Be kind to your oil pan plug hole

180 Out · Mar 28, 2013

I just got off the phone with the machinist who's got the oil pan off my '83 400i and his estimate for fixing a stripped out oil pan plug hole is four hours labor, plus an insert kit and, if I understand correctly, a one-off drilling tool, altogether costing $550 to $600 (estimated).

How I got to this point begins with the first oil change I did about one year ago, shortly after buying this car. The oil plug didn't come out very smoothly, or go back in very smoothly, but it did go out and in. What I should have done this first time was to inspect the plug threads, and if they weren't *perfect* I should have ordered a new plug -- they're less than $20 -- and let the car damn well sit while I waited for delivery.

My second oil change was incidental to performing the O-ring replacement to the two tubes which connect the oil filters to the main oil gallery in the "V" of the engine, with the tubes running through a water jacket, that's inexplicably located along the length of the "V". Anyway, the drain plug came out *un*smoothly again. But this time it would not go back in, no way. This is when I took a closer look at it and it has aluminum embedded in the leading threads, the ones that need to engage the helicoil in the plug hole. Also, I notice that the helicoil has backed out of the hole a turn and a half. So the plug is probably not going to seal, even if it would screw in.

At *this* point I probably should have dropped the pan right there, and taken it to the machine shop with the helicoil still in place. Who knows if that would have been a better idea. Maybe it wouldn't; maybe the threads in the pan were already kaput. We'll never know. What I did was I thought I could unscrew the helicoil and put in a new one, with the pan in place. What happened was, yes, the helicoil did come out, in a very twisted state, but this choice also pulled out what was left of the threads that Ferrari had cut into the the pan when it originally installed the helicoil.

So now what I've got is a very large rough opening of 17.3 mm, with the ghost of the original threads still visible. And what my machinist is going to do is to bore the opening, and thread it for an insert, to re-use the original 16 mm drain plug. He's also going to spot face the seat, because he says it's not a good seat, as is. FYI, he also says the pan's aluminum is a very brittle kind and porous and not good for welding.

So here I am in bend-over-and-like-it Ferrari land. Unless somebody has an oil pan they would be willing to sell.

Moral to the story: be kind to your oil pans.

Ashman · Mar 28, 2013

Wow, sorry to hear that but totally understandable. I could tell the first time I did an oil change on my 400i that the oil pan and plug needed to be treated very gingerly, it just didn't feel all that strong and I knew that I had to be careful in threading the plug in and in not overtightening it.

You would think that a used pan might possibly be available somewhere, what with the long production run of the engine. Have you checked around with all the usual suspects?

Years ago there was a guy in upstate New York named Fred Petroske who broke up all sorts of foreign cars for parts and was said to have one or more 400/400i cars for parts. He was (maybe still is?) a frequent advertiser in Hemmings. You might try to track him down and see if he has a pan.

Good luck with fixing it.

Edit:

Here is Fred Petroske's website:

http://mostlybritish.com/index.html

samsaprunoff · Mar 28, 2013

Good day Bill,

You should try to find the fellow that made these repair adapters. Effectively the fellow machined an adapter for just this type of issue. One drills out the knackered threads and re-taps the larger hole to accommodate the adapter. Then the adapter is threaded in with a thread-locker, etc leaving a new orifice for the OEM plug. I bought this one off Ebay a few years ago, as I thought it was a great idea and it was relatively inexpensive... $25 or so comes to mind.

Anyway, if you are interested let me know and I will go through my records to see if I can find the fellow who did this and report back.

Cheers,

Sam
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180 Out · Mar 29, 2013

I did call around for a second-hand pan, with no one having one. You'd have to find someone who's willing to part out an engine, and I didn't find such a person.

The problem with an insert is that the remaining material, with a 17.3 mm hole in it, is too thin to re-thread. As I understand it, my guy is putting in a billet plug and then he'll bore a threaded hole in that.

