M38 runs great till I turn it off then it wont restart

[doctorflatfender]

I have a 52 M38, I can start it and drive for hours with no problem. When I turn it off, after waiting a few minutes it will not start until the motor is cold again. A mechanic friend suggested the coil, I replaced that and still have the problem. Any suggestions would be greatly appreciated.
I also would like to install the electronic ignition, in reading through some of the other posts I believe a notch will need to be ground out of my distributor housing, can you point me towards the most accurate way of doing this, I really don’t want to mess that up. Thanks

[wesk]

It would help to clarify a few points:
1-Is it a stock jeep? (24 volt waterproof ignition etc)
2-Does won't start mean the starter spins the engine but it won't fire or the starter does not operate?
3-Have you tried priming the carb with raw gas injected in the venturi?
4-Have you confirmed fuel to the carb during the start attempt by removing the fuel inlet line at the carb and cranking the engine?
5-Do you have the thick (almost 1/4") insulating spacer between the carb base and the intake?

6-Is your heat riser open or closed?

See operation illustration below.


M38's had an Army service bulletin to reroute the fuel line from the pump to the carb so it was further from the exhaust manifold.


The coil failure would affect both running and start. Coils which break down when hot will quit while you are running it and not start again until cool.

Pointless ignition is just that , a replacement of the mechanical points with an electronic switch based on Hall Effect. There is no appreciable increase in performance. Only the saving of the time spent with the maintenance effort of cleaning and gapping points periodically. In my opinion (Old fart who has a love for old cars and points and has no problem adjusting them in a couple of minutes) the conversion is not worth it. A true electronic ignition that monitors engine operating parameters and meters fuel and adjusts timing as needed constantly would be worth the effort.
That said if you really must go pointless then rather then try the complicated modification route just buya ready made unit or kit from MSeries Rebuilds http://www.mseriesrebuild.com/ Be sure to tell Charles Wes K (Alias Cuz) sent you.

The two primary causes of no start when hot are:

1-Starter electrics internal issues.
2-Vapor lock of fuel system including boiling of fuel in bowl caused by excess heat transfer from exhaust manifold.

The easiest way to sort which one is the cause is to get her hot. When she won't start put a strap on it and tow her in 2nd gear and start it without the starter. If it starts you need to get the starter overhauled. If it doesn't start you need to remedy the vapor lock issue caused by heat on the fuel plumbing usually near the exhaust manifold.

[maeserik]

I did the (MUTT SWISS type ) pointless ignition in 2008. Still works great, i never had problems since that time.
I know not original, but nothing visible at the outside and replacing back the original parts is no problem.

link :
http://www.g503.com/forums/viewtopic.ph ... f83d81c4c0

[doctorflatfender]

I guess I did leave a lot out,
1-it is not 100% stock but ignition is 24 volt waterproof.
2-starter spins the engine but it will not fire, I am geting spark but it does not appear very bright, not sure what it should look like.
3- yes raw gas and starter fluid, and it still dosent hit a lick.
4-no, I will check that when I get home this weekend.
5-not sure, I will also look at that.
6-same as 5, I will check on that to.

Thanks alot, you have given me several things to look at this weekend, I will let you know what I figure out.

[alphonzo]

Is there a rebuild kit for the heat riser? Mine is rusted open,I'm trying to free it up by soaking in rust remover. Would heating it up help any.Thanks for any ideas,I don't want to have to buy another manifold,but may have to .Alphonzo

[wesk]

Jason, What did you figure out?

Alphonzo, I believe the CJ style heat riser kits are still available. The solvent of preference for me to free exhaust parts up is Mouse Milk.

[hillbilly21]

OKAY WES K ...I will bite !!! whats Mouse Milk ???

[alphonzo]

Wes,Thanks for the tip . Your illistration of the heat riser helped me to figure out why my m38 wasn't operating correctly.thanks again for your help. Al.

[alphonzo]

Wes,Thanks for the tip on the solvent. Your illistration of the heat riser helped me to figure out why my m38 wasn't operating correctly.thanks again for your help. Al.

[wesk]

Mouse Milk is the brand name of the best penetrant I have found over the years for exhaust components. I've used it for 40 years on turbo systems.
http://www.mousemilk.com/

[doctorflatfender]

Wes,
Looks like I need some Mouse Milk, my heat control valve is all messed up, the spring is not attached and it will not budge. Looks like it is half open, by the position of the arm. Almost afraid to take it apart, scared I'll never get it back together right, any suggestions as far as parts go, what I might want to order or have on hand when I tackle this.

I tried to mail you my data plate info, but it came back undeliverable, I sent it to a century link address, got another address to send it to?
Thanks for the help, this site is great, especially for a novice like me.

[wesk]

Unless you do a lot of cold weather driving it is simpler to just force the valve to the heat off position and tie it there. Just soak and tap until it is full heat off. Then forget about it.

If you do a lot of winter driving you are looking at a bigger project then you think.

1-Remove manifolds from block. Here's where the studs are broken trying to free the manifold nuts. If you break the aft one the engine must come out.

2-Separate the intake and exhaust. Here's where more bolts are broken.

3-When inspecting the manifold to block flanges and the contact area of the intake to the exhaust you will usually find severe erosion of material dictating a machining of these surfaces. This machine work must be done very accurately and carefully to be sure the block, intake and exhaust all align with each other still when assembled.

4-Now you can start on the heat riser valve.

I haven't bought a valve in years but most of the big name vendors have them.

My email wsknettl@centurytel.net has been working fine for dozens of other submitters. Are you sure you are using the correct address?

[doctorflatfender]

Looks like I may just go simple and keep it parked in the winter, I havent saved the money for a new top anyway.
I used century link instead of centurytel, I guess it is because I do so much work for century link.