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Coolant leak... FROM EXHAUST

40thAnniversaryTom

40thAnniversaryTom

New member
Last year, after an oil change, i started my L67 up and got out to check everything was ok. I looked to the back of the car and it was pouring out white smoke. I immediately turned the car off. Went under the hood and found green coolant leaking from an exhaust leak that wasn't sorted out when i installed the exhaust. I have currently been slowly tearing down the engine, got the alt, fuel rails, and supercharger off but I'm not sure if i should go all the way down to the head gaskets. After taking the supercharger off, i notice alot of oily coolant just sitting in the intake manifold. I really should do a compression test to see if it is even the head gaskets but would like some opinions from here first before i go any further. Its going to be at least another week before i do anymore work on it, since i was trying to wait until it warmed up a bit. What do you guys think? Do the head gaskets really go that often that i should even check on them? The reason for the green coolant is because i let an incompetent mechanic touch my car.. Like he replaced a brake line and didn't even take the old one out of the car. All fluids will be changed multiple times before i even consider driving the car again but some extra feedback would be helpful.
 


The HG rarely go on these motors. Usually it's the LIM gaskets that let go. There are also coolant passages for the throttle body. Conventional green coolant is fine for these cars as long as the old Dex has been completely flushed from the system beforehand. I run green in both my 95 Bonne and 00 GPGT and have had no issues.

Good on you for changing the oil several times before driving it again. Don't want any spun bearings on the lower end due to coolant in the oil. When you fix the source of the leak just use some cheap oil/filters between changes to clean the system. When you are sure there isn't any coolant there fill it up with a good premium oil/filter and you should be good to go.
 
I got the intake off today and it was def the lim gasket. one of the coolant passages on the back side finally let go. The coolant was an orange color but when it came out of the exhaust, i remember it being bright green and there was still some red coolant (not diluted with green coolant) in the overflow canister. I really dont know what that guy did to it, but thank you for your help. Im just going to go ahead and put it back together with new gaskets after i do a quick compression test on it. Hopefully everything turns out ok...
 
Don't mix the orange Dex and conventional green coolant. Either do one or the other. Either way, at this point I would flush the entire cooling system and then refill with distilled water and your choice of coolant. Most here go with the normal green stuff to avoid future issues. Also, if you aren't familiar with the coolant system bleeding proceedure for these cars do a quick search for it on here as they will get air in the system and do strange things if not bleed out.

Do an oil change BEFORE you start the car again, then refill it again and run it for 100 mi. and then change it again. This will ensure you get any coolant out of where it shouldn't be. It sounds like a waste of money, but then again so is killing the motor due to coolant trashing a bearing or 2.
 
Once you put it all back together, just to make sure it isn't the head gaskets, rent a block tester from your local parts store and see if you're getting any exhaust fumes going into your cooling system. That way you will get some peace of mind knowing it's not the head gaskets.
 
Ok, so go with green coolant+distilled water(it wasn't me who mixed the coolant), look how to flush system... doing a compression test will check the head gaskets wont it? I was honestly going to change the oil, run it for 10 minutes, then change it again, then run it for 100 miles or so then change it yet again. This car is my prized possession, i dont want anything to happen to it at all, my mom bought it new in 2002, it had 20k until i got my license in 05, and it was still under 60k when she died in 2010.
 


Ok, so go with green coolant+distilled water, look how to flush system... doing a compression test will check the head gaskets wont it? I was honestly going to change the oil, run it for 10 minutes, then change it again, then run it for 100 miles or so then change it yet again. This car is my prized possession, i dont want anything to happen to it at all, my mom bought it new in 2002, it had 20k until i got my license in 05, and it was still under 60k when she died in 2010.
 
I'd probably actually run it up to temp with straight water a time or two just rinse any reminants of old coolant out. Then refill with new 50/50. I tend to like the mix with any stuff too just in case.

You used the new metal style LIM gaskets, right? Also replace the plastic elbows under the alt with the metal type while your at it.

If you really want piece of mind, you could rent a cooling system pressure tester after you seal it all back up.
 
So i got it running. I ran straight water today and ran it for about 5 minutes. Its still pouring white smoke out of the exhaust. I'm going to change the spark plugs in the morning to see if that helps... The new LIM was the metal ones, yes. The compression test turned out good, 150psi across all cylinders. I just got the plastic elbows from GM to replace the old ones, just seems like the cheapest way at the moment for $20. Im just really concerned that its still doing that. I have 2 codes coming up, a misfire on cyl 4, and an injector circuit code. I lost the clips for the one injector to keep everything buttoned down but it is plugged in, but that might be causing the circuit code. Its really discouraging at the moment because I've worked so hard to fix it but it still seems to be having the same problem... The last thing it could be is the head gaskets but its not leaking coolant from the exhaust leaks like it was before... Maybe its just the remnants of that leak that are still in the exhaust, but the smoke was still very thick...
 
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