This is why I advise, at the first sign of difficulty with the drain plug, STOP what you're doing and examine the plug, or replace the plug, or consider dropping the pan right then and taking it to a machinist. Even though the pan gasket itself is not cheap -- about $50 from Eurospares -- and it's very far from easy to remove the old one, my advice is to consider dropping the pan and seeking expert help, before doing something rash and expensive.

deeprivergarage · Mar 29, 2013

Sorry about you oil pan plug, but certainly a repairable issue.

Unfortunately, the cost of repair can vary widely, depending on the shop and type of repair.

However, the stripped oil pan plug threads is a very common problem for all cars and motorcycles, both steel and aluminum pans.

I have had very good results with Heli-Coils, or comparable brands, and would not hesitate to use a kit in must not fail situations. I think it actually makes a stronger thread in most cases. It is a very common repair method in aviation, motorcycles, automotive, and machine shop repairs.

I am sure Heli-Coil has a 16mm kit.

DRG
Jerry

deeprivergarage · Mar 29, 2013

check this thread:

search "helicoil pulling out"

There may be other threads on FC regarding Heli-Coils.

DRG
Jerry

Rifledriver · Mar 29, 2013

180 Out said: ↑

I did call around for a second-hand pan, with no one having one. You'd have to find someone who's willing to part out an engine, and I didn't find such a person.

The problem with an insert is that the remaining material, with a 17.3 mm hole in it, is too thin to re-thread. As I understand it, my guy is putting in a billet plug and then he'll bore a threaded hole in that.

This is why I advise, at the first sign of difficulty with the drain plug, STOP what you're doing and examine the plug, or replace the plug, or consider dropping the pan right then and taking it to a machinist. Even though the pan gasket itself is not cheap -- about $50 from Eurospares -- and it's very far from easy to remove the old one, my advice is to consider dropping the pan and seeking expert help, before doing something rash and expensive.
Click to expand...

Is Dan Marvin doing it for you?

He has repaired a few of those for me over the years. The big cost is due to the drain hole orientation in the pan. It is not a straight forward job of just drilling and installing a heli coil.

180 Out · Mar 29, 2013

Rifledriver said: ↑

Is Dan Marvin doing it for you?

He has repaired a few of those for me over the years. The big cost is due to the drain hole orientation in the pan. It is not a straight forward job of just drilling and installing a heli coil.
Click to expand...

The guy I've got is Tim at Morgan's Machine in Walnut Creek. This is what he said also, that the location of the hole in the middle of the casting requires a very long drill bit to get to it. The shop has several V-12 Ferraris in the works, and even a Bugatti engine. Tim says many of the restorers send the engine work to him.

I just thought of some more advice to pass along. Those who are planning to do the oil tube O-ring replacement, if you are doing this in your driveway and you've raised the front end to drain the oil, be sure to let the car down and sit on the level for a bit, as well. The oil pan is full of baffles, and they'll trap the used oil at the low end (toward the rear) if you don't let it sit level. Because oil floats on water, what this really means is that you're leaving coolant in the pan, if you don't let it drain from level. In fact, this is probably a good practice for every oil change, for those who jack up just the front of the car to get to the drain plug, to set the car back down to level for a bit. It's possible that many oil pans have a little water in them at oil change time, from combustion byproducts.

tr0768 · Mar 29, 2013

We use a hardened insert called a Thread Cert. We use these in aluminum Subaru engine blocks for head bolts that have been stripped out.

Thread Certs are hardened inserts with a countersunk gripping flange. The kit comes with a tap to oversize the original hole, then there is a cutter to countersink the flange area of the larger hole. Then you use a special tool provided to install the flanged hardened insert with locktite. Now you have the new flanged insert flush with the original flat surface. Incidently the flange has self locking ribs on the underside of the flange to lock it inplace. When finished you end up with an original sized hole.

We have used this system with many stripped threads and have never had one fail, unlike the cheaper Helicoil spring system. Porsche uses the threadcerts as a factory approved process for saving blocks.

