C1 Oil Pressure Line Confusion

[Bob Malone #35242]

I've checked the archives and only confused myself more. I have a replacement oil pressure line that runs from the back of the block to the oil pressure gauge that I bought from Paragon. It came with the steel line and a fitting for each end. I know enough about household plumbing to expect these to be compression fittings. There was nothing in the kit to slip over the line to compress when tighened down. Only the two fittings that screw into the block and gauge back.

Is this correct? If another piece is required wouldn't you think it would be included in the kit? I can't find anything in any of the catalogs mentioning it. How else would it seal? The fittings are tappered like they should seal against something.

[John H.]

Re: C1 Oil Pressure Line Confusion

Bob -

It's been a while since I did mine, but as I recall, these are not conventional household-type compression fittings that require a separate double-tapered compression sleeve; they are a GM-unique fitting design where the taper inside the engine and gauge fittings compresses the matching taper in the hex fittings that go on the pipe to secure and seal the joint, assuming the pipe is fully bottomed-out in the receiving fitting on the engine or gauge. Found exactly the same thing when I replaced the oil pressure line on my '69 Z/28 several months ago - it uses a plastic pipe, but has exactly the same fitting design (no compression sleeve), with a tiny brass insert inside the I.D. of the pipe at each end of the line so the plastic pipe has something solid inside it for the hex fitting to compress the plastic wall against. The GM engine and gauge-end fittings are virtually impossible to find, but the replacement pipes come with the correct hex pipe fittings.

[John H.]

Re: C1 Oil Pressure Line Confusion - Addendum

Part of the confusion is that GM calls the hex fittings on the pipe "sleeves", not "fittings"; but they are NOT compression sleeves as we are accustomed to seeing in household plumbing - they're hex fittings which, when mated with the correct engine or gauge fitting, require no separate compression sleeve to seal.

[Bob Malone #35242]

Re: C1 Oil Pressure Line Confusion - Addendum

Thanks John.
I wondered if that might be the case. In looking down at the fitting in the block, it appears to have a "mating" taper but I still questioned if it would compress enough to hold the line in place with pressure on it. I found a drawing in the Corvette Central catalog that shows the line, the fitting and the mating piece in the engine block. They sell the kit with three fittings. The one I bought only had two. That makes me wonder if the fitting at the guage is the same configuration. My guage was rebuilt so it has a new receiving fitting but what if it didn't? I assume you can only use these once. Is that a safe assumption? I still have the old fitting in the block. Do I need to change it?

[John M.]

Re: C1 Oil Pressure Line Confusion - Addendum

Bob, John is correct, the taper clamps down on the tube and seals it. There shuold be no reason to replace the fitting in the block. Some vendors include the block fitting in the line kit, and some do not. John

[John H.]

Re: C1 Oil Pressure Line Confusion - Addendum

Bob -

I don't know for sure, but I assume you can disconnect and re-connect them at either end without leakage for service; the pipe on my '57 had been crushed when I found it, so I replaced it with a new pipe and fittings (with the original block and gauge receiving fittings). Did the same thing on my Z/28 with the plastic pipe - new pipe and fittings, original receiving fittings on the block and gauge. The tiny brass reinforcing inserts in the ends of the plastic pipe were a marvel - I doubt if the orifice inside the insert was more than .010" in diameter.

[John M.]

Re: C1 Oil Pressure Line Confusion - Addendum

John, As a matter of fact, you can even re-use the fittings if you are careful. I could not get the line through the 4 hole grommet on my 60 with the fitting on, so I cut the fitting off with a tubing cutter and punched the remianing tube out of the fitting. Punching the tube out, opened it up slightly allowing the tubing to be slid through the fitting and tightened up again. Fitting sealed up again - no problem. John

[Bob Malone #35242]

Re: C1 Oil Pressure Line Confusion - Addendum

Thanks guys,
That gives me the confidence to move ahead without fear of spraying hot oil all over the new instrument cluster and wiring under the dash.
I appreciate the input and will let you know if I have any difficulty or other questions.
Regards,
Bob

[Dale Pearman]

Don't forget

to put a single loop in the line on the engine side. Also, the steel line was originally plated with lead! I use electronic solder and a big hot iron to accomplish this finish. The solder discolors to appear as lead over time.

Dale.

[Bob Malone #35242]

Re: Don't forget

Dale,
Where is the placement of the loop and approximately what diameter should it be? Is it immediately above the fitting on the block and inside the ignition shielding?
Thanks,
Bob

[Bob Malone #35242]

Re: Don't forget - Addendum

Also, I think I remember reading on this board that bleeding the line is not necessary. Is that correct?
Thanks again.
Bob

[Dale Pearman]

Generally

(and I do indeed LOVE that word) the loop is four to five inches from the firewall and the loop is about an inch or slightly more in diameter. It's not necessary to bleed the line.

I do indeed check for lead coating when judging. Might as well get it right.

Dale.