Oil supply line leak

[bazar01]

I thought I would post my difficulty here in the engine rebuilding department where there are lots of engine wrenchers..
I have tried to dismantled the oil line fitting and reseal it with a new crush washer but this thing still drips a 3-inch puddle in my garage.
The case thread is not stripped but I am afraid to strip it when I turn it half one more time.
What is the best way to seal it? Thread sealant? Any torque spec on this fitting.
Thanks for any reply.

Here is the source of oil leak:



This is the fitting and crush washer:

[speedkillz]

Have you tried a good quality thread sealer?

[bazar01]

Hey Craig, No I have not tried any thread sealant yet.
I am scared to put a thread sealant so I just replaced the aluminum crush washer and tightened everything back up.

What would be a good thread sealant? Teflon tape? Teflon Pipe dope? Loctite 574?

Thanks.

[Jim Sims]

Neither side of this fitting seals on the threads so thread sealant may not work. If the leak is on the aluminum washer side I would clean off the oil on the washer and the matching sealing surfaces on the line and the case, then coat both sides of the washer with Loctite 574, reassemble and tighten immediately. Do not retighten later. Do not put Locktite 574 on the line to fitting spherical sealing surfaces.

[speedkillz]

I was thinking Curl-T. non harding, and will allow movement/vibration without releaking. ???

[bazar01]

Thanks.

Jim, yes the leak is on the aluminum washer side and not in the hex fitting nut and tube compression ring.
I am getting scared of removing the exhaust heat exchanger so many times that I might strip the studs.
So I really wanted to get this fixed once and for all. I will use loctite 574 this time and see if it will do the trick.
I will post the result later.

Thanks guys.

[Jim Sims]

Coat the exhaust studs with anti-seize compound and reduce the nut tigtening torque by a couple of ft-lbs to ensure easier future removal.

[bazar01]

Thanks Jim. Yes I will get a bottle of copperized anti-sieze and coat those exhaust studs for easier future removal.
Do I have to replace those exhaust sealing rings the second time around?
I knew I would get more sensible solutions here. Great site!

Thanks again.

[Henry Schmidt]

On later engines 78 on, that fitting comes sealed with green Loctite. The thread locker acts as a sealant. You would think that the aluminum seal would be enough but the factory felt green Loctite was needed.
Be cautious about over tightening the fitting. I have seen more than one boss cracked and even broken off from over tightening.

[bazar01]

Thanks, Henry.

Called the local Grainger supply house and they have a 10ml Green Loctite 290 for $10.83. Description says it is used for locking pre-assembled fasteners no. 2 to 1/2" and penetrates by capillary action and removable with hand tools,
Is this the one?

Would you happen to have a torque setting on this fitting which is at least an M20 or M22.


Thank you again.

[goldgunner]

As to Green Loctite, the only Greens I've been able to identify are:
290 Loctite (Green) is a low viscosity thread locker usually used for wicking into already assembled components
609 Loctite (Green) is a medium strength adhesive recommended for the bonding of cylindrical fitted parts. Eg bushings and sleeves
648 Loctite (Green) is the same as the 609 except it is high strength

Anyone know which of these - or some other - is most suitable for the type of application discussed here?

[Henry Schmidt]

Our experience is that what ever the factory uses it's very strong.
I believe a low strength thread locker will work but in truth we use 574. I seems to seal and is for easier to work with if for some reason you must remove the fitting.
So many of our engines are for racing purposes that we need to be able to disassemble them with relative ease.

I have never seen a torque spec on that fitting but I would speculate about 24 ft/lb.
Remember that the quality of the aluminum sealing ring may dictate the maximum amount of torque this fitting will take in this application.

[Jim Sims]

I will conjecture that the primary function of the green thread locking compound applied by the factory was to keep the case to fitting threaded joint from loosening with the aluminum washer being the primary oil seal.

[bazar01]

I have new aluminum crush washers coming in. It is the same size and same part number as the oil drain plug washer but I still have not decided what adhesive to use that will function as a thread locker and a sealant at the same time.

I have used Loctite 574 in sealing machined surfaces in aluminum transmission housings with great success but I have not tried it for sealing threaded connections. It might work and it might be worth a try to seal the threaded case, the boss, fitting and the washer flat sections. I'll give it a shot.

Thank you for the replies and I will post results.

[Henry Schmidt]

Originally posted by bazar01
I have new aluminum crush washers coming in. It is the same size and same part number as the oil drain plug washer ....................

When I stated " the quality of the aluminum sealing ring" I was referring to the material the washer is made of. Over the years I have seen some very soft alloys used for sealing washers on Porsches. I assume it is for cost saving or an engineering error.
That is why we only use gaskets, crush washers and seals from Wrightwood Racing. I hate oil leaks and top quality parts are the best insurance to prevent them. That and experience.

[bazar01]

Ok, I got everything I need. New supply of crush washers and Loctite 574.
Will let the oil drip evernight and finally degrease and dry the fitting and case hole thread tomorrow.

Anything else I need to seal this leaky oil supply fitting once and for all?
Is the washer supposed to be a liitle wider? It looks too narrow for the application.

[WERK I]

bazar01,
The crush washer may look small on the fitting, but how does it appear when you compare the washer to the surface area of the case?

[bazar01]

I checked the case hole again, the washer OD is 27mm and the case boss flat surface area is 30mm OD.
The washer is just 3mm smaller in dia. than the boss or 1.5mm each side. Yes, WERK-I, the washer is just the right size.

The fitting hex needs a 32mm socket.
The fitting hex nut in the tubing needs a 36mm wrench.

[bazar01]

Cleaned and degreased the case threaded hole this morning.
Guess what I found! Green and hardened adhesive in the thread. Had to use a pick tool to get them off the thread. Really hard stuff.

Geez Henry, you were correct. Factory used some green thread sealant. I did not catch it the first time.

This time, this baby will completely seal up with Loctite 574 and new crush washer.

[goldgunner]

What's the plan - or advice?

Apply the Loctite 574 Just to the threads?
Or to one or both sides of the aluminum crush washer-seal?
Or all 3?