Howard Musolf
1981 308gtsi
1982 400i cabriolet
1994 348 spider

It's Ross · Mar 30, 2013

Too late now but why not simply re-tap the hole, perhaps to an oversize, SAE even?

Rifledriver · Mar 30, 2013

For all of you that have never seen the pan the fix is harder than you suspect.

Rifledriver · Mar 30, 2013

180 Out said: ↑

The guy I've got is Tim at Morgan's Machine in Walnut Creek. This is what he said also, that the location of the hole in the middle of the casting requires a very long drill bit to get to it. The shop has several V-12 Ferraris in the works, and even a Bugatti engine. Tim says many of the restorers send the engine work to him.

I just thought of some more advice to pass along. Those who are planning to do the oil tube O-ring replacement, if you are doing this in your driveway and you've raised the front end to drain the oil, be sure to let the car down and sit on the level for a bit, as well. The oil pan is full of baffles, and they'll trap the used oil at the low end (toward the rear) if you don't let it sit level. Because oil floats on water, what this really means is that you're leaving coolant in the pan, if you don't let it drain from level. In fact, this is probably a good practice for every oil change, for those who jack up just the front of the car to get to the drain plug, to set the car back down to level for a bit. It's possible that many oil pans have a little water in them at oil change time, from combustion byproducts.
Click to expand...

Dan is in Berkeley, right off Gilman and was one of the machinests for Griswold Restoration. He does more old Italian **** than anyone alive.

Rifledriver · Mar 30, 2013

It's Ross said: ↑

Too late now but why not simply re-tap the hole, perhaps to an oversize, SAE even?
Click to expand...

Why would you butcher it like that?

Tassie · Mar 30, 2013

I had the same thing with my 512BB. Had to buy a new sump. Original material too low quality to weld (tried and it cracked). Very disappointed.

It's Ross · Mar 30, 2013

Rifledriver said: ↑

Why would you butcher it like that?
Click to expand...

How is this butchery?
Please don't tell me it's butchery not to use an OE Ferrari drain plug.

deeprivergarage · Mar 30, 2013

From Ricambi America, Inc. parts list:

103388 [103388 HELI-COIL] $22.36 each

Ask a question
about this item

HELI-COIL
This item is used in the following applications:

Vehicle Quantity * Table Location Where Used
348 2 9 27 FUEL PUMP AND PIPES
348 (1989-1992) 2 9 27 FUEL PUMP AND PIPES
400i 1 2 43 OIL SUMP ******
400i 1 4 49 CYLINDER HEAD (RIGHT)
412 1 2 43 OIL SUMP
512TR 1 3 62 RIGHT CYLINDER HEAD
F355 M2.7 (1995) 1 10 27 FUEL PUMP AND PIPES -VALID FOR CARS WITH SINGLE FUEL PUMP-
F355 M2.7 (1995) 2 9 27 FUEL PUMP AND PIPES -VALID FOR CARS WITH DOUBLE FUEL PUMP-
F355 M5.2 (1996+) 1 9 27 FUEL PUMP AND PIPES
F50 2 12 24 FUEL TANK AND PUMP
F512M 1 3 62 RIGHT CYLINDER HEAD
Mondial t 2 12 23 FUEL PUMP AND PIPES

DRG
Jerry

fastradio · Apr 1, 2013

tr0768 said: ↑

We have used this system with many stripped threads and have never had one fail, unlike the cheaper Helicoil spring system.
Click to expand...

Each type of insert has its place. A HeliCoil insert is hardly a "cheap" spring system nor is it prone to failure. They've been around 60+ years and have numerous MIL-spec applications. When installed correctly, both systems work perfectly. In the event I misunderstood, a HeliCoil is oftentimes less expensive to purchase.

tr0768 said: ↑

Porsche uses the threadcerts as a factory approved process for saving blocks.
Click to expand...

And on a Boxer or TR, with recessed threads deep within the case halves, a Helicoil repair is the only type that is possible in the event of a pulled stud.

