Oil return tube plan...PLEASE comment!

[kilodawg]

Sorry for bugging everybody with this over the past few days but it hasn't been a fun experience so far and I haven't even started yet.

A quick summary: An ’88 930S. My driver’s side rear (in relation to the car the one with the better access) oil return tube started leaking like a sieve at the head side. The oil return tubes that are currently in place are collapsible steel ones complete with circ-clips. Unfortunately, I have the air injection tubing in place although the pump itself was removed by a PO so the system is not functional.

I ordered four new oil return tubes and some extra seals from out host and in doing some additional research came across the comment from John Walker’s shop that the only way to replace the tubes on the drivers side was to remove the heat exchanger.

I really wanted to tackle this job myself but in no way am I ready to attempt the removal of a heat exchanger and I’m a little bit concerned about having this done in general. So here is my plan. Please let me know what you think.

1. Remove and replace passenger’s side oil return tubes. I understand that I may have to separate the air injection lines to gain access first.

2. Now here is the part that’s a little different than usual. Instead of just crushing and twisting the tubes to remove them, I want to try and see if I can re-collapse the tubes and possibly replace the head side O-ring while the tube is still roughly in place. If that's possible, I would still go ahead and replace the old tubes with new ones but it would give me some confidence that this technique might work for my leaky tube on the driver’s side rear.

3. So if it works I’ll have fresh tubes in the passenger side and at least my leaker on the driver’s side will be fixed. That will buy me a little more time to see what I want to do next.

4. If it doesn’t work I replace the passenger’s side one, and make an appointment at the shop..

[Rot 911]

You should have no problem at all collapsing the tubes you have on there. Just pull the circlips, collapse, pull off, pull the tube apart, replace all o-rings. Make sure you use a good silicon lubricant on the o-rings. Do not use oil as it will make it more difficult to re-expand the tubes.

[Ned, NYNA11]

Kilo,

I had a leak at the head end tube in my 87 Carrera.

I got the circlip out of the way, looped a couple of hose clamps around the tube and used a chunk of wood as a pivot for a big screwdriver and eased the tube out of the head.

I replaced the o ring and lived happily ever after.

[mgbruno]

Hey,
I replaced my return tubes a little while back and - trust me - have very little mechanichal ability. I removed the heat exchangers. This was a piece of cake and really kindof fun. Ok, I sound weird. All you have to do is get the tool from our host and the spray a bunch of WD40 on the bolts. Let it soak - and then you can pretty much remove the entire exhast system. These cars are built so simply and well - thats the beauty of them. Anyway, getting the heat exchangers out of the way really helped me - but getting those damn tubes in was a pain!!! And the circlips were hard to get on too! You need a circlip tool as well as another pair of hands. Feel free to write me - michael.bruno@usmc.mil

Mike

[kilodawg]

Okay guys thanks for all the replies. I also spoke with my wrench and he assured me that even with the air injection tubing in place I should be able to repair or replace the leaker. He did it just last week in fact and has never had to remove the heat exchangers. He admitted that the front on on the drivers side is a bear but for now I think Ill just address the leaker. I'll let you know how it goes...

[3.2 CAB]

The only problem with doing the drivers side tube is the space to work in. But, it can be done without removing any of the exhaust items, just takes a bit more time.

[Mike Andrew]

Subbed.

[WERK I]

Be sure to lubricate the new o-rings(hopefully they are viton) with a light coating of silicone paste. It helps the rings glide into the recess and when in use, it helps the rings expand/contract in their respective recesses. Minimizes the chance of them sticking and possibly leaking.

[kilodawg]

They are the Pelican seals and I have Dow Corning 111 so I should be covered. Thanks!

I'll be taking pictures of this job too for adding to this thread.

[Superman]

The DC-11 will do two things. It will probably ensure the new o-ring will not leak. And it will make the mechanism MUCH slipperier, to facilitate the procedure.

[kilodawg]

I understand. My concern though is that the possibility exists that I won't have access to install a replacement tube. I've heard both yes and no to this. I will be finding it out for myself.

My initial approach will be to collapse the tube enough to just replace the seal if that is all the access I have. I'm pretty confident I have access for that. In that case I won't be able to take advantage of the Dow Corning 111 on the inner O-rings. If however, I can collapse the tube (without damaging it) and can remove it that SHOULD mean I can install a new replacement. If that's the case I'll do that and take advantage of a new tube that should be easier (with the Dow Corning 111) to extend into place.

This is going to be an interesting project no matter how it turns out...

[Superman]

One of the better suggestions I have heard is to install a hose clamp near the end. That gives you something to pry, in order to seat the o-ring into the case and/or head.

[kilodawg]

Yep. To help collapse a tube a bit to get to the leaky seal I think it's probably one of the only ways to get the required leverage. So I'm thinking of using two clamps and a block of wood (as a pivot) and a screwdriver as a pry bar. Just like Ned said...

Right now I'm more concerned about collapsing it than extending it...

[WERK I]

Originally Posted by Superman

One of the better suggestions I have heard is to install a hose clamp near the end. That gives you something to pry, in order to seat the o-ring into the case and/or head.

+1
hose clamps work great

[Kraftwerk]

Hose clamp helps for sure. Recommend the aluminum style return tubes over the steel ones. Al. is a bit more cash but much nicer to work with, they slide and un-slide smoothly and are easier to instal. Use the Dow lube on the rubber rings makes for an easy job.

[Ned, NYNA11]

Kilo,

You put a couple of hose clamps around the tube that you want to move.

Then get a block of wood between the clamps and the head to use as a pivot point.

Use a small pry bar or a screwdriver to lever the hose clamp and thereby move the tube. Note you will need to relocate the hose clamps after the tube moves to get a good push.

Don't forget to move the circlip to allow the tube to move.

My head side leaked, pass. side.

[kilodawg]

Thanks Ned!

Well again my leaker is on the drivers side towards the rear of the car and I have the air injection tubes in place. I'm taking things slowly and carefully because in case I can't get a new tube in I don't want to do anything destructive to the tube that's in place. Tonight I got the circlip out of it's spot and onto the smaller diameter tube. With the access you have on the driver's side (especially with the air injection tubing) it was a bit of a challenge getting a pair of snap ring pliers in there but that's behind me now.

I still think it will be possible to install a new tube but just in case it isn't I'm working as if I'm only going to replace the leaky seal and re-extend the tube.

Tomorrow evening I'll get the hose clamps on and everything set up for Saturday. It will probably be difficult to collapse the tube since access is so tight.

[C4 Pazzo]

I'm curious as to why you don't want to just replace the seals on the existing collapsible tubes. The collapsible tubes should be reusable with new seals.

[kilodawg]

Replacing the seals on the existing tubes will be the first approach. My concern is that I don't know how difficult the tube will be to re-extend. I've read all the horror stories from the folks who used oil and not Dow Corning 111 as an O-ring lube. So if it gets too difficult based on the access to compress or expand it I may be left with just the option to crush the old one and replace it...

[88911coupe]

Just to clarify...on my rebuild I'll be replacing the seals and want to make sure to get Viton but are these the green ones...how do you tell? Also, since mine are off the car I won't need to expand them but just to be clear...what is the difference between "silicon paste" and Dow Corning 111 or are they the same thing? My concern is making sure no one, including me, uses anything in this critical area that may have unintended consequences with the oil system or engine internals. I'd hate for someone to use something that hardens over time and clogged something up.
Didn't Wayne do a write up on case sealants and where they should be used, and not used?