M38 Engine Sound

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wesk
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Post by wesk »

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When I was pulling alert duty there in the 70's we kept 8 G's on the tree and 4 soft alert G's on sites 1 thru 4 (you can see sites 1, 2 & 3 at the upper right of the above photo). Then we kept 8 KC's on the north ramp across from those first 4 sites. We also had 4 buffs satellite alert at Shepherd AFB and two Tankers on satellite alert at Blytheville.
Wes K
45 MB, 51 M38, 54 M37, 66 M101A1, 60 CJ5, 76 DJ5D, 47Bantam T3-C & 5? M100

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RonD2
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Post by RonD2 »

I'm guessing that post and photo have been declassified....... 8O....only a few H's flying nowadays, and I believe we let everybody and their brother with a satellite camera fly over anyway..... :D...nice photo!
Last edited by RonD2 on Sun Aug 05, 2018 6:13 pm, edited 1 time in total.
Ron D.
1951 M38 Unknown Serial Number
1951 M100 Dunbar Kapple 01169903 dod 5-51

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MarkR1951M38
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Post by MarkR1951M38 »

RonD2 wrote:I'm guessing that post and photo have been declassified....... 8O....only H's flying nowadays, and I believe we let everybody and his brother with a satellite camera fly over anyway..... :D
After 40 years...I would hope so.

Been reading a lot about the oil pressure issue I'm having and didn't realize the timing could be off if the oil pump is not timed correctly. Before I pulled the pan and during my last engine run, I moved the distributor a little both ways off 5 BTDC and during one move, the rod knock went away. After bearing wear check and timing gear TDC/dot check...I may focus on the oil pump timing. This engine was supposedly rebuilt by someone unknown...but with the issues I'm having, I wonder of they are still in business.
1951 M38 MC 22731
(Converted 12v, Carter WO carb, single action fuel pump, electric wipers)

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45auto
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Post by 45auto »

Nice photo Wes!! I spent 35 days in the building on the Christmas tree during Hurricane Katrina. We parked the semi's with supplies on the tree and the two trailers to the right was where the truckers took their showers.
I did get to go inside where the B52s were once serviced and seen the remains of a bygone era!! The extra heavy duty phone on the wall really showed its age!!
I will note that there were signs posted stating that no filming or counting of planes was allowed---I even seen one trucker and his wife get picked up for filming the base and they did not return.
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1945 GPW
1950 CJV-35/U
1951 M38 1952 M38
1962 USMC Contract M38A1
1953 Strick M100 1967 Johnson M416
1968 CJ5 4-Speed 1969 CJ5 V6
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4x4M38
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Post by 4x4M38 »

A heartbreaking look after seeing the above photo...
Google Earth or other sat or aerial site to Davis-Montham AFB outside
Tucson.

I guess to show the Reds we demobed the nuke capable Buffs they
just cut the front section off the fuselage.

Makes me sick.
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MarkR1951M38
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Post by MarkR1951M38 »

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Engine at 5 BTDC

Image

Shouldn't points be open and on the lobe when the engine is at 5 BTDC? I know the crank/cam gears are correct since I replaced the cam gear twice, but I'm unsure about the timing of the oil pump...Do you think it might have something to do with my issue/rod knock?

I still haven't got under to plasti-gauge the rod caps, but oil pan is off and draining.
1951 M38 MC 22731
(Converted 12v, Carter WO carb, single action fuel pump, electric wipers)

http://www.willysmjeeps.com/v2/modules. ... _album.php
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wesk
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Post by wesk »

The points should be just about to open or just starting to open at 5 BTDC. Your cam follower is starting up the ramp now in that photo.
Wes K
45 MB, 51 M38, 54 M37, 66 M101A1, 60 CJ5, 76 DJ5D, 47Bantam T3-C & 5? M100

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MarkR1951M38
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Post by MarkR1951M38 »

Yea Wes, that's what I see too...I would have thought the points would be a little open at 5 BTDC since that is when the #1 plug is suppose to fire, but they are definitely shut tight, though at the ramp.

Could the oil pump be 1 or 2 splines off the cam? Asking because I did not investigate the oil pump when I had the engine out.
1951 M38 MC 22731
(Converted 12v, Carter WO carb, single action fuel pump, electric wipers)

http://www.willysmjeeps.com/v2/modules. ... _album.php
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wesk
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Post by wesk »

Most people seem to overlook the proper indexing of the pump. It is indexing of the pump not timing of the pump. Actual ignition timing is accomplished by rotating the distributor body. The pump must be indexed properly for the mating with the indexing tab at the end of the distributor shaft so when you do time the distributor you have adequate rotational travel of the distributor body before the body hits the block. This issue is more important with the military distributor which is oblong instead of round. It also can in extreme cases force your ignition (plug) wire indexing off one count in either direction in the cap.

