Joined: May 14, 2009 Posts: 972 Location: South Dakota
Posted: Wed Jul 27, 2011 9:32 pm Post subject:
Still here and reading along. You don't have a idle circuit fuel delivery problem. Timing indeed should be set at a slow idle around 600 RPMs. Old rule of thumb is to advance and retard (slow) the engine until you have the fastest idle at around 600 rpm. Then retard the distributor 100 RPM and tighten the distributor. You should be within 2 degrees of the correct timing. Your constant description of trouble sounds like a flooded engine with a carburator that is not shutting off at the correct float level. Good fuel pressure too. If your fuel line is cool enough to touch, it's not too hot near the manifold causing vapor lock or fuel boiling. When it cuts out, and dies, is the carb base showing wet gas down by the thick base insulating block? If you remove the top of the carb and look into the bottom of the float bowl, is there brown rusty stuff or dirt in there? If so, no matter who and how many times it was rebuilt, you need to clean it out and blow out all passages. Then install a good quality fuel filter ahead of the carb. You may need to pull the tank and clean it. If you had a vaccum leak, it wouldn't run any better when cold, unless you left the choke on. I'd look for dirt next! John
Posted: Thu Jul 28, 2011 5:53 am Post subject: Engine Cutting Out
Hi, thanks so much for your recent posts. Both of you make excellent points. I have a follow up question for Artificier as I want to be sure I understand you correctly--it could be very important: You state:
"I use a vacuum gauge for most things including timing & provided you have it hooked in right you should do the same...."
First, we have a direct entrance of our gauge into the port of the T that screws into the windshield side of the intake manifold. We used the top port by removing the plug which we used to block the port that we removed the vacuum line from. Because of Wes's comment, we will use the side port in the future and not remove the top plug.
Please, exactly what do you mean: "by moving your distributor to get best idle rpm & best vacuum on the gauge then move the distributor housing back about 3/32" & locking up."? I read this to mean to turn the distributer to the point where we get the best rpm along with best vacuum reading but then turning the distributer back 3/32 inch---this is unclear to me as I just don't understand why I would change the best performance.
I am hoping for a picture of the correct fuel line route. In the meantime, if anyone has time to take a quick look at their M38 and let me know the distance of the line as it enters the engine compartment from the exhaust pipe, it would be helpful. Semper Fi Ben and Ben
rtificier _________________ Semper Fi Ben M38 & M100
Joined: Feb 16, 2007 Posts: 206 Location: Gold Coast Australia
Posted: Thu Jul 28, 2011 6:51 am Post subject:
I am unsure of your precise vehicle as the OZ military did not have same but not too important!
So what vacuum you have & wipers etc are really irrelevant if you are not trying to use them.
So dis connect 1 line which plugs into the intake manifold [if you want plug the line to wherever it goes] & that intake manifold port is INTAKE MANIFOLD VACUUM....rest is as stated plug in thread.
Loosen you distributor & have engine running....
the rest is just moving the distributor which will effect vacuum readings....
get the best then back of a little [which will still be close to best] & re-clamp distributor.
Road test for no pre- ignition [pinging ] sound. [load engine uphill} _________________ John GIBBINS
ASE Master Medium/Heavy Truck & Auto Technician 2002 USA
Licensed Motor Mechanic NSW # MVIC 49593 Current
YOU CAN'T TROUBLESHOOT WHAT YOU DON'T UNDERSTAND
Posted: Thu Jul 28, 2011 3:47 pm Post subject: Engine Cutting Out
Hi all, no progress, I am very sad to say. We spent our few hours today chasing rainbows I guess. We review all that you great people have written and talked with a couple of local mechanics. We believe that we are close enough on the timing and vacuum not to cause a shut down; tests with carb cleaner produced nothing.
