: Blown Coolent crossover gasket....$$$$

03-31-04, 05:15 PM
My 96 STS started crapping coolent like it was going out of style, so I took it into the shop. It was coming out from under the water pump, so I assumed it was just that. Wrong, as it turns out, GM doesn't runn coolent through the intake mani like most cars. Instead, they run crossover tubes between the block and the intake mani. Anyways, to replace those, you have to drop the motor, and seperate the motor from the tranny to get to 2 of the bolts on the tubes....I say screw that at a cost of $2900. I talk to a neighbor who was a mechanic at Cheverlet for 14 years and asked him about it. He had seen it time after time on Caddy and Auroras. He said, olot of times, they come in from auction like that and they drop in GM Cooling System Seal Tabs and the leaks stops then and there. I say no way in hell a leak this big will stop by some little disolvable tablets but what the hell at 5 bucks for 6 tablets. So I go to GM and get some, 2 packages worth, part # 1#3634621. I start the car, pop the radiator cap of and one by one, crush all 6 tabs up and put them into the coolent tank. TO MY FRICKIN AMAZEMENT, the leak stops...completly....within 1 minute. I say ok, but maybe for a day or two. Nope, that was a month ago...I wanted to make sure it would work before I post it. It may not last forever, but hell, works for now. First that Lucas oil additave stops all oil burning, and now some cheap tabs stop a massive coolent leak.....I am amazed. All I need now is some duct tape on this thing and it can truely be ghetto wrigged. :p


03-31-04, 06:51 PM
Thanks for the funny story!

My 99 SLS had a similar problem at about 70,000 miles. It never leaked a drop again- I got rid of it at 130,000 miles. I replaced it with a 2001 STS. But I've had a love affair with Sevilles for years...

Remember, GM recommends popping a few of those pellets every time the coolant is replaced, so they must know something we don't!:)

03-31-04, 10:49 PM
Okay, now tell me about this Lucas oil additive. Will it stop the consuption/leakage on my 4.9?

03-31-04, 11:11 PM
The coolant crossover actually connects the water inlets to the block and the water outlets from the head....nothing in the intake manifold is involved. Replacement of the coolant crossover gaskets can be done with the engine in the car without dropping the engine or trans or anything. Someone is feeding you BS....

In any case the GM coolant supplement pellets will seal up most incidental leaks like that....that is why most all manufacturers install the stuff at the factory....It is one of the few aftermarket additives that really works as described. Probably because there was so much development done with the autocompanies....LOL.

04-01-04, 05:25 PM
I called BS on the motor droping as well. The 2 bolts in question are tight, but, could be done with a little time. None the less, I called BS and went with the cheap stuff first. As for the Lucas, My 96 4.6 NS was burning about 1 qt every 1000 miles. NO OIL LEAKS. I but in the lucas additive, the ratio ended up being 1.4 qts lucas and the rest motor oil. Sure enough, all oil burning stopped. I also had a very small knock at idle, normal on NS's, but that completly went away. The funny part is, they say is will work for about 3000 miles. And sure enough, within 200 miles plus or minus to 3000 miles, the knock at idle came back and it started to consume oil again. I have used it for 4 oil changes now and love it. Seeing as how the computor tell you when your 7500 miles is up (way too many IMO) just listen for the knock and your at 3000 miles....lol. Its like 5 of 6 bucks a qt for the lucas. I did a write up on it several months ago in this forum, i think it was in performance or the seville section, not sure.


04-01-04, 05:59 PM
can you please email me at (JeromeJohnson1@aol.com) and let me know where I can buy some of that lucas oil additave. I'm burning about a quart and half every oil change and I would like to put an end to that because I'm running Mobil 1 in my STS and that's big bucks.


04-01-04, 08:43 PM
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