Joined: Sep 14, 2006 Posts: 20 Location: Maumelle, AR
Posted: Sun Sep 23, 2007 7:43 pm Post subject: M38 Ran fine...until now
I have a 1951 M38 that was running fine until one day three weeks ago it just wouldn't start any more. The day before, I had fuel coming out of the unused port on the fuel pump (between the two mounting bolts). So I rebuilt the fuel pump, works great, but M38 will still not start. I took plugs out and cleaned them up. They were covered in carbon because it had been running very rich. I put ether in the air intake but still nothing, not even a sputter. I have let it sit for several days between attempts, so I don't thing there is fuel sitting in the intake (flooded or anything) Sparkplugs fire, but not very well, so I ordered a new set. Will be here in a few weeks. Timing shouldn't be off unless it somehow skipped!
How do I check the timing? Can I use a timing light? The TM9-804 manual wants me to take the engine apart to check timing.
Any other thoughts?
Also, underneath, is the bell housing behind the engine supposed to have a plug in it? I didn't think it was supposed to. I am getting some oil leakage there, what does that mean?
Sudden failure of an engine to run is seldom caused simultaneously by two or three different malfunctions.
Changing or rebuilding components simply because they seem suspect without testing each system first gets expensive and frustrating.
TM 9-804 and TM 9-8012 both have very good troubleshooting chapters. These take a step by step approach starting with the easier and cheaper things first.
These two Tm's do not require any engine disassembly to time the ignition system. They require you to insure your timing marks are visible and well marked, they require you to have an ignition lead adapter and a timing light. They require you to have a basic set of wrenches. They require you to disconnect the ignition lead from #1 spark plug and insert the adapter. They require you to loosen one bolt at the base of the distributor so it can be rotated. They require you to attach the timing light to the adapter and to start and run the engine at idle. Then with the timing light triggered and shining on the timing marks they require you to rotate the distributor housing slightly to bring the timing marks into alignment. Then they require you to tighten the bolt, then accelerate the engine to about 3000 RPM and your timing should advance smoothly another 5 or 6 degrees or twice the distance between your two timing marks for TDC and 5BTDC. If all is well then remove adapter and light and reconnect spark plug lead.
The plug in the bell housing drain hole is to be installed for fording operations only. When not fording water it is to be removed and stored in the glove box. This is shown in both the manual and the placard that goes on the dash.
Oil leakage from this hole can be tranny gear oil or engine oil. You must smell it to determine which oil it is. If it's tranny gear oil then either the tranny is or was overfull or the input shaft gasket and or slinger are leaking. This requires tranny removal. If it's engine oil then either the rear main bearing cap seal is leaking or the cam's rear journal welch plug has been knocked loose and is leaking. The easiest way to repair either of these engine oil leaks is to remove the engine. Sharp professional mechanics can accomplish the task with some degree of success with the engine installed but there is always the risk of the attempt not being successful and necessitating another attempt. The engine only takes 1.5 hours to remove and 2 hours to install.
I would suggest you look around your area for other MV owners who have done a lot mechanic work and solicit their help and or guidance when the tough spots appear. These forums can be a great help but you must be caustious how you use them. If you have exhausted your resources and the data in your manuals then you bring an issue here to the board where you will often get many "shot in the dark" suggestions. These are great to store and remember but they will cost you more money and time in the long run if you don't stick with an organized troubelshooting chart and apply them as the chart gets to them. For example the weak plugs you cited and back ordered just may be fine and the coil may be weak, or the capacitor/condenser may be bad causing rapid point deterioration and a weak spark, or the distributor housing may not have a good ground or the primary wire entering the distributor housing from the switch may have a short to ground reducing availble current, or the ignition noise filter capacitor in the connector for that wire may have high resistance causing your weak spark. A shotgun approach to these issues is not the way to go. Unless of course you are a millionair and don't care how much money you throw at a problem but then that guy would just pay a pro to fix it. _________________ Wes K
45 MB, 51 M38, 54 M37, 66 M101A1, 60 CJ5, 76 DJ5D, 47Bantam T3-C & 5? M100
Joined: Sep 14, 2006 Posts: 20 Location: Maumelle, AR
Posted: Mon Sep 24, 2007 8:26 am Post subject:
I have had this jeep sitting around for 20 years. I have never spent a dime on it until last year when I finally brought it home and changed all of the fluids. I don't mind the shotgun approach, because I am convinced that all of this needs to be done anyways (especially the fuel pump). If the last thing I fix corrects my problem, I will be glad to have the new parts for future reliability. I am still fairly new, and haven't done much with the Jeeps until now. I am still not spending much money, because my grandfather ('42 MB, '47 CJ-2A, '47 Jeep Wagon) has a barn full of NOS and aftermarket parts (trans, axles, lockout hubs, etc) and rebuild kits (carb, fuel pump, etc.) some of which he picked up at NAPA in the 70's for his and mine ('51 M38).