So, we thought we would start over and do as has been suggested time and again and retime using the light and vacuum tester AFTER we got the RPM right. Breaking out my old Sears engine analyzer for 12 and 24 volt system and hooking it up, the RPM was at 800 and as we started to bring it down, the tester quit working as far as RPM is concerned. Whether or not we lost a capicitor or other component we don't know. Any way, we discussed between ourselves and then locals, we decided that since every thing was new about the ignition, maybe even a new item had a default; since we have changed the distributor and all there in and the coil 3 times, we decided to change the plugs and put a new set in. As has been the case, it cranked the first turn, ran like a top and we let it idle until it reached temp; it seemed run a bit longer with out fault but then it began the same pattern of beginning o die and did so.
As soon as we get a tool to set the RPM, we will go through the steps as you all suggested to get it right on but one question for everone, do you really that with being within 3/32" of being 5 DBTC, within 100 RPMs and all the other things we have checked being ok, that we would be off enough to make this critical difference?
We still do not know for sure if we have an ignition, fuel or vacuum problem. One local whose profession for 40 years as an owner/mechanc of a shop suggested that tomorrow we start it and let it idle until it does it thing and then immediately remove a sparkplug wire and see if we have any spark. If so, then the probability is that we have a fuel proablem and that is what we are going to do.
Next, we are going to change back to my sparkplug wires that were on the vehicle before I rebuilt it; then, we are going to remove the top of the carb and take a look to see what we can see.
We read and consider and try all of your suggestions. Thanks so much, Semper Ben and Ben _________________ Semper Fi Ben M38 & M100
Joined: Feb 28, 2011 Posts: 148 Location: Escondido, CA
Posted: Thu Jul 28, 2011 7:59 pm Post subject:
Major Ben,
I've been following this thread but haven't had much to add except perhaps some empathy. I can comment on some of your latest questions:
Yes, it is very possible for new electrical parts to be bad, especially if they are NOS vintage parts. I had a friend who had a devil of a time with his '46 Ford quitting when hot, and the trouble was traced to a replacement NOS coil that had a case crack. I've installed a new oil pressure sending unit in a modern car only to discover that it was bad out of the box.
3/32 of a inch at the rim of the crank pulley is somewhere around 1.5°-2° on timing. I say "around" because I don't have the diameter of the pulley handy; I used 6" as an estimate. The equation is TA=S x 360/D/Pi, where TA=timing angle in degrees, S=distance at the rim of the pulley, D=diameter of the pulley, and Pi=~3.174. 2° is significant for a loss in peak performance, but not enough to cause the engine to quit or not start.
This may be stating the obvious, but you really need to narrow it down to fuel or spark at the time when it is dying. In my experience, the symptoms are different: spark causes either a regular miss or an erratic miss, depending on if the fault is post or pre distributor, and fuel causes a general poor running or gradual dying. Hard to describe in words, but the symptoms of flooding are quite different than those of starvation. I have a small trigger-pump oil can that I put gasoline in and use to squirt into the air horn of a carb (used for priming engines that haven' been run in a long time). It's useful to verify a starvation symptom - if I can keep the engine running with my manual throttle-body fuel injection and it dies otherwise, I know there is a fuel starvation problem. If the plugs are soaking wet after it dies (or before you get it started), it's flooded. Fuel issues are not likely to cause sudden dying on a system that can run smoothly from cold start up to operating temperature. And if the death isn't sudden, then you have time to play with the squirt can to see if it is starving for fuel. Anyone who has run out of gas while driving should be familiar with the symptoms caused by lack of fuel: chug, chug, sputter, gasp, die . . .
If there is no (or weak) spark under the conditions in which it died or won't start, using the most basic of test for spark methods, then there's the problem. You could probably see that with a timing light unless it quits suddenly: you should see a regular, periodic flash if everything is working correctly, and if it starts getting erratic, then it looks like a spark issue. On a conventional older engine, you can put the timing light on the primary lead (coil to distributor) to get a flash for every cylinder, but that's not possible with the M38. Your local's suggestion of pulling a plug wire right after it dies and checking for spark is a good one.
