mysterious vacuum hose.


SimplyTheBess

10+ Year Member

Joined
Jan 24, 2011
Messages
37
Points
1,601
City
St. Louis, MO
Vehicle Year
1998
Transmission
Manual
Hey all. I replacing the spark plugs and spark plug wires the other week
http://www.therangerstation.com/forums/showthread.php?t=105057
and noticed this then but didn't take a picture of it. Really bugged me because I could not find where this little vacuum line goes. It would seem to want to go to the air intake (after filter but before MAF) but I don't see where it ever connected to.

Truck is a 98 Ford ranger (4 cyl in line) No CEL, truck runs great, heat/AC works etc... (As far as I can tell nothing is wrong!) Pics below. Any help would be appreciated. Thanks!

mysterious vacuum hose.


mysterious vacuum hose.


mysterious vacuum hose.
 
I have 2 spot on my engine where it would seem a line would run into but nothing hanging... I blame the friggin squirrels that keep putting acorns in my air box lol.
 
They'll woe the day they fall asleep under my hood!!!!
 
If I had to guess, I would say it goes to the heater bypass valve even if the heater and A/C appear to function normal.

mysterious vacuum hose.
 
Yea, there should be a nipple on that valve.
 
If it was an F-150 I'd say it's the vent line for the vac hubs. On your truck, I agree, probably to the heater bypass. The heat will work fine with no vac to the bypass valve, but it might take a little longer to get it to temp.
 
I agree with everyone saying it may be for the heater bypass valve.

While you are looking there check out the nipples on the valve that the hoses slide onto, make sure none are cracked or leaking. I have a 99 and was driving home last summer and one of the nipples literally broke off of the valve. Pumped out half my coolant before I could get off the road. I haven't heard of it being a common problem but it couldn't hurt to check and if it looks like it's trying to crack better to fix it in the parking lot than on the side of the road.

adsm08 said:
If it was an F-150 I'd say it's the vent line for the vac hubs. On your truck, I agree, probably to the heater bypass. The heat will work fine with no vac to the bypass valve, but it might take a little longer to get it to temp.
Click to expand...

If it were for a 4wd I'd have said the same thing, the 98-00 Rangers had a similar set-up.

Actually the heat won't be affected at all, neither will getting it up to temp since the valve is normally open. Vaccuum actuates that valve when "MAX A/C" is turned on. It is used to cut off flow of coolant through the heater core making your A/C more effective.
 
Last edited:
Okay guys think I found where it was it appears to connect near the heater hoses. I ran max A/C today and it seems find. Not sure if it worth the hassle of replacing.

Pics

mysterious vacuum hose.


mysterious vacuum hose.


mysterious vacuum hose.
 
Your A/C won't be as cold, but it's not an absolutely necessary item to fix. I would at the very least cap the vacuum hose off.

EDIT: I know I would most definitely notice the difference in the June/July/August heat wave.
 
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