vaccum wiper motor troubles

nealseale · Post by **nealseale** » Wed Aug 31, 2011 10:47 am

When you pull on the wiper, either side, the blade swings to the left fully but does not return. When you push the wiper switch off it swings fully back to the right as it should. Anybody know what's going on with this. Thanks for the input!

oilleaker1 · Post by **oilleaker1** » Thu Sep 01, 2011 11:58 am

You may have vacuum leaks. Run a temporary hose from the engine intake port direct to each motor and try them. The hose ends themselves need to be tight and the valve on the windshield should be checked. If it still goes through the double acting fuel pump, that is another culprit. If they don't run good direct, then the motors need to be washed out and re-greased. Extreme slow care when popping the tops off. Very thin delicate gasket , two piece, is in the joint. I use a knife blade to very slowly break the seal. Regular thin grease gun grease is what I put back in. If it is badly worn and grooved, it costs about 110.00 each to be re-built, or you can watch for a deal on brand new M151 wipers and modify them to work. I bought two sets off ebay for 30.00 a pair!!!!! Great deal. Original used sometimes are good, but usually no better than yours. They ALL stop going up a hill when you step on it. Why else would they have a assist arm?

John

nealseale · Post by **nealseale** » Thu Sep 01, 2011 2:04 pm

Thanks much!!

I'll get right on it!

Bill

Post by **wesk** » Fri Sep 02, 2011 12:06 am

Save yourself some work and/or grief and first take a vacuum gauge reading at the on/off valve.

M38, M38A1 and M170 are 10" @ 200 RPM and 12" @ 1500 RPM

If this is low then you may have a leak or a bad vacuum side of the fuel pump.

If the vacuum is good then squirt a little WD 40 in the suction fresh air in side of the wiper (that's the side that is vented or plumbed to the right side of the windshield and on to the air cleaner).