I don't see any of your symptoms fitting a vacuum leak problem. My money is on spark.
Jim _________________ Jim M.
1952 M38 son-father project
Discovering more worn out parts, one assembly at a time
You have my list and following it correctly to every detail should have already indicated which system was causing your grief. With the current level of confusion in this thread I feel if you are lucky you will trip over the source of the problem sooner or later.
To answer your question to John.
The reason you must slightly retard the distributor timing after you locate the peak idle/vacuum setting is that if you don't it will be advanced so far it will cause the engine to turn very slowly when trying to start it. When the engineers listed 5 deg BTDC it was listed not because it yielded the best cruise performance. It was listed because it was the best compromise between good driveability and easy startability.
Any jeep owner on this board with a good running engine can set his timing at 0 degrees or 10 degrees advanced then start his engine and it will not die while idling.
Your problem is not ignition timing and you are spending way too much time on it. Since your problem only surfaces after the engine warms up shows that your attention needs to be on issues that arise when warm. On the ignition side of the house that would be things that can change as they warm up. The most likely culprit here is the coil then the radio noise filter and then the condenser. On the fuel side of the house vapot lock will cause lean running and sticking float needle can cause either rich or lean depending on the mode in which it is sticking. Also if perculation of the fuel is the issue then the heat riser is the prime culprit. _________________ Wes K
45 MB, 51 M38, 54 M37, 66 M101A1, 60 CJ5, 76 DJ5D, 47Bantam T3-C & 5? M100
Posted: Fri Jul 29, 2011 7:56 am Post subject: Engine Cutting Out
Hi Wes and Jim, my son will be ecstatic when he reads your two posts. He mentioned several times yesterday that we are spending too much time on the RPM stuff; that we need to find the 'hot' problem and then go back and maximize the RPM, timing, and whatever.
Wes writes, "The reason you must slightly retard the distributor timing after you locate the peak idle/vacuum setting is that if you don't it will be advanced so far it will cause the engine to turn very slowly when trying to start it." I want to stress that when the engine is cold, the starter begins to spin and would but it starts immediately (within the first revolution or so of the motor turning) so Wes I infer from you statement that the timing is not the issue.
One thing I forgot to mention is that Ben JR immediately removed No. 1 sparkplug (one of the set of new ones we installed just before this test) and it was not wet. On the contrary, it was what I call fouled with a carbon build up that should only be seen after many miles of driving. To me, that indicated that we are getting firing; yet, we seem to remember that several days ago he removed the plug soon after it quit and found only a weak spark; so this is confusing. We will do the test again today.
Again, I can only thank all of you for your posts. As time goes on, I realize that one of the biggest reasons the answers might be a bit confusing is because I did such a poor job posing the question. So, please keep your comments coming. We'll beat this thing. Semper Fi Ben _________________ Semper Fi Ben M38 & M100
Posted: Fri Jul 29, 2011 1:29 pm Post subject: Engine Cutting Out
Hi All, I want to report the results of our tests today.
Please keep in mind that we only concentrated on problems dealing with heating. When we started, we believed we had fuel problem rather than ignition. We think we have confirmed that belief. When the engine was cold, we removed No. One Wire and saw a real strong nearly wire long spark with a snap and the engine started as we were doing the test. After it heated up and died, we made the same test and we had the same real strong white spark with a snap; we repeated this test with No. 1 and No. 4 and got the same results. We conclude that we have a fuel problem.
We then began to make the test to see if a spay of fuel into the horn would bring it out---we used starting fluid and the opposite happend, it died immediately rather than continuing its long dying process. We thought that since it was hot, maybe the starting fluid being atomized, etc might have been too strong and flooded the engine. So, we proceed to test with a spray of raw gasoline and the same thing happened with caused a sudden death.
