Vacuum leaks

[James Morse]

Yeah, my book shows 2 common outlets as well. There could be error/variation from the book. I don't see how it could work unless the reservoir had only one connection.

So I took that connection in the pic apart and you can suck or blow (gently) on the engine side so there's no check valve there. On reservoir side you can get some vacuum, it kind of holds it.

I'm kind of at the point of getting a plain check valve and put in there and see if it makes a difference. The way it is now the reservoir might as well not even be there.

 

[James Morse]

Google put me on to a post from RonD 3 years ago he was saying a lot of times the check valve is integral to the reservoir.
When I do the test he first suggested it'll tell me if that side is holding vacuum or not.
Oh I forgot to say I looked at Mazda, it's same setup (no in-line check valve) so it started me thinking probably they're both not missing something. Book must have old info.

 

[ericbphoto]

Google put me on to a post from RonD 3 years ago he was saying a lot of times the check valve is integral to the reservoir.
When I do the test he first suggested it'll tell me if that side is holding vacuum or not.
Oh I forgot to say I looked at Mazda, it's same setup (no in-line check valve) so it started me thinking probably they're both not missing something. Book must have old info.

My book is for my 93. It's the same Ranger generation (3rd). But earlier in the generation. That's why I said it should be similar enough to get you close. The system works the same. But mine has vacuum blend door and no coolant bypass valve. Some components may look a little different or be in different places. But they both have a check valve somewhere for the same purpose. They both have a reservoir. They both involve vacuum controls. When you don't have the exact drawing you need, you learn to interpolate from what is available.

 

[RonD]

My 1994 has the small torpedo reservoir that sits on top of the heater box, just the one connection and the 3 port check valve
1994 and earlier used cables and sliders for vent control, not vacuum

1995 and up should have larger reservoir(the ball) with 2 ports, vacuum controlled vents
Built in check valve can happen but far more common to find one of these: https://i.ebayimg.com/images/g/66UAAOSwRepi6fEq/s-l1200.webp

On the vacuum line running from intake to reservoir

 

[James Morse]

Yes I have the ball reservoir with 2 ports as you say.
I am still confused when you (Ron) said splice in a piece to the black line inside did you mean cut it and splice in a line to test or were you meaning to disconnect it somewhere and splice a line to it? I'm thinking the first?
I guess I could connect a line to the side of the reservoir that goes to the firewall and see if reservoir holds vacuum, that would test part of it. If it doesn't hold vacuum there it would tell me check valve internal to reservoir isn't working, in which case I could put in-line check valve like you show and see if that changes anything.
The thing about splicing those little lines is I believe they have to have a collar around them to go onto a connector so like you had said I'd need some little parts there.

Or one easy thing I could do is just take the connector that is inside the connection in last pic, and get a check valve that fits it. That would be be easy assuming it's a common part. I'd think any check valve would work that fits, doesn't necessarily have to be Ford, though that would be nice.

 

[RonD]

Trace the black line from reservoir to firewall, it will most likely be cracked, cut it where its cracked, and remove enough line to have a good unbrittle line to splice
You can then put on a longer rubber hose and test if cab system can hold a vacuum, suck on it

If the black line to cab looks OK then unplug that line at the reservoir and test it the same way
If it holds a vacuum then plug it back in
Now unplug the other line on the reservoir and plug in you longer hose and suck on it, if its doesn't hold a vacuum then reservoir is cracked

 

[James Morse]

So I did this quick test. With it running, on Max a/c, I took the line off the piston that opens the recirculate door, you can reach right up under the dash, that's where air gets sucked in when the door is open. There's no vacuum there and there should be. But the controls all work fine, tried to replicate the default-to-defrost on acceleration, couldn't make it do anything (more) wrong (that would be a symptom of bad check valve).
When I switch from a/c to Max a/c you can feel just a momentary slight vacuum then none and it should be pulling strong vacuum there to open the door (and close the heater core valve).

I'm actually a little confused why it has to change the heater core valve because it seems like that should already be closed if the temp control is on cold, but, side issue.

Anyway that sounds to me like either the selector isn't putting vacuum to that line, or it's plugged, or there's a small leak that isn't enough to affect anything except the additional stuff that has to be activated when on Max. Am I making sense? The rest of the controls have to be getting vacuum or none of the stuff would work. To me while it doesn't rule out a leak somewhere, clearly that white line has to be pulling vacuum on Max a/c and it's not. This is consistent with what guy at shop said when he tested for vacuum at the heater valve there was none.

