Need advice with vacuum problems

[londoner]

I have a 2001 Ex 7.3 Limited 4 X 4 with 185,000 miles. Last year 4 WD on front hubs went out so had new hubs & seals. New vacuum pump also. Now getting intermittent problem with A/C damper only blowing defrost which indicates vacuum problem. I think 4 WD goes in and out also.

Local mechanic replaced vacuum lines but can't find the problem, suggested dealer take a look.

Does anyone have any thoughts as to what might be causing problem before the dealer goes to town on it? I can check simple suggestions but mechanical ability is limited to opening the hood!!! Have researchd the site but nothing seems to help.

would appreciate any help so I can have "educated" conversation with the dealer - thanks

[dhanna6powerstroke]

Originally Posted by londoner

I have a 2001 Ex 7.3 Limited 4 X 4 with 185,000 miles. Last year 4 WD on front hubs went out so had new hubs & seals. New vacuum pump also. Now getting intermittent problem with A/C damper only blowing defrost which indicates vacuum problem. I think 4 WD goes in and out also.

Local mechanic replaced vacuum lines but can't find the problem, suggested dealer take a look.

Does anyone have any thoughts as to what might be causing problem before the dealer goes to town on it? I can check simple suggestions but mechanical ability is limited to opening the hood!!! Have researchd the site but nothing seems to help.

would appreciate any help so I can have "educated" conversation with the dealer - thanks

Just start tracing the rubber vacuum hoses and lines that run from the hubs up to the vacuum pump. That's the most common issue. You could get a vacuum gauge and connect to the lines and see if it will hold a vacuum.

[justinmix]

Originally Posted by dhanna6powerstroke

Just start tracing the rubber vacuum hoses and lines that run from the hubs up to the vacuum pump. That's the most common issue. You could get a vacuum gauge and connect to the lines and see if it will hold a vacuum.

Pretty much what he said. Hubs are a rather common thing to leak on these, but unless your driving around in 4wd all the time it shouldn't even be trying to pull vacuum on the hubs. So if it's doing it in 2wd I'd be tracing the other vacuum lines going into the cab.

[ocrush]

I ran into the same issue a couple years back around 100k. I ended up having a few incidents where I would attempt to engage 4x4 and one or neither hub would engage. I ended up switching out the automatic hubs with Warn manual hubs and I traced the vacuum lines and plugged those that formerly routed to the old hubs, this solved the A/C blowing on the windshield defrost setting only. No regrets here approx two years running. Good luck!!