Aux Oil Thermostat Removal - Report & Follow-up to Recent Posts

[JRSIII]

I wanted to provide some feedback and follow-up to some recent threads discussing options for removal of the auxiliary oil thermostat and other oil cooling components. While I realize that this may subject me to some criticism and possibly even some ridicule, I wanted to pass on my experience in the hopes that maybe by doing so someone else can avoid making the same mistakes that I did. Long read but hope it helps. If after reading you have any specific questions, feel free to PM me.

It had been suggested that rather than trying to loosen the hard oil line connections at the thermostat on the car, it would be easier to remove the whole system (the four hard oil lines that connect to the thermostat, the short soft lines to the cooler, and the cooler) all in one piece. I had advocated this method, as I’d tried unsuccessfully to loosen the connections in place, and it seemed logical.

What I found out was….it is NOT POSSIBLE to remove the thermostat with the lines attached to it on a car with a G50. You may ask, what the heck does the transmission have to do with oil cooler lines. Well, it turns out is has everything to do with it. Think about it, and more below.

Also, it is NOT POSSIBLE to remove a Carrera style front cooler without disconnecting the short flexible lines. If they are attached, there is simply no room to lift the cooler up for the bottom studs to clear the bracket. Finally, it is NOT POSSIBLE to cut through the soft lines using a PVC pipe cutter. They are apparently made of some sort of steel fiber re-enforced material, perhaps like the sidewall of a tire. The trick here not to try to loosen the connection between the hard and soft lines, but instead loosen the connections at the cooler itself. After twisting one of my hard lines and rounding off the nut, and after destroying both of my soft lines trying to cut them, in desperation I tried the connections at the cooler and they came right off. I should have tried them first. Like Frank Drebin said after it was already too late, “I realize that….now”.

Now that I had the front connections loose, it’s back to the thermostat. I’d previously disconnected the hard lines at the oil tank (and removed the tank) and the crossover pipe. So I figured, now, everything should just drop out. WRONG! Remember the G50. Unfortunately, the G50 cars have extended rear torsion bar cover tubes, which basically go all the way to the body. See photo. Because of this, there is just no way to get the assembly out in one piece. And yes, I know my spring plates and covers need refurbishment. It’s on the list.



At this point, I’m about to pass out from the heat. It’s 100F in the afternoon in Houston these days. Literally. 100F. And anybody who’s been here in the summertime knows it’s not a dry heat. So I’m soaking wet with sweat, frustrated, and annoyed. So I resorted to drastic measures and broke out the tubing cutter. I guess I’d been looking for an excuse anyway to buy those cool ER finned lines, and now I have one.

At the end of the day, I’m not too annoyed as I was able to remove the critical components (oil tank, thermostat, and cooler) without damaging them. I’ll begin cleaning them up and testing them for re-installation, as well as replace the 240F thermoswitch on the front cooler with a lower temperature version so that the fan activates at a lower temperature. The oil lines will all need replacement. I recall in one of my earlier posts, before attempting this, I prophetically said “I have a strange feeling something is going to get destroyed and I’ll be calling Chuck at ER.” How true this was. See photos below.

I’m reminded of Judge Smales after his wife knocked the bow sprit off his new sailboat….”Well don’t just stand there…somebody get some glue!!!!!”

[Joe Bob]

Screw the oil cooler t-stat. Toss in a lake....Put in a switch so you can manually turn on the fan when the oil gets warm.

As to cleaning you could have done it on the car with rags and brake cleaner with a little elbow grease......

[KTL]

Looks like you picked the wrong week to stop sniffing glue?

https://youtu.be/ZqtNxNRCcGg?t=3m19s

The connections at the t-stat in the wheel well and the connections at the oil cooler certainly are troublesome. People often have trouble with these connections because dirt finds a way into the back side of the connection and seizes the nut to the tubing. This is where the female nut acts like a collar to press the spherical male end of the hard line into the receiving aluminum fitting on the t-stat or oil cooler to establish the compression seal. So its a good idea to strike the connections with a hammer or wrench to try to free up some of that dirt & corrosion. That dirt & corrosion acts like a wedge and doesn't let the grip loosen between the threads as you're trying to loosen the nut.

