Hole in motor behind starter on Volvo Penta MD22L

[dgz3]

I'm not so sure this would have been caused by a Bendix or drive pinion failure. The whole purpose of that housing is to contain such failures.
I think it more likely that the engine was dropped during installation. Perhaps even onto that very large and upright bolt in the foreground of your first pic? Looks like maybe an engine mount?
An errant blow with a hammer might also do it. Perhaps during starter replacement? Or even some over enthusiastic prying with a pry bar? Maybe by someone trying to pry the engine into place or alignment?
As noted by others above, stop drilling the cracks would certainly be a good idea. If you can get a good angle on them with your drill.
And I'd be keeping an eye out for a replacement casting. In the mean time, I might want to fabricate some sort of cover just to protect it from the elements.
It should be fixed. Because it is the diabolical nature of such things to wait for years, maybe decades, for just the right moment, and then...

[Cadence]

I would not worry about it. I'd agree with a previous Bendix having taken a piece out of the casting.

[Calif.Ted]

Speaking of the apparently empty engine mount adjacent to the broken bell housing is it possible the broken piece was a mounting point ?

[DougR]

Originally Posted by Calif.Ted

Speaking of the apparently empty engine mount adjacent to the broken bell housing is it possible the broken piece was a mounting point ?

Nope, that's not how it's done on that engine. I see the mount bracket sandwiched between the two adjustment nuts on the vertical stud, and the bracket extending behind the housing where it is bolted to the rear face of the flywheel housing. You can see one of the bolt heads.

[mike d.]

That looks like a volvo ! If you have oil liquid in the bell housing your engine rear seal probably leaking. It looks as there is a lot of oil residue on the tranny ! Is the valve cover leaking ? If not, if you just recently got the, there was poor prior maintenance ! As to the damage a bendix drive can most certainly cause that to an aluminum bell housing !

[Madehn]

i would stop drill the cracks then fab a new plate from sheet aluminum to put on with a form of JB WELD-- its not gonna look perfect but should hold and serve the function- also if the plate comes off it would be a warning sign that something is flexing way too much. replacing that thing is going to be a real pain in the tookus. If i was going around the world i might worry about it otherwise- hey it has sails that can move it right?

[sailingchiro]

Just a guess but PO might have punched the hole to pry back gear during a stuck bendix gear. It is amazing what we will do in an emergency. (In a storm with Lee shore with shredded sails.)

I would leave it for future use if needed and put metal HVAC tape over it to keep dirt out of it.

[a64pilot]

It was a real common occurrence in drag car to have the clutch explode, so common that many years ago cars were equipped with a scatter shield to catch the exploding clutch before it tore the drivers legs off.
I doubt it, but I guess it’s possible that a drive plate let go.
I have not myself seen a starter bendix do that kind of damage, but as others have reported it, I think especially as it has a new starter that it’s the most likely explanation

[Cadence]

Originally Posted by sailingchiro

Just a guess but PO might have punched the hole to pry back gear during a stuck bendix gear. It is amazing what we will do in an emergency. (In a storm with Lee shore with shredded sails.)

I would leave it for future use if needed and put metal HVAC tape over it to keep dirt out of it.

That is an interesting prospective. I would not of thought of that, but then again, I'm not the sharpest knife in the draw.

[skenn_ie]

As long as a crack doesn't spread from it, it is harmless. The thing that damaged it is almost certainly gone. If you can see the ring-gear, have someone slowly rotate the engine while you check the gear for damage. Ring-gears do wear on the forward corner of the teeth, so a close inspection will display that too. Do keep an eye on the hole (100 hour inspection) and if you suspect a crack, there is a die available that will highlight it.

[MCOS]

Originally Posted by Sailmonkey

There is no fluid in that part of the engine, it’s just the flywheel and ring gear.

Seeing as the starter is new or rebuilt I’d expect that a massive failure of the bendix knocked out that hole.

I agree 100 % - Looks like the engagement part of the bendix came loose, wedged between flywheel and housing and the housing gave out. I would have expected damage to the ring gear also. Perhaps that was replaced and the mechanic saw no reason to replace the housing which is now ventilated? Or perhaps you could consider it an inspection port?

[transmitterdan]

What does the opposite side of the bell housing look like? Is there a motor mount attached there? Take a picture of the opposite side and post. Might give a clue what all is missing on the busted side.

[AmberSands]

I had something similar. The crank case had been leaking and the guy before thought it wiser to knock a hole in to let the starter solenoid stay dry. It was on a bmc Commodore. I’d replaced the starter motor twice and realises why he’d done it. Ended up a full engine rebuild. Guys at www.dfjauto.com solved it for me.

[topmast]

Sometimes some ham fisted mechanic doesn't used a torque wrench when installing a drive plate. A bolts breaks or just winds out to jam in the bell housing. Sounds like gunshot even if it doesn't burst out. No biggie ,just carry on till it fails completely

[Northbound44]

Your engine was also branded Perkins Prima name. On the pictures, the original “Lucas” starter was replaced by the “Prestolite” equivalent that is in my opinion better than the original. I support the idea that part of the bendix came loose and damaged the housing as seen on your picture.
This kind of engine use a timing belt that should be replaced every 1500 hours or 3 years. If you have any doubts that your belt has been replaced, I would highly suggest you to change it.