A/C Compressor Replacement and Pulley Alignment

[cwilson jr]

well, i got a longer bar for leverage and managed to get the belt even tighter and so far it has made a difference.  now, i'm going to see if it will stay that tight.

[cwilson jr]

that didn't last too long.  the ac quit working today.  popped the hood and the belt is sitting on the pulley sideways.  i see cracks so my belt is shot again and i wonder if it rolled from the slight slant thats on the ps pulley.  i'm going to try and get some pics posted tomorrow.

[cwilson jr]

here is what i noticed with the compressor and power steering pulleys being off-set.  also, you can see how the belt rolled as well.

[cwilson jr]

any ideas?  if this is the power steering causing this and not the compressor, is there a way to re-align it?

[gildardo01]

your compressor is misaligned with the pump.. you have to move the compressor back about 1/4 of an inch or so... you can do this with washers as if they were shims... leave the pump the way it is, if you move the pump you will misaligned it from the engine... and dont tighten it too much because you put extra stress on the belt...

[bd]

any ideas?  if this is the power steering causing this and not the compressor, is there a way to re-align it?

Misalignment of the A/C compressor is fairly common with the compressor mounting configuration you have.  You need to establish the plane in which the A/C compressor is misaligned, and then determine how skew that plane is with the correct plane of the water pump & power steering pump. 

Place a straightedge along the flat, backside of the compressor pulley, so the straightedge extends first toward the water pump pulley and then toward the p/s pump pulley.  When the compressor pulley is properly aligned the straightedge will be parallel and coincident with the back of the w/p pulley and the center ridge of the p/s pump pulley.  How far off is it?  Realignment often requires varying amounts of change at the three compressor mounting points (i.e., compressor lower pivot, left outboard adjustment, and top inboard adjustment).

I just completed this exact same realignment on my A/C compressor, so I will do what I can to guide you through it.

[cwilson jr]

i tried several different things along with different washer and bolt combos, no matter what i did i could not get the compressor to back up like i needed.  there was just no room left on the lower rear bracket.  the one that goes down to the exhaust manifold

before i got your post, i took it down the road to a guy that i deal with sometimes and has a shop and he said the issue is not in the power steering pulley, because it aligns with everything else and said the same thing i had found out, it needed to be moved back and there wasn't room.  he looked up some things and it turns out there are the same r4 compressors with different pulleys.  i had purchased the first one listed below that was for an 85, which was the same one that i removed originally.

NOW, keep in mind my 85 truck originally had a 305 and someone dropped in a 350 a long time ago, BUT the locked compressor i pulled off originally matches up to the one i ordered the first time.  obviously, not the correct pulley in the truck originally though.

SO, to continue, he found the same compressor with a pulley that has the belt track further back, which is listed for 80-84s.  i have this one posted in the second link.

originally on truck and installed exact replacement and the one i'm having a pulley alignment issue:
http://www.autozone.com/autozone/parts/Everco-A-C-Compressor/1985-Chevrolet-K10-1-2-ton-P-U-4WD/_/N-ijkpwZ91sgi?itemIdentifier=328559_147281_3515_

now ordered this one and hopefully this'll do the trick:
http://www.autozone.com/autozone/parts/Everco-A-C-Compressor/1984-Chevrolet-K10-1-2-ton-P-U-4WD/_/N-ik3mgZ91sgi?itemIdentifier=162909_147353_3515_

[cwilson jr]

ok, so, i have a mess on my hands.  i'm going to give you what details i know and see if anyone has had a similar issue or knows about these subtle differences.

i have an 85 k10 with a 350, originally a 305.  was purchased this way.  i purchased a replacement a/c compressor which matched the old one installed already that was locked.  there was no belt installed.  this the compressor in the first link:

http://www.autozone.com/autozone/parts/Everco-A-C-Compressor/1985-Chevrolet-K10-1-2-ton-P-U-4WD/_/N-ijkpwZ91sgi?itemIdentifier=328559_147281_3515_

it look liked the #1 picture below, installed.  obviously you see the aftermath, but you get the picture with the alignment.


then i purchased this compressor:
http://www.autozone.com/autozone/parts/Everco-A-C-Compressor/1984-Chevrolet-K10-1-2-ton-P-U-4WD/_/N-ik3mgZ91sgi?itemIdentifier=162909_147353_3515_

which was pretty much the same result, except misaligned on the other side.  picture #2.

is there a  pulley thats in between these two, or are there wrong pulleys on the motor?  everything, but the ac compressor is in line.  there seems to be so many differences in the r4 pulley types and from year to year?  we have tried different things with washers and bolts and it only misaligns things worse.