These connections also benefit from applying heat, a LOT of it, to help expand things which frees up the dirt crud and/or stubborn threads. Heat it up, hit it with a hammer or wrench (don't get crazy and beat the hell out of it), heat it up again, repeat. Also spray some penetrating lube around the fitting after heating it. Yeah it can catch on fire but it's easy to put out. It also cools the heated parts and can break up some of the corrosion & crud. Also it's not a bad idea to apply a bit of tightening force to the wrenches to help loosen things up. Sounds illogical but sometimes it helps free the threads & the dirt.

When all else fails you can cut the female collar nuts with a rotary cutoff wheel (Dremel type tool works fantastic) to avoid major damage. Often times this is the best way to go to avoid damaging the threads on the t-stat and/or oil cooler. Elephant racing makes a replacement nut kit to do this. Elephant Racing | 30mm Oil Line Tube Nut Replacement Kit | Porsche 911

But if your flex oil lines from the engine to the t-stat are original, you're usually better off replacing the entire oil line since the rubber flex section is old and dried out. The small flex lines connecting the oil cooler to the hard lines are indeed pesky but also not terribly expensive @ $35 each. So you're usually better off sacrificing those to the nut cutting trick and replace them. Yes the hose in the little flex lines is a steel reinforced pressure rated hose. A sawzall metal blade makes short work of cutting that. Or a small hacksaw.

I know you've already had your fair share of bad luck. But honestly you're lucky that the fittings at the oil cooler came loose so easy. A great friend of mine (RIP) decided to remove the oil cooler way back in '99 when he first got his '86 Carrera that I now have. Those fittings were stuck tight and he didn't think of cutting off the nuts. He trashed the aluminum fittings on the cooler and thankfully Otto in Venice CA (also RIP) was able to able to have the trashed fittings removed and new ones welded on.

You're correct that the extended spring plate tube of the '87-'89 911 prevents you from dropping the t-stat out of the wheel well with the oil lines attached. Need to remove the spring plate if you're going to leave the rearward hoses connected to it. Not saying it's an easy job but if you approach it the right way (mark your alignment bolts on the trailing arm, mark the angle of your drooping spring plate on the wheel well) you can pull out the spring plate and put it back together w/out needing an alignment. Then you can tackle all the t-stat/oil line mayhem on the workbench. Plus taking off the spring plate gives you a look at the bushings, which are probably pretty wasted after almost 30 years.

Working on the t-stat with it held in a workbench vise is the way to go. Because the t-stat has nothing supporting it in the wheel well, except for the oil lines. So when leaning on the nuts with a wrench, you lose a lot of your applied force when the oil lines let the t-stat move. Sure, eventually the t-stat gets wedged against the wheel well. But you're still at a disadvantage because there's not much room in the wheel well to move a wrench. Even if you make your own custom wrench (buy a big cheap non-metric wrench at Menards, cut open the 12 pt. closed end) it's still a very frustrating position to be in. Been there, done that.

Really sorry to see that your hard oil lines are trashed. But honestly that twisting of the hard lines shouldn't have happened. The hard lines have a hex on the end for counter-holding the line while you're using all your muscle to loosen the pesky collar nut.

Look at it this way. Now you have the experience to know how NOT to do it the next time? Carl Spackler so profoundly once said "I got that going for me. Which is nice......" https://youtu.be/DTa94kSlV0U?t=32s

Probably won't ever be a next time, I know. But maybe you can save someone else some future grief.

[JRSIII]

Kevin,
Thanks for the feedback. Yes, those are all very valid points and lesson's that I've learned. Despite needing new oil lines, I'm now in a position where I can put the t-stat in a vise and remove the fittings properly.

You're right, twisting that oil line was a bonehead move. I did have the right tools and was holding backup....



....but somehow it got away from me. Anyway, I applied what I learned there to the fitting at the crossover pipe and used a jack to support the 30mm backup wrench while I was applied force to the 36mm nut. Came off easy peasy.

Anyway, as you've said, in my case what's done is done, but hopefully this will help someone else out in the future. I think things are going in the right direction now.

[JRSIII]

And on another positive note...a couple of other Pelicans had a need for some of the bits and pieces from my damaged oil lines, so it's not a complete loss...