g741.org

Looks like I fixed it...

Even though it appeared that I had a civy oil pump, I still bought a new one to replace it.. It just didnt seem right with that slightly out of round slot to the shaft. something was wrong. well the new civy pump fixed the wobble..

thanks all for posting!!


I have a civilian plymouth 218 motor, recent rebuild, 3rd party purchase,..installed in my 1941 wc12. I used the oil pump that came with the engine assuming like the rest of the engine parts that the builder used a new one, or correct one.. I never touched it.

My trucks distributor has always moved a bit when the truck is running, cant tell if its a side to side movement, or rotational, but it rotates, or moves. lets call it a "wobble"

that was my old distro, its now out for rebuild.. I thought maybe the bushings being worn was the contributing factor to the movement.
Now I just installed the brand new NOS unit I received the other day and it too does the side to side/ rotational movement.

now I cant remember is ALL of my past trucks did this. I dont think they did.

at first I thought that the engine re-builder might have re-bored the oil pump to distributor hole a bit non-eccentric causing this. Then I thought, is that possible? do re-builders even touch that bore?

So what could it be, and is it common?

I am leaning toward perhaps a bent oil pump shaft causing this?

the answer I got from readers/posters on the PW site was they thought perhaps an M37 oil pump might have been used in this engine build.

Ill buy that, but is it even possible to mate a civilian distributor to a military M37 oil pump with the offset "tang" or whatever its refered to?

I am thinking if I was able to mate the two (civy to military) that it would indeed cause this rotational "wobble" I see, and escalate any distributor bushing wear.. as well as maybe even create a distributor shaft failure with constant flexing?

so my question is: has anyone installed, or seen, a civy distro installed with a M37 oil pump? and would it show this "wobble" while running?

My distributor is a NOS unit... I just installed, it, but if a worn or bent shafted oil pump may be the culprit, I wish to not run this brand new DIstro long for fear of wearing out the bushings (maybe)

Eliminate the guesswork. Just pull the pump off and look at it. If the slot is centered, it is a civy unit and your wobble (Which should not happen) is there, you have other issues. If the slot is offset, there is the issue, change pumps.

You have to look close, if you just glance at it, it can be easy to miss that its off center. I looked at the military distrubutor several times before noticing the tab wasn't centered.

yea thats where my ignorance comes into play.. I have never looked closely at the oil pump, on ANY vehicle, to notice.

today I decided to take the guess work out, as JUST ME noted, to take a look. To me, upon close looking, it does appear to be "offset" by a slight amount. Non-concentric is best to describe the "offset" looking at it. See attached.

at first I am thinking, this is ALL the offset everyone mentions? if so, its so very slight I can see someone ordering the wrong oil pump in a build up and with a little resistance I suppose a civy pump would indeed line up.

so, is this the "offset" I am looking for, this small amount? it would definatly make the distro wobble even with this small offset.

this look like an OFFSET oil pump to yall? its tough getting a good close up shot with mt cameras phone

Get a photo with the slot vertical, so the shadow isn't affecting it as much, it will be easier to see that way

Ok i ried a number of photos.. hard to do!

took the best I could of the pump end to show.

its a subtle difference for sure,with the counter bore and slot maybe 1/32" inch non concentric to the shaft or so?

Anyone have an uninstalled M37 oil pump to post a pic of for me to compare mine too ? Like I said the difference is pretty subtle for sure that's what makes this difficult I guess

I have a civilian in the pile at home. I'll look at it tonight.

Thank u

Here's the shaft. Looks like you have a civilian pump. I'll post a pump once I get my phone to send the darn photo!

Andy

Here's another shot.

So the offset is in the direction parallel to the tang, or in the case of the pump, the slot? See I was looking at it from a concentric perspective. Dang. Looks like I got other issues if the distro wobbles and I got a civy pump now eh?

Civilian pump and dist.

That's definitely a civilian pump, the offset is very obvious in the M37 military pump.

Joe

Do a google search using the following term in images.google.com "dodge m37 offset tang" you will see pics of the pumps and shafts identifying the various types.