'87 GTA L98: So it seems I've sprouted quite the coolant leak over the last several months. What started out as a slow drip has turned into a serious leak!

Today, I put a pressure tester on it, pumped to 15lbs, and immediately heard that dreaded hiss and gurgling from the rear of the engine by the firewall. Looking underneath from the passenger front wheel, the fluid is dripping heavily from around the starter area. I was not able to find the precise location of the leak, but here are my findings using a snake camera:

1. The intake gasket near back of the engine is wet on both sides, but it's not producing the volume like what I see dripping underneath
2. Now looking from underneath by the starter, it is not leaking from the fan switch, or any hose that I can see.

Under pressure I probably lost a quart of fluid in about 30 minutes. Given the volume of the leak, does that speak to whether or not it's the intake gasket, a bad hose, or something else?

Ryan

 

That's not "leaking badly"; that's "leaking well".

Likely one of the freeze plugs toward the rear. Either the one right above the starter, or the one on the pass side of the rear of the block.

 

I would also suspect a freeze plug. These cars are 29-39 years old, sooner or later all of them will need new plugs. I had three thirdgens with at least one leaking freeze plug this summer in my garage. And it was ALWAYS one of the two plugs (three on V6 cars) between engine and tranny.

 

Wow... OK. I've been combing through the forums trying to find some instructions on how to inspect the rear freeze plugs and possibly replace. A friend of mine thinks the tranny will need to be removed.
Does anyone have any experience with this? I'm not finding much in terms of a procedure.

Thanks!
Ryan

 

I've never had to replace one, but I believe they are only on the sides of the block.

 

If it's a rear freeze plug the trans will need to be removed.
If there's anti freeze on the back of the intake. I would start by looking into the intake gaskets as your issue, they are much easier to change than a rear freeze plug.

I had anti freeze on the top of my intake. I pulled the intake and found the gaskets were in very poor condition causing the leak.

 

Heater hoses and piping are also over there. They could be spraying on the stuff you're seeing wet.

 

The problem I have is that the starter is obstructing the view. I jacked the passenger front, and tried using both a camera snake and a mirror. Access up in there is very limited and hard to see where it could be dripping from. That's why I'm thinking the starter needs to come out to really see the leak??

 

I pulled my starter just to get access to the temp switch, it does block a lot of room. Push the butt end up first and bring it down snout down or a world of misery awaits you.

I would say you do need eyes directly on the leak to know how deep you need to go to fix it, and sometimes it's easier and quicker to pull parts than struggle around them.

 

Here's a pic someone showed me a while back when I thought I had a leaking core plug and wanted to know where they were. As you can see there's no way you can get to them without removing the transmission unfortunately.

 

Note that in KR81's pic, the freeze plugs are brass. (the one in the middle, right above the crank, isn't a freeze plug; it's the back of the cam tunnel) Stock ones, and the vast majority of replacements, are steel. They rust from the inside.

I say "freeze plug", but that's not really what they are; they don't protect the engine from damage by freezing. What they REALLY are is, the method by which the casting sand used in the final stage of block assembly, is allowed to drain out of the interior of the casting. They often pop out due to freezing, of course, but that's not their "purpose".

There are 2 on the rear of the engine, 2 on the front, and 2 on each side. All 8 are exactly the same. Unless someone has changed one out at some point in the car's life due to failure, they are all made of the exact same material, have been subject to the exact same conditions and immersed in the exact same coolant that becomes acidic as it deteriorates for the exact same length of time, and are therefore all in the exact same state of decay. If in fact one has rusted through, I STRONGLY recommend replacing all 8 WITH BRASS, because if you only replace 1, you will most likely find yourself with 2 more that leak, SOON; like, next week. At least, if you're lucky like me, which is to say, not the least bit lucky at all. I have found that Murphy was an optimist, and that the REAL law is Sofakingdom's Law, which states that "if anything can go wrong, it already has; you just won't find out about it until it already has and it's too late to do anything about it; and it will destroy at least 10 times its own value of stuff around it before you can remedy it".

 

Took it in to my trusted mechanic. It's the intake manifold gasket. :-(
Interestingly, the previous owner had that gasket replaced in 2014 by Firestone and only 9K miles ago. I don't understand why that gasket would fail that quickly. I'll know more when he gets in there, which should be sometime tomorrow.

Ryan

 

They probably did it fast, and not well. Or they didn't know to seal the water jackets, or put thread sealant on the bolts, etc. My intake manifold gaskets were shot, and when I got it apart, I definitely wasn't the first one in there. I don't think the surfaces were ever cleaned to bare metal, likely cheap gaskets were used, red rtv was used on the China walls causing gunked up oil seepage everywhere, it was a mess. I spent several hours cleaning all the mating surfaces properly, probably not a profitable amount of time for a shop.

 

Good to know. My mechanic also mentioned the possibility of corrosion on the aluminum surface if the mixture wasn't proper 50/50 or the vehicle sat and they seldom drove it, which at least I know that piece is true.

 

Definitely a possibility. As long as you're willing to admit that perhaps this was inaccurate, or whatever. This is what made us all think you'd already covered that base.

For that matter, it could have already been corroded, and they did whatever they could do, but it's too far gone.

Being a TPI intake, it's not like you're just gonna find one laying by the side of the road somewhere, or order it from Summit or off Amazon or something. Not "rare" or anything of course, but there are NO "new" ones, and any take-off you find has a good chance of having old-age problems like corrosion. You might not end up any better off than you are now with just some other used one.

If that's the issue, it's not impossible to weld that back up and mill it flat. For that matter, you could probably do a creditable job with nothing but JB Weld and a file, after you clean to bare virgin metal, neutralize, and prime it..

 

For any of you guys that have had issues with the Cylinder-Block Casting Core-Plugs (what you guys call Freeze-Out Plugs)...
As SoFakingDom already said, aftermarket Brass Plugs are superior to Steel or Galvanized-Steel Plugs.
Also as he said, sand will fill the empty spaces in the Cylinder-Block (Coolant Passages) during manufacturing...
This is the reason why the Cylinder-Block Casting Core-Plugs exist.

More modern Manufacturing Processes have allowed for far less usage of these Cylinder-Block Casting Core-Plugs.

The Oxidation of the Brass Plugs (turning greenish) is much less significant than the Oxidation of the Steel Plugs (rusting/ rotting).
Thus making the Brass Plugs superior.

I offer two different solutions for people that live in problematic environments, or have significant exposure to Salt-Water.
I offer Brass Plugs that have clear/ translucent Power-Coating applied to the inside and outside faces of the Plugs (no coating on the OD of the Plug).
As well as in-house custom threaded Aluminum Plugs, that I Powder-Coat to appear like Brass...
I will also have to machine the Cylinder-Block for all of the Threaded Plugs.