Valve Cover Gasket Visible

[Daysanator]

That’s not a bad plan B at all. I’m going to have to look into getting one just to see what room I have. Since it’s so close to the intake. Thanks, man. I appreciate that.

 

[Wes Harden]

You could drill and tap to 1/4" pipe and use a regular reducer, same deal easier to find. Use lots of grease to collect metal chips

 

[Killain]

I think it was cracked when it was a small seeping leak. Now the block has busted out about ¼” of threads or so and made a gushing leak. I’m going to try everything I can before I throw in the towel on this block. We’ll see how it goes.

Please do not try to re-tap the oil pressure sending unit hole. This is dangerious as your going to inadvertently introduce metal shaving to the oil system. That can cause you infinite problems like scored bearings down the road. I 100% doubt the iron cast block is cracked, could be, but doubt the block would crack right there, rather than the brass pressure unit. At this point if you have removed the distributor, then drain the cooling system and take off the intake manifold. Remove every trace of gasketing and remember to keep the 'Valley Clean' put paper or rags across the valley to keep anything from falling in, but remove the gasketing and get a new set of top engine gasket set, it'll have both the intake manifold gasket and two new valve cover gaskets in the same package. Wipe down everything with Acetone or lacquer thinner. Make sure everything is clean and dry. put the intake manifold gasket in place and use som gasket silicone if necessary but limit the amount you use, too much can cause a problem later on. Fix any distortaion in the valve covers, but they look new, so I'm forced to think you just did a poor job of installing them. But now, you have time so use it to pre-position all of the gasketing and work on one job first. Once in place put the cleaned intake manifold back on, taking your time and get help if you need it in holding the intake manifold back into place. Remember your only goint to do this job once so take your time and doit right. once down and in place, clean the manifold bolts, making sure all the threads are clean, and start them and wind them in till they are all the way, then stating with the center bolts, tighten slowly working your was towards the ends and use a tourque wrench to do your final tightening. Tighten to specs. Next get 8 1/4-20 x 3/4 bolts like original valve cover hold down bolts, Those tall wing nut bolts are notorious for either under tightening or over tightening. Once the intake manifold is in tightened and move on to the valve covers (do not over tighten the valve cover bolts, tighten enough but not to much, if you see a leak later then you can tighten a bit more. These gaskets were well known for leaking which is why GM went to center bolts in later models or the engine. If you haven't pre centered the #1 piston at TDC, do so but if you have, don't do it now, you don't want to screw up your timing. Hopefully you marked the distrubutor in relation to the way the rotor was pointing and slowly lower the distributor back into the engine. But the dist. hold down bolt into it's threaded hold and tighten it loosely, and try to start the engine, provided it starts shut it off and refill the cooling system and button up the engine. Start the engine and watch the intake manifold and valve covers as the engine warms up. See if you still have any leaks. sung down the valve cover bolts if necessary. Good luck and post if something goes wrong or if you need more help.

 

[diesel4me]

You could drill and tap to 1/4" pipe and use a regular reducer, same deal easier to find. Use lots of grease to collect metal chips

The reason I mentioned the oil drain plug idea was because that has straight SAE threads that won't act as a wedge and possibly force the crack to spread even further..NPT threads will,as they are tapered..

I agree it is rare for a block to crack there,but as mentioned previously I have seen a few do it..caused by careless engine removal or a broken motor mount or some doofus over tightening the sending unit,or forcing a adapter with the wrong threads into the port when installing a pressure gauge..

I personally wouldn't worry much about any chips ,that port is under pressure,greasing the tap will catch 99% of any metal shavings and you could always spray brake cleaner in the port,then start it up for a few seconds and let the oil pressure flush out any that remain..

A cam lobe or two gets worn off often on many small blocks but you rarely see any damage from the metal they lost--it either gets trapped in the oil filter or sinks to the bottom of the oil pan and sticks to the gunk there in my experience..

 

[Daysanator]

It is rare and When my dad says “Oh gosh, Curt. I’ve never seen that happen”. I know it’s bad. It’s not cracked. It’s completely broken off. I’ll try to get a better pic. My fan unplugged while I was sitting in the engine bay and I was getting eaten alive by mosquitoes. I’ll continue to update.

