I am having a repeat problem with my 2002 Blazer. The front axle actuator that engages the four wheel drive keeps tearing. The black rubber breaks. We have had to replace this part three times in the past six years. This most recent one was put on in August 2014. Any ideas as to why this keeps occurring? Any help would be greatly appreciated.

 

Are you replacing the entire assembly or just the vacuum actuator? If only the actuator, does the cable move freely?

Any battery acid dripping on the actuator?

Not had any problem with my '02, so just thinking as I type.

 

I have only replaced the actuator. I can pull on the cable, it moves about 3/4 to one inch. The battery looks fine, I don't think its leaking acid. I will check into the cost of a cable and replace it. I got 160K on the Blazer, so it might not hurt replacing cable. Thanks for the info.

 

The amount of cable movement is ok. Have you tried putting some speedo cable lube or liquid graphite onto the cable.

I cannot think of any reason as to why the vacuum atuator diaphram keeps breaking...other than battery acid dripping onto it. How does the battery tray look? Nice and clean or is there evidence of battery acid?

Other than cheap junk parts from China...I am out of ideas.

Good luck with it.

 

Any tranny fluid in the diaphragm when you remove it, or is it dry?

Transmission fluid can cause the rubber to break down and prematurely break the part.

Just an idea.

 

If there is trans fluid in there then you also need to flush the vacuum lines and replace the transfer case switch. Easy job.

 

The unit is pulling away from the diaphragm, be tough for the fluid to get there

 

I got my actuator from advanced for 49(dorman) but on rockauto the have another brand for 81.00. Maybe it has a heavier rubber?

 

Except for when the vacuum is vented from a particular vacuum controlled device; which causes air to flow towards the device. Otherwise, fluid would not get into the vacuum system at all, yet I have cleaned a few HVAC & 4wd vacuum systems on these trucks. The last one I cleaned, the actuator itself was almost full of ATF causing sluggish 4wd activation. The owner couldn't figure out where almost 6 quarts of ATF had gone...

ATF will degrade the rubber diaphragm rather quickly, but I would expect the OP to mention the presence of ATF as it tends to get all over the place when the diaphragm tears.

 

I kinda figured he would have mentioned it also. But, just figured I'd throw that out there.