Small coolant leak when cold
 

So, since I have built this engine, I have noticed is has a very slight coolant leak when it gets really cold outside. It appears to be coming from the drivers rear and pass front corners of the engine. I have tried the trick of pulling the lower bolts out and re-sealing them with permatex thread sealer, and it's still weeping coolant when cold. If the temp is 40 or higher, nothing, it's bone dry, only does this in winter, but it really annoys me so I don't want to live with it. Any ideas/thoughts on if it could be something other than head gaskets, or do I just bite the bullet and tear it apart and put in the Ford competition gaskets. Really trying to avoid tearing it down, and was contemplating trying to re-seal the lower bolts one more time with a different teflon sealer before going through the hassle of pulling the heads.

I really want to get this out of my garage as I have a new project sitting in the driveway that I need to pull inside to work on.

Any thoughts?

One thing to add, when I did reseal the bolts, it took a few heat cycles/days before there was any sign of leaking again. That is why I am thinking it could still be the corner bolts. Thinking the sealer I am using may be no good (I have had it for a while), so I ordered a thing of ARP thread sealer (would need it regardless).

Thanks.

Time for another update, this car is absolutely infuriating. After yesterday, I decided that today I would go out and start draining the coolant in anticipation of resealing the bolts again. Crawled under the car, and both spots that were leaking are bone dry. It was pretty cold last night so just would have thought it would have seeped some. I ran it for a while and got it good and hot, still dry, no signs of leaking. Only thing I can think of is that it needs to sit for a few days in the cold before it leaks. I’m going to let it sit all week and then check and see what I find.

Any thoughts on what it could be?

Pop 2 of these bad boys in and call it a day. https://www.napaonline.com/en/p/NCBH...iABEgKVpvD_BwE These are the same thing that Ford used to put in every new car coming off of the assembly line. We used to carry a Ford-branded version of these at the dealership.

Jason, I applaud your determination to "Do it Right", However, nothing at all wrong with taking tbone's suggestion and getting this niggling little issue behind you. I suspect that if you have the opportunity/desire to drive your car as a daily for a while, a lot of these frustrating issues would disappear or become something that's accepted as being just "the way it is". No reason to obsess when you could be grinning/giggling/driving a pretty sweet little car.

Good Luck,
RonR

I tried those tabs a few years ago when I noticed the minor seepage on the pass side. All they did was leave a layer of muck in the bottom of my radiator that I had to flush out.

Well DAMN! I bet the bottom of the radiator wasn't leaking, though...

Lol, no leaks from the radiator.

Mine had a mystery leak a few years back. It had something to do with a low coolant level in the engine, and a loose overflow coolant bottle hose. It seemed to disappear after draining the system, tightening the hose, and refilling with a vacuum filler.

Been checking daily, as of today, not a drop. This car pisses me off.

Well, took 5 days, but the leak is back. Was dry this morning, checked it before dinner and there was a spot on the ground and it is wet at the drivers rear corner where the head meets the block. Not sure what to do at this point. May try one of the recommended tablets again. Getting sick of this crap.

So, after hours of on-line searching, I am going to take a shop at using K Seal cooling leak repair. Seems to have great reviews/results from what I have read, and I am hoping it will shore up the very minor gasket leak. Being that there is no coolant in oil/combustion chamber and no other signs of issues or poor running, just the very minor leak from the block corners when below 40 degrees, I'd rather not pull the heads to replace the gaskets. Hoping this is enough to do the trick. Fingers crossed.

So, the car has been parked outside and it has gotten pretty cold, and I have run it to heat cycle it multiple times, and so far, no leaks since using the K Seal and running it a few times. Fingers crossed this did the trick. I plan on flushing the system in the spring to get the remaining sealer out and get it back to just coolant/water mix even though the bottle says you can leave it in with no problems.