 

[Killain]

It is rare and When my dad says “Oh gosh, Curt. I’ve never seen that happen”. I know it’s bad. It’s not cracked. It’s completely broken off. I’ll try to get a better pic. My fan unplugged while I was sitting in the engine bay and I was getting eaten alive by mosquitoes. I’ll continue to update.

View attachment 341913

It's hard to believe that the block is cracked at the OPS, unless someone took a hammer to it ? This a low pressure and visitation location on the block ! But I would not re-tap it. Clean it up and look down and see what the shape of the threads. I doubt your going to get a threaded sending unit to go that deep into the block to prevent another leak. Having said that, the alternative to this problem isn't very optomistic. removing the engine for a replacement engine/block isn't great. You could use the oil galleries outlet above the oil filter for the oil pressure sending unit, and then see if you can block off this damaged port ?

 

[Killain]

The reason I mentioned the oil drain plug idea was because that has straight SAE threads that won't act as a wedge and possibly force the crack to spread even further..NPT threads will,as they are tapered..

I agree it is rare for a block to crack there,but as mentioned previously I have seen a few do it..caused by careless engine removal or a broken motor mount or some doofus over tightening the sending unit,or forcing a adapter with the wrong threads into the port when installing a pressure gauge..

I personally wouldn't worry much about any chips ,that port is under pressure,greasing the tap will catch 99% of any metal shavings and you could always spray brake cleaner in the port,then start it up for a few seconds and let the oil pressure flush out any that remain..

A cam lobe or two gets worn off often on many small blocks but you rarely see any damage from the metal they lost--it either gets trapped in the oil filter or sinks to the bottom of the oil pan and sticks to the gunk there in my experience..

Well you have a good point there. It looks like there is a used transmission in there as well. In the late sixties there were a ton of the small blocks like the 307 that were notorious for wiped out cam lobes. I think I did 8 in one year. They just didn't do the face-hardening on the cams so once they had knocked down 60K miles you could expect to develope a miss. Towanda kept the big blocks just fine, but flint I guess had management problems that watered down the quality control folks mission and it showed. It's funny looking back, every make built their own engines. So few were susceptible to one flaw alone. After the lawsuit in 77, it was the death bell for all those different engine plants. and the late seventies and eighties had their own personal challenges.

 

[Chief Brody]

i had an oil leak that I couldn't figure out until I finally found it. It was the tiny manual oil pressure fitting right underneath the distributor.

 

[Killain]

i had an oil leak that I couldn't figure out until I finally found it. It was the tiny manual oil pressure fitting right underneath the distributor.

Happens often.

 

[diesel4me]

I had one 307 in a '68 Caprice wagon that flattened the #1 exhaust lobe and a few others were wearing down at 58,000 miles..

I put a Sealed Power Speed-Pro cam in it that was a bit more performance rated over the stock one and that engine ran stronger than some of the 350's I had ..(later '70s smog engines)..

I have a '73 307 in my '81 G-10 van and I bought two more 307's off craigslist last summer cheap ,(only two carbed SBC I saw in quite a while around here under $500 so I snagged them up)--not sure if those two need a cam or not,I think the one in the van must have already been replaced because it runs strong for what it is..

I can tell if a cam lobe is flat just by the sound of the engine now I have heard so many--they gargle at high rpms thru the intake usually..

GM had a lot of bad cams in 307's and 305's,but the other small block engines also had some lose lobes as well,it wasn't just those 2 ..its like they forgot to harden the lobes on a few cylinders..

I have had a few engines that had quite a bit of metal flakes in the oil and the sludge at the bottom of the oil pan,like the 400 V8 in the '69 GTO I had..one valve lifter over pumped up,and the lock clip popped out that holds the push rod seat cup in place--I found the clip and "cup" stuck in the oil pan sludge,along with cam gear teeth and aluminum sprocket dust, and there was quite a bit of metallic in the oil,but after a new set of lifters & cam gear & timing chain was installed and everything was flushed clean, it ran great again..(I drove that car a good 6 months before fixing that too!)
I knew I should have scrapped the cam too,your not supposed to put new lifters on a used one,but it looked OK and I was not rich..