With your round cap IAT type distributor I wouldn't worry so much about the pump indexing. More important is that you have #1 plug wire in the correct socket in the distributor cap. This will insure you have adequate rotation to properly time the distributor. You do that by bringing #1 TDC on compression. As it comes up on compression you stop at 5 Deg BTDC. Now make sure #1 plug wire is installed in the cap directly above the rotor tip.

Now you can time the distributor with a timing light or manually.
Wes K
45 MB, 51 M38, 54 M37, 66 M101A1, 60 CJ5, 76 DJ5D, 47Bantam T3-C & 5? M100

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MarkR1951M38
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Post by MarkR1951M38 »

So you are saying that the indexing of the oil pump will only go in one way and not be off one tooth or two?

I ran the engine and it ran good for a few days, but then started that rod knock when the oil got carboned up. Granted the bearing clearance will clear a lot of unknowns up...but setting the timing with a timing light at 5 BTDC, the engine has this knock as if it were retarded (or advanced) too much. That's why I'm wondering once I check rod bearing clearance, if I might have to focus on the pump.

My #1 plug wire is near the rotor when I remove the cap at 5 BTDC.

So the answer I'm seeking is...can the oil pump be improperly indexed off 1 or 2 teeth causing the distributor to be off (since the distributor aligns in the pump), resulting in retarding of the timing?
1951 M38 MC 22731
(Converted 12v, Carter WO carb, single action fuel pump, electric wipers)

http://www.willysmjeeps.com/v2/modules. ... _album.php
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mdainsd
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Post by mdainsd »

One trick I like is to do. is check the timing with a vacuum gauge. It will let you know if that 5 degrees you are timing to is close. Plumb the vacuum gauge into the intake manifold. If you have the vacuum section on the fuel pump, you don't want that affecting the reading. A good place to plumb in is the port where the line from the vacuum pump goes. Then start her up, let it warm up a bit then time for highest vacuum. Should be 20 or so depending on your altitude.

Once set, use your timing light and see where the timing marks are showing up.
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MarkR1951M38
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Post by MarkR1951M38 »

mdainsd wrote:One trick I like is to do. is check the timing with a vacuum gauge.
Sweet...another tool :P . I like this idea...just need to find a port to do it. I'm running a single action fuel pump and electric wipers with no other vacuum options. Need to look at manifold and see if I can port into it.

Thanks and still awaiting answer from last question.
1951 M38 MC 22731
(Converted 12v, Carter WO carb, single action fuel pump, electric wipers)

http://www.willysmjeeps.com/v2/modules. ... _album.php
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wesk
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Post by wesk »

So you are saying that the indexing of the oil pump will only go in one way and not be off one tooth or two?
I did not say that.

Image
The gear that is driven by the cam's timing gear is the gear on the oil pump.


Image
The pump is properly indexed to the cam drive gear when it's offset tab receptacle is in the proper position. There is no teeth counting that is done in this process. The proper clocking or indexing of the oil pump is the result of very closely following the procedure in the manual to end up with the view above of the top end of the pump shaft. The goal is in degrees of an angle not any set number of teeth.

Image
Once the pump is clocked/indexed correctly the distributor shaft will only fit into the end of the pump shaft one way.

Now the act of timing the ignition begins by adjusting the rotation of the distributor housing while the end of the distributor shaft is fixed in the oil pump.
Wes K
45 MB, 51 M38, 54 M37, 66 M101A1, 60 CJ5, 76 DJ5D, 47Bantam T3-C & 5? M100

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Mikemc
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Post by Mikemc »

If I read correctly you earlier said carb was flooding. Oil diluted with gasoline is a quick way to eat up a bearing. The other thing that can happen is turning the motor over with a cylinder full of gasoline can knock a bearing out or even bend a rod. I hope this isn’t your problem but it is sure possible.
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MarkR1951M38
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Post by MarkR1951M38 »

Mikemc wrote:If I read correctly you earlier said carb was flooding. Oil diluted with gasoline is a quick way to eat up a bearing. The other thing that can happen is turning the motor over with a cylinder full of gasoline can knock a bearing out or even bend a rod. I hope this isn’t your problem but it is sure possible.
Carb has since been replaced with a professionally rebuilt carb and they said it was run and adjusted on a test engine. All I did after I received it was to adjust the throttle stop screw. But thanks for that info.
1951 M38 MC 22731
(Converted 12v, Carter WO carb, single action fuel pump, electric wipers)

http://www.willysmjeeps.com/v2/modules. ... _album.php
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