How To Weak Vacuum Line and grinding noise FIX

[Mil T]

Did you replace the actuator at the same time you replaced the iwe? If one of the gears is warn down at all it will cause the gears to disconnect under load. How much all depends on how warn the gear is. The gears only mesh about a 1/4 of an inch or so. So when they are warn it is easy for them to slip. This is the main problem with this system. Not enough gear mesh. Hope this helps explain it.

 

[farman]

First off amazing post this is what I love about FRF. Second this got me thinking I should go out and check my vacuum system for leaks. And I do I guess, it leaks about 1 psi every 5 minutes. Not very much I guess, but from what I read it shouldn't at all right? Next I checked the vacuum at the brake booster and each hub while running and they all read 25 psi. So I am guessing the truck is able to produce enough vacuum to compensate for whatever small crack I have, and shouldn't have any damage do to loss of vacuum since there really isn't any while running? Also I found the relief line on the passenger side was melted shut, does anybody know what effect that would have on the system?

 

[mokan]

I noticed a popping noise several times while in 4 High range pulling a heavy load up a hill on gravel. It sounded like a front differential pop almost like an axel spline but then went away. Never lost traction just a little concerning. I racked it up to the torsional front axel design but do you guys think its an issue? Thanks.

 

[Mil T]

First off amazing post this is what I love about FRF. Second this got me thinking I should go out and check my vacuum system for leaks. And I do I guess, it leaks about 1 psi every 5 minutes. Not very much I guess, but from what I read it shouldn't at all right? Next I checked the vacuum at the brake booster and each hub while running and they all read 25 psi. So I am guessing the truck is able to produce enough vacuum to compensate for whatever small crack I have, and shouldn't have any damage do to loss of vacuum since there really isn't any while running? Also I found the relief line on the passenger side was melted shut, does anybody know what effect that would have on the system?

When you say relief line. Do you mean the dual rubber line that comes out of the IWE? That relieves the vacuum out of the actuator when being switched. It is very common that the actuator will get contaminated through this line if you have a lot of rain or are in a lot of water etc. That can cause the actuator to become contaminated. I address this in my original
post.

 

[Mil T]

I noticed a popping noise several times while in 4 High range pulling a heavy load up a hill on gravel. It sounded like a front differential pop almost like an axle spline but then went away. Never lost traction just a little concerning. I racked it up to the torsional front axle design but do you guys think its an issue? Thanks.

If the IWE and Actuator gears are warn at all it will definitely make the popping noise. It is loud and very unnerving. I have changed the way I switch into 4 wheel drive. I either stop and switch or make sure I am at least under 25 mph and lift my foot off the gas until my dash says it has completed the switch and say 4 HI. That gives the IWE and Actuator the best chance of fully engaging before you put power to it. I know your not supposed to have to do it that way but the system is flawed so you have to adapt and overcome.

 

[mokan]

We haven't had much snow so I haven't used 4x4 much. But I will take your advise and try that. I just wish it would work as designed....

 

[farman]

When you say relief line. Do you mean the dual rubber line that comes out of the IWE? That relieves the vacuum out of the actuator when being switched. It is very common that the actuator will get contaminated through this line if you have a lot of rain or are in a lot of water etc. That can cause the actuator to become contaminated. I address this in my original
post.

Sorry I was talking about the hard plastic line on the passenger side that goes over the shock tower and terminates just past the shock tower. It looks like it comes back up as a vent tube. Didn't know what effect it would have on the system if it was melted shut. And thanks for the reply I keep rereading your posts but I am a slow learner.

 

[Mil T]

Sorry I was talking about the hard plastic line on the passenger side that goes over the shock tower and terminates just past the shock tower. It looks like it comes back up as a vent tube. Didn't know what effect it would have on the system if it was melted shut. And thanks for the reply I keep rereading your posts but I am a slow learner.

I explain that line in my orig. post. It goes from the plastic to the rubber line that goes down to the Actuator. It is the vacuum line. The smaller tube on the double rubber line is the vent tube for the actuator. This is the one that you need to extend up into the engine compartment to avoid contamination. it ends at the shock tower. If you look at the plastic vacuum line just before it goes into the double rubber one at the shock tower, there is about an inch that is exposed outside of the protective sleeve. This is the area that usually will break. It sounds like yours is melted. This would definitely show that the heat gets to that portion of the line to make it brittle and that is why it usually break. I have not seen one melted but that doesn't mean it couldn't happen. If it is truly melted shut then that means you are not getting vacuum to the actuator when you shift to 4 wheel drive. Which probably means that your IWE and actuator are engaged all the time. Best way to check that is to lift the truck up in the front. spin the wheel with the engine running. If it turns the axle your IWE is engaged and the vacuum is not working. Do the driver side the same way to see if it is also engaged or if it disconnects on that side when the engine is running. When there is no vacuum the hubs are engaged. I hope I made that clear for you to test. The fix would be very easy by putting a piece of shrink tube that will go over the burnt area or use a piece of vacuum rubber hose to bridge the plastic burnt piece after cutting it out. Let me know how that works for you.

 

[farman]

So I was doing some more testing with my vacuum gauge tonight, and noticed that when I hooked it directly to my passenger side actuator (pulled the rubber hose off and stuck it on the bigger metal tube coming out of the actuator) it was leaking about 1-2 psi a minute. I then tried it on the drivers side and it held indefinitely. So I am guessing something is screwed up inside the passenger actuator, and was thinking I should probably replace both sides just to be safe. Which makes me ask is there a detailed write up how how to replace the actuators, I swear I have seen one somewhere on here. Unfortunately I will have some time to search and study since someone got ahold of my debit card info and decided to almost drain my account(not that there was much there) so It will be weeks before I can order parts.

 

[Wilson]

So I was doing some more testing with my vacuum gauge tonight, and noticed that when I hooked it directly to my passenger side actuator (pulled the rubber hose off and stuck it on the bigger metal tube coming out of the actuator) it was leaking about 1-2 psi a minute. I then tried it on the drivers side and it held indefinitely. So I am guessing something is screwed up inside the passenger actuator, and was thinking I should probably replace both sides just to be safe. Which makes me ask is there a detailed write up how how to replace the actuators, I swear I have seen one somewhere on here. Unfortunately I will have some time to search and study since someone got ahold of my debit card info and decided to almost drain my account(not that there was much there) so It will be weeks before I can order parts.

Lol try the first post
Milt t is the op