Help! I can’t stop my coolant leak.

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.

eskimomann209

Full Access Member
Joined
Jan 9, 2019
Posts
1,849
Reaction score
2,000
Location
Modesto
First Name
Marcus
Truck Year
1973
Truck Model
C10
Engine Size
5.3
Well then, thank you for the compliment! I must be beyond 'decent'! Maybe should raise my rates, hmmm.. :deal:
Dunno haven’t seen ur welds. Im always up for weld porn!
My background is fabrication and sanitary welding wine lines. And even that was a few years ago. I’m a rail roader now.
I have done old oil pans for motorcycles that were out of production cast aluminum and soaked in oil. Had to sweat them out. But personally. I try to back purge everything I can. And I don’t have a high freq welder at home and I doubt he does too.
And that being the case it’s probably cheaper to source another one!
 

shiftpro

Full Access Member
Joined
Aug 31, 2012
Posts
4,855
Reaction score
6,085
Location
BC Canada
First Name
shiftpro
Truck Year
73-87
Truck Model
1500, 2500, 3500
Engine Size
350, 383, 454, 496!
Dunno haven’t seen ur welds. Im always up for weld porn!
My background is fabrication and sanitary welding wine lines. And even that was a few years ago. I’m a rail roader now.
I have done old oil pans for motorcycles that were out of production cast aluminum and soaked in oil. Had to sweat them out. But personally. I try to back purge everything I can. And I don’t have a high freq welder at home and I doubt he does too.
And that being the case it’s probably cheaper to source another one!


I'm just getting back into welding/fab... at 60 yrs instead of retiring I'm returning to my original and favorite trades.
I recently purchased an Everlast 250EX... which I haven't even fired up yet... still ass deep in my home reno and shop additions. Hopefully by this fall
I'll have shop phase 1 and 2 together... after that is shop phase 3 with my 4 post hoist.
I've been collecting tools used and new for a few years now. New when on sale! It's taking a long time but the good thing is, I get to shop around and wait for great deals.

I fixed aluminum intakes in 80's... not with tig but with mig. The typical damage are the 'ears' on the corners getting broken from over torquing or...
dropping! I'll admit I've never repaired a cracked runner but I'm aware of the issues with this.

And yes you're right, sourcing a new (new used!) intake would be cheaper than a repair job.... but I don't think your intake is broken. Hopefully..
 

Doppleganger

Full Access Member
Joined
May 24, 2019
Posts
11,713
Reaction score
54,172
Location
OH-MI: Just like it sounds
First Name
Chris
Truck Year
1985
Truck Model
K20
Engine Size
5.7
I used to have issues like this on various 4-bangers with aluminum covers, housings, etc. Between pitting, ever so light warping and the utter crap quality of the gaskets, it got to the point I used RTV with their gaskets. If I applied then tested within 6hrs, I had a 60% chance it would eventually leak, weep or even wick again. If I let it set overnight, was about a 5% chance.
 

eskimomann209

Full Access Member
Joined
Jan 9, 2019
Posts
1,849
Reaction score
2,000
Location
Modesto
First Name
Marcus
Truck Year
1973
Truck Model
C10
Engine Size
5.3
I used to have issues like this on various 4-bangers with aluminum covers, housings, etc. Between pitting, ever so light warping and the utter crap quality of the gaskets, it got to the point I used RTV with their gaskets. If I applied then tested within 6hrs, I had a 60% chance it would eventually leak, weep or even wick again. If I let it set overnight, was about a 5% chance.
I usually put a thin bead on the intake. Smear it with the ole finger put the gasket on. Smear some on the neck... hand tighten. Let it sit for 15 minutes come back and torque it to spec. Let it sit for 12 hours at a MINIMUM 24 being best. Then rock it.
But that is a route taken when the gasket fails to seal on its own.
 

