Oil leak

kenneth1669

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So I have been working on a 77 K10 with my grandma for a while and we got it running and stuff a little bit ago. I have started to notice that this truck likes to leak out of almost everywhere. About a month ago I replaced the pinion seal because I found out my dif was almost out of fluid from a leak and now I am starting to notice a lot of oil leaking from what I think is my valve covers and what I think is the front seal thingy. I don’t know if thats a thing but it looks like oil is coming out of the front of my engine from the belt side. My grandma says it’s normal for old trucks like this to leak a lot but I am starting to worry about the amount of leakage. Thank you for anyone that could give me insight.

The first photo is of about a weeks worth of oil leakage. The second photo is the bottom of the oil pan and the third is right under the pulley thingy I think is what it’s called lol.

Thank you for any advice given and feel free to ask for more photos
 

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Frankenchevy

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It’s common for valve gaskets to leak. They are easy to replace. The puddle of oil is excessive. Could be front main, timing cover, oil pan and/or rear main.

Use some engine degreaser and wipe it all down as best as possible. That should help you to pinpoint the leak a bit better. Don’t shoot brake cleaner at anything rubber that looks like a seal. Ask me how I know…
 

kenneth1669

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Alright I will do that thank you.
 

Shorty81

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Check your pcv valve (positive crankcase ventilation) in your valve cover. Sounds like your engine is pressurized and pushing oil out every where it can. Could be compression getting by weak rings also.
 

kenneth1669

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Alright I’ll home and check that as well thank you
 

fast 99

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Start looking furthest forward and highest.

Older design GM engines do have a tendency to leak. Valve covers, intake front or rear, damper seal, rear main seal, oil pan and drain plug. Do check the PCV and for excess blowby.

Spot on the floor is excessive, should be fairly easy to locate the worst of the leaks.
 

Royal Sierra 454

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I just finished my valve leak issue. I even bought the high-end valve cover gaskets, still leaked. 3rd time was the charm. I bought valve cover stud kit. Ended up using standard type gaskets with a very small bead of RTV silicone to both sides. RTV on the gasket and to the valve covers. I have the aluminum factory style valve covers. The studs make it easy to hold/install the gasket and covers. tighten them down, wait 24hrs. The leaks are gone.
 

74Blaze

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Best formula that I've found for SBC valve cover gaskets.
- Use Fel-Pro cork Gaskets
- Put a light coat of Vaseline on both sides of the gasket
- Don't over-torque
- Re-torque after first heat cycle
 

ulm4lyf

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Recently repaired a valve cover leak, oil pan leak, and timing cover leak on my '78 with a 350.
 

85K304SPD

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By the time that you chase down all of those leaks and fix them with the engine in the truck, you might just want to pull the engine and put all new gaskets in it with it on a stand and put it back in. It will be a great learning experience, at the very least. Just a thought.
 

Scott91370

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I had leaks as well.
1) Oil pan was not tight. I found the tq specs and get them sorted out.
2) Previous owner tightened the valve covers too much and cracked one.

New valve cover load spreaders, valve covers and these GASKETS. Totally stopped all the leaks.
 
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75gmck25

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Original steel valve covers have relatively flexible flanges and there are supposed to be small spreader bars at each bolt hole to make it seal better. However, gaskets leak, spreader bars get lost, and bolts get tightened too far and bend the valve cover flange.

- check the holes in the cover to ensure the flange is flat in that area, and use a metal straight edge to verify the flange is completely flat. If necessary, use a hammer and a very wide metal punch to flatten out any dents or bends. Just don’t get carried away.
- instead of the bolts, get a set of valve cover studs. They make it much easier to keep it all lined up when you tighten it down.
- use a quality gasket. I am currently using rubber gaskets with a metal reinforcement, but these are quite expensive. A good quality cork gasket should also work if the flange is flat and even.
- Make sure you don’t get too carried away when you tighten them down. Use a small ratchet and tighten them down evenly in a crisis-cross pattern. I usually just grab the entire 1/4” ratchet handle in one hand and use my wrist action to turn it snug.

