SAWMAN556

What number am I looking for?

Bossgame

Mine was doing the same thing and would seem like all was well when idling. But when I got under a certain load it would happen. I would be driving on freeway around 65 in overdrive. Start to go up a slight incline and I would get the grinding of gears. It would stop when I took foot off of gas and stepped on it so it dropped into third. Replaced solenoid and all fixed. It's worth a shot. $35.

SAWMAN556

I checked the vacuum. The passenger side was a clear 18. The drivers side would only give me 15 and I had to somewhat force the vacuum guage thingy deeper into the hose.

So my question is... will the new solenoid fix this? Is it just one solenoid or is there one on each side? If so do I need to replace both of them? And does anyone have the part numbers I need?

Thanks,
Patrick

VTX1800N1

You should have the same vacuum on both sides. I would start looking for a leak in the side with lower vacuum. Follow all the lines. A single solenoid controls both sides.

Bossgame

^x2. What he said. Only one solenoid. But multiple check valves and a reservoir box. Test all down to the side that wouldn't hold enough vacuum

You gotta check the hubs vacuum
Holding ability also. Lots of little things involved in this system. Any can cause an issue

SAWMAN556

It is possible to just replace the whole vacuum line on my drivers side? So it's possible that I don't need a new solenoid?

Bossgame

Both are possible yes. I've seen on here guys making their own out of vacuum tubing. Or you can buy it made already from ford probably. Look for some type of schematic on the 4x4 vacuum system for these trucks. There's gotta be one out there

mbct

This will make you nuts. Vacuum at both IWE's only 12 while vacuum from engine was a stong 21. After crawling all over and under checking vacuum lines, check valves and fittings, I discover that both the old and the new solenoids only put out 12 - 15 inches of vacuum even though 20+ is going in. Is this reasonable or is my next step checking all the electrical input?

VTX1800N1

The solenoid should pass all the vacuum directly through. In any case, 7" of vacuum should be enough to operate the IWE.

mbct

Yeah, that's what I assumed. So either I got a bad replacement solenoid or possibly there is something screwy with the input voltage that does not allow the solenoid to open completely. The IWE's work fine in the driveway, but at speed, I get intermittent "glass-in-the-blender" noise. No noise if the electrical supply is disconnected, or when I shift into 4HI. So I assume that when engine vacuum drops, the reservoir vacuum is depleted and the solenoid isn't supplying enough vacuum to keep the negative pressure at the IWE above 7".