LIM?

[Refuse Winst]

Well, I posted about this in someone else's thread, but wanted to make my own with a bit more detail to see if I could get some help.

I've had my car for about 4 1/2 months now. Obviously, when I bought my car I checked all the fluids, and everything was fine. A few weeks afterwards, my "Low Coolant" light came on for a second, then went off. I pulled into a gas station, checked the surge tank, and it was kind of low, so I filled it back up. After that, I had no problems with the coolant being low.

A little over a month later, I went and had the oil changed, and was told that the coolant tested as "unsafe". So, about a week later (around the end of June, beginning of July), I did a complete flush of the coolant. I regularly check my oil and coolant levels, and the coolant has not been getting low at all. I even figured that after the flush I might have to add a bit of coolant in case there were any air bubbles or anything that needed to work out of the system, but it never got low.

Last night, I realized it had been about two weeks since I had checked my fluids, so after driving home from work, I checked them. Oil was full, coolant was full. No problems, cool.

Today, I left the house, and went to get a money order to pay my car insurance. Drove about five blocks there, then maybe 3/4 mile to the office (which was closed for some reason, but anyways). Got back in my car, started it, and my Low Coolant light came on for a few seconds again. My first thought was that maybe the sensor got stuck, or maybe I didn't tighten the cap when I checked the level last night.... I drove about 1 1/2 miles to the car wash, and in that time my temp gauge shot up. As I pulled into the car wash, it was just starting to go into the red. Got out, checked my coolant, and the surge tank was damn near empty. I had a bottle of Prestone in my trunk from the flush, so I poured it in there... and once it was full, it started burping and spitting coolant. Washed my car, started it, Low Coolant light again. Checked the surge tank, it was empty, though no coolant leaking under the car that I could see (probably emptied from the surge tank into the engine/radiator).

When I got home (coolant still full at that point), I did some research on here, and found that if it is the LIM that's causing it, there will be a milky mix in the oil (there isn't) or coolant on the driver's side of the UIM under the thermo housing (there is). I drove the car around a bit after that, and it's holding coolant just fine.... and still is full right now.

Now, since I found coolant in the spot mentioned, I'm obviously assuming I have the LIM problem. But I thought that the LIM would cause a slow leak for a long time... and then maybe spill it all. Not hold perfectly fine for months, piss out all the coolant in a few minutes one day, then hold fine again? Also, I read that when that happens, it dosen't cause the temp gauge to rise, but mine sure as hell did!

Upon further inspection of the engine, I did see fluid leaking out of some kind of gasket where two parts of the engine meet, and I just want to be sure that this is actually the LIM. The leak was worse on the driver's side, but there seemed to be a bit coming from the pass too. Unfortunately, I couldn't get a clear pic of the driver's side, but this is the same thing on the pass side.... is this the LIM gasket?

http://img219.imageshack.us/img219/503/fdlim005bqx3.jpg

Ok, and a shitty pic of the driver's side...



http://img219.imageshack.us/img219/3628/fdlim001brb0.jpg

[Refuse Winst]

Ok, so imageshack pics don't seem to want to show up here right now...

Pass.;

[Refuse Winst]

Driver side

[dandragonrage]

Can you see melted cheese in your oil fill plug or PCV valves, or does your dipstick look like it came out of a milkshake?

Edit: It's kind of hard to tell from those pictures, but is it really wet in those spots?

[Refuse Winst]

The driver's side is kind of wet.... the oil looks fine, no milky thick mix of coolant or anything.

[Refuse Winst]

Ok, it is the LIM

Well, believe it or not, I got the cheapest quote from the dealer at $600. The only local mechanic that I trust told me it would cost $720 for him to do it. He also said he had never heard of it going from no leak to a heavy leak and losing it all that quick.

So it's either $600, or see if I can get my uncle or my dad to help me and try doing it myself.... fun stuff.

