Severe flooding issue

1948willyman · Post by **1948willyman** » Mon Sep 03, 2018 10:30 am

Have an M-38 All original carb, although rebuilt and a second set of diaphrams put in, but still flooding bad. I guess I need to check needle and seat next but was wondering if the fuel pump could cause this also? So bad it flooded into the oil yesterday and it cut off. Will have to drain the oil and replace , Just wondering if it could have gotten into the transmission also.
Any one else had a flooding issue this severe with one of these? It also has a rebuilt fuel/vacumn pump on it ,although has been a couple years for both

oilleaker1 · Post by **oilleaker1** » Tue Sep 04, 2018 7:12 am

Check the float to see if it has fuel inside it and isn't sinking to the bottom, and also make sure the vent for the float chamber is venting into the cross tube and not plugged. Possible dirt on the inlet valve seat and not letting it close off when the float rises.

keats · Post by **keats** » Tue Sep 04, 2018 11:42 am

don't neglect checking the fuel pump. if the diaphragms are leaking, fuel will go right into the crankcase. where are you seeing fuel? does the carb bowl overflow? Manifold at the carb gaskets leaking?

Post by **wesk** » Tue Sep 04, 2018 12:01 pm

wondering if the fuel pump could cause this also?

Not normally. Unless of course the pressure is too high and forcing the float needle off it's seat. If the pump is stock, and was assembled correctly and all the relief/check valves in it function correctly and the correct spacer is placed between the pump & the block output pressure should be correct. It does not hurt to gauge the pump's output pressure. The specs are in the Fuel system chapter in the TM 9-8012.

Ray101 · Post by **Ray101** » Tue Sep 04, 2018 1:45 pm

Shouldn't have gotten in the transmission, unless it pushed fuel into fording vent system, then it could have gotten into everything the vent system is hooked into.

1948willyman · Post by **1948willyman** » Wed Sep 05, 2018 4:28 pm

Thanks for the replys. Will get into these items this weekend and hope to find the problem. I will post the results soon as I know. Also in response to the fuel in transmission , I did notice fuel dripping from the vent under the body that goes to the transmission or transfer case and has a vent filter on it. If I remember correctly, it is the one when fording you were to remove and place a plug in that position? Did not notice any fuel running out around the carb though,So it must be all going straight through into the intake and oil.

Post by **wesk** » Fri Sep 07, 2018 10:04 pm

There is a drain plug threaded hole in the bottom of the bell housing and a Vent just like those found on the diff's on the top of the transfer case up front by the shifters. They are the only two normally left open to drip or vent. The fording instructions tell you before you ford to install the drain plug in the bottom of the bell housing and then remove it again when you are doen fording.

1948willyman · Post by **1948willyman** » Sun Sep 09, 2018 6:59 pm

Just an update on the flooding issue today. I checked both diaprahms on the carb. again today and they seemed ok. Put in some old used oil to check again and good thing I did because it flooded the oil again with gas.
Checked the bowl vent which was ok,, also took top of carb off and gas was
setting at a normal level in the bowl, metal float was very lite and seemed ok. The needle and seat seemed to be ok although no rubber on the tip of the needle which I couldn't remember if any was on it when rebuilt? Fuel/oil was dripping from the vent under the jeep again that goes from the fuel/vacumn pump to the top of the transfer case. I know it was mentioned that this tee should not be there but it was on the jeep when purchased years ago. Maybe it was just there as a connection point? Never has leaked anything out of there until this issue suddenly appeared and engine began flooding badly. Pressure seemed to be normal on the fuel line as I ran the engine with the top off the carb and gas pumping into a can. Sounds to me like a diapraham in the pump must be busted and sending fuel into the oil? Just wanted some more input to what others think may be going on before removing the pump. I guess they were so much gas mixed with the oil that it still ran rough even with the top off the carb and gas pumping back into the can? I kept adding a little gas to the bowl manually to keep running although it still seemed a little rich with fuel line unhooked. I assume they should be no fuel/oil feeding into the transfer case vent that comes from the pump unless something is leaking internally in the pump??

Post by **wesk** » Sun Sep 09, 2018 7:51 pm

It's an old issue and has been discussed here a dozen times over the years. Looks like you need to fix your pump. Google M38 fuel pump contaminates oil with gas.

1948willyman · Post by **1948willyman** » Mon Sep 10, 2018 5:36 am

Thanks I will

1948willyman · Post by **1948willyman** » Thu Oct 18, 2018 5:03 pm

Just a note to let everyone know that the problem was due to the fuel pump diaphragm . It had degraded to the point of failure on the gas side.
Just a plug for Then And Now Automotive who aided me with the replacement parts to get me moving again. I could use a new set of spark plugs for it although I do not want to pay 20.00 for one plus postage. Anyone know of the Autolite 2245 I could get ? Used would be fine if still firing?

4x4M38 · Post by **4x4M38** » Fri Oct 19, 2018 7:29 am

Also be sure and look up the fording vent system here. There were two versions on the M38. It sounds like you have the later setup.

Post by **wesk** » Fri Oct 19, 2018 11:31 am

I do not want to pay 20.00 for one plus postage. Anyone know of the Autolite 2245 I could get ? Used would be fine if still firing?

Current dealer pricing for them is off the planet. I would shop the surplus stock sources and remember there are several brands of that same # spark plug.

There are 6 numbers there to search for.

I always watch civilian and military auctions for things like this. For example I was viewing a civilian stock auction that listed several aircraft spark plug #'s by the bulk boxes. Today the basic aviation piston engine spark plug runs $28 to $35 each. I found over 300 of the plugs that my customer needed for his aircraft new in the box with the old discontinued part number but still useable in his engine for $200.