Hi --I have a 2003 Buick PA with 140 K miles on the 3.8 liter, non-turbo engine. A year ago, I replaced the water pump & both upper and lower intake manifold gaskets. I am experiencing a random coolant leak ( 1/2 pint or so) on the garage floor when parking. have been watching the coolant temp. When it is running at 190 deg, apparently no problem, but when getting home and climbing my 150 foot high hill, the temp spikes, and the pressure must rise. As it is leaking with a fast drip, I can watch it from under the engine. It is running down in the area of the oil pressure sender. I can't see any leak from topside -- no o-rings or water pump leaks. By the way, my oil pressure sender was also leaking, which I replaced with some difficulty in those tight quarters.

Today, I removed the alternator bracket, exposing a freeze plug in the end of the rear head. I polished the plug and surrounding Cast Iron Block, and applied some JB-Weld epoxy, in case the leak was coming from there.

I plan on pressurizing the coolant system when cold in order to better find the leak.

Where could this coolant be coming from?

If the leak persists, my next step is to add a can of K-Seal to the coolant. Is that a good idea??

Thanks for listening. Any advice would be most appreciated.

Dick Kruse

I'm not a fan of the stop leak stuff just because it usually creates more problems, such as clogged heater core, thermostat etc. Pressurize the system and the leak will be much easier to locate.

Joel

I agree, don't EVER use Stop Leak for a coolant leak. Fix it right the first time, otherwise you will have issues further down the road.

Pressure test it and find the source of the leak.

I'm not a fan of stop Leak either, but this K-Seal doesn't contain any particles that would plug the system. have you heard of it?

Thanks for your response. My worry is that even with a pressure test, if the leak is hidden by the alternator bracket, I still won't be able to see it. If the freeze plug was leaking, will epoxy fix it, or will it take a new plug?

How Does K-Seal Stop Coolant Leaks? | K-Seal

It does not sound horrible, but still it sounds like it works like the other products work, myself I'd not risk using it, as I do not see it being a permanent fix for any leak, just a temporary one.
Before I'd guess that I'd not be able to find a leak via a pressure test, I think I'd try to see if I can before I attempt a temp fix that may, or may not even work.

I doubt it is a freeze plug, could be your coolant elbow, or maybe the water-pump gasket did not seal well.
Did you use high temp sealant on the water-pumps bolt threads?

Anything in a bottle is not a fix for anything, unless it'* a cold one, after cutting the lawn on a hot day....

What ^ said

You mentioned the alternator bracket. On my 2002 Lasabre there are 2 plastic by pass hoses that actually attach to the alt. bracket. I've had to replace them twice because they either crack or the o ring goes bad. In my case they only leaked when the engine was cold.

Are you talking about the 2 heater hoses that go to the tensioner assembly?
It sounds like youa re referring to the coolant elbows, Dorman makes an aluminum version that won't have the cracking issues.

Yes, that'* what I'm talking about. I have also read somewhere that there

have been issues with the o rings on some of the after market elbows but I

don't know which ones. I do know that the original ones lasted 10 years and the

ones I replaced them with lasted 2 years. This time I used original GM parts. I

probably should have gone with the aluminum. We'll see.