Coolant leak near carbs

[nkopp]

it’s not coming from the carb cooling bypass hose.

Could be coming from the intake or exhaust manifold though? I don’t have the intake/exhaust torqued down, but would coolant flow through there? Shouldn’t it just be air and fuel?

head gasket maybe? That didn’t appear to be wet, but maybe I missed it. 

any ideas would help. Thanks!

Edited November 24, 2022 by nkopp

[heyitsrama]

Could be a leak in the manifold.

 

[dutchzcarguy]

Isn't that a coolant outlet bolt? just take out that bolt and put some liquid sealant on the threads and put it back in a cleaned threaded hole.. easy..

(Don't know if this is the coolant outlet but these blocks have one maybe someone had a leak there and decided to drill it out and but a bolt in it.. )

Let us know what it was.. (I think normally the coolant outlet bolt to drain the engine is bigger than the one on the pic.)

[zKars]

That is the block drain. The plug or whatever in the picture is not the stock one, who knows what someone used in the past. Remove whatever is there (it will drain 99% of the coolant so be prepared, drain the rad first) and see what you have.

That hole is 1/2” BSPT threads.   In this case, since NPT is the same thread per inch as BSPT (14), you may get a 1/2 NPT plug to fit and seal if you have trouble sourcing a 1/2” BSPT plug. 

1/2” NPT on the left, correct block plug with 1/2” BSPT on the right.  

Edited November 25, 2022 by zKars

[dutchzcarguy]

If the coolant does not come out after removing the bolt.. hit it with a ice pic!!... or something 😉 (often lot of dirt in there..)

[Racer X]

If it was a head gasket leak, the coolant trail would start at the parting line between the head and the block, most likely close to where the the bores are closest to the side of the block.

A small side note, checking cylinder head bolts for tightness is part of the routine valve lash check and adjustment. I have found, and corrected, many loose head bolts this way, and averted a head gasket failure.
 

As mentioned, the item circled is the drain for the cooling jacket around the cylinders, and yes, there is a standard male pipe fitting that will fit. I always put a brass petcock in the engines I build, the brass conforms easily to the BSP threads, and I use a small amount of Teflon thread paste to ensure a good seal. Makes for easy draining of the cooling system for maintenance and tear downs.

Edited November 26, 2022 by Racer X

[Racer X]

6 hours ago, dutchzcarguy said:

If the coolant does not come out after removing the bolt.. hit it with a ice pic!!... or something 😉 (often lot of dirt in there..)

Yes, the opening is at the very lowest point in the cooling jacket. Rust scale builds up along both sides of the passages around the cylinders. I’ve seen them so full of sediment that simply picking what could be reached didn’t get the passage open.

After getting a block back from the machine shop I always reach down from the cylinder deck through the coolant passage holes with a tool I made to break as much loose as I can, and get the passages as clean as possible. 

[nkopp]

Awesome. Thanks for the photo @zKars 

I’ll pop that off and see what it’s like inside.  And see if I can source the right plug. I think that would allow for no thread tape, right? If not, the brass option should work too. Thanks @Racer X 

I had another leak up front from some stripped water pump bolts, going to pop off the timing cover to fix that with some helicoil. And while I’m at it, doing the head gasket. SMH. Happy thanksgiving!

Edited November 26, 2022 by nkopp

[Racer X]

3 hours ago, nkopp said:

Awesome. Thanks for the photo @zKars 

I’ll pop that off and see what it’s like inside.  And see if I can source the right plug. I think that would allow for no thread tape, right? If not, the brass option should work too. Thanks @Racer X 

I had another leak up front from some stripped water pump bolts, going to pop off the timing cover to fix that with some helicoil. And while I’m at it, doing the head gasket. SMH. Happy thanksgiving!

I quit using thread tape when the Teflon thread paste came out. Easy enough to apply to one thread, one complete circuit around, and not the whole fitting. The tape is easily over used, with excess coming loose and going places you don’t want it.

And you need a thread sealant on BSP threads too, any tapered thread that is sealing fluids should have a sealant. 

 

Edited November 26, 2022 by Racer X

[nkopp]

Perfecto. I found a brass NPT plug at ace and Amazon has the sealant same day. Cross that part off at least 🙂

thanks!