Home » Public Forums » GMCnet » Re: [GMCnet] Engine oil dipstick tube mystery
| Re: [GMCnet] Engine oil dipstick tube mystery [message #320861] |
Sat, 22 July 2017 21:55  |
James Hupy
Messages: 6806
Registered: May 2010
Karma: -62
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Senior Member |
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Larry, the dipstick is not supposed to go straight into the block at the
angle of the hole bored through the block. Rather, it bends to almost
parallel the side of the oil pan. This keeps the dipstick away from the
crank and rods, and goes into the oil supply at right angles. That being
said, MANY OF THE TUBES have been replaced with TUBES that go straight in.
They do not measure correctly. Best way is to change the oil with a new
filter and 6 quarts of oil. Start the engine, run for a couple of minutes,
shut it off, wait 5 minutes or so, then check the oil. Where your oil shows
on the stick is where you mark the full mark.
Jim Hupy
Salem, Or
78 GMC ROYALE 403
On Jul 22, 2017 7:28 PM, "Larry Engelbrecht"
wrote:
So I pulled the broken left exhaust manifold off and found the engine oil
dipstick tube rusted through vertically. I know that sounds weird but the
side facing the exhaust manifold was flat gone. Now that I was finally able
to see how the heck it snaked between the exhaust manifold and cylinder
head, I gingerly went to extract it as carefully as I could. It literally
lifted right off, so I figured the rest was still in the block. This was a
few months ago. So today, after reading how to pull out the rest, I went to
try to determine the ID of what I thought was the remains of the tube in
the block. First, I carefully inserted a pushrod (I had the heads off
anyway) and was able to easily insert it ~8". I didn't want to letting it
drop
all the way in, so I pulled it back out and saw oil on the last inch or so.
Hmm, I thought I saw pics on here where there was a turn in the part of
the tube that goes through the block, so why didn't the pushrod stop
sooner? Next, I carefully inserted several drill bits to determine the ID.
Would
the ID turn out to be the tube or the factory dipstick tube hole in the
block? A 3/8" drill bit was as big as I was able to insert.
Since the pushrod didn't hit anything, I cut a wire coat hanger so that
each end had a little bit of a hook left on it. This way I figured I could
feel any "rings" that would make the tube fit tighter in the block as I had
seen working on a friend's Cutlass - but of course, this is a FWD V8. The
wire coat hanger went WAY in, picked up oil, and the only "catching" it had
was a bit over an inch in, presumably the end of that block hole.
So where did the lower end of the tube go?
Did it:
A) fall all the way in at the hands of a PO?
B) was it never there to begin with, perhaps an earlier engine pull before
I got it?
C) did my early '73 not come with a lower extension?
D) could it have rusted THAT deep?
Going straight in it obviously picked up oil. I'm just concerned that
perhaps the lower portion was to guide it into a deeper part of the sump. I
do
remember the pic I saw on here showing how critical it is to properly align
it so as not to have it or the dipstick itself collide with the crank (I'd
use a stethoscope seeing how my engine is still installed). Any insight?
Thanks in advance!
--
Larry Engelbrecht
San Diego, CA
'73 26' ex-Glacier
TZE063V100319 03/07/73
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| Re: [GMCnet] Engine oil dipstick tube mystery [message #320862 is a reply to message #320861] |
Sat, 22 July 2017 22:10  |
LarryInSanDiego
Messages: 336
Registered: September 2006
Karma: 0
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Senior Member |
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So, can I slightly bend a 3/8" tube just enough so the upper part does not collide with the block and still fit between the head and manifold? My engine never had a dipstick when I got it anyway, so I'd have to "adjust" whatever dipstick I'd use to measure correctly as you suggest. I'd just have to figure out how to somehow swedge (swage???) the tube or otherwise make it have a slight interference fit or fab a small bracket.
Larry Engelbrecht
San Diego, CA
'73 26' ex-Glacier
TZE063V100319 03/07/73
[Updated on: Sat, 22 July 2017 22:11] Report message to a moderator |
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| Re: [GMCnet] Engine oil dipstick tube mystery [message #320868 is a reply to message #320862] |
Sat, 22 July 2017 23:10 |
Ken Henderson
Messages: 8726
Registered: March 2004
Location: Americus, GA
Karma: 9
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Senior Member |
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Larry,
The missing part of the dipstick tube is probably lying in the bottom of
the oil pan -- safely out of the way of moving parts (where a couple of
dipstick ends are in one of my 455's, due to interference when the sticks
were inserted). You might get luck and see it over the drain hole after an
oil drainage and be able to fish it out; I wouldn't worry about it.
As for keeping the dipstick at the right location, I've used two methods:
1. Take a brass 3/8" tubing ferrule coupling and run a 3/8" drill through
it to remove the ridge meant to limit how far the tube is inserted. Then
position the coupling, a ferrule, and a nut where you want the stop.
Tighten the nut to compress the ferrule. Remove the coupling and nut and
store them for the next time you need a tube positioned.
2. Cut a small triangle of steel, 1/16"+ thick, with a 3/8" hole in it, to
fit the flat area around the dipstick hole in the block. Position the tube
through the hole in the triangle at the desired position, mark it, and
braze or weld the two together. I used that method to make sure the bent
tube inside the engine remained pointed where I wanted it.
I never liked the flat dipstick running all the way to the front of the GMC
because it tended to bind in the adverse curves. So I made one from 1/8"
steel cable. A 1/2" thick Lexan handle, with the cable secured into it
with a set screw through the capital of the "T", also has a recess around
the cable to fit over the top of the dipstick tube. At the measuring end,
the cable is brazed for about 3" to prevent fraying and flattened to accept
calibration marks. It goes in and out easily, regardless of orientation.
Good luck,
Ken H.
On Sat, Jul 22, 2017 at 11:10 PM, Larry Engelbrecht <
larryengelbrecht@gmail.com> wrote:
> So, can I slightly bend a 3/8" tub just enough so the upper part does not
> collide with the block and still fit between the head and manifold? My
> engine never had a dipstick when I got it anyway, so I'd have to "adjust"
> whatever dipstick I'd use to measure correctly as you suggest. I'd just have
> to figure out how to somehow swedge the tube or otherwise make it have a
> slight interference fit or fab a small bracket.
> --
>
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Ken Henderson
Americus, GA
www.gmcwipersetc.com
Large Wiring Diagrams
76 X-Birchaven
76 X-Palm Beach
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