911T oil leak

[Forssling]

Hi All!
I'm at the end of a 5 year total restoration of a -71T. The engine has been rebuilt to mostly stock spec. The only deviation is the oil bypass mod. I have not upgraded the oil pump. I have not upgraded to oil fed tensioners.

Today I started it up for the first time with the 20 min 2000rpm procedure. It all went very well except for some oil leaks. One minor at the oil hose that I gave some more tension.

The other drips from pretty high up on the right side and drops off the tension release valve plug. It is hard to see exactly.

My guess is the upper seals of the oil cooler. All seals replaced of course but maybe they need to be tightened a bit more.

My questions are:
1) Do you agree with the above?
2) If not, what would you guess?
3) Can a bit overfilling of oil cause this? I was too excited and forgot to check the dipstick.
4) Anything else I should look fore before the next start?

I assume I can get to the upper bolts without dropping the engine but I need to remove carbs and fan shield. If I do this I want to know if to check anything else.

Appreciate all your input!
Jörgen Forssling
Gothenburg
SWEDEN

[356911930]

Hi Jorgen,

Nice looking 71T!

First, I would get the oil level corrected.

I am no expert and I would wait for our resident esperts to chime in...but I do not htink it is the oil cooler unless it is cracked. It does not seem to me that tightening the oil cooler would seal it up better because the sealing rubber rings should seal as long as the nuts are tight even if under torque spec by a few #s.

My guess would be a rocker arm has walked out or is not tightened enough and is leaking. You will nedd to pinpoint the leak better.

You have spent 5 years working on this, another engine drop will be well worth the effort, if necessary.

I'm looking forward to what those with more experience have to say!

Best of luck,

Rahl

[dannobee]

Can you take pictures of the oil leak on top? Even if you can't stick your head in there, use your phone and take some pictures.

Hard to say without having a look.

[Forssling]

Thanks for your input!

Here are some pics. What you see is the right side of the block and the oil cooler. I have wiped the plug where it was dripping from. But you can see oil above it so I don't think it's the plug leaking.







The oil pressure sender and oil thermostat is above this point. And since the shroud are covering these areas it is hard to detect any leaks.

Thanks for trying to help me out.

//Jörgen

[dannobee]

As you said, oil thermostat and oil pressure switch. Also the fitting that the oil pressure switch screws into. I'd try to look back there with a mirror and a flashlight, or a remote camera/borescope tool.

[Forssling]

Originally Posted by dannobee

As you said, oil thermostat and oil pressure switch. Also the fitting that the oil pressure switch screws into. I'd try to look back there with a mirror and a flashlight, or a remote camera/borescope tool.

Yes, I will try to get in there with a borescope. I'm at the next stage of the break in and will be trying to tune the carbs on next oil fill.

The oil thermostat opens up the oil cooler route. So, if I don't have an oil leak before it is warm I can assume it is oil cooler related. Right?

I'll let you know what I find after next startup. It will be in a few days.

In the meantime you can check these links on the first startup. If you're into that kind of porn...

https://youtu.be/sCshFWC0o0o
https://youtu.be/Sjuh7BBcyxk

//Jörgen

[356911930]

Hi Jorgen,

Well, it does not look like typical rocker leak. I would start looking at the top of the engine as dannobee sugested. The front of the engine although hard to get to is probably where the leak starts. It will take a long time to get to the plug where it is dripping so the "if I don't have an oil leak before it is warm I can assume it is oil cooler related. Right?" may not be valid.

Rahl

[Forssling]

Hi All,
I removed the oil pressure sender and could definitely see some moist there. I put in new gaskets and repacked both the fitting and the sender with some Curil T. Tightened them a bit harder than last time also.

I wonder if that little leak could lead to that kind of oil spot. I ran it for 20 mins so maybe..?

That would be great if the fix was that easy. Cross my fingers...

//Jörgen

[Forssling]

Here are some images before the engine went in. The sender is definitely in the problem area. See marking.

Also a shot when sender removed.

//J

[Forssling]

Hi All!
So this is where I'm at for now.

As I was thinking about the above mentioned leak from the pressure sender and tension release valve plug I think it was a combination.

So today I started it up for the second time. Eager to not overfill I put in just short of 6 liters. I find it really hard to read the dipstick. I know it's supposed to be checked with warm engine and at idle. I did that and poured another liter in the system. Now I think I have a reading on the stick. My oil level gauge is not working at the moment but I will adress that later.

As said, started up for the second time today. Carb adjustment and checking for leaks on the program.

The first leak is fixed! But I found another one. It drips on the right heat exchanger so it is not shown immediately. I felt the oil on the lip around the front of the heat exchanger.

I saw a drip on the bottom edge of the dreaded oil cooler. So I got my borescope out and I could see the leak clearly. These are shots of my borescope screen so excuse me for the quality.

I think I have to pull the oil cooler to get it repaired. What do you think? I've heard that this is possible without pulling the engine. My garage is very, very small so I'll try to avoid that.

I had some other "minor" issues as well. The carbs popping on acceleration and not getting the first gear engaged. I think I'll solve the gear lever adjustment but I will post the carb/timing question in another post.

Appreciate any input on the leaking oil cooler.

//Jörgen

[Forssling]

I have now had another look at my situation. From what I can see it has to be the oil cooler leaking. There is nothing else in that area it could be. That being said, fluid can take some irrational ways...

So, it looks like I have to pull the oil cooler and get it repaired. I understand it is possible without taking the engine out. I will investigate this before I dig into it.

So a few more (not so good) images. It is hard to get into the area but I have had my endoscope in there from below and from above. I definitely see moist around the bottom left part of the oil cooler.

On the images you see where it drips and wanders around the circumference of the heat exchanger. It also leaks when it is standing in the garage, so it doesn't have to be under pressure.

Would you check any other areas for leaks ending up on the lower nuts of the oil cooler?
I'm positive it's not leaking from the breather, oil pressure sender or oil thermostat.

Appreciate all of you trying to help me out.

//Jörgen

[Neven911]

To get to the top bolts on the cooler you have to remove the engine shroud, which unfortunately probably means engine out. The shrouds were modified in 72 to have a separate piece over the cooler on the top (91110640601) so it could be performed with the engine in the car

[Forssling]

Originally Posted by Neven911

To get to the top bolts on the cooler you have to remove the engine shroud, which unfortunately probably means engine out. The shrouds were modified in 72 to have a separate piece over the cooler on the top (91110640601) so it could be performed with the engine in the car

I had a look at it and I can't see why I wouldn't be able to remove the shroud. Where would you say I get into trouble?

Remove carbs and intake
Left and right air cooler ducts
Right front cooling tin

That should be it as I see it. But please chime in if you know that it will not work.

KR
Jörgen