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Engine Leak near fuel pump: Dipstick plug?

Brian K

Member
Howdy all!

So I've got my last leak identified (I think).... '78 Scout II, 345. It looks like there's a pretty decent leak coming out of the engine block plug where the dipstick would go if it were a truck or a travellall....being a Scout, it's got just some sort of a plug there.

Before I go and just slather it over with jb weld, I figure there's probably a "correct" way to rectify this leak. Anyone know what it might be?

I've never seen how those little plugs attach into the block.

Ideas would be much appreciated!

Thanks again!

Brian
 

Robert Kenney

Super Moderator
I rebuilt an engine for a buddy and same issue that was solved by pressing a plug in. If I recall it was a normal inch size like 5/16 or 3/8. Either way use a small piece of rod stock the correct size and press it in with sealant.

It was a truck block that had the ds in the front, not the pan like the light line (Scout) stuff.
 

Michael Mayben

IHPA Tech Moderator - Retired & No Longer Online
The dip stick tube hole on these blocks measures a nominal 0.375". It knocks in from the top of course at the point of assembly, the actual plug probably measures 0.380".

So you can possibly remove the plug from the outside with visegrips if you are careful. I normally knock um "up (or down)" with a punch from inside the block. Once they are out, you can easily seal the hole with jbweld on the clean plug itself.

Many ihc vehicles other than Scout II used the front mount dipstick. Any vehicle which has a front sump oil pan uses that position. The Scout II engine app is the old ball with the pan-mounted dipstick due to the double-hump oil pan.
 

Brian K

Member
Ok all,

I finally figured it out! It's the damn fuel pump itself! Along the housing, there is a little "weep hole" on the left side of the extension that bolts to the block. When I come to a hard stop, oil shoots out of the little hole and all over the place. I finally figured it out by stuffing the whole area with paper towels and driving up and down the street.

The crazy thing is that it's a brand new fuel pump!

Can I just slather a little sealant over that hole or is it necessary for venting or something? Otherwise, I guess I can take that pump off and return it under warranty for a new one.

Any advice?

Thanks!!

Brian
 

Michael Mayben

IHPA Tech Moderator - Retired & No Longer Online
ok all,

I finally figured it out! It's the damn fuel pump itself! Along the housing, there is a little "weep hole" on the left side of the extension that bolts to the block. When I come to a hard stop, oil shoots out of the little hole and all over the place. I finally figured it out by stuffing the whole area with paper towels and driving up and down the street.

The crazy thing is that it's a brand new fuel pump!

Can I just slather a little sealant over that hole or is it necessary for venting or something? Otherwise, I guess I can take that pump off and return it under warranty for a new one.

Any advice?

Thanks!!

Brian
That small hole in the pump body is a vent. Any diaphragm-type pump like those must be vented to the atmosphere.

Yes, it's also vented (to a degree) inside the pump body to the crankcase, but that's not enough.

If you plug that hole, you will have a decided lack of fuel at engine speeds much above an idle.

Return the pump for a replacement. I've had to do the same over the past 7/8 years occasionally also, even though these fuel pumps are "new".
 

anthonybalmert

New member
Hi guys, I am swapping in a 392 that has an open dipstick hole. I didn't notice it was open until I bought a new dipstick and the motor is already in. Is there a good way to plug these?

As for the new dipstick now going through the pan, does some sort of sealant or an o-ring need to be used?

Thanks!
 

ihpartsjeff

Administrator & Owner
Staff member
We will put a little rtv sealant around the dipstick tube after installing it into the oilpan. As for plugging the hole, you can call our parts department and purchase a used one, or use an old IH pushrod as they are the perfect diameter to plug that hole.
 
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