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White smoke after LIM gasket replacement

B

bbowles

New member
I replaced LIM gasket over the weekend. While in there I replaced the hoses, thermostat, injector orings, gasket/hose under/in the plenum, and cleaned up throttlebody as mush as possible. I added half a can of seafoam to the new oil with the intention of changing it again in about 50 miles. I followed all torque specs in GM factory manual. I filled the radiator with 50/50 until I can get it flushed. Went for a drive (about 30 miles) and I am getting white smoke out of the exhaust. Some initially came out of the oil hole in the valve cover.

Any suggestions of what is wrong or is it just the Seafoam burning out of the oil? Thanks for any help.
 


JoshsGTP said:
the LIM might not have sealed, do it again:(
Click to expand...
If that is the case do you have any tips to ensure it seals next time? I very throughly cleaned all surfaces and even lightly sanded the LIM with 160grit on a long board sander to get the old burnt in gasket material off.
 
Did you use RTV on the corners of the LIM after the gasket was set on it? If not...that's your issue brah.
 
^^ What he said. Works like a charm. I'm pretty sure it needs to be redone and quickly before you get too much coolant thru the engine. Good luck
 
How cold is it in Idaho? The white smoke you are seeing may just be normal exhasut on a cold day. Did you happen to try and smell it briefly to see if it has a hint of antifreeze (a sweet smell)?

Is the rad. and overflow bottle still full (are you loosing coolant at all)?

Did you flush the lifter valley with fresh oil and then remove said oil before changing the oil completely and starting it up after the replacement? If the gaskets were leaking badly they seep into the valley and mix coolant into the oil.

When you used the sander did you check the LIM after to make sure it was still nice and straight? I've done 3 LIM jobs and have never bothered to get every last bit of discoloration off the LIM. Just a normal scrape to remove the gasket material and then a wire brush. Seeing as how its easy to score aluminum I don't use any other harsh methods of removal. Not one of the replacements leaked.

And yes, I used RTV at all 4 corners, some under the gasket, then some on top. Plop the LIM on and torque away!

Hope you don't have to do it again, but be prepared to.

Jay
 


I got a P0171 - Too lean on bank 1 - SES on my drive back to my shop today. Could this have anything to do with my problem?

I also picked up a coolant system pressure tester because I was told that a pressure test would let me know if my gasket sealed without having to take it apart again. Is that correct?

Will post results.
 
Pressure Tester should pick up a leak, whether it be internal or external. Good idea.

As far as the code goes, check the EGR tube that comes out of the LIM and runs to the EGR. They are pretty thin metal and can crack if not moved with the utmost caution (i.e.- just enough to get the LIM out). If cracked this will cause a vac. leak.

If this looks ok, then it still sounds like you might have a vac. leak somewhere. Check all connections/lines, and also around where the LIM meets the heads. One area that I've had issues with is the large vac line coming from the brake booster to the back of the upper intake. There is an o-ring on the UIM on this fitting that can go bad once removed. Also check the PCV valve. There should be TWO o-rings here. One that goes on the metal body of the PCV itself, and a larger one the goes inside the lip of the UIM where the top snaps on to cover it. If one is missing it will cause a vac leak.

Spray carb cleaner around these points while the motor is running and see if the tone/speed changes. If so, the that's a vac leak.

Then only other thing that comes to mind is a bad MAF. Is yours clean and connected properly? Double-check the electrical harness and make sure its securely in place and not loose. It could cause the car to go into "limp mode" and run off some pre-programmed tables which will get you home, but no good to be driving around on as a DD.

Jay
 
That sucks. Well at least you know what's all involved this time so it shouldn't take as long. Just remember to use the aluminum LIM gaskets from GM and sealant and you should be good to go.

And word to the wise, when removing the small bolt that holds the braket for the fuel return valve on the pass. side of the motor (bolts to the alum. engine brace), be sure you REMOVE the bolt and put it in a safe location, or you may not like where it ends up, lol... trust me. Just speaking from experience :th_thumbsup-wink:

One other thing I've noticed is that once you get the LIM to the proper torque specs, I always let it sit for an hour or so, then go back and recheck the torque. Each time I found at least 2 bolts that had loosened up a bit and had to be retorqued. So get the LIM on, then go grab some food and go back and check.

Jay
 


and PLEASE PLEASE for the sake of your own engine, do NOT run that engine any more until you do your LIM and flush your oil. twice if possible. just go buy cheap 10w-30 and crank it up drank it and repeat. get all the coolant out. i spun a bearing so trust me on that you don't wanna replace the engine.
 
I got everything taken apart again and checked the torque of the LIM bolts with a new torque wrench. They all tightened some more to get to the 11ftlbs. I didn't see anything that appeared to be a leak on the gasket itself so should I reuse it or just get another new set? Also what type of threadlock or threadseal do you recommend? Thanks.
 
If the gaskets are brand new which they should be because you just done the LIM job, use those same gaskets. Make sure to get a good amount of RTV sealant in the four corners AND just to be sure you don't have to do this again, go get you a can of Copper Coat Gasket Sealant and spray both sides of the gaskets thoroughly (just watch your fingers it is VERY sticky). You don't have to worry about it drying too fast or anything, just take your time and get the gaskets and LIM seated correctly and then, start in the center using X form and get all the bolts snug. Once they are all snug, go back to the center using the same X form and torque them one at a time. That will ensure that you get the LIM seated evenly on the gaskets.
 
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Thanks for the tips. I'll have to get a new set since I tore one of the side pieces taking them off. I'll look into the copper coat though.
 


Have you pulled the blower to see if theres any coolant leaks in the blower?

I recently noticed mine was pitted where the LIM meets the S/C with those two coolant o-rings thus causing a leak.
 
This attempt yielded worse results. I now have coolant burning and a coolant leak somewhere from the back of the engine on the driver's side. It doesn't seem to be wet at all around the LIM gasket and I can't tell where the coolant is coming from. Is it time to seriously consider a head gasket now?
 
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