRST failure was catastrophic with the pulley slicing off all 4 bolts which destroyed the radiator.)
The safety tab strips are shown and were fully gripping the bolt heads when disassembled.

 

 

Here is my mod:  I drilled and tapped 2 holes for cap screws that secure the pulley to the flange and will not be affected by a fat piece of plastic in the bolt stack.  You can see the minor hole slotting in the pulley as it was starting to hammer into the bolts.

 

 

Here is a pic of the water pump flange where you can see the 1/2" slotting resulting from the FIRST failure.  (I've already drilled and tapped the cap screw threads. 

 

FYI the flange is hard as f**k and I had some 1970's Rigid Taping Oil that is loaded with Sulfur which you cannot buy any more.  

With modern tapping oils, I was concerned I might break the tap.  With the "obsolete" (more like "hazardous") Rigid oil, it tapped like ordinary steel.

 

[Cardinal Grammeter]

3 minutes ago, datzenmike said:

 

A puller is nice but there's no room and I have never used one. I use the 27mm socket for the bolt and tap the pulley forward. 50-60 taps and off she comes. Probably done over a dozen this way.

 

Wiggling isn't right but it's the 120 ft lbs that holds it still once tightened on. It's only spinning the alternator and the water pump. Are the woodruff keys damaged or have they been replaced with a wrong one???

 

Rats, I guess I'm going to have to pull the pulley off - can I see the key or is it "inside" the timing cover? 

 

Sounds like there should be no "slop" regarding the key. 

 

Also, I expect to slide the pulley off with my hand - with the bolt loose I can rotate through the "backlash"  - it feels like backlash in a differential - loose on the snout.

 

....I'm going out in the garage, spin the bolt off and see if the pulley slides right off.  

[Cardinal Grammeter]

just thinking, if that key is totally loose and also "inside" the cover, when I slide the loose pulley off, could the key fall out of the crank into the bottom of the timing cover.  

 

EDIT:  PULLEY LOOSE AF ON SNOUT.

 

With the bolt off, I could wobble the pulley on the crank.  It slid off like an alternator pulley.  

 

I am going to measure and see what the clearance is - I have a brass shim assortment that goes down to .001 inches.

 

And I'm probably going to soak the snout and shims down with Red Loctite.

 

Also the key does not protrude beyond the timing cover much but it was SOLID in the snout and did not fall out.

 

EDIT 2:  Clearance was less than expected: no more than .002 inches.

 

I'm going to slide it on, then put some Red Loctite 271 in the pulley bore at the end of the snout and let whatever wicks up.  Then a couple drops on the bolt and torque.  Let it sit over night.

Edited May 6, 2022 by Cardinal Grammeter

[Cardinal Grammeter]

The way the bolts clamp the plastic fan seems problematic since they are clearly "digging" into the plastic.

 

Their clamping force could be uniformly spread over the entire outer face of the fan.

 

Imagine another pump flange that would sandwich the plastic fan if placed under the bolt heads - you could clamp them to extremes and they would not deform the plastic and produce whatever clamping force was required.

[Crashtd420]

6 hours ago, Cardinal Grammeter said:

The way the bolts clamp the plastic fan seems problematic since they are clearly "digging" into the plastic.

 

Their clamping force could be uniformly spread over the entire outer face of the fan.

 

Imagine another pump flange that would sandwich the plastic fan if placed under the bolt heads - you could clamp them to extremes and they would not deform the plastic and produce whatever clamping force was required.

Could you possibly place some sort of metal into the fan to correct the holes? 

Something like this...

[banzai510(hainz)]

I have a L18 and I needed a puller to get pully off.

 

all other motors I just tapped them off with a hammer

 

find a another fan if possible if hole oblonged

[Cardinal Grammeter]

16 minutes ago, Crashtd420 said:

Could you possibly place some sort of metal into the fan to correct the holes? 

Something like this...

 

That is a great concept although I don't quite understand how the fasteners are to be used.

 

The simplest solution to have a solid metal bolt stack that could be properly tightened would be

a) shoulder bolts  (shim to increase plastic crush)

b) simple bushing in fan  (reduce bushing length to increase plastic crush)

 

Clearly a simple bushing would be the easiest!  AND you can order bushings of the correct ID/OD of a variety of standard lengths from McMaster.  (of course, final length would have to be fit.

 

Another easy solution would be to find Stud Bolts with thin, wide heads (I found some on net, did I post them here???)

 

BUT

 

EASIEST might simply be STUDS with a TRICK:  with nuts holding pulley to flange, lay fender washers over the nuts to give a lot of bearing area for the fan, then secure fan with nuts and the OE safety tab strip. 

 

THIS IS MY VOTE which uses READILY AVAILABLE FASTENERS and DOS NOT MODIFY ANY OE PARTS (!)

 

NOTE:  My problem was once I had my truck torn apart, I had to come up with a solution using what was available in my shop.

