I have been working all week installing things through the firewall, but I have hit two roadblocks. The four-hole grommet is for the throttle and choke cables (no problems), but it is also for the temp sending tube and the oil pressure tube as well. Both of these have large fittings at each end. The temp sending tube seems to be fixed to the gauge on the instrument cluster. How do you feed these through the grommet? As far as the oil pressure tube, it may be related to an earlier thread about the ferrule vs. flare on the brass tube and fitting. If you remove the connector at one end, it will be easy to get through the grommet. Does the temp sending tube disconnect from the back of the gauge? I have pulled on it slightly, but I am afraid to pull too hard and break it. Is this a slip-fit connection? or is it threaded? Greg
It was a challenge You're on the right track for the oil line. I heard that the temp line is charged with ether, elimninating the option of disconnecting it, so I slit the rubber to one of the holes in the rubber grommet to slide the line into. My '48 has a metal retainer compressing the rubber, holding everything to the firewall. The slit can be sealed with black silicone if necessary. Not sure how correct this procedure is, but I'm satisfied with the results.
Don't pull on it! Once the magic leeks out it is useless. I'm no expert, but I'll bet you are supposed to feed the temp sensor ( and any other things with big ends like oil pressure lines) through the grommit before you put the grommit in the firewall. If necessary, use an X-acto knife to cut from the pre-formed hole in the grommit to the outer edge so you can slip the tube in from the outside.
Thanks guys This is what I was leaning toward, so thank you. I found out I needed to use gasket adhesive to secure the grommets to the firewall anyway. Greg
Throw the grommet in a cup of hot water to get nice and flexible. Lube up the temp sender first, consult your thesaurus for alternative colorful language...you will need it. Now with lbe and language, persuade the sender through. Now for the fun part....the nut. More of the same and you should be able to get it through. Now the oil line....you can remove the compression fitting from the end of the line and push the line through. Now insert in the firewall, then pull cables through. If you cut the grommet, as I have done, it will shrink back and likes to fall out with any little jiggle..
Firewall Grommet As Bill said , it should be done . The original grommet has _one_ hole slit , that's for the temp. gauge's Bourdon tube so it's simple . Then , remove the ferrule off the oil pressure tube & slide it through , remembering to use STEEL or Stainless tubing as copper _will_ break in time . The grommet has a round retainer so it cannot ever fall out no matter how much it shrinks over the next 50 years....
