I knew I had problems at the taco plate because it was really leaking there. Lots of grime and oil. I suspected a bad o ring, missing bolt crush washer or some one left the paper gasket off. Started to clean off the area when I found lots of RTV under the dirt. I started peeling back the layers and found 1/4 of the case ring was missing. No damage anywhere to the rest of the case or the motor bar. I am lost as to how this got damaged. The only thing that comes to mind is a floor jack. I guess I will be looking for a new case and doing an overhaul. I just love DAPO's.

maybe one of the knowledgeable engine builders will have another solution. You can't be the first to have this issue.

Unreal!

Sorry to hear about this, that's brutal.

Hopefully someone will have a solution to save you an overhaul and new case.

I had a similar problem, just not as big.

I machined a 1/4" thick piece of aluminum with a groove around the outer edge to hold a big o-ring and a small countersunk area around each bolt hole for small o-rings. It held good.

I could draw up dimensions for another. It isn't a complicated thing to machine. I'd pay $100 to have another duplicated if it helped me avoid a rebuild.

Here is a picture of my nylon prototype Click to view attachment.

Ouch...

Mark's idea is likely the best solution for now.

Ahem

But how did this happen
:??

And

If I don't have a taco plate then what do I have

Xplain in depth please

Another job for epoxy,as advertised on tv.
Try the JB Weld or LePage Steel to build up the broken lip oversized then carefully grind back to the original dimensions to carry and seat the seal.
Clean well before application,a "key"to assist adhesion is a good idea.I've drilled a series of fine holes and inserted ss wire pins to fit at odd angles.
1mm drill,1mm wire.A roughened surface will work best for adhesion,superclean.Ideally grind back to within .005"of original surfaces.
Won't be pretty in appearance,only in utility.

Jewels is a good idea as well as Mark's plug idea. Is it possible that you ran over some road debris? Good luck

Combination of jb weld to recreate lip and aluminum plug. Combining the two will look more factory than getto. Bet it lasts the life of the engine. Way cheaper to try than a rebuild.

Why is not the question there is only fix.
Fix it like above and then if you don't like the ghetto fix start collecting for a new long block.

It was hit with force, hammer, rock, whatever, I don't see a jack doing that.

I've fixed that before - in my shop.
Not in service, only with the case disassembled, although it would be "possible" without doing a teardown.
A good welder can build up the aluminum so the seal bore can be recut in a Bridgeport.

Wait overnight until all the oil is drained, put the strainer back on with the O-ring and then dab the area with Hondabond(google it). It will seal the area just fine. I had a case where the drain bolt was over tightened and the through bolt was stripped. I put the bolt back through with hondabond and tightened the drain plug and this was 10 years ago. Not one drop of oil on the ground since the repair. JB weld sucks!

Same principle. I use Yamabond 4 I think. I sealed an active pressure fed oil leak on my 928 engine between the block without pulling the head. Clean, clean, clean, reinstall the cover, apply the Yamabond, let it set over night. Save you from pulling the engine and splitting the case, welding and machining.

I got the car this way from previous owner. I am just now getting around to the underside stuff and getting ready to pull the rockers. I was just planning to put new lower gaskets, new tube o rings and valve covers.

Real way with out replacing the case. Drop the engine.Mount on a stand, flip it over, clean it up very well, take a piece of copper and form a dam on the inside following the radi you need. This will save you from having to machine the darn thing. And then get some one to TIG weld it up for you. You can then grind it back to the proper look, and be done. Thats the simple way out. IT won't look quite the same, but it will be functional.

The cheap way:
Yamhabond the taco plate to the case. I love Yamhabond, great stuff, between it and some Teflon Locktite stuff used to seal pipe fittings my -4s where always leak free.

Or use both, fix it, then use sealant to make sure it does not leak.

so glad i found this thread... i have the same problem.
How did you go about fixing it?

I am getting an aluminium plate laser cut. Then I plan to clean the area perfectly and use yamabond or similar.. bolt it in and hopefully never need to do anything else...
My engine is on a stand so I can turn it upside down...

Curious to find out if you repaired or replaced?

It went for the replacement case. There wasn't anybody with welding skills that wanted to weld the case.

Looks like someone may have jacked the car up on there in the past?

Is this the really be careful very low torque center bolt ?

No, it was the taco plate. one thing you do have to be careful about is over torquing the M6 bolts. But if you do that's a simple helicoil fix.

My bet goes with dropped on the floor when out of the car for service.

I'd like to see picts from someone, who has made a case repair and their method.

Dave

My first guess would be to have a new aluminum lip machined.
It would look just like the ring on a Ball-Jar lid.



Then JB weld that into position and suck it down with the tacto plate till it cures.
Then disassemble and add gaskets/RTV.

I have the same issue with my car. The plan is to have a aluminium plate cut out, and then to use case sealant to provide a more permanent seal. With that in mind, what product would anyone suggest to use?

I figured that I should still build up the lip, so I cleaned and cleaned and cleaned! So far, it looks as if all the grease is out.. then I put a jar lid on the inside, and used masking tape on the outside. This created a "moat" which I filled with JB weld...
Once set, it was filed and shaped to similar shape of the case.

It looks as if I might still be able to use the normal, o-ring and taco plate cover.. but if there is a chance of leaking again, I don't see the point.

Any comments as to the method I'm planning??

Mike.

I'm truck mechanic . We use this stuff called Bellzona, not sure of the spelling, very expensive, to repair engine blocks where the block was damaged it is machineable when cured.

How about MarineTex?

I had some 5mm aluminium plates, laser cut to replace my taco plate cover...


The plan is to use case sealant to provide a more permanent seal. I don't have a temp gauge...

With just a very light filing around the perimeter of the plate, it is a perfect dropin fit and the bolt holes line up perfectly.

Hope it works!

I personally use Devcon F

Aluminum based 2 part putty. Has same thermo expansion rates as aluminum, so with the shrinking and expanding of aluminum it won't eventually crack and separate.

Without pulling the motor, I agree with the MOAT approach and sealer.

My vote is caused by misplaced floor jack while lifting

I personally use Devcon F

Aluminum based 2 part putty. Has same thermo expansion rates as aluminum, so with the shrinking and expanding of aluminum it won't eventually crack and separate.

Without pulling the motor, I agree with the MOAT approach and sealer.

My vote is caused by misplaced floor jack while lifting