2NA · Apr 1, 2013

Rifledriver said: ↑

For all of you that have never seen the pan the fix is harder than you suspect.
Click to expand...

It's a production just setting it up to drill it.

Tassie said: ↑

I had the same thing with my 512BB. Had to buy a new sump. Original material too low quality to weld (tried and it cracked). Very disappointed.
Click to expand...

My experience is that the castings are somewhat porous and decades of soaking in oil can make welding problematic.

fastradio said: ↑

Each type of insert has its place. A HeliCoil insert is hardly a "cheap" spring system nor is it prone to failure. They've been around 60+ years and have numerous MIL-spec applications. When installed correctly, both systems work perfectly. In the event I misunderstood, a HeliCoil is oftentimes less expensive to purchase.

And on a Boxer or TR, with recessed threads deep within the case halves, a Helicoil repair is the only type that is possible in the event of a pulled stud.
Click to expand...

Helicoils aren't the best for repeated assembly/disassembly. They work best when installed and left alone.

Rifledriver · Apr 1, 2013

It's Ross said: ↑

How is this butchery?
Please don't tell me it's butchery not to use an OE Ferrari drain plug.
Click to expand...

The entire car is metric. It is only a matter of time until it goes to a shop for an oil change and Ferrari shops keep metric drain plugs and drain plug seals in stock. No one will be expecting an SAE thread. It will only be a matter of time before the wrong plug is installed wrecking the repair.

None of that takes into account the the casting is very thin there and little material is available for oversizing. That would be begging for a cracked sump.

Both of the machinests mentioned are very experienced, talented and capable. Both have arrived at the same solution for a repair for good reason. They are not making a mountain out of a molehill. I have had several of these pans repaired by one of them and it is not a simple problem to resolve with a good quality, reliable outcome.

Rifledriver · Apr 1, 2013

2NA said: ↑

It's a production just setting it up to drill it.

My experience is that the castings are somewhat porous and decades of soaking in oil can make welding problematic.

Helicoils aren't the best for repeated assembly/disassembly. They work best when installed and left alone.
Click to expand...

Ferrari uses helicoils on many drain plug holes at the factory and they work fine but it is not a good choice for this particular pan due to its design.

180 Out · Apr 1, 2013

180 Out said: ↑

Even though the pan gasket itself is not cheap -- about $50 from Eurospares -- and it's very far from easy to remove the old one, my advice is to consider dropping the pan and seeking expert help, before doing something rash and expensive.
Click to expand...

I sure wrote a mouthful there, about the gasket removal not being easy. I spent at least four hours lying on my back yesterday to get it done, using a gasket scraper and some 3M abrasive pads. The OEM gasket appears to be made of a fiber-reinforced rubber-like substance. Due to this composite construction, and after 30 years of heat cycling, the gasket will not stay in one piece during removal. Nor can you even get your scraper between the block casting and the gasket. I used something from Loctite called "Chisel" and even though it was so toxic its aerosol droplets stung my face like paint remover, it had no effect at all. I am glad that nasty job is out of the way, and I can only hope I didn't "install" a bunch of leak sites in the process. I hated to use a steel scraper and the abrasive pads (even if they're labeled "for aluminum"). But what can you do?

So this is another reason to follow the advice in the thread title: be kind to your plug hole!

It's Ross · Apr 2, 2013

Rifledriver said: ↑

The entire car is metric. It is only a matter of time until it goes to a shop for an oil change and Ferrari shops keep metric drain plugs and drain plug seals in stock. No one will be expecting an SAE thread. It will only be a matter of time before the wrong plug is installed wrecking the repair.

None of that takes into account the the casting is very thin there and little material is available for oversizing. That would be begging for a cracked sump.

Both of the machinests mentioned are very experienced, talented and capable. Both have arrived at the same solution for a repair for good reason. They are not making a mountain out of a molehill. I have had several of these pans repaired by one of them and it is not a simple problem to resolve with a good quality, reliable outcome.
Click to expand...