[daman]

Originally posted by Refuse Winst
He also said he had never heard of it going from no leak to a heavy leak and losing it all that quick.

i have,, get it fixed ASAP

it's the common LIM failure,you can do it your self for a couple
hundred or less. :)

[RocketFast321]

It was leaking on our 3100 malibu for almost 2 years before we fixed it. It was real bad in the winter. But only a little mixed with the oil.
http://img127.exs.cx/img127/9850/f4wdscf1411.jpg
It was almost 800 to have the dealer do it.
More pics at
http://www.gaownersclub.com/forum/showthread.php?threadid=35534

[tdewitt27]

Make sure you get the updated kit. gm came out with 2 types of gaskets. get the updated set it will be the more expensive one, if you are into doing the work yourself it will take a full 8-10hrs of work. there are plenty of threads to help you out with this. I did mine about a month ago and no more problems.

[daman]

Originally posted by tdewitt27
Make sure you get the updated kit. gm came out with 2 types of gaskets. get the updated set it will be the more expensive one, if you are into doing the work yourself it will take a full 8-10hrs of work. there are plenty of threads to help you out with this. I did mine about a month ago and no more problems.

Or fel-pro,,they have a update kit with a metal frame for the UIM
gaskets,thats what i used on two 31's now,nice kit!!!

[rixGAphx]

The LIM gasket leaks to one of three locations:
* Into the crankcase, where the coolant mixes with oil and is homegenized into the 'watery chocolate milkshake' appearance.
* Onto a spot below the t-stat housing, where it can remain liquid for several hours or days without evaporating.
* At the ends, where it seeps only slightly and leaves that tell-tale 'tear stain' on the ends of the heads.
It's *generally* a constant slow leak, but can sneak up on you and leave the system very low.

The side tanks of the heater core are plastic, and the nipples (where the hoses connect) frequently crack part-way across. This creates another slow leakage point, and the coolant almost always evaporates before it's visible as drip.

When the system is very low, other damage can be caused in a matter of minutes.
* The side tank(s) of the radiator may crack, resulting in a small leak or a major one depending on crack size.
* The head(S) may warp from massive expansion of heating. The warpage may allow a massive outflow of coolant, or maybe nothing. The warpage is prolly permananet, but if the overheat was slight, the head may return to previous flat shape.
When the head is warped (usually a slight upward curvature in the middle), the headgasket may blow.

When the coolant system is low on coolant, it will overheat and needle will go into red.
If the system is STILL leaking, eventually so much coolant will be lost that the level drops below the waterpump. With no coolant in it, there's nothing to circulate. With no coolant around the gage sensor, no 'hot' signal is sent to the gage and the driver doesn't know the engine is in 'melt-down'.
Apparently your engine didn't get this hot.

BUT, because of the massive coolant loss all at once, I fear a warped head and/or 'blown' headgasket.
You need to examine the block and engine bay very carefully, with good lighting and some mirrors. Verify if there are any coolant stains on the block that aren't accounted-for by the LIM gasket failure.
A compression check of the cylinders will prolly NOT show this type of 'blown' headgasket.

See my posts to 'willa' regarding her known-blown headgaskets.

Gaddam m#$%&f#*$ing GM LIM gasket engineers :banghead:

Best of luck,
-Rick

[GreenGA98]

sorry about the LIM.............mine did it at 139,000

im surprised it lasted that long

my coolant and oil never mixed, all i had was that puddle of coolant on the floor every night in the garage

before that, the coolant wasn't circulating, and the fan was replaced
now i have a HUGE industrial fan, that creates a kind loud noise when it is on,.........but hey, it works


then after i got the lim fixed ($800 later), coolant was pouring out everywhere onto the garage floor..........like 4 months later
found out that my heater core went

so its always something with the cooling system of this car,:(

but it looks nice, and the interior is clean:D


i'll work extra to pay for all the repairs, before I buy some ricer car like a civic:lol:

[Refuse Winst]

Rick, thanks for all your info... I highly value all of your advice on this forum, and you always seem to know what you're talking about.

The temp gauge only started to touch the bottom of the red when I turned it off... I'll definitely check things out and make sure no further damage was done, but I think I should be okay. In fact the time between when it hit around 230* and when I shut it off was about one minute... probably less. It wasn't cmpletely out of coolant... when I originally opened the surge tank, it was about a quarter of the way full... or a quarter of the way to the "full cold" line, I should say. Damn near empty, but not quite.


There has been no visible or significant loss of coolant since the incident. I drove around twice as much today, and it was just as hot... maybe hotter out than yesterday... and it didn't get low at all, nor did the temp rise higher than normal.

