Author Topic: TC Head-to-Block oil tube  (Read 439 times)

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Offline Fotog

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TC Head-to-Block oil tube
« on: Monday,November 21, 2022, 02:01:23 PM »
I have some significant oil leakage, and I think most of it is from this tube.  I understand that it's rubber and I believe I've heard that it can be replaced in-situ; without removing the head (I don't want to do that!).

I gave it a little squeeze with some Channel-lock pliers and it does seem to be rather flexible.  If I warm it up with a heat gun and pull it out, can I re-install it after cleaning things up with some degreaser, using a little bead RTV?

Any first-hand experience or advice would be appreciated.  Maybe I should go with a new one; God knows how old this is.

-Vince

Offline Bryan Boyle

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Re: TC Head-to-Block oil tube
« Reply #1 on: Monday,November 21, 2022, 04:20:41 PM »
I have some significant oil leakage, and I think most of it is from this tube.  I understand that it's rubber and I believe I've heard that it can be replaced in-situ; without removing the head (I don't want to do that!).

I gave it a little squeeze with some Channel-lock pliers and it does seem to be rather flexible.  If I warm it up with a heat gun and pull it out, can I re-install it after cleaning things up with some degreaser, using a little bead RTV?

Any first-hand experience or advice would be appreciated.  Maybe I should go with a new one; God knows how old this is.

-Vince

Ahhh....the infernal return tube.  Just did mine a month or so ago...it's a messy and icky job, no matter how you slice it.  Couple pointers from my experience:

1. Replacements are cheap from the usual suspects.  Can't go wrong with just pulling the old one out and sliding in a new one. 
2. Pull the old one out.  Grab it with your channel locs and pull.  Then get up in there with a rag and some lacquer thinner and clean off both mating surfaces of old RTV.
3. Put the new tube in a pan of water and boil it for 10-15 minutes.  Yes, boil it.  You want to soften the thing so it will be more pliable.  A heat gun will be too aggressive.  When cool, or right out of the package, it's stiff.  Trust me.  Boil it, then bring the pan with the hot water and the tube into your garage.
4. Head and block clean?  Great.  Take the tube out of the water (it will stay pliable for about 10 minutes), dry off, and apply a bead of high-temp RTV to the base of both ends where the flange meets the part that inserts into the holes.
5. Insert the top serrated portion into the head, then, using a thin (thickness) putty knife as a compression tool, lift up on the lower serrated end and slide the tube to its location, holding it in place (it takes some muscle...), slide out the shim and finagle the hose into the lower hole on the fuel pump mount area.
6. Take your channel locs and gently rotate the tube to evenly spread the RTV to seal (a quarter turn should be more than you need).
7. Let the RTV set per the package.
8. Clean up what gets squeezed out by smoothing around the perimeter of the exposed flange before it sets up.  Lacquer thinner works fine.  Clean your hands, too, because it is messy.

Did mine, used the 500 degree red RTV, and it's not leaked since (I have a weep from the head/block joint back there, but that's another issue). This is how I did it, from memory; others may chime in with other ways.  Pick what seems to make the most sense...and good luck...:)
Bryan Boyle
Fall River MA
Morrisville PA
Commercial Pilot/CFII/FAA Safety Team
Amateur Extra Class Operator & FCC Volunteer Examiner
Currently working on 3291R, ex 444R, 693R, 65/2163, 004R, 65/2678
http://www.lotuseuropa.us for mirror of lotus-europa.com manual site.

Offline Fotog

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Re: TC Head-to-Block oil tube
« Reply #2 on: Monday,November 21, 2022, 06:43:47 PM »
Thanks Bryan.  That sounds pretty complete.  👍

Vince

Offline TurboFource

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Re: TC Head-to-Block oil tube
« Reply #3 on: Tuesday,November 22, 2022, 11:57:54 AM »
That thing was eliminated on my car, apparently with no ill effect.....
The more I do the more I find I need to do....

Offline BDA

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Re: TC Head-to-Block oil tube
« Reply #4 on: Tuesday,November 22, 2022, 12:00:30 PM »
You don't have an oil drain from your head back to your block? I think you really want it. My BDA has oil drains from the head to the block too.

Offline TurboFource

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Re: TC Head-to-Block oil tube
« Reply #5 on: Tuesday,November 22, 2022, 12:18:44 PM »
CW eliminated it....it drains through the pushrod holes and into the timing cover...on the exhaust side they only drain into the timing cover anyway
The more I do the more I find I need to do....

Offline TurboFource

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Re: TC Head-to-Block oil tube
« Reply #6 on: Tuesday,November 22, 2022, 01:09:26 PM »
I seriously doubt much oil is draining through it since it connects to one 7/16" vertical hole that is at the same height as where the valve cover sits.
The more I do the more I find I need to do....

