Oil Leak at rear of oil pan

[DRH]

Well, thanks to SD, I got the SU's in better shape--enough to be confident about driving it. Now disaster!! As I was doing the final SU tuning, an oil leak sprang up at the rear of the oil pan between the pan and the bell housing. Quite a bit of oil. Question is, is it coming from the rear seal or from an oil galley plug at the rear of the block? The oil pump is back there too. Seems I recall that the 1275 does not have a rear seal-----it has a 'flinger' to push the oil back into the pan. I'm not sure about this though. I've been running over 60psi at the oil gauge and have been driving the car for 8 years or so. This is the first leak at this spot. Does anyone have any pics of the rear of the 1275 block? I'm looking for reasons for the leak--oil galleys etc. Friends say it is a leak behind the block and that I'll have to pull the engine. I'm hoping it is the rear oil pan seal. Has anyone had this problem that would comment on it? Thanks, Don

 

[SD Bugeye]

could the leak be due to inadequate crankcase ventilation?
how are you venting?
if your using the gulp valve maybe it is stuck.
pluged vent hose?

 

[nomad]

How long since the pan has been off? I just fixed leaks at both ends on a 1275. Shrunken cork gaskets.

Kurt.

 

[BlueMax]

If the rear main cover shows signs of ware you can line hone block with cover in positioned to correct leakage, or install a oil seal conversion kit.

 

[DRH]

Thanks for the assistance guys. BlueMax. does your block have threaded holes for the oil galleys? I'm looking at a 948 block I have here and there is a 'freeze plug' brass cap that is covering the right side galley hole in your picture. Maybe there is a threaded plug underneath but I cannot tell. I did not rebuild my 1275. The PO did that but I've been driving it for 6-8 years without any problems. I can't imagine something going wrong with the oil galley plugs at this stage.....unless they are 'freeze plug' type seals only. I'm running about 60-70 psi in oil pressure though.

 

[BlueMax]

If your planning a detail rebuild having the block hot tanked? If so, then I would remove the oil galley's plugs as well freeze plugs. You will also need to have the cam bearings removed too. I would thread the galley's holes before I hot tank, after hot tanking I would bristle brush with caustic cleaner and hot water rinse. Install threaded plugs with JB Weld and you should be good to go. The photo is a 1275 block but, the cover function the same.

 

[DRH]

BlueMax......re the galley holes threaded in your block?

 

[Joe Schlosser]

DRH
The stock blocks do not have threaded freeze plugs. This is usually don during a major rebuild. You said you have been driving it for 6 or so years without a problem. Has it been sitting for a long time, more than over the winter??
If it has been sitting a long time there may be frozen ring or such allowing a lot of blowbye. The A Series motors are very sensitive to crankshaft pressure.
I would look at the crankshaft vent system. Check out the lines from the front cover to the PCV.

 

[DRH]

The engine was rebuilt before I got the car. It was all cleaned up and painted and in the car---but not running. The guy added a 'hotter' cam too. I trust this guy so I'll not go through it again. Anyone know if those galley holes are threaded at the factory?

 

[BlueMax]

Yes they are threaded. This 1275 block was machined to a 1380. After boring and decking the block was impregnated and then Glyptal. Before final assembly the threaded plugs were installed.

 

[DRH]

Joe.....I did let the car set for a year or so but that was before the new year. I've been driving it off and on during this spring when yesterday I decided to re-tune the carbs. It was during the retune that I noticed the oil on the shop floor. Friends came over and we checked out the front timing chain vent can and hose. Everything seemed OK. This AM I opened the oil filler cap and put a rubber glove over the hole. I didn't get and inflation of the glove. The leak begins to drip/run after about 3 minutes of engine running at idle. Do you think the oil could 'find a way' out of the rear plug hole and down the bolted tight rear engine plate and finally to show a drip at the rear pan? Would the plug travel far enough out without being stopped by rear engine plate to allow a leak? Thanks for your help.

 

[Gerard]

Don,

Original galley plugs were not threaded, but were thick brass plugs about 3/8" thick. Current replacement plugs are thin metal caps and I have found them to be inadequate for a sure seal. I suppose it is possible for them to start leaking after all these years, but not terribly likely. I have found they leak immediately if the fail. I either use brass plugs custom made to original specs or have the block threaded for pipe plugs. However, I would agree with comments made by Joe S. Also, there are two types of vent/PCV hookups, depending on which SUs you have. Please post pix of your setup with the carbs and intake manifold clearly visible.