We tried other things: The heat riser arm does not go all the way to the top when hot but holding it open for a long period did not help. Puzzling as it it, holding it down caused a sudden rise in RPM for a few seconds but then back to it normal rpm and dying. At one time, when we removed the rubber cross over, it idled for a long, long time and we thought maybe we had found a very simple cure. But no, eventually the same period.
By Pulling the dash throttle out one click bring the rpm to an estimate 1200+-, the engine never faltered---we continued the increase for about 10 minutes and it maintained a smooth acceleration.
Trying to remember back about a month, we believe the engine runs better in that it no longer floods and starts immediately when hot or cold. We think it is because we had the timing advanced way too far but we are not sure. We are not totally satisfied with the idle as it is not as smooth as we would like but we think this will come out after we maximize RPM and timing.
We are going to concentrate on the fuel and the first is to call the guy who overhauled the carb and went through it the second time. My son has several questions that I can not answer. We will see where this leads.
As always, we welcome your thoughts and comments. Semper Fi Ben _________________ Semper Fi Ben M38 & M100
Most of you post deals with a shortage of air or an excess of fuel whichever way you prefer to think of it. Bottom line is she's too rich and loading up at idle. This is often a high float level or sticking float valve issue. Since she seems to do it hot only another thought is a cracked carb housing and the crack expands as she warms up allowing excess fuel to enter the venturi.
You should confirm which spring arrangement your heat riser has and that it is moving in the correct direction as the engine warms up. Superheated air can lead quickly to flooding. _________________ Wes K
45 MB, 51 M38, 54 M37, 66 M101A1, 60 CJ5, 76 DJ5D, 47Bantam T3-C & 5? M100
You've said that the engine idles badly when warm and wants to die, but if you give it some throttle it perks up again. You also said that pulling the choke out a little will make the engine idle smoothly again. Does it run ok if you go out and drive it? Does it have power and run smoothly while you cruise down the road?
Having it run smoothly with the choke out indicates that is going lean at idle when warm. I know that you said you've had a professional go through the carb, but it sure sounds like the idle circuit in the carb is not working right. You've pretty much eliminated vacuum leaks as an issue, so it seems like it is time to look at the carb again.
And since heat is seems to cause the problem, do you know for sure the heat riser in the manifold is ok? You said it moves, but are you sure the flap is really in there? By itself, that shouldn't cause your problem, but if the carb is running on the lean side, it might make it worse when it warms up.
Actually if a carb is running lean (too much air) then heating of the inlet air will thin the air resulting in a richer mixture.
Ben you haven't told us how the jeep drives on the road above idle.
Can you confirm it only quits when you allow it to idle for a prolonged period?
Does adding choke really salvage the idle or did it just make it idle a short while longer.
My money right now is on the heat riser operating improperly, a carb internal leak or incorrect positioning of the two fording valves. _________________ Wes K
45 MB, 51 M38, 54 M37, 66 M101A1, 60 CJ5, 76 DJ5D, 47Bantam T3-C & 5? M100
Posted: Sat Jul 30, 2011 6:27 am Post subject: Engine Cutting Out
Hi Wes and Oldsalt, thanks for your posts. I need to clear up a couple of mine, I guess.
I did not mean to infer that it runs badly when at idle. Cold it idles quite well just not as perfect as I would like to hear and I think will when we are able to maximize the RPM and Timing. It is when it gets hot that it will miss a beat, recover, miss a beat, recover and do this until it dies with the miss a beat getting closer together just before it dies.
If we start it cold and let it idle, it will do so for several minutes without missing a beat even some time after the temp gauge indicates it is at temp. This period can last several minutes, say up to 10 to 15. But, if we start it cold and drive it 2 miles in the heat of the day here in Missouri with the temperture 95-100, when we stop it at home, it will quickly start the miss, recover, miss type behavior.
