Unknown coolant leak
 

I have a leak that runs straight down the seam between the engine and transmission on the passenger side. I can't really get under the car till things warm up. Could this be coming from the intake manifold? All coolant hoses are dry and this leak seems gravity fed since I haven't driven the car for 2 days and is actively dripping. Thanks in advance.

I would guess from the intake as well. Has been extremely cold up there? You have antifreeze in there right? Maybe the cold caused contraction and a small leak. Hows the coolant level?

It appears that it's been leaking for a while, but yes it has been cold here. I do use a 50/50 mix. Definitely going to use freeze plugs this go around if it's leaking. Just a huge job getting the carb off and all the spaghetti out of the way to access this.

If throwing in freeze plugs you will also want to block off the exhaust gas port, if not I think exhaust gasses will circulate through the intake with out any coolant to cool.

Thanks, I hadn't thought about that. I didn't see that in the write-up in the archive. I'll try searching around for that, definitely do not want to take this apart again!

Found it, thanks again, I'd have missed that for sure. Can't wait till my shop is finished, can't really work on anything in the driveway.

As mentioned above, more than likely you are seeing failed o-rings between the intake manifold and the engine. They are easy enough to change and after replacement, will last another 20 years. No need to block them off with freeze plugs honestly. They have never given me trouble after replacement.

Hey speaking of the intake O-rings, does anyone know what ID/OD they are? I'm about to replace mine too and the PO left some packaged O-Rings (no PN) in the car and they look right but last time I tried to install them they seemed ever so slightly too large. The O-rings touch the paper gasket and seem like they would cause a leak. They're also too large to sit within the recess in the housings but will fit if you press them in. I seriously doubt they would shrink so much over time, so I'm feeling like they're not the right part.

I'll measure the 'new' ones I've got later today.

Thoughts? I'm figuring that this is a similar enough question that I'm not threadjacking...

The inner diameter for the freeze plugs is 20 mm (from memory) so the orings would need to be at least that diameter or slightly large and be thick enough to provide a seal.

TG is correct on the plugs, I have to o-rings and will post once I get home tomorrow.

Awesome, thank you :)

Inside diameter .92 inches, outside diameter 1.18 inches and it is .12 thick. I'm sure I could have said this better, but hopefully it makes sense.

Well I just measured mine and OD is 1.25", ID is 0.99", and thickness is about 0.13".

Metric-wise it's about 32mm OD, 25mm ID.

It's a little larger than yours, and I know I saw a slightly smaller one in a bag at one point in time, but I've got no clue where that went.

What's the risk in reusing the old ones, considering that they measure approximately the right thickness? Maybe just a little RTV to help it out and call it good? Also, I seems to remember the stock ones being smaller, 'cause I've swapped intakes before and I compared them to these new ones. I never measured the originals however.

I'm swapping intakes tomorrow morning so... I'm thinking just reuse the old ones if they check out?


Edit: Well your measurements slipped my mind while I was writing the above, and they're actually a lot closer than I thought - still a bit of a difference though. The biggest issue I remember was that these new seals touched the paper gasket and I figured that might cause a leak. Anyhow, thoughts?

If you install freeze plugs you will no longer circulate coolant to the intake manifold which will cause the intake manifold and carburetor to warm up much more slowly than intended.

This will reduce your gas mileage and cause a rough idle until the carb finally gets up to temperature.

The O rings are cheap and really easy to replace. You can get the intake manifold gasket and O rings as a set from RockAuto for $7.17.

https://www.rockauto.com/en/catalog/...ket+/+set,5424

And like Dave says, replace the O rings once and you're good for another 20 years (that's twice as long as a colonoscopy).

Thanks for the info. Both things are about equally fun😂.

Well just to finish out my situation in case this thread is looked up in the future...

I ended up getting the new O-rings to fit. They took a little persuasion, but after I had thoroughly degreased them and the depression they sat in, they were able to stay in long enough for me to get the intake back over. No leaks whatsoever :).

Oh, and just to note, the old ones were a bit too flat to warrant reusing.