 

 

 

 

 

[Cardinal Grammeter]

22 minutes ago, banzai510(hainz) said:

I have a L18 and I needed a puller to get pully off.

 

all other motors I just tapped them off with a hammer

 

find a another fan if possible if hole oblonged

 

The fan does not oblong, but the First failure oblonged the holes ONE HALF INCH!!!!   (I hope I didn't throw that pulley out, there may be pictures of it on Ratsun somewhere....)

 

My pulley definitely has some wear in it, but I caught it pretty early.

Loctite has an application manual which is AMAZING - they have a whole section of Keyed Shafts (!)

They have 2 categories of looseness:

 

*)  .002 to .004 inches  (mine is .002 max)

*) up to .010 inches

 

The first does not use primer (this is some kind of catalyst I believe) but the second does.  

The first one takes 4 to 24 hours to cure (evidently because no primer).  Argh!  I'm probably going to start using truck after 14 hours of cure - hope that is enough.

[Crashtd420]

17 minutes ago, Cardinal Grammeter said:

 

That is a great concept although I don't quite understand how the fasteners are to be used.

 

The simplest solution to have a solid metal bolt stack that could be properly tightened would be

a) shoulder bolts  (shim to increase plastic crush)

b) simple bushing in fan  (reduce bushing length to increase plastic crush)

 

Clearly a simple bushing would be the easiest!  AND you can order bushings of the correct ID/OD of a variety of standard lengths from McMaster.  (of course, final length would have to be fit.

 

Another easy solution would be to find Stud Bolts with thin, wide heads (I found some on net, did I post them here???)

 

BUT

 

EASIEST might simply be STUDS with a TRICK:  with nuts holding pulley to flange, lay fender washers over the nuts to give a lot of bearing area for the fan, then secure fan with nuts and the OE safety tab strip. 

 

THIS IS MY VOTE which uses READILY AVAILABLE FASTENERS and DOS NOT MODIFY ANY OE PARTS (!)

 

NOTE:  My problem was once I had my truck torn apart, I had to come up with a solution using what was available in my shop.

 

 

 

 

 

It was just a picture to possibly spark an idea... I was thinking a simple bushing too but I liked the flange that was around the one a posted.... i figured insert into the fan then bolt on.... 

I think the hope would be to find one the right diameter and depth that allows you to tighten the bolt without crushing the plastic to much but actually bottoms out the insert against the pulley... 

[Stoffregen Motorsports]

If you bring the motor up to TDC, the key should stay put when removing the pulley.

 

You don't normally need a puller to get these pulleys off. It's not like a Chevy V8.

 

The keyway in the pulley is softer than the crank and usually wears first. You can peen the key slot with a hammer and punch to tighten it back up again.

 

Do not use any sleeve retainer on the pulley, but yes with the red loctite on the bolt. If the bolt is tight, some wear in the key, keyway, pulley won't be a problem. You likely wouldn't even have noticed if I hadn't brought it up...

[Cardinal Grammeter]

7 hours ago, Stoffregen Motorsports said:

If you bring the motor up to TDC, the key should stay put when removing the pulley.

 

You don't normally need a puller to get these pulleys off. It's not like a Chevy V8.

 

The keyway in the pulley is softer than the crank and usually wears first. You can peen the key slot with a hammer and punch to tighten it back up again.

 

Do not use any sleeve retainer on the pulley, but yes with the red loctite on the bolt. If the bolt is tight, some wear in the key, keyway, pulley won't be a problem. You likely wouldn't even have noticed if I hadn't brought it up...

 

Since I could visibly wobble the pulley on the snout and also rotate it back and ford due to looks key, I did put 271 on the snout - "ironically" I did it not unlike the application manual:  I did put a couple drops at the top of the snout at the front which flowed towards the bottom due to gravity, but none on the keyway, slid the pulley on, they put a few more drops in the corner between the snout face and pulley bore - I figured whatever wicked occurred, that would be enough, installed the bolt and torqued, let cure for 14 hours.  The App Man said just what I did but also on the key.  

 

My goal was to NEVER have any future problems with the pulley and crank bolt - if I have to heat to 500* to get it off, I'll deal with that.  Also, while I sprayed the surfaces down with carb cleaner, I'm sure I did not get the surfaces completely free of oil, so the "permanency" of 271 should be somewhat compromised.

 

I've started driving it today and the narrow 185r14's in the front are awesome - much easier to steer and I actually throw the truck around more like a sports car because steering is easier.

 

AND for some freak reason (fingers crossed) the carb lean situation in the primary system is GONE.  No flat spots, can womp on pedal and the engine responds with immediate torque.  4th gear lugging power is back.  But I wonder just a few drives before I did this repair, I had to drive in heavy torrential downpours to the point where the water looked like it was going to foul out the ignition.  I'm wondering if the water could somehow have been involved in the carb working properly so far.  I have no idea.  The choke pulloff is still dead but I'll be hesitant to touch the carb if it is working this good.