View Full Version : Hole in crankcase - is this a problem?

03-28-2010, 09:13 AM
This is a 1275 engine (with the timing chain cover removed) that I bought years ago to put in my slowly rusting 1970 Midget.
See that hole?


03-28-2010, 09:30 AM
I'm not very familiar w/ 1275's (got a 1500), but from experience, I'd say there might/should be a water jacket on the other side. Don't hold me to it. This might be a serious problem.

03-28-2010, 10:22 AM
I think Kelley is right. However, it's been several years since I had the 1275 out of my Mini.

Do not despair if it is into the water jacket OR just into the crankcase. With some care the hole can be shaped round, tapped, and a threaded plug installed (with epoxy) to seal the opening. Do not consider the block a gonner.

So... what are your plans for the 1275 Adrian?

03-28-2010, 10:50 AM
Hmm, I think I've seen that hole before. I thought that was the feed for the oil to get to the timing cover and get on the slinger to lube the timing chain set. I'll have to go out and look at the spare block I have on the stand later today. I'm not positive yet bet I think that hole might be normal.


03-28-2010, 11:49 AM
Thanks for the replies so far.

As far as plans - still pondering!

I have sentimental attachment to the 1970 Midget - I've had it for 17 years. The engine was burning up so much oil that eventually it quit. So the car has been sitting around for about 10 years - the floor boards and sills are rusted out. Kind of a shame. I'm keeping it around maybe to rennovate but also if the 1500 engine ever dies I could make up a good engine between the 2 1275's and put that in the 1975 Midget. I'm not equipped for welding so maybe I should forget the rennovation idea.

Anyways, I was cleaning up this engine and found that hole. You should have seen my face! Thanks for the idea about rounding and tapping - never thought about that.


03-28-2010, 11:57 AM
Here's what that hole should look like:

Just a little off.

03-28-2010, 01:25 PM
Wow, thanks for the photo.
That's amazing - so it's normal.
You would have thought they'd clean mine up a bit.


03-28-2010, 01:50 PM
Note there are two holes one below the crank for oil in and then the slinger to throw it around and that hole to let it go back to the sump.

03-28-2010, 04:52 PM
OK, very good. Thanks for clarification Jack.

03-28-2010, 05:04 PM
Thanks to both of you for clearing that up!

03-28-2010, 05:50 PM
This is one case I'm ~VERY~ glad I'm wrong!

03-29-2010, 08:24 AM
Hopefully this will help clarify things a little bit.

The two holes in the front main bearing cap are the drain holes back to the sump. The rear main bearing cap has two just like it, only a bit bigger. Oil is pressure fed to the front main bearing and to the front cam bearing and on up to the rocker assembly. As the oil film drains off the bearings, it collects in the bottom of the timing cover and drains back to the sump. The timing chain passes through the pooled oil and lubricates the chain and both cam gears. The slinger/shield helps direct oil onto the chain and keeps too much oil from the back side of the seal. Don't gob on the silicone when putting the timing chain cover gasket on. Excess silicone can clog up the holes and prevent drain back to the sump.

I like to use a little assembly lubricant on the chain and the gears when building the engine. Put this on with a small brush just before the cover goes on. Helps give the chain and gears some lubrication before the engine's oil pressure gets up and oils the assembly per design.

The hole in the picture, about halfway up the block is a vent hole and could act as an overflow relief if the two drain holes are clogged. The front timing cover is vented on the 1275 and that is the primary path for the crankcase ventilation. If you are rebuilding the 1275 in the top picture, take a grinding stone and clean up the casting flash blocking part of the hole. Round the edges to eliminate stress risers. Be sure to clean the block with plenty of hot water, soap and then blow dry. Spray the bores/machined surfaces with WD-40 type lubricant for water displacement before blowing dry.

Also, in the top picture, the lower bolt holding the front plate on is a hex-head bolt. Be sure to use the counter sunk bolts as shown in the second picture. Otherwise, there could be interference with a double row timing chain.

Take care and hope this helps with your original question.
Mike Miller

03-29-2010, 08:51 AM

Most excellent write up. Many thanks. I'll do as instructed when/if I rebuild.
(Also, at last, a use for WD40!)


03-29-2010, 10:45 AM
Sidebar to this thread:
Has anyone else experienced an issue with this board over the past few days where once a photo is embedded in a post, the screen width goes "nuts"? This is the second or third post I've seen where the thread is ridiculously wide (left to right) forcing me to use the scroll bar to read all the text. I thought it was my home PC acting up but now it's happening at work also.

03-29-2010, 10:52 AM
The picture in theleisure's post is huge, the forum is correctly resizing it for me. Maybe it isn't working for you?

03-29-2010, 01:06 PM
Yeah, happening to me as well. Kinda annoying. Probably me with the big photo - let me resize it and see what happens.

03-29-2010, 01:10 PM
That didn't do anything - I think I'll blame theleisure, ha!