I would also check the bolts on the oil pan, and take a look at the two bolts and gasket for the fuel pump. After you clean it, check the power steering hoses for seepage or leaks.

To check your PCV valve the simplest test is to pull it out of the valve cover and shake it. If it rattles easily it’s probably still working. It’s purpose is to pull air out of the crankcase into the carburetor base and reduce crankcase pressure. The piece inside the PCV just pops up and down as the engine pulls vacuum. The valve cover on the other side has a breather cap (the air intake) that usually has a hose running to the air cleaner, with a small filter inside the air cleaner housing.
 

kenneth1669

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Wow I am just now seeing all of these replies. I will look into all of these and thank you guys so much for the help.
 

KnockingDiesel

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Wow I am just now seeing all of these replies. I will look into all of these and thank you guys so much for the help.
Replacing gaskets and seals in these trucks aren’t difficult or expensive. I had a mild valve cover gasket leak and just did all the gaskets to get it over with. They were all dry and leaking was only a matter of time.

How does the truck run? I’d do a compression test to get an idea of what shape the engine is in. If it’s in great shape (140-150psi) I’d pull it, clean it, paint it and replace gaskets. If it’s a little tired (115-125psi) I’d just replace the gaskets while it’s in the truck.

Either way isn’t really expensive or difficult, engine out is just a little time consuming. I did my rear main (2pc) and pan gasket in about 2hrs on jack stands by myself. Maybe 3hrs if you haven’t done it before. If the front main seal is leaking ad another 30min-1hr since you have to pull the balancer. The pan doesn’t need to come off for the front main seal but you will need to rent a balancer removal/install tool. Starter and oil filter removal makes it a lot easier. I got the blue felpro one piece came with hardware and cool clips that hel the gasket and pan in Place while you install the new hardware it comes with.

Again all of this is straight forward and pretty easy as long as you take your time and get familiar with standard replacement procedures.

FYI a compression test isn’t the only way or even best way to test an engine but it gives you a general idea. Even the psi numbers I mentioned aren’t exact. They don’t all have to be 150psi. You’ll want to look for consistency, no more than 10% deviation, more than anything.

Sorry for the long post but I’m not on here too often and like to offer as much advice as I can.
 

kenneth1669

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Replacing gaskets and seals in these trucks aren’t difficult or expensive. I had a mild valve cover gasket leak and just did all the gaskets to get it over with. They were all dry and leaking was only a matter of time.

How does the truck run? I’d do a compression test to get an idea of what shape the engine is in. If it’s in great shape (140-150psi) I’d pull it, clean it, paint it and replace gaskets. If it’s a little tired (115-125psi) I’d just replace the gaskets while it’s in the truck.

Either way isn’t really expensive or difficult, engine out is just a little time consuming. I did my rear main (2pc) and pan gasket in about 2hrs on jack stands by myself. Maybe 3hrs if you haven’t done it before. If the front main seal is leaking ad another 30min-1hr since you have to pull the balancer. The pan doesn’t need to come off for the front main seal but you will need to rent a balancer removal/install tool. Starter and oil filter removal makes it a lot easier. I got the blue felpro one piece came with hardware and cool clips that hel the gasket and pan in Place while you install the new hardware it comes with.

Again all of this is straight forward and pretty easy as long as you take your time and get familiar with standard replacement procedures.

FYI a compression test isn’t the only way or even best way to test an engine but it gives you a general idea. Even the psi numbers I mentioned aren’t exact. They don’t all have to be 150psi. You’ll want to look for consistency, no more than 10% deviation, more than anything.

Sorry for the long post but I’m not on here too often and like to offer as much advice as I can.
Alright. That will probably have to wait before I do something like that. I don’t even have a tool set. I’m working out of crappy 50 year old craftsman wrench’s my grandma gave me because he hates craftman and wanted to get rid of them. But that’s good to know and I will probably do that once I’m more familiar with repairs and stuff. I am not too knowledgable on cars yet.
 

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