Snoots

Full Access Member
Joined
Jan 23, 2013
Posts
8,179
Reaction score
16,009
Location
Georgia
First Name
Roger
Truck Year
1973
Truck Model
Jimmy Sierra
Engine Size
350
Use a #2 Bastard file to check the flatness of the intake. Just a few strokes will show you any uneven spots. I wouldn't use plumbers dope. I'd stick with Teflon tape and use BRASS plugs.
 

legopnuematic

Licensed Junk Dealer
Supporting Member
Joined
Oct 27, 2016
Posts
1,728
Reaction score
3,721
Location
MO
First Name
Spencer
Truck Year
1971, 1̶9̶7̶4, 1976, 1979,1̶9̶8̶5, 2002
Truck Model
Dart Swinger, Sierra 10, C10 Cheyenne, C10 Big Ten, Silverado 10, Ram 2500
Engine Size
225/6, 350 c.i., 350 c.i., 5.9l Cummins
A bastard file or A flat rigid sanding block works good and hit the thermostat housing on a piece of glass (or granite) with sandpaper on it to make sure its flat.

I too have battled thermostat housings, I have found that the best solution is to find a cast iron water neck, but when I hopped my 76 up I got a GM 10108470 for $7 from summit and haven't had any leaks with it installed on an Edelbrock 2101 manifold.
 

nabeshin

functioning lunatic
Joined
Jan 23, 2020
Posts
464
Reaction score
857
Location
Cozad, Nebraska
First Name
Grae
Truck Year
1976
Truck Model
K10
Engine Size
400
When I changed the thermostat I had test fitted the neck without gaskets and noticed it rocked slightly. Filed it with a smooth bastard and then hi-tack on both sides of the new gasket, no leaks.
 

ali_c20

Full Access Member
Joined
Sep 20, 2016
Posts
1,016
Reaction score
1,373
Location
Austria
First Name
Alexander
Truck Year
1974, 1979
Truck Model
C20, K5
Engine Size
350, 350
This "cheap" thermostat housings suck. I had to rework the surface and the cast on every water neck I bought (7-20$) price range. I really don't like to have to fix or modify parts that should be bolt on out of the box but I'm definitely not paying 50$ for a non leaking housing.
 

Octane

Full Access Member
Joined
Dec 31, 2019
Posts
2,004
Reaction score
3,571
Location
Atlanta
First Name
Eddie
Truck Year
1977
Truck Model
K10
Engine Size
350
This "cheap" thermostat housings suck. I had to rework the surface and the cast on every water neck I bought (7-20$) price range. I really don't like to have to fix or modify parts that should be bolt on out of the box but I'm definitely not paying 50$ for a non leaking housing.
I had an o ring type housing once that had the o ring groove cut to deeply so the thing would seal till the coolant got hot and then it would leak and spray coolant onto the manifold etc and make a mess.I removed o ring and used a gasket instead to fix it.
 

KS2506

Junior Member
Joined
Dec 15, 2018
Posts
20
Reaction score
5
Location
SW Kansas
First Name
James
Truck Year
1982
Truck Model
K1500 Suburban
Engine Size
350
If the engine is going to be replaced, JB Weld it to the manifold.
 

CORVAIRWILD

Full Access Member
Joined
Mar 28, 2015
Posts
176
Reaction score
71
Location
Uppa US
First Name
UGLYTRUK
Truck Year
1984
Truck Model
K2500 Suburban 4x4
Engine Size
6.2
Run thicker coolant...
 

F-64

Full Access Member
Joined
Jan 11, 2020
Posts
116
Reaction score
98
Location
nyc
First Name
mike
Truck Year
1987
Truck Model
R10 lwb
Engine Size
5.7 tbi stock
A decent welder can weld aluminum. But it takes a little more than decent to TIG cast aluminum.( both the man and the machine.) The fun thing about aluminum is the cracks can and often are longer than they look. And this thing has channels in it. but it’s not my intake nor my truck.

Just an interesting aside. I had an aluminum head with a crack in the combustion chamber to water jacket. My machine shop wouldn't touch it.
I called Reher-Morrison and asked their opinion. He said nope. The weld would collapse and make a bigger hole.
 

Latest posts

Forum statistics

Threads
42,068
Posts
908,348
Members
33,544
Latest member
Twistedgmt400
Top