Offline BDA

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Re: TC Head-to-Block oil tube
« Reply #7 on: Tuesday,November 22, 2022, 02:26:24 PM »
I don't have a twin cam so I looked at that workshop manual. That tube is called a breather not a drain as I was calling it. I'd be hesitant to delete it since it cost them money to put it in and Lotus sure liked to save money so I wouldn't think that they would spend that money on something that wasn't a bit more than nice to have.

I did some poking around on the Elan forum and the setup I liked the best was a head breather and a block breather both plumbed to a "catch tank." Others mentioned putting a 'T' in the rubber breather that just vents the head and block to the atmosphere. I've seen a lot of race engines with a vent drilled into the cam cover and a hose fitting screwed into that. Presumably, there is also a breather for the block, but maybe not.

I'm not in a position to say what is enough breathing or not enough breathing. I would think the more, the merrier and it certainly doesn't have to be the same setup the factory gave you.  This is just a note to make sure you think about it.

Offline TurboFource

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Re: TC Head-to-Block oil tube
« Reply #8 on: Tuesday,November 22, 2022, 03:50:43 PM »
Thought I would put a light in the subject.....as you said it is for a breather.

TCST has two point on valve cover for that purpose that CW added.
The more I do the more I find I need to do....

Offline Bryan Boyle

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Re: TC Head-to-Block oil tube
« Reply #9 on: Tuesday,November 22, 2022, 06:47:22 PM »
I don't have a twin cam so I looked at that workshop manual. That tube is called a breather not a drain as I was calling it. I'd be hesitant to delete it since it cost them money to put it in and Lotus sure liked to save money so I wouldn't think that they would spend that money on something that wasn't a bit more than nice to have.

I did some poking around on the Elan forum and the setup I liked the best was a head breather and a block breather both plumbed to a "catch tank." Others mentioned putting a 'T' in the rubber breather that just vents the head and block to the atmosphere. I've seen a lot of race engines with a vent drilled into the cam cover and a hose fitting screwed into that. Presumably, there is also a breather for the block, but maybe not.

I'm not in a position to say what is enough breathing or not enough breathing. I would think the more, the merrier and it certainly doesn't have to be the same setup the factory gave you.  This is just a note to make sure you think about it.

Whatever it is, the reason for it is described in Wickins' book...I have an air/oil separator can that I'm going to plumb in to where the breather tube that was supposed to go to the Stromberg airbox was deleted by a (d)PO somewhere along the line, and run the outlet back to the airbox.  A fellow forum participant sent me a Vegantune fitting for the front of the valve cover; I may mod my cover to mount it on the front and run a secondary line back to the separator to provide additional extraction of the crankcase pressure.  Every little bit helps, right?
Bryan Boyle
Fall River MA
Morrisville PA
Commercial Pilot/CFII/FAA Safety Team
Amateur Extra Class Operator & FCC Volunteer Examiner
Currently working on 3291R, ex 444R, 693R, 65/2163, 004R, 65/2678
http://www.lotuseuropa.us for mirror of lotus-europa.com manual site.

Offline GavinT

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Re: TC Head-to-Block oil tube
« Reply #10 on: Tuesday,November 22, 2022, 09:05:29 PM »
A mate of mine with an Elan fabricobbled a replacement oil drain tube using two telescoping pieces of ally machined to accept an internal O-ring in the middle allowing it to be 'concertina'd' for installation.
He said he'd copied the idea from someone else but there's a number of similar ideas out there.

He might have copied his version from here:

https://lotuselan.net/forums/viewtopic.php?f=50&t=46831

Offline Fotog

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Re: TC Head-to-Block oil tube
« Reply #11 on: Wednesday,November 23, 2022, 05:06:02 AM »
Looks nice.  Could probably get one of those made for a few hundred $$!  ;)

Offline Grumblebuns

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Re: TC Head-to-Block oil tube
« Reply #12 on: Wednesday,November 23, 2022, 05:58:51 AM »

Offline Kendo

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Re: TC Head-to-Block oil tube
« Reply #13 on: Wednesday,November 23, 2022, 07:17:08 AM »
That’s a pretty cool design, Grumblebuns. Did anyone pinch the design and start manufacturing it? I’d be interested.

Offline GavinT

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Re: TC Head-to-Block oil tube
« Reply #14 on: Thursday,November 24, 2022, 10:24:38 PM »
Looks nice.  Could probably get one of those made for a few hundred $$!  ;)

True.
That's why it's important to have a mate with a lathe.  ;D