oil leak

I can't be any more discouraged this morning. After countless hours off and on over the last few years, The 64 Sprite with a 1275 was started this weekend. Rebuily by me OEM carbs. Rebuilt by me engine. Started great. The discouraging thing is, I have significant leakage from the bell housing weep hold. Like a lot. I dread the prospect of having to pull the engine. And I guess I don't really know if it's engine or tranny oil. Thoughts

Need to know a couple things for a complete answer, but that much oil (as you describe) would not come from the gearbox. So... as many do, the leak is almost certainly from the back of the engine.

Did you install an oil pump cover? If so, did you seal it well on both sides?

Did you inspect the back plate for cracks? It's not uncommon for there to be a hairline crack between the oil pump cover opening and the crankshaft. The will allow the oil pump cover to leak.

Do you have a PCV installed?

Did you have the block line bored or honed? The rear main has what's called a scroll seal. If the main cap and half moon piece had any wear, the air gap will be out of tolerance and not function as designed. If you removed the upper half (half moon piece held with 3 bolts to the block), this has a specific procedure for reassembly. If you just bolted it back in place, you didn't assemble it correctly.

Do you see any oil dribbling down the back plate between the oil pan and back plate?

Any of the above can be causes for the leak, but typically, it's the scroll seal. If all other measures prove fruitless, I make a seal kit for the rear main that works.

This link will give you some insight into the working of the scroll seal:

https://gerardsgarage.com/Garage/Te...rdsgarage.com/Garage/Tech/SealKit/SealKit.htm

Thanks Gerard for the quick responce. I didn't bounce right back as I had to walk away from it and collect my thoughts.

The engine was pulled and completely diasassembled. No machine shop work, the bearings and cylinders measured acceptable. It was over a year ago but I would say yes, I installed a new gasket and sealed the pump cover. The back plate was sandlasted clean and then painted. I can't say I consciously inspected it for a crack but if the crack was obvious I should have noticed it.

No PCV. And that is an interesting point. The leak did not appear immediately. The engine was spun many times the weekend before to confirm oil PSI. The engine was then started (first time in 17 years so I was told) and run several times on Saturday for very short periods (30 - 45 seconds). I then mounted the radiator and filled the system with water and let it run for a while. That's when the leak started.

At first the oil was only seen on both the back wall of the oil pan and the back plate. I then tried to compress the rear oil pan seal and tighten the bolts a bit more. That's when oil starting dripping from the bell housing weep hole.

Where would I mount a PCV line and valve?

I found your seal kit information. I'm guessing all work can be done from outside. Dropping the tranny is probably my easiest route.

Thanks, Chris

Thinking some more about the PCV valve. The oil cap on the valve cover is anything but a tight fit. I would think the engine would breath enough through that loose fit.

What about rings, did you replace or just reinstall the existing ones? Did you crosshatch the cylinder walls before reassembling? If you replaced rings, did you measure ring land tolerance before reusing the original pistons? What about the cylinder head; did you at least lap the valves and seats, and surface the head; new guides or at l;east check tolerance of existing ones?

Venting to atmosphere is usually not enough, you need an active vacuum to create some negative pressure, but sometimes, even that is not enough. The scroll seal depends on air being down in through the air gap to function properly. That gap is spec'd at .0004" -.0015; more and it will fail.

The PCV setup depends on the carbs you have. Can you post pix of the engine that way you have it now? In particular, I need to dee the carbs and manifold you are using. Do you have the carb with the brass tubes angled towards each other?

Hi Gerard,

An interesting thing about this engine. I think somebody worked on it 20 years ago. Internally it struck me as in very good condition. As I mentioned, cylinders with in spec and not oval. Journals with in spec. No pitting on the lifters. I didn't see anything that bothered me. At times I was wondering if I was throwing money away withnew parts. But I'll grant you, I'm not all that experienced and have no experience with British engines.

So, yes new rings. Honed the cylinders. Lapped valves but that was all. Did not do all the measurements I could or should have done.

Attached are a couple pics I found on my phone.

The intake does have a nice 1/4 or 3/8" tapped hole available. No hole in the valve cover thought. That can be remidied.

I read a bunch of forum postings during my lunch break, there was much discussion on PVC. Seems to me PVC would be a very inexpensive and simple thing to try first

.

Well, I can't see if you have the vent tubes or not. The valve cover with you vent would be the type that would have those carbs, but those are easily changed. I suggest you use only the Smith PCV, and attach it accordingly. (see attached diagrams for whichever cabs you have. You don't need to add a vent to the valve cover.

I also just noticed that you don't have the correct timing chain cover for a 1275. I'm sure this is not helping either.

Sooo. Anyone know where I can buy one of these?

Hello,

I wanted to right a couple sentences to capture my experience and findings regarding a significant oil leak when running only a couple minutes..

It was pointed out that I had the wrong timing cover for the 1275 engine. The correct one with a port and oil separator for PCV is no longer available . After some searching I found one. Installed it, installed the Smith PCV on the intake manifold. And low and behold, I ran the engine for 1/2 hour on Saturday and not a hint of a leak. Conculsion, PCV is a must on the 1275 engine.

Thanks

Glad to hear that solved your problem.

chris57 said:

Hello,

I wanted to right a couple sentences to capture my experience and findings regarding a significant oil leak when running only a couple minutes..

It was pointed out that I had the wrong timing cover for the 1275 engine. The correct one with a port and oil separator for PCV is no longer available . After some searching I found one. Installed it, installed the Smith PCV on the intake manifold. And low and behold, I ran the engine for 1/2 hour on Saturday and not a hint of a leak. Conculsion, PCV is a must on the 1275 engine.

Thanks

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