[Helge71]

Yesterday whilst driving in the (unexpected) rain for the first time in quite a while with my 65 Catalina windshield wiper developed a strange and quite annoying behaviour:
After switching the wipers on (low or high setting doesn't matter) the wipers work for about 5 to 10 full swipes and then just stop in mid-swipe. After a couple of minutes the wipers get back on for something between a short jerk to about 2 full swipes before stopping again...and so on. Only after being switched off for a longer period (30 minutes or so) before switching on the whole sequenze (5 -10 full swipes...) starts again.
I checked all contacts and the fuse and everything looks fine. I does not matter if the car is moving or standing still, so a loose contact is in my opinion unlikely.
I have no clue what the problem could be...is there anything like a thermo-overload protection switch in the wiper system that somehow gets triggered and has to cool down before switching back on?

Any help or ideas would be highly appreciated.

Thanks

Helge

["QUICK-SILVER"]

The fuse in the fusebox is the only wiper circuit protection that I'm aware of.
I would not be so fast to rule out a lose contact. A lose wire terminal; be it burned, dirty, corroded, or just plain lose for what ever reason, can heat up and break connection. You've got wire terminal ends at the wiper motor, through the firewall, and at the wiper switch. The wiper switch ground contact (metal strap maybe)to dash could be lose. Then everything involved with supplying power to the wiper motor to think about: power to ignition switch, out of ignition to fuse box, through firewall, then to wiper motor.
Needless to say, you've got several connections that could heat up and break contact. If any one contact is lose to the arching point, heat will make it lose connecton not shaking or movement from driving.

Grounding high and low at the wiper motor should tell you a whole lot. If the wipers work with a direct ground from under the hood, switch ground would be suspect.
If they don't work grounded under the hood, something in the power supply or wiper motor itself will need checked out.
A fused jumper to the wiper motor can be used to diagnose a power supply problem.
Jumped power and grounding under hood will tell you if the wiper motor is at fault.
It wouldn't hurt to check for binding/tight linkage that could be putting too much load on the wiper system causing a wire terminal or contact to overheat.

The underhood high/low speed ground check and the fused jumper for power at the wiper motor should get things narrowed down pretty fast.

Post back if you need more help with and how to test.

[Helge71]

Thanks Quick Silver. Great instructions...now i have somewhere to start looking and testing. I will post the results when i'm through the system.

Helge

[Helge71]

Well...seems like i found the problem, though it was a bit more complicated than i hoped in the beginning:

After checking all external parts (contacts, wiperswitch, ground connections) and doing the above described ground checks on the wiper terminal with no results i removed the complete motor unit from the car for a bench test as described in the shop manual. Even during the bench test the strange behaviour continued...however in the shop manual i found the mention of a circuit breaker inside the motor casing itself, so i decided to open the motor casing and have a look at this circuit breaker. When taking out the armature shaft i noted that the end play was much too tight! The circuite breaker itself looks more or less like the contact in a distributor and seems to be some kind of bi-metal overheat protection device. I just cleaned the points carefully and reassembled the motor with correctly adjusted armature shaft end play. After succesful bench-testing the unit everything was installed back to the car and seems to run fine now... I assume the much too tight end play caused the motor to overheat after some wiper swipes and the circuit breaker was triggered. I just do not really know how the end play got so tight as the wiper worked quite well in the last years...

Helge

["QUICK-SILVER"]

I reckon that's as good as it gets, is in my book anyway.
It takes a REAL car person to figure something out and fix it instead of just swapping parts.
And got some good info posted for reference to boot!
The built in stuck wiper overload protection slipped my mind.
Thanks for the jogging.