 

[RonD]

Temp control knob only controls the electric Blend Door actuator
The Blend Door is located where the air from the fan/blower comes into the cab after going thru the AC Evaporator
Blend Door then directs the air either thru the heater core(HOT) or around the heater core(COLD) or anywhere in between

The heater core by-pass valve in the engine bay is there to reduce radiated heat in the cab from the heater core to maybe lower cab temp a degree or two in MAX AC

The main extra cooling in MAX AC is from closing the Fresh Air vent
Once cab starts to cool down with AC on and say the temp outside is 100deg and temp in cab is 80deg
The AC system can cool down 80deg air from inside the cab better than it can cool down 100deg air from outside
So in MAX AC the fresh air vent is closed and the fan/blower now sucks in cooler air from under the glove box to be cooled, so Maximum AC, lol

MAX AC is also good to use on dusty roads or anytime there is outside air quality issues, i.e. smoke or smells
You don't have to have it on COLD, so MAX AC can be used in summer or winter, anytime you want to keep the outside air, outside, lol

Just FYI, heater by-pass should also have vacuum when selector is in the OFF position, this also closes Fresh Air vent

 

[James Morse]

I found the connector block behind the glove box, so you can take that off and do that test you are talking about without cutting anything there.
There is also no vacuum to the white line in the OFF position.
To do the test you were talking about, I took off the connector block, run the engine, put my finger over the black side, it pulls good vacuum, I turn off engine, it holds vacuum, if I wait a bit (with no discernible loss of vacuum) then take my finger off I can hear it sucking air back in. To me that seems like all good there.
If I take out the radio I may be able to see where the white line connects to the selector maybe it is just loose there. I was screwing around with the radio at some point maybe I knocked something loose. It acts for OFF just like for Max, momentary slight vacuum at the recirculate door then zero vacuum.

 

[RonD]

Good testing

You can test each hose at that connector by adding your own hose and sucking on it, and maybe hear air being sucked in behind the dash

 

[James Morse]

I got rubber line 3/32 ID. It fits over the connector block outlets and fits inside the female side so pretty good for testing this area.

Edit, actually when I tested going through the selector it does -not- work. Thought it did. Actuator for door works with direct vacuum but not any other way so either vacuum is weak / slow leak or something else. I should be able to hook up the black and white lines only and it should work the door if I plug the other ones.

It might be good to get a basic vacuum tool and see how much vacuum it's pulling, maybe it's low that would tell me leak the front side of the firewall like we been talking about.

Gave up for today... will revisit...

 

[James Morse]

Leak is between firewall connector and heater valve.

What I did for temporary is disconnect at the firewall, run a short line connecting the black side, and put a golf tee in the white side. Then everything works normally (except of course the heater valve is out of the picture).

It looks to me like the firewall connector and the 2 lines on the engine side are made in one piece. There's a rubber grommet there I assume you'd pull that out and pull the lines through to the inside. I can't reach it at all on the engine side.

I guess I need to find that part. I don't see anything weird visibly with the line to the heater valve but if you plug one end and try to get vacuum in that single piece, there's none, it clearly leaks bad. If I knew the leak was in the part I can get to, I'd probably splice something in there.

 

[James Morse]

1998-2011 Ford Ranger Vacuum Harness F87Z-19C828-DA | TascaParts.com

Ron this says does not fit my '97 truck but it sure looks similar, not sure about the reservoir connector but all the rest looks identical. Do you know if it's the same?

 

[RonD]

It goes in from the cab side so plug may not fit in the hole in firewall, but holes can be made bigger, lol
And if hole is too big then plugs can be made bigger, wrapped in tape

But yes that looks like a part that will work

 

[James Morse]

Well.... if they say it doesn't fit chances are it doesn't. Kind of not excited about trying to fit it via mods.
Options - spend 15-20 dollars, get it, if it's not right, give it to somebody else.
Maybe you could somehow get the lines out, -if- they're the right length (probably), and put in existing grommet. I think that probably wouldn't work.
Or, ask my shop, tell them, I've isolated the leak, can you get the part & put in? Swapping in the new part should be fast; finding the problem is what's time consuming.
Here's the thing, whether heater core turns off or not isn't that huge a deal. It probably helps a little. Having the recirculate door working is fairly important. I mean, everything is important in terms of saying "everything works". Problem is right now I have a short line going black-black at the firewall, but if it falls out, you lose all functions for the vents (no vacuum at all). Now you'd know that right away, and you don't have to take things apart to put it back together, and because there's vacuum on it, it's not likely to fall apart, but it can, and it's not really kosher.
If anyone can locate the right part I'd sure like to know. Bugs me it's only 1 year off but gen changes can be a killer.
Also option to ask junkyard to pull one and test it make sure it's good, probably would cost more than the '98 part new.
Also option to pull the part from my truck, try to find the leak and try to fix it but that's not really how I'd like to go. You could imagine if you find the leak, put vacuum on it, put some cement... might work, but if it pulled the cement into the tube it'd plug it and they are tiny.

Just kind of thinking out loud... best option is find the freaking part new, I think second is junkyard, if it tests ok, should be ok.

Out of all this though I really learned how the system operates and how to find leaks. If you have that 3/32 ID rubber line and a few golf tees that gets you a long ways as to doing tests, the 3/32 fits the outside of the nipples and the inside of the female side (on the connectors / connect blocks) so you can set up different scenarios to isolate things. Didn't spend anything except under $10 for the tubing (and a bunch of time). So the project was 'successful' in terms of finding the problem.

I'm pretty sure rest of stuff is ok. If I run the truck, then turn it off, then turn the selector to "Off", it activates the door and holds it (I don't know how long, but, a while). You can even switch from Off (with engine off), let it close (or open depending how you look at it) partway, switch back to Off, it stops. That tells me except for the known problem, it holds vacuum.

Thanks for all the help and encouragement, nice to not be on my own with this stuff.