LIM... 3rd time is a charm????/

[oldnslo]

Vehicle is a 2000 GA with 3.4 V6

Like the title says going on my 3rd LIM gasket change. Replaced one around 60K, replaced it again around 73K and now at 90K. Since this will be the 3rd gasket in 30K miles I have some questions for you all.

1) Since the leak stops for 13-17K miles I do not believe I have any cracks or warped components. Is this logical or not? Will probably bring the LIM to a machine shop to check for flatness, cracks etc.

2) What is the proper toque for the LIM bolts. I have been using the Haynes manual and following the recommended torque values. I think these are around 160 in/lbs (from memory).

3) Any suggestions on what else I should look for when doing surgery, (other than another vehicle :-) ?

4) I will be using the Felpro MS980003T gasket set, replacing the LIM bolts, new coolant, new thermostat.


In reality, how often or long should these gaskets last?

Thanks

Roy

[1990hemigale]

I searched and found this.

It said to use blue loctite too.
# Tighten the lower intake manifold bolts in sequence to 7 N·m (62 lb in) on the first pass.
# Tighten the lower intake manifold bolts (1, 2, 3, 4) in sequence to 13 N·m (115 lb in) on the final pass.
# Tighten the lower intake manifold bolts (5, 6, 7, 8) in sequence to 25 N·m (18 lb ft) on the final pass.

also read that GM gaskets are the best.

[prescill]

A little suggestion for you, GET RID OF IT, I had a 99 3.4 that I did the lim at 63, 110,130 about, and it gets worse ,did the head gasket 8 months latter, had to do the head gasket again plus replace two heads$$$$$ a year after that(20,000km). All around 1500 thausand yes thats rights 1500 thausand into that engine and it keeps getting worse. I always thought it would start getting better but nope, plus I had the other repairs on top of this(wheel bearings(absproblems), fuel gage, brakes, rotors,.
The problenm with these engines is the weak cooling system, and constint heating and cooling of two different metals.(heads, block). So I had the last head gasket replacement and heads done in January2007, june comes, guess what , lossing coolant again , plus pushing it out the overflow tank ( meaning exhaust gases in the cooling system).. Meanwhile my mech which I been dealing with for 15 yrs, can't fig out why. He doesn't want to fix it again. This car put me into alot of debt, so I made the decision back in june to finally get rid of it. I got 1300.00 for it at a dealership and I'am some glad its gone.
I replaced it with toyota corolla sport, and also have 2004 toyota highlander that has 120,000km and not one repair, whoops forgot had to replace the front pads at 105,000km. I'am not saying go buy a toyota, but pontiac/ chev is not to reliable.
Just telling what you are in for with this vehicle....Good luck

[b2089]

There are people here with the same car going on 100k miles with the same LIM, and others like you who shred them often. I'm going to go out on a limb here and say that you must have something slightly warped to keep loosing it. Perhaps the new gasket is rigid enough to hold but the warped spot eventually creates a new leak. Think of it like this, the first one lasted how many miles? In that logic the new one, if it is just the gasket itself, should last approximately the same. If it doesn't then look elsewhere for the underlying cause.

[rixGAphx]

The V6 is very prone to run low on coolant for various reasons, and you MUST keep that air bubble out of the top of the engine.
Think about it:
If there's any air in the coolant system, it's gonna rise to the top, and stay there.
Where's the top of the entire system? The LIM itself.

The coolant is pumped into the blockat the front, then goes into the heads thru passages at the 'corners' of each cylinder.
It leaves the heads at the front and rear, thru passages in the LIM and heads to the t'stat at the rear of the LIM.
Then thru the hose, rad, hose, waterpumpp, block/repeat.

So, you have a nice, flat piece of aluminum (the bottom of the LIM) with hot coolant running across it.
The coolant heats the aluminum where it touches it; but if there's air in the system, then the aluminum is only being partially heated by the hot liquid that 'washes' across like waves on a beach.
So it's only expanding in some spots, and not others.
This causes flex (distortion) of the LIM, and can cause permanent distortion (warpage).

All this is independent of the similar thermal action/stresses in the heads to which the LIM mates.

Absolutely have your LIM checked/milled/replaced if necessary.
It's probably been warped since before the FIRST change of LIM gaskets.
The Felpro set is a vastly improved design over the OEM originals, and it *should* last the life of the engine.

And keep the system free of air by proper bleeding when you fill with coolant initially, and everytime thereafter when the level has dropped more than about 1/2 inch.
* * *

As well as replacing the LIM bolts, be sure to 'chase' the threads of the old holes.
New bolts and LocTite don't do sh!t for old, dirty holes.
Make your own 'chase tool' (tap): Clean one of the old bolts and hacksaw/file a cutting groove into one side, just like a $10 tap.
Run that into each hole to scrape the thread surfaces down to bare aluminum.

Hope this helps,
-Rick

[oldnslo]

I would like to thank all of the people who replied. I am hoping that the weather holds for a couple more weeks so that I can get time to repair the LIM. Long as weather is good I am on two wheels so the GA doesn't see much use.

Roy