Not a good day today. As those on the forum have read I purchased a North American market '88 VDP about six weeks ago and have been working on the few things that needed sorting. Since I had a feeling fluids had been sitting in my car for a while regardless of mileage I embarked on a simple, easy oil change today. Except it wasn't.

When I removed the oil drain plug bolt from the oil pan a little over two threads' worth of aluminum (or aluminium for those who speak the Queen's English) from the oil pan came out with it. After the oil pan drained I tried to re insert the bolt in hopes of driving it to a mechanic (and no further) and another half a thread stripped. I am guessing the threads were all severely weakened by previous over-torquing as I was being careful. Obviously I am going to have to leave the car sit until I can either repair this myself or get it on a flatbed and off to the mechanic.

My hope is to get some wisdom from the forum on the various alternatives:

1) Perform some sort of helicoil repair and use the original bolt with some sort of new thread inserted into the drain plug hole. I know little to nothing about helicoils and will have to research this, and I have heard that such a repair might be prone to leaks.

2) Somehow tap a larger hole and put in a larger bolt. I don't know how well this would work.

3) Put a brand new oil pan on the car. Unfortunately my quick look at things indicates this may require an engine out repair to do it and looks like it's more than just dropping a few bolts and replacing the pan and gasket.. This is obviously expensive and well beyond my ability to do in my own garage.

4) Something else I haven't thought of?

I'm just really irritated right now. I knew 100% when I bought a 30-year low mileage car that I might have to deal with electrical gremlins, hydraulic issues, issues due to low mileage and British weirdness in general. I signed up for that willingly and actually had fun last weekend fixing electrical issues. This, however, is not British car unreliability - this is down to some careless mechanic that couldn't help himself from over-torquing a steel bolt in an aluminum oil pan. Just a needless thing and one that if it is not repaired properly puts the car at risk of oil pressure loss and a blown engine.

 

I believe you have answered your own question with choice number one. Repairing the threads would be the easiest and most cost-effective method to repair the sump.

It's a good thing you're not dealing with German 'weirdness' and over-engineering.

 

Here is more information on fixing 'aluminum' sumps:

https://www.google.com/search?source...O6bg#kpvalbx=1

 

I have used one of the options that show up at the link NBCat posted:

Dorman Oversize Oil Drain Plug

I have successfully used these on my son's BMW and a friend's Jaguar. They're probably not as good a long-term solution as a helicoil insert or a new threaded plate welded onto the pan, but the one on my son's car has been working fine for at least 5 years. They come in "oversize" and "double oversize." You select one that is just slightly larger than your original plug. They are self-tapping, so to install one, you thread it in a turn or two, back it out half a turn to clear the chips, thread it in another turn or two, back it out a half turn, and repeat until it will thread in all the way. Then remove it and carefully clean away any remaining chips before reinstalling and carefully torquing it to no more than the original factory spec.

Cheers,

Don

 

I thought I should give an update. Between travel and the time required to try and get all the parts and pieces together I did not get a chance to try and fix things until this past weekend.

My plan was to helicoil the threads and do a permanent fix and I had purchased a helicoil kit - it wasn't cheap, either. Due to the massive size of the drill (13/16) trying to drill a hole required dropping the transmission pan and getting the dipstick pipe out of the way. That wasn't going to be a big deal as I planned to redo the trans fluid and filter anyway and that part turned out to be a pretty straightforward job.

The problems started when I went in to drill for the helicoil. The metal is so soft that the drill bit kept grabbing. I did the best I could and got an okay starter hole drilled in the hopes that the tap would clear everything out. Unfortunately when I went in with the tap the metal was so soft the the tap would not thread nicely, grabbed and messed everything up. It certainly appears that trying to install a helicoil while the pan is still installed is pretty much a doomed endeavor, so I figured I would give fellow forum members the warning.

So, at this point I have arranged to have the car put on a flatbed and sent to the local Jag specialist. From our discussion it looks like he's done more than a few of these and seems to think he can repair it a different way even with what I have done to worsen the problem. Well, if he can fix it, great - if not then I will have to pony up for another oil pan and the massive labor involved to install it.

In the end, it's irritating but not the end of the world. I may as well have him give everything a good checkup while it's there anyway and then I can be confident about the mechanicals.

 

I have done this repair a few times and although the procedure is tricky, I found getting the hole PERPENDICULAR is the hard part. I did not get it perfect most of the time and ended up using coarse 'scotchbrite' pads on angle air die grinder tools with adapters to 'adjust' the drain plug seat surface.

Use the drain plug tightened without washer to make a mark on the pan and then POLISH the surface away until the 'high-spot' is diminished.

When the drain plug makes a COMPLETE circle mark when tightened, you will have your SEALED SURFACE. Install sealing washer and you are done.

Just my experience.

bob

 

I appreciate the input. Had my problem been that I got the helicoil inserted and it was a bit off angle that totally makes sense. In my case the tap simply didn't take well and the oil pan material got messed up and wouldn't take a thread. That material is really soft.

 

I have done this on both a ‘40 and my S11. Both times I have used a brass reducer and plug. The reducer is lock tighted into the sum (after tapping the oversize hole) and then the plug is used to do the oil changes. This removes he problem of the Ally threads departing company from the sump. Both times with the sump insitu.

 

Just a tip for future readers who attempt a similar repair: it helps in the drilling process to start with a bit just slightly larger than the original drain plug hole, then work your way up in bit size 1/64th or 1/32nd inch at a time until you reach the hole size needed for the new insert. The job takes longer to complete, but this method reduces the amount of material the bit has to remove each time and usually eliminates the grabbing and jerking that can be disastrous.

Cheers,

Don

 

The other option if you are stuck with the dill size that you have is to grind a small zero rake on the drill point, as you would when drilling brass
https://www.google.co.nz/search?q=dr...d4bSXESongA_M:

 

I finally have a happy ending to the oil drain plug saga, although it involves no heroics on my part. I simply put the car on a flatbed and sent it to the local specialist who has done a number of these and he fixed it. While I was messing up the job in the first place I also noted that I had a leak from the right front suspension boot. It turns out I also had a bad steering rack, also duly replaced by the specialist. Although not cheap, the financial damage wasn't too severe and still well within the range of what I figured I'd have to put into the car.

Of course, there's always "just one more thing" with an old car. I got back to the mechanic to pick the car up and found out that the aftermarket anti-theft system I didn't even know existed had immobilized the car and it would not start on its own. I had the mechanic bypass it and start the car so I could drive it home and deal with that mess myself. The good news is that the installation was pretty obvious and four hours of work yesterday sufficed to tear the stupid thing out and return the car to something resembling the original electrical connections. I was very pleased when the car fired up on the first try.