1975-79 Owners

[Joe L.]

A question came up recently regarding the oil pressure sender BUSHING. This is the brass "connector" between the block, just above the oil filter, and the oil pressure sender unit. Could some of you with 75-79 cars that are reasonably sure they're original please check this for us. It's really easy to see from above or below. What we're curious about is the LENGTH of the bushing. Is it about 1" long or is it about 2" long?

[Joe L.]

Re: 1975-79 Owners

Isn't there ANYBODY out there with a 75-79 that could check this out and report what they find?

[Mike T.]

Re: 1975-79 Owners

My 76 looks to be longer than a inch

[Roger O.]

Re: 1975-79 Owners

Measuring while still in the block its 1 3/4 so it must be 2" plus a shade.

[Brian G.]

Re: 1975-79 Owners

I'm getting approx. 1 5/8" on our '75. Definitely more than 1".

[Joe L.]

Re: 1975-79 Owners

Mike, Roger, and Brian------


Thanks very much. It looks like this application did use the special, long bushing. I can't figure out why they would have done this, but I'm sure there was a reason. It would seem that with this long bushing + the length of the oil sender, itself, the sender is really going to be "hanging out there". Is there some sort of clearance issue with engine compartment equipment that this configuration accomplishes?

[Roger O.]

Re: 1975-79 Owners

Mike, Roger, and Brian------


Thanks very much. It looks like this application did use the special, long bushing. I can't figure out why they would have done this, but I'm sure there was a reason. It would seem that with this long bushing + the length of the oil sender, itself, the sender is really going to be "hanging out there". Is there some sort of clearance issue with engine compartment equipment that this configuration accomplishes?

There is a clearance issue. If the choices of bushings were 1" and 2" the 1" would have allowed the bottom of the sender to hit the block around the oil filter. A 1 1/2 might have worked but a 2 cause no issues with the sender being out "too" far.I can take a pic if you want.

[Gary R.]

Re: 1975-79 Owners

Joe,
My 75 L82 was stone stock when I bought it. It has approx a 2" bushing but I don't recall any reason for it.

[Bill F.]

Re: 1975-79 Owners

Joe,
I have a bone stock 75 convertible L-48 w/ 31,075 miles w/ original drivetrain up through the carb. I have owned the car for over 13 years, and I do not believe the engine was worked on by any of the previous owners. I cannot see the fitting from above, but sliding a tape along the shaft I am coming up w/ a length of 1 1/8" to 1 1/4"to the block.
Hope that helps.

[Joe L.]

Re: 1975-79 Owners

There is a clearance issue. If the choices of bushings were 1" and 2" the 1" would have allowed the bottom of the sender to hit the block around the oil filter. A 1 1/2 might have worked but a 2 cause no issues with the sender being out "too" far.I can take a pic if you want.

Roger-----


Excellent information. That's the one thought that passed through my mind that it might have been an installation/removal clearance issue. However, I was thinking that the nipple on the oil sender was longer than it, apparently, actually is. The configuration of the block at that point would make installation/removal of the sender difficult or impossible if the sender had a short nipple and the bushing was of the normal, standard configuration and length.

So, thanks to the assistance of yourself and others, we now know what configuration bushing was used for 1975-79 and, most importantly, we now know WHY.

[Roger O.]

Re: 1975-79 Owners

Sometimes a picture helps.

[Joe L.]

Re: 1975-79 Owners

Sometimes a picture helps.

Roger-----


As they say, a picture is worth a 1,000 words (I say they are often worth WAY MORE than a 1,000 words). It appears that the nipple (part of the sender) must be a lot shorter than I thought it was. Your sender looks to be original to me.

[Douglas B.]

Re: 1975-79 Owners

My 78 L48 seems to be approx 1 5/8. More than 1" for sure.

[Roger O.]

Re: 1975-79 Owners

Roger-----


As they say, a picture is worth a 1,000 words (I say they are often worth WAY MORE than a 1,000 words). It appears that the nipple (part of the sender) must be a lot shorter than I thought it was. Your sender looks to be original to me.

The car is not mine but the sender does appear to be fairly old , as does the leaking oil.

[Joe L.]

Re: 1975-79 Owners

All-----


There have been a lot of these senders used in PRODUCTION and SERVICE over the years. For SERVICE each was supercessive to the previous:

1975--------GM #6462137

1976--------GM #370801

1977-79-----GM #547034

Then, subsequently, there have been several SERVICE supercessions over the years. GM #547034 was discontinued in October, 1983 and replaced by GM #14039612.

GM #14039612 was discontinued in April, 1990 and replaced by GM #14040816.

GM #14040816 was discontinued in October, 1992 and replaced by GM #15591103 which remains available to this day.

Attached is a Delco-origin photo of the 15591103. Note that it has a very short nipple. I feel pretty confident that all its predecessors likely had such a short nipple, too. So, all would likely require the long bushing to be installed at the above-the-oil filter location.

Some aftermarket senders have a significantly longer nipple. I once thought the GM pieces did, too, but I was incorrect.