Are the manuals available on this web site? I thought I would be able to locate the electronic files, but have not. I have the TM9-804 and believe I sent you the PDF I made last year.
If you look at the top of the page you'll see this set of links:
Home · · Forums · · Articles · · Downloads · · Photo Gallery
The files that we have moved from the Yahoo groups are in the Downloads section. The rest of our tech files are still over in the 4 yahoo groups. You must join each group to access the files but only the main group has a working message board.
We did not bother to load the TM 9-804, TM 9-8012 and the ORD 9 SNL G-740 since it is best that everyone with a M38 have at least one of these TM's and the ORD 9 in paper so they have the everyday info right at hand. The portions of the system specific Army manuals that apply to the M38 are loaded on these sites. For example TM 9-1828 Fuel Pumps has the portions that apply to the M38 and M38A1 fuel pumps loaded on the site.
I caution folks against using any kits with rubber parts that were manufactured mor than 10 years ago because the average shelf lif of rubber parts is 10 to 12 years. Also do not use any rubber parts older than 1973 because the composition of their rubber parts does not last long in todays unleaded gas.
I am a professional mechanic. You'll find that most of us that fix these things for a living do not shotgun and run the customer's bill up. We prefer to keep the cost down so we see the customer again and we prefer to isolate and fix the real problem right away and not try to guess later on which new part we put in may have fixed whatever the original problem may have been. Most of our customers want to know what the specific problem was and what actually was done to fix it. For these reasons most of us are not comfortable with the shotgun approach and seldom are we willing to participate in it. _________________ Wes K
45 MB, 51 M38, 54 M37, 66 M101A1, 60 CJ5, 76 DJ5D, 47Bantam T3-C & 5? M100
eric did you check your distrbuter cap for a crack or carbon trace? did it die with a mighty bang or did you shut down as always and then try to restart. wes is absolutely correct when he says you need to do this methodiccaly are you 24 volt or 12? ballast resistor can die suddenlyit boils down to spark or gas...also as granville king used to say "who worked this bucket last? which means did you just do anything to it?
Joined: Sep 14, 2006 Posts: 20 Location: Maumelle, AR
Posted: Sun Oct 21, 2007 2:45 pm Post subject:
I had spark but not a very good one. So, I took the carb off. I had 1/4 inch of fuel sitting in the inlet manifold. By the way, the carb has bad diaphrams on both sides. I got that out and checked the spark again, now no spark. So I replaced the distributor, went with a new set of plugs and wires to top it off. Started right up then. I am a little concerned about distributor cooling, because I thought I saw some posts indicating that that was critical. My grandfather just puts around his house in his jeep, but I have been driving top speed on county roads.
Does anyone know how the air lines are supposed to be hooked to the distributor box? I see two ports but one was plugged with a grease zerk and the other had a tube that goes near the intake crossover tube but was disconnected.
Joined: Apr 03, 2005 Posts: 271 Location: Chester County, PA
Posted: Sun Oct 21, 2007 3:04 pm Post subject:
There is pluming that goes to the crossover tube from the distributor.
There is also pluming that makes its way from your distributor to a tee I believe around the other side of the engine from the vac pump. This piece of plumming is critical for ventilation. It should also be noted that there is a restrictor there.
This is illustrated in the manual. _________________ Bob Collins
1954 M38A1 MD79056
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