When it begins its little act, choking does not help; primimg directly into horn with starter fluid or raw 87 octane gas does not help. Only acceleration will bring it about. BTW, DOES ETHENOL IN GAS HAVE ANY AFFECT ON THESE OLD MACHINES AS THAT MIX IS ALL WE HAVE TRIED.
We can not clearly remember the driving distance record over the 6 year period. We do know that before restoration, I drove it 25 miles to deer camp, 25 miles back home, and 10 days around a 600 acre farm with no problem but it was colder weather. We do remember driving it about 8 miles after restoration when it did cut out badly at running speed just before returning home. However, do to medical reasons, the most it has been driven in the past 2 or 3 years is about 2-4 miles within the subdivision where maximum speed is 20 mph; it has always performed with power and with no problem until we return home and let it set at idle---that is when it starts its act. We believe that Wes's thoughts about absorbing heat and causing bad starting also applies to coming to idle where there is little air being drawn in for cooling.
We know that we should take it on a long run but the situation has not allowed it without a chase vehicle and driver.
I remember installing a new heat riser with new spring, etc. I spent hours on this project alone with the exhaust manifold at the bench. I had read so much about it freezing an causing problems that I used a torch to heat it and watch it open and close several times. That is not to say that it is not a problem. The weight/arm does not top out as I had figured it would but mechanically raising it does not make any difference.
I was just as fussy about the two fording valves and disassembled them to where I could verify that they were open unless the cable was pulled.
I have no idea about a possible crack in the carb but hope to visit with the professional this weekend---we have several questions. Some have written about possible crud accumulation in the bowl but it had to have done it quickly after restoration as the problem commenced shortly thereafter and Ben JR keeps asking, what would heat have to do with that possibility or why does it not do its act when cold, if that were the case.
Keep your comments coming. Many years ago, Wes reassured everyone that these jeeps ran great when in service and will continue to do so when we get them right---keep the faith, right? Semper Fi Ben _________________ Semper Fi Ben M38 & M100
Heat is the instigator of your problem. Clearly you have a heat riser that is not functioning (flapper is directing heat across the bottom of the intake) super heating the air causing an overly rich mixture when hot and idling. The higher flow of air above idle makes the problem manageable above idle. The flapper can separate from the shaft and stick in the wrong position. Also the two different spring setups can be intermixed and operate the flapper backwards.
A crack in an idle or metering passage in the carb will open as the carb heats up. This can cause your issue as well by altering idle mixture or main metering at idle where you will see it's effect more clearly.
All the other parameters you have toyed with to date are not the cause and you have already determined that they will not cause the hot idle stumble and quitting issue.
It's time to bite the bullet here and save yourself a lot more aggravation and do two things (ONE AT A TIME)
1-Remove the carb and intake manifold and confirm operation of the heat riser.
2-Remove the carb and substitute a known good one (military or civilian makes no difference) _________________ Wes K
45 MB, 51 M38, 54 M37, 66 M101A1, 60 CJ5, 76 DJ5D, 47Bantam T3-C & 5? M100
Posted: Sat Jul 30, 2011 2:58 pm Post subject: Engine Cutting Out
Hi Wes, thanks for your post. We have done No. 1 in that we visited with the professional who overhauled the carb and later rechecked it and he wants us to send it back to him for a third check and we plan to have it on UPS tomorrow---we have removed and packed it. Before we did, we removed the top and notced how much loose carbon particles there was which may have been caused by the excessive flooding it did before removing the hand gas pump.
If we remove the intake manifold, do we do a heat test with a torch as I did or any other suggestions to be sure the riser is functioning correctly.
We discovered when we installed the NOS distributor, that the it traveled nearly as far as it could to gain BTC; we are removing it and the oil pump to shift the oil pump gear one or two teeth to get the distributor set screw as close to the middle the slot as possible to allow easier and more acurate adjustment when we locate an RPM analyzer. Thanks Wes, Semper Fi Ben _________________ Semper Fi Ben M38 & M100
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