[zieg85]

The AC belt goes around the rear pulley of the PS pump.  My 85 is somewhat off as well.  It seems to be smack dab in the middle of the double pulley.  I run the 7 series belt which so far has been OK.  It is not right but at least it works.  I don't know the answer to this either.

[bd]

The 305 and 350 small blocks should use the same compressor for any given year/model.  The vehicle probably had the wrong replacement compressor installed when you acquired it. 

Although a 1987, my compressor mounting (i.e., brackets and belt configuration) is similar to yours and it aligns perfectly after minor shimming (see image).  I use this Everco/Four Seasons compressor P/N 58235.

Measure the distance between the machined front face of the aluminum compressor body and the back of the steel pulley, near the top of the belt groove.  The 58235 compressor body-to-pulley distance measures 1.125".  Would that bring your belt into alignment?

[cwilson jr]

bd,
would you happen to have or be able to send me additional pics?  i'm taking this back in and it would be great if i could have one showing the shims and also the entire compressor with all related brackets to guide us if we need it.

[bd]

Using a straightedge to establish a starting point and estimate the extent of misalignment between the compressor to water pump pulley and the compressor to power steering pump pulley.  Measuring the distance between the compressor body and the rear flange of the clutch pulley.  Rear compressor bracket for comparison.

[bd]

The 1/8" thick one-piece spacer installed on the compressor top bracket.  The spacer sandwiches between the backside of the bracket and the cylinder head to rotate the inboard mounting of the compressor forward.  I chose a one-piece design so I could permanently secure the spacer in place using a socket head bolt.  Two 1/8" thick washers would have worked just as well.  The compressor bracket has a stepped mounting surface that requires a matching step in the spacer.  The extra 1/8" thickness of the spacer required a longer Grade 8 flange head bolt.  Since I run aluminum heads, I was able to increase bolt penetration an additional 1/4".  The thickness of shim selected will be unique to every engine.

[bd]

Following installation of the top bracket with its 1/8" thick spacer, compressor alignment with the water pump was significantly improved, but needed some additional tweaking to make it perfect.  However, compressor misalignment with the steering pump was still too far rearward.  After reevaluating with the straightedge, it was evident the top outboard edge of the compressor needed to move rearward about 1/8", which effectively would rotate the bottom of the compressor pulley forward, bringing the compressor into alignment with the steering pump while at the same time nudging the inboard edge of the pulley forward into perfect alignment with the water pump pulley.  In gradual stages, I removed about 5/32" of height off of the outboard, top rear adjusting bolt (the stacked bolt-in-a-bolt passing through the compressor body), rechecking the belt alignment constantly.  I intentionally removed enough material to install a Grade 8 washer between the stacked bolt and the rear support bracket to improve clamping of the slotted adjustment (the gold colored washer in the image).

Essentially, your compressor uses a three-point mounting.  The lower bolt is the pivot point; there is no slotted adjustment at the pivot.  Hence, I left the pivot unchanged and used that as a constant reference.  The remaining two attachment points useful for compressor alignment are where the upper bracket bolts to the engine and where the compressor body fastens to its rear bracket at the adjusting slot. 

As you make changes, take your time and observe how the plane of the compressor pulley shifts in relation with the water and power steering pumps.  Adding spacers is trial and error.  Shimming too much is easy to correct.  But, if you need to "remove" material, removing too much material is more of a challenge to rectify.  Be patient.  Think through any changes before you commit to them.

Edit: spelling

[cwilson jr]

thank you, this should get us moving in the right direction.

i believe i have all of the brackets, but i did notice in your first pic in the last post, it appears there is a bracket in the upper rear that bolts to the intake manifold?  not the support rod, but a seperate bracket or a section of one?  i'm not sure, so i included a pic of everything i have.  could you tell me if i'm missing something?