Your characterization of making a mountain of a molehill is pretty much what I had in mind
when making my suggestion but since I haven't layed eyes on mine in quite some time and cannot comment on the available amount of material to work with, in fact cannot remember the plug size(M14?) I shall defer to those more intimate with this particular situation.
I will say that I've made many expeditious, reliable and effective in situ repairs by using a next oversize fastener when conditions permit. SAE fasteners sometimes offer a convenient step up. Some may turn up their nose but it works. Doing this to parts already on the bench is another matter. It's simple enough to inform anyone else servicing down the line and in the event the threads get buggered later you are simply back where you began.
I hope I'll remember this topic next time I'm face to face with that sump and will perhaps understand your position better.
Ross

blkprlz · Apr 25, 2013

180 Out said: ↑

I sure wrote a mouthful there, about the gasket removal not being easy. I spent at least four hours lying on my back yesterday to get it done...
Click to expand...

Fortunately, I didn't run into the same troubles as you but thought it would be a good place to post some pix. I don't see any advantage of jacking up the front end while draining engine oil.

First 2 pix: sump outside & in (note the baffles in the center pick-up well),
Second 2 pix: front & rear view of engine bottom, &
Last one: final assay.
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bobzdar · Apr 25, 2013

samsaprunoff said: ↑

Good day Bill,

You should try to find the fellow that made these repair adapters. Effectively the fellow machined an adapter for just this type of issue. One drills out the knackered threads and re-taps the larger hole to accommodate the adapter. Then the adapter is threaded in with a thread-locker, etc leaving a new orifice for the OEM plug. I bought this one off Ebay a few years ago, as I thought it was a great idea and it was relatively inexpensive... $25 or so comes to mind.

Anyway, if you are interested let me know and I will go through my records to see if I can find the fellow who did this and report back.

Cheers,

Sam
Click to expand...

I could use one of these for my f355. The threads are fine but the car has been bottomed which, of course, scrapes right where the drain plug is on this car and has caused the plug to no longer seal properly so I get a very slight drip. If I could install one of these plugs with thread sealer in place of the helicoil, it'd fix the issue.

180 Out · Apr 27, 2013

I have been meaning to post these photos, taken on March 17 and April 7.

The first two photos depict the O-ring replacement project that got me in all this trouble in the first place. The first one shows the slide hammer I borrowed from O'Reilly's to remove the two tubes which connect the oil filters to the main oil gallery. (If I look confused, that's my typical Sunday afternoon in the driveway expression.) I had to use the adapter that's intended for pulling a pilot bearing, into which I screwed a bolt. I used the head of this bolt to hook under the tubes, in order to pop them out. I had to grind off most of the bolt head for it to fit in the tube, leaving just enough to hook the tube from below. The second photo shows me driving in one of the tubes.

The third photo shows the oil sump. The fourth shows my new $600 hole, home to an 18mm drain plug, $6 at O'Reilly's. The fifth shows the hole from the inside. The sixth shows the sump, with its four trap doors.

The seventh photo shows why it's a good idea to have the car level when draining the oil. This is the rearmost partition of the casting. You can see there's a step up to the threshold of the trap door. This step is going to trap some of the oil (or coolant) even with the car level. (If you've got coolant in your oil -- which you will have if you do this O-ring job -- the oil's going to float on top of it and the coolant is what's going to be left at the bottom of the sump.) But if the car has the front wheels off the ground, this entire partition, as well as the sections to the right and the left, are likely to be covered with oil (or coolant).

Edit: I just noticed, the second photo shows the 8mm MSD plug wires I put in recently. They turned out well, and they seem to have cured a coil arcing problem I had, both with the OE wires and with a cheapie Autozone set I tried next. The MSD wires themselves are not too expensive, about $60 at Summit Racing for a set of eight. I also got a couple sets of Taylor brand straight-in distributor boots, which I would highly recommend because of the lack of room on the 400i's 12-cylinder distributor cap.
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