Adjustments on an early m38 flat nose starter switch

Hammerun · Post by **Hammerun** » Mon Aug 04, 2014 1:32 pm

I have this early m38 flat nose starter part #MBP4301UT.
It has a floor switch part #118845
I have it apart and cleaned it. I found what would be the usual arc marks on the terminal switch assy and the plunger switch with blade assy. There is thou a set screw in the opposite end of the blade assy, the end towards the lever shaft. It looks like this set screw would determine the height of the blade assy.
My question is what is the correct height of the blade assy off of the body prior to reassembly. I know there is another adjustment out on the lever but I can assume there is a starting point for the blade assy.
When I put the cover back on it I can tell by moving the lever when the blade is engaging the terminals and when it's not. Is that a good point to start?

Hammerun · Post by **Hammerun** » Mon Aug 04, 2014 4:18 pm

This might give a little more insight.
What happened, this jeep is done, just paint left. Ten days ago I started it for a minute of so. I have been waiting on some hoses and things. I got them, installed them and yesterday I finished it. I jumped in, turned the master power switch on and stepped on the started and nothing. Not a noise, bump, grind nothing. I have 24.3 volts on the starter switch. The grounds from body to frame, motor to frame, ground bar from neg side of switch to starter body are there, all on bare metal not paint.
I'm thinking now something inside the starter motor, a wire grounding off or something. I also readjusted plunger blade and lever adjustments.
I have now pulled this starter out three times and still the exact same results, nothing.

Post by **wesk** » Mon Aug 04, 2014 9:24 pm

Have you jumped the power strap directly, bypassing the switch entirely? If not then now is the time to decide weather the switch or the electric motor is at fault.

Hammerun · Post by **Hammerun** » Mon Aug 04, 2014 10:25 pm

Well I went nuts and dove into it. I removed the commutator end, nothing looked out of the ordinary. It was actually very clean, i was surprised. I then removed the other end, there again nothing out of place until I noticed one of the four brush cables was detached from its field. I don't know if this is the root cause but it might be a good possibility.
Suddenly realizing this was beyond my wage grade and knowledge Ive got a friend that knows an old guy in Victorville that rebuilds this kind of stuff.
I didn't cross the terminals, maybe I should have.
As far as the adjustment on the plunge blade. Have you heard of this? I can screw the plunge blade in and out and turn the set screw up to it. I'm just kind of miffed as where to start it. The TMs I've got have got zero on the subject. Chuck at Surplus City didn't know either.
Thanks again Wes, for your response.

Post by **wesk** » Mon Aug 04, 2014 10:53 pm

Last time I was at Victorville I had dinner with a well known actor and his wife from whom my customer was buying their airplane. It was at the Olive Garden.

Are you using TM 9-1825B? Your answer is on page 335.

I don't have it loaded in our downloads section yet but you can download a PDF copy here: https://files.secureserver.net/1fmMVdba5MS1f2

Hammerun · Post by **Hammerun** » Tue Aug 05, 2014 12:35 am

Do you remember Richard Keil? (jaws in 007 and in the longest yard) My wife knew him when he was out here. I don't know where he is now but his place was about five miles from here.
Ill get that TM from the PDF, thanks again

Hammerun · Post by **Hammerun** » Sat Aug 09, 2014 3:06 pm

Wes,
I got the starter back and it checked out on the bench. I can tell, there was new ark marks on the blade and contacts. So I put it in the truck, wired it in and nothing. I crossed the terminals and just got a small spark but nothing enough to turn the motor. All of the grounds are good and on metal. Gen terminal A/#4 to positive side of started, (outside) battery positive to positive side of starter. Ran a multimeter on it and 25.1 volts between ground and posi side of starter. I ran the meter between the two terminals and got 24.5 volts.
I'm lost. Is it somewhere in the wiring? This doesn't make any sense.

Hammerun · Post by **Hammerun** » Sat Aug 09, 2014 4:18 pm

Here's what I'm trying to figure out. Why would this starter work on the bench and not in the truck? To me this is screaming bad ground or no ground. I have removed every ground cable and cleaned everything down to metal. Body to frame, block to frame, regulator to frame. Why wouldn't the starter motor kick in when the terminals are crossed? If not, what's happening between the switch and the starter motor? What is happening in the starter switch that's not right?

Hammerun · Post by **Hammerun** » Thu Aug 21, 2014 12:22 am

My suspicion was correct, bad grounds. The thing starts and runs great.

Post by **wesk** » Thu Aug 21, 2014 12:46 am

Which grounds were bad? You had said earlier you took apart and cleaned them all already.The majority of these jeeps work fine on the strap between the engine front plate and the right front motor mount at the frame.

The starter when properly installed is grounded through the bell housing with two bolts and the front "L" bracket to the block with two bolts. Unless you have a ton of paint on the mating surfaces.

Hammerun · Post by **Hammerun** » Thu Aug 21, 2014 8:23 am

Using a flapper disk I cleaned the L bracket, block and ran a new ground strap to the frame just in front of the regulator, and recleaning that point. I added another strap from the bell housing at the 3/8s bolt just under the lower starter mounting bolt to a mounting point on the frame at the side of the regulator. This point has the body to frame strap and the Neg side of the battery cable. Did I find a specific point that I thought was the cause? No.
I did add star washers to all connections and made sure that all ends were good and clean. I thought the same thing as you, the starter is grounded at the bell housing and the L bracket. Which one or what? I haven't got a clue.

Post by **wesk** » Thu Aug 21, 2014 8:30 am

My money says that now that you have cleaned all the paint and crud from between the starter and the block/bell housing you can throw all those extra ground straps away and live peacefully as a regular single engine ground strap M38 guy now!

Hammerun · Post by **Hammerun** » Thu Aug 21, 2014 4:58 pm

With what I've been thru with this silly thing I think I'll be happy and leave good enough alone. Besides my wife is chomping at the bit (this is her jeep)
This jeep has a funny thing about it though. It stands 4" taller at the rockers than my other jeep. Both are 1953 A1s. I'm going to have to get them on concrete and put a tape to them and see what is the difference. I'm going to have to nickname it TallBoy as opposed to Betty.