My 1971 521

[Crashtd420]

lol I swapped it and drove it around and this where my temp gauge sat (50 degress here):

 

 

So is that better or the same as before?

[wayno]

You know that if your thermostat housing doesn't have the bypass you need to drill an eighth inch hole in the thermostat, the jiggle valve is there to let air out, it is not a large enough hole to act as a bypass, they do not make thermostats with holes in them anymore, so the L16 thermostat number gets crossed to the L20b thermostat.

One day while your driving down the freeway your water temp will start fluctuating all over the place, it will get hot and then cool way down only to get hot again, then one time it gets hot it will stay hot and if you do not catch it in time it will over heat, if the head gasket doesn't go then it will go in the near future.

[datzenmike]

Find me a $10 thermostat besides stant?  RA just got a bunch of $5..or better yet if you don't like stant what do you like? 

 

 

What range? Needs to be 185F or 190 / 195F in the winter. You're not saving anything if your thermostat over heats your engine and leaves you stranded... or worse. If it sticks open you have to take it out and replace it.... even if it's free replacement. You don't get anything for the time and aggravation. That's no deal. You want to do it right ONCE.

 

You don't need a hole or juggle valve to allow bubbles out. Those are for engines where the thermostat is mounted on it's side and some bubbles can be trapped at the top. L series thermostats sit horizontal. The first time it opens in use, any trapped air gets out. Just check the coolant level and top it up.... you should check it anyway.

[d.p]

It’s warmer than it was before so it’s better now. Before it was just right of the cold line and before I swapped the dizzy cap/carb it was right at the line if not right of it.

 

It’s a 190 if that matters.

[thisismatt]

Hey, a stock temp gauge that works!

[d.p]

I got a loud humming noise when in 4th and cruising around 35-40MPH.  It didn't used to do that but it definitely seems speed/load related as when I slow down it goes away.  Could that be my rear diff? 

[mainer311]

Higher or lower pitched? 

 

Higher pitch is usually the ring and pinion mesh. It typically sounds more like a whining noise. Could be bad pinion or carrier bearings, or just worn R&P. If you're doing 40 and take your foot off the gas, does the sound go away or change? If the sound is the loudest right at throttle tip in, that usually means the pinion bearings are worn, or the preload is too low.

 

Lower pitch humming/rumbling could be badly worn tires, or a bad axle shaft bearing. Typically doesn't change with load, but will come on with higher RPM. If the sound persists even when not on the throttle, I'd start looking into the rear axle shaft bearings. 

 

If the sound changes when cornering, front spindle bearings. 

 

This past winter, I rebuilt my Roadster axle end to end. When I test drove it in the spring, it had a loud whine and it turned out that I didn't set the pinion preload high enough. These axles typically have a pinion shaft spacer with shims on both ends, unlike newer cars that have a crush sleeve to set preload. When the bearings wear, the preload goes down and you'll end up with slight axial misalignment, which causes the R&P to sing a little bit. 

[Crashtd420]

Can't catch a brake can you....

Those noises are hard to find.

 

Diff is possible.... maybe check the oil in it.... or even just replace if you haven't since you've owned it.....

 

Also see if the driveshaft is loose at all... check the u joints and the bearing...

Ideally if you could get it in the air running that would be good.. atleast you could get close to the diff and see if the noise I coming from it or where it is coming from.... basically anything rotating could cause it.....

 

4 Jack stands will work but it is a little sketchy....

[datzenmike]

That can be from be from bent, or damaged driveshaft,  driveshaft weight fallen off, bad U joint, or lowering the vehicle height which throws off the driveshaft angles*. Damaged tire or wheel weight fallen off is a much lower frequency vibration. If worried about the differential you can remove the fill plug and oil should drip out. You should be able to dip finger tip in it. If low or dry it should be evident with a wet spot, usually around the pinion seal.

 

(*most likely)

 

Try 3rd gear at those speeds. If the vibration stays at the same speed then not something in the trans / engine out of balance.

 

Check that exhaust pipe is not rubbing the frame or body or clamped down without some noise isolation rubber mounts

 

Had an axle bearing start to growl but only on corners and at all speeds. Yours may be different.

[d.p]

Its low pitch and if I take my foot off the gas and truck slows down the sound goes away.  Tires are practically new with maybe a 1000 miles on them so I doubt they are the issue.  Not a vibration either, just loud.  Basically the truck gets louder between 35-40, anything higher or lower than that the sound goes away.   3rd gear the same noise.  

 

Rear diff doesn't appear to be leaking, its dry to the touch, exhaust pipe isn't moving and the truck is dry as a bone underneath.  Don't have a big enough socket to check the diff level, what size is it?  Pushed and pulled on the drive shaft and it didn't move, it would turn ever so slightly but no up/down or side to side movement.  ujoiunts look to be original, same color/shade of rust as the shaft.  