My '77 GMC had a 400 SBC and one day I drove it to the dump to dispose of trash,and I smelled oil burning off the exhaust..

I pulled over and left it running in park and opened the hood--I saw a tiny stream of oil pissing out of the tubing to the oil pressure port for the oil gauge,and it was landing directly on the exhaust manifold on the drivers side..about ten seconds later I saw a flash and it went "WHOOF" and caught fire..luckily after I shut it off it quickly died down and went out..I had to mash the tubing shut with a hammer so I could drive it home,still dripping!..

I told a friend today who runs a auto shop about the oil port in the OP's engine and he told me a story about a 350 he had that for whatever reason the oil sending unit snapped off in the block on his way to go fishing..
He was miles from any garage or parts store,to make it back home he took several lead sinkers out of his tackle box and pounded them into the busted sending unit's threaded part with a hammer and a piece of wood off a tree branch,and he was lucky he had some oil with him..said it made it 15 miles home and it didn't leak..said he feared the lead would pop out and he'd lose all the oil and blow it up before he knew it failed--but it held!..

 

[Wes Harden]

After studying the picture some more, on a bigger screen than my phone, it looks like the sender is broken off in the block. If this is ture an easy out will remove the broken piece and a new sender should solve that issue.

 

[diesel4me]

I can't get a good enough look to tell if that is the case or not,even after magnifying it larger--it appears a chunk is missing on the RH side of the threaded hole..it would be nice if its just the sender busted off..

He has a broken green wire going to another device next to it too..

 

[Killain]

After studying the picture some more, on a bigger screen than my phone, it looks like the sender is broken off in the block. If this is ture an easy out will remove the broken piece and a new sender should solve that issue.

Yeah it does look like there's something in the port, like an old sending unit, but if that were the case then he wouldn't be able to put a new sending unit in, (perhaps that is yet to come) The thing is that is most likely the most secluded ledge on the whole motor. There's a wiring harness back there, and it looks like there's a second hand trans in there, but damaging that particular spot is hard to imagine ? I'm hoping like you say, there is a broken off sending unit in there and a Ez-Out gives him back a good port.

 

[Daysanator]

My final solution is to clean everything. Plug. JB Weld. Relocate sending unit above oil filter. So I order a gripper plug at work (great idea if I do say so myself) and an ⅛” brass plug. Insert both and support wires with cable ties as high as I can.

I power washed the rear of the motor and front of tranny. Looks awesome. Take a toothbrush and go to town with degreaser. Then I see it.... someone else has been back here before. Son. Of. A.

 

[Killain]

Yeah, looks like it. I guess your in the market for a rebuilt shortblock !

 

[MEMO43]

I agree time for a new shortblock
That's a nasty place to have a break in the block
Sorry amigo wish it was better news

 

[Killain]

In all my years, I don't ever remember seeing a SBC broken or damaged in the back like that, well some in breakers yards, but not someones truck. Me thinks someone else knew that ?

 

[Killain]

In all my years, I don't ever remember seeing a SBC broken or damaged in the back like that, well some in breakers yards, but not someones truck. Me thinks someone else knew that ? But might turn out that is the best thing for the OP as this is a good time to step up to a much better power compo like a better lower end and a cam that will do something, and a new set of Edlebrock aluminium heads ? Just thinking out side of the box here.

 

[Daysanator]

I figure I have absolutely nothing to lose but labor. I think I’ll clean all the junk off and try to patch it in for now. I’d rather start setting money back for something great instead of a knee jerk reaction towards a budget engine now. I’ve dropped too much into this thing to justify a big investment now.

 

[MEMO43]

Just remember to keep an eye on the oil pressure/level if you opt for trying to repair it.
Don't need to tell you what happens to engines that loose all the oil.
I agree on the knee jerk reaction part.
An remember its an investment that only you can put a price on.