Is it even possible to have a completely leakless 350?

Disclaimer: Links on this page pointing to Amazon, eBay and other sites may include affiliate code. If you click them and make a purchase, we may earn a small commission.

Grit dog

Full Access Member
Joined
May 18, 2020
Posts
6,970
Reaction score
12,220
Location
Auburn, Washington
First Name
Todd
Truck Year
1986, 1977
Truck Model
K20, C10
Engine Size
454, 350
This one been sitting in my boat for 17 years. No leaks.

You must be registered for see images attach


This one in the old boat is straight out of the mid 90s. Didn’t leak a drop when we sold it in ‘09.

You must be registered for see images attach


But if it’s old and clapped out, you may have to fix the engine as well and not just the leaks. Yours sounds like it has blowby among other things.

Edit, have had many sbc’s with oil leaks too. They’re not any more or less prone to leaks than any other engine in general imo.
 
Last edited:

PrairieDrifter

Full Access Member
Joined
Dec 28, 2014
Posts
3,853
Reaction score
5,646
Location
North Dakota
First Name
Mason
Truck Year
84,79,77,76,70,48
Truck Model
Suburban k10, bonanza k10, k30, k20, c10, gmc 1/2ton
Engine Size
350, 350, 350, 350, 350, 350
Yes after

Yes after 100, oooor 200, 000 miles. Back in the late 50s early 60 engines were wore out and leaking oil at 50,ooo
I've seen plenty of these new cars especially turbo cars, pushing oil out in multiple places less than 20,000. It's not just a select few or brand, it's a lot and all brands.
 

PrairieDrifter

Full Access Member
Joined
Dec 28, 2014
Posts
3,853
Reaction score
5,646
Location
North Dakota
First Name
Mason
Truck Year
84,79,77,76,70,48
Truck Model
Suburban k10, bonanza k10, k30, k20, c10, gmc 1/2ton
Engine Size
350, 350, 350, 350, 350, 350
Controversial, but. I know a lot of the older guys swear by em. But I've never had a good experience with cork gaskets. That's why the 50-80's engines leaked at lower mileage. IMO
 
Joined
Apr 24, 2023
Posts
38
Reaction score
81
Location
san diego
First Name
rob
Truck Year
1973
Truck Model
Cheyenne 20
Engine Size
350
This one been sitting in my boat for 17 years. No leaks.

You must be registered for see images attach


This one in the old boat is straight out of the mid 90s. Didn’t leak a drop when we sold it in ‘09.

You must be registered for see images attach


But if it’s old and clapped out, you may have to fix the engine as well and not just the leaks. Yours sounds like it has blowby among other things.

Edit, have had many sbc’s with oil leaks too. They’re not any more or less prone to leaks than any other engine in general imo.
I doubt it has blow by because i tested the compression which was 150-165 in all cylinders
 

Grit dog

Full Access Member
Joined
May 18, 2020
Posts
6,970
Reaction score
12,220
Location
Auburn, Washington
First Name
Todd
Truck Year
1986, 1977
Truck Model
K20, C10
Engine Size
454, 350
^Have you straight edged the valve covers, maybe they’re getting a little pinched at the bolts and opening up on the ends?
I know they make/some have long washers to spread the clamping force out and not concentrate it right around the bolts.
 

Matt69olds

Full Access Member
Joined
Jan 8, 2018
Posts
2,451
Reaction score
3,819
Location
Central Indiana
First Name
Matt
Truck Year
81
Truck Model
GMC 1/2 ton
Engine Size
455 Olds
If it ain’t leaking oil, you better add some!

It’s pretty rare to find any old engine designs that don’t leak a little oil. They may not leave puddles, but the dust and dirt collects where the oil ever so slightly oozes out.
 

PrairieDrifter

Full Access Member
Joined
Dec 28, 2014
Posts
3,853
Reaction score
5,646
Location
North Dakota
First Name
Mason
Truck Year
84,79,77,76,70,48
Truck Model
Suburban k10, bonanza k10, k30, k20, c10, gmc 1/2ton
Engine Size
350, 350, 350, 350, 350, 350
I gave you the formula... did you buy some cheap chrome covers?? Cork gaskets suck like i said before, as well as you need to use a little rtv. All before that it needs to be heavily cleaned with carb cleaner.

If you don't want to put the time or energy into doing it proper then you'll have to learn to love your leaks..
 

PrairieDrifter

Full Access Member
Joined
Dec 28, 2014
Posts
3,853
Reaction score
5,646
Location
North Dakota
First Name
Mason
Truck Year
84,79,77,76,70,48
Truck Model
Suburban k10, bonanza k10, k30, k20, c10, gmc 1/2ton
Engine Size
350, 350, 350, 350, 350, 350
Cast covers are the saving grace here I do believe, as well as felpro blue silicone gaskets.
 

Ricko1966

Full Access Member
Joined
Apr 11, 2017
Posts
5,449
Reaction score
8,686
Location
kansas
First Name
Rick
Truck Year
1975
Truck Model
c20
Engine Size
350
Rusty said it and I'll say it again make sure the pcv is working correctly, I use stock valve covers or aluminum, never chrome just like DD said I use use ultra Grey ,felpro gaskets and my sh!t doesn't leak. Check your oil pressure switch too that's always been where I get a leak if I get one and if you swapped manifolds or distributor make sure your gasket is there. Good luck use the search engine,find cwblack oil leak we went round and round but his is fixed.
 

Ricko1966

Full Access Member
Joined
Apr 11, 2017
Posts
5,449
Reaction score
8,686
Location
kansas
First Name
Rick
Truck Year
1975
Truck Model
c20
Engine Size
350
 

Ricko1966

Full Access Member
Joined
Apr 11, 2017
Posts
5,449
Reaction score
8,686
Location
kansas
First Name
Rick
Truck Year
1975
Truck Model
c20
Engine Size
350

Lots of oil leak tips here.
 

Latest posts

Forum statistics

Threads
44,163
Posts
950,679
Members
36,276
Latest member
2manysquares2care
Top