[mainer311]

Mike, reread, he mentioned nothing about a vibration.

 

DP. when I say take your foot off the gas, I mean momentarily, not enough for the truck to slow way down.

 

Judging by the symptoms, it sounds like a bad wheel bearing. They usually cannot be heard until higher speeds, and are a low frequency growling/humming noise, kinda like a box of rocks. Of course, a dry u-joint will also make that noise (sometimes they squeal), and not have any noticeable play in them. The same goes for the carrier bearing if you have a 2 piece shaft.

 

Is the fill plug a square drive? It's almost always either a standard 3/8" or 1/2" ratchet.

[d.p]

Yeah 2 piece drive shaft and the carrier bearing is where the 2 ends meet?  Yes to square drive as well.  

 

Truck is on jack stands now, is there anything I can do to see if the wheel bearings are in fact bad?  I read its a bitch to change them out on these trucks.    I also noticed that under mediate to hard braking the truck vibrates or wobbles so usually I just ease into braking to avoid that.  So maybe I have had this problem for a while but its getting worse.  

[racerx]

Don't think its u joints. From my experience, u joints will make make like a clanking noise when you take off. I would check ur rear differential, u sure its a socket. Did u go under and check.

[Crashtd420]

I'm leaning towards what mainer said....

i would still make sure the diff has oil but sounds more like wheel bearing...

I think the only way to check the rear wheel bearing is basically wiggle the tire and rotate it and listen close for a grinding sound....

Is the sound definately coming from the rear of the truck?

[d.p]

Nah don't think its coming from the rear.  I just wiggled the shit of my front wheels and passenger side does have some movement in it whereas the driver side is rock solid.  Is that wheel bearing, kingpin or something else??  Vid below. 

 

 

 

 

Rear diff:

[Crashtd420]

Pull the dust cap off and make sure that nut is tight.... I've seen the cotter pin break before and the nut slowly backs off..

[Crashtd420]

Also take that wheel off and slowly rotate the hub.... if bearings are bad you'll feel it..... might have to pull the hub to really tell

[wayno]

Just take your 1/2 inch breaker bar and take the rear diff fill plug out and check the rear diff oil, if it is an amber color then you are likely good there and it is easy to do and rule that out, if it is silver then you have an issue, if you cannot feel any gear oil then again you have an issue, it will take 10 minutes to check, rear diff noise(howl) is almost always speed related.

To check the U-joints properly you need to remove the drive line, I have seen u-joint appear solid in the truck, but they were loose when out of the truck.

I would also check the transmission fluid level.

[racerx]

Next question for fluid type is what kind...use API GL5..I think I used sta lube. Don't get one that's says meets the specs. Be specific saw 90, gl5

[d.p]

Pulled the grease cap and the cotter pin is there, only a little play in the bolt, basically turns a little left to right.  Turn the drum and it scraps a little but I just assume that is the drum and not the bearing?  The little rubber control arm bumpers on the fronts are shot, missing one on driver side and one basically disintegrating on pass side.  Not sure those would cause my problems? Rear diff has fluid in, black amber color and I can put my finger tip in and feel/see fluid.  And its not leaking, dry as a bone.  

 

 

 

[mainer311]

Gear oil looks dark, but not bad. If there are no chunks or a heavy metallic swirl, then it's likely okay.

 

That is a LOT of play in that wheel you were wiggling around. Could be a combination of worn king pins and loose bearings. That is almost definitely the cause for the shake during hard braking. The amount of play that you have left to right is...scary. Top to bottom is a result of the king pins. Left to right is either steering tie rods or super loose/worn hub bearings.

 

The rubber control arm bumpers are only for down travel and will not cause any issues. 

[Crashtd420]

How does the hub feel with no drum...

Also pull the nut first and see if the hub comes off easy... then you can really inspect the bearings....

 

I would snug that nut up.... you don't want to crank it on super tight but you don't want it loose....

 

Everything else sounds fine... New oil in the diff won't hurt....

[racerx]

I would change the rear diff fluid for sure. And its hard to explain how to check wear of bearing by grabbing and tugging. A good friend had to show me many moons ago. I would take the inner and outer bearing and inspect them through my.

[mainer311]

With the dust cap off, does the hub move around independently of the spindle/nut? If so, that may be your problem, the nut backed off like Neil said, and your hub is loose. Tightening the nut on a front spindle is an art. You don't want to go too tight, and you don't want to go too loose. It has to be done by feel.

[Crashtd420]

Ya on mine the bearing felt good on the truck.... once I had them in my hand it was another story....

Remember the inner bearings are listed wrong on every parts sight.....

I have a part number somewhere for the correct inner.....

I have seen correct sets being sold or you can get the spacer from mike klotz and use the 620 inner bearing......