LT2300

I suspect this has come up somewhere before, but I can't find an answer, so I'll hit it again.

I have a minor (?!?) vacuum issue that I've been chasing for a while now (using Willcox' troubleshooting procedure). In the process I've replaced a number (if not all) of pieces (including hoses) and I'm still not sure what's causing the issue. One thing I've found is that often the replacement pieces I've tried to use were faulty. Among other issues, override switches' nipples were slightly undersized, so that the stock formed rubber fitting didn't seat snugly.

Anyway, my car is a 69 small block manual roadster w/o power brakes. When I start it, the W/W door briefly opens, then closes.

In the troubleshooting process I found that my original vacuum tank would not hold vacuum. After waiting too long for a replacement to arrive, I replaced it with dual tanks from Summit. As a result, the headlight and W/W door vacuum systems are now isolated from one another.

However, I think it's important to note that the problem existed before I went to separate systems, and there was nothing wrong before (nor is there now) with the operation of the headlight doors.

The W/W door operates normally in response to both the W/W and override switches. It's only the open / close when starting that's a problem.

This is essentially a minor irritant, but I've also had some trouble achieving and maintaining a consistently steady idle, so I can't help but suspect that may also be a result of the vacuum leak that just keeps eluding me.

Gotta be someone out there who's seen this before. I can't even begin to add up all the hours I've spent trying to pin this down and the money spent on replacement parts when I've thought I had it figured out. See the observation about the quality of some aftermarket stuff in the second paragraph, above.

Thanks in advance to whoever cracks the code. Further, while I can't ship alcohol, I'm willing to spot a bottle of very good whatever to whomever does help me solve it. This has been going on far too long.

Thanks.

damvette

If my memory serves me right I believe I have read that this problem was caused by a faulty wiper door solenoid located behind the tach.
I hope this helps,
Derrick

Dave J

I've helped a number of guys diagnose and fix their wiper door issues. I can give you a step by step if you would like. Do you have a Mityvac or similar vacuum pump?

LT2300

I appreciate the quick response. However, there's one thing (actually probably about 9 things) I forgot to mention in my narrative.

I tried to buy a new wiper door solenoid. I encountered a several month backorder situation, so decided to try an alternative. I removed the hose from the T-pipe to the solenoid and ran the hose that had gone from the override switch to the solenoid directly from the override to the T-pipe, effectively removing the solenoid from the circuit. Nothing changed (other than having to manually open the W/W door to run the wipers). Still open / close on start. From that I concluded that the solenoid wasn't the problem (it had already been replaced a few years ago) and canceled the backordered solenoid.

Was my conclusion correct? Or not? Or is it impossible to tell? I've replaced so many things, another solenoid won't matter, but I'd like to have some confidence it will change the outcome..

LT2300

I have a vacuum pump and also Willcox' troubleshooting procedure, which I followed. That's how I landed on the solenoid (see the response from damvette, below, and my reply to him). All tests had indicated it's the problem.

But taking it (the solenoid) out of the circuit and still having the malfunction led me to wonder if it really was the problem. If taking it out of the circuit had cured it, I would have felt confident that spending the money and waiting for the backordered part was worth it, but the fact that the malfunction remained just confused me more.

I've been chasing this so long that I don't know where to turn. As I said to damvette, buying another solenoid at this point is nothing in the overall scheme of things, but at $150+ I'd like to have some confidence that it will solve the problem.

Dave J

I wouldn't keep throwing money at your problem until you get all the components fully tested. I have actually encountered very few solenoids that were bad. Report back with the results of these two tests.

1 - Connect the Mityvac to the top or control chamber of the wiper door relay and pump it up. It should hold vacuum.

2 - (And probably your problem) remove the wiper grill, and locate the wipers in the operating position and stopped with the switch located between the two override switches. This can easily be done without starting the car.

Locate the wiper door safety valve found under the base of the passenger side w/s wiper. You should find 3 hoses connected to it. Mark and disconnect the middle and lower hoses. Connect the pump to the MIDDLE hose. Pump it up and it should hold vacuum.

Next, park the wipers, which depresses the valve plunger. Block the lower hose with your finger or a short section of blocked hose and pump it up again. It should hold vacuum again, and release vacuum when you disconnect the lower port.

The following two diagrams illustrate the vacuum path for the solenoid in either of the two positions. You can test it in the car or out. Vacuum must pass through it in either position, and not leak anywhere. Simply block one side, and pump up the other to test. It should hold vacuum.





Report back with your findings.

JimLentz

For the idle issue why not disconnect everything vacuum operated, except the distributor and plug the ports. If the idle improves it is a vacuum issue otherwise it is not.

69Vett

unplug everything vacuum going to the engine, and cap them off.
connect vacuum gauge, normal engine about 12-14 vacuum, this is your baseline vacuum.
now start connecting or isolating vacuum system, if you cannot maintain your baseline vacuum find the leaking components. by isolating the vacuum lines.

Haggisbash

Assuming no vac leaks and still an uneven idle, are you using ported or manifold vacuum for your ignition vac advance? You could have an over advance issue at idle with high manifold vacuum if using manifold vacuum. See Lars post on restricting the vac advance.
I have a similar issue but when I put the car in drive the idle is perfect so I have left it alone for now.