My 95's vacuum pump has failed in fairly dramatic fashion - the pulley wobbles out of axis about 30 degrees each way. I went looking for a replacement but it seems the vacuum pump for it is one year only and not in stock at the local stores. The 96-97 pump is a different part number but is in stock.

What's the difference between the 95 and 96-97 vacuum pump? Is it possible to fit the later pump? Would the pump be an upgrade?

 

Surprised there's been no reply yet.

Anyway, I took the pump off and found a couple things. First, the clamp bolt for the pulley was missing. Second, well...


Third, the pump appears to be the 96-on pump with the external hose connecting upper and lower halves of the vacuum pod.





So, should I go get another 96-on pump or should I go back to the 95 'no hose' type pump?

 

I don't know, but I wouldn't think it would really matter to be honest.

 

Neither would I. Match it up at the parts store. As far as I know there is not supposed to be a bolt in there. That is for instal. The pull-up is a press fit

 

Ah, yeah, forgot that it doesn't have a bolt. Well, the whole thing is boned anyway...

 

Looks like the pulley's shot as well as the pump. Accuratediesel sells what they claim is a new OEM pump, not reman, no core, for about what you'd pay for a reman at the FLAPS. 'Course, since you probably need the pulley as well, I *THINK* there are some pumps available with the bolts already in place and a new pulley installed. Just have to use a gearwrench to install it.

 

for what its worth, that pump looks identical to the ones off of the 96 and 97 ones i've done. hard to tell by picture of course, but as long as the newer one mounts up, you shoudl be good to go.

 

The '94.5 and '95 don't have that hose. The pics on accuratediesel's site show the differences. But AFAIK they mount the same, connect the same, and produce pretty-much the same level and volume of vacuum. If you have the right pulley, I doubt it matters, and I'm surprised the aftermarket continues to make both designs.

 

that hose is for a dual action vacuum - so that i pulls vacuum on both sides of the diaphragm, by virtue of a check valve or two between the two sides. probably just pulls max vacuum a bit faster than the old version. if it mounts the same, i'd say the OP should "upgrade" to the newer one!

 

^^^^^^ Dang, wish I knew that when I bought the old-school version a few years ago.

 

i bet the old one is cheaper though, so there's that. as long as you don't get to highway speed and need to slam on the brakes within the first 5 seconds of starting your truck, you'd never notice the difference in the two, i'm sure :-)

 

Apparently the old one is actually more expensive.

I had a bit of luck, a friend was making a junkyard run and he scored a 97's complete pump/pulley assembly for really cheap. They do seem to be bolt for bolt compatible and I'll know more about that later. (Pictures are clickable for larger versions.)





However, one issue has appeared. The donor truck had apparently been sitting for a while and the smooth surface of the pulley is rusty. I know that the belt will often clean the surface off in short order by itself without damage, but I need a sanity check. I took some Eagle 1 Metal Polish and some 0000 steel wool to the pulley to do a cursory rust removal, with these results.









Should I just install as is or should I be taking a wire brush to this?

 

I would try to get that pulley cleaner. What the photos don't tell us is, how smooth does it feel?

 

There's a couple of rough patches. Wire wheel it is.

 

That pulley will be fine, after a few miles it will be clean.