Not only did the one mechanic tell me that he had never heard of it going from an unnoticable leak to such a significant leak that fast (he seemed to know what he was talking about... not only did he say "they all do!!" when I told him my LIM was leaking, but he also had two in the back he was doing the job on when I went in there), but the mechanic at the dealership that looked at it seemed to think that it didn't look like the leak had gotten that bad. I started to tell him "I haven't been noticing any loss of coolant bu-" and before I could tell him what happened yesterday he cut me off and said "Yeah, you're not losing a lot, but it's going to get worse."

This is my theory, and if I'm way off, please let me know... but I think the reason I lost that much coolant yesterday wasn't because of the LIM leak (which I do have, and plan to get fixed very soon before it gets worse), but more likely was the result of me not tightening the pressure cap on the surge tank as tight as it should be when I checked the level the night before, causing it to have no pressure in the system, and boil over when the car reached around 210*. That was actually my original theory, but then I saw that there was fluid around the LIM gasket, and I automatically assumed that was the cause. I realize that the problem can "sneak up" on you.... but we're talking from being completely "full cold" the night before, with having no coolant added for two months (and no puddles at all under where I park my car every night), to losing probably half of the coolant in the system in 10 minutes, to losing nothing for a day now.

Again, let me repeat that I am going to get this LIM leak fixed soon, this isn't me procrastinating and saying "Well, it dosen't have to be fixed for a long time because that's not why I lost the coolant" I just honestly don't think that was the reason that I lost so much coolant yesterday. To me it seems really unlikely that out of nowhere, for 10 minutes the gasket leaked that much coolant, and then for the rest of the day and all day today it wasn't leaking any significant amount at all. I think it seems much more likely that after I filled it back up, I actually tightened the cap down so that there was pressure in the system, and it stopped boiling over and leaking.

Either way, it's kind of a good thing this happened, otherwise I may not have looked for or noticed the LIM leak for some time.

[Refuse Winst]

Originally posted by daman
Or fel-pro,,they have a update kit with a metal frame for the UIM
gaskets,thats what i used on two 31's now,nice kit!!!

That's the one I'm planning on using..... it's the kit that runs for around $80?

[daman]

Originally posted by Refuse Winst
That's the one I'm planning on using..... it's the kit that runs for around $80?

Yes

[Refuse Winst]

I think I'm right on my assumption... I just went out and checked the coolant... still at the "Full Cold" line... when I put the cap back on, it felt tight, but I had it on a bit crooked. I think that's what happened the other night... I put the cap on crooked and it didn't seal.

Last night I washed the car, and sprayed off where the fluid had been leaking from the LIM (so I could see how bad it actually is leaking), when I checked it just now, it was still clean, no more has leaked yet... which tells me that this is definitely a slow leak.... not one that would cause such a massive coolant loss that fast.

[rixGAphx]

The LIM is actually like a sandwich, where the aluminum head is one slice of bread, the LIM gasket is the meat, and the iron block is the other slice of bread:

[edit]LIM: l___________________/
Gasket: __________________________
[edit] Head: ___________________________

The leak occurs BETWEEN the metal and the gasket, as the coolant is forced out by the internal pressure of the heated/expanded coolant.

If the cap isn't sealing properly, two things are gonna happen:
1. The coolant will get hot (185+*) and evaporate into the air, just like a simmering pot of water on the stove. The water vapor and air will escape thru the bottle neck (under the cap washer).
Just driving along at about 45 mph, the GA will evaporate about 1 pint per 5 minutes; that's a quart every 10 mins, and a gallon every 40 mins.
2. The will be NO pressure in the cooling system, other than the negligible 2 psi produced by the waterpump.
Very little, if any, coolant will be lost thru the LIM leak, since there's so little pressure to force the liquid between the metal and the gasket.

Now, if the cap is good and it's properly set, the system will develop 14 psi of pressure.
This pressure will push coolant thru the LIM gasket failure point; and thru the crack in the heater core nipple, and past a loose hose clamp, and thru any other breach in the system.
If the LIM gasket has failed in two places, about 1" long each, IMO the internal pressure MIGHT force out just as much coolant as the 'evaporation': 1 pint/5 mins = 1 gal/40 mins.

Remember that the cap must go on squarely, and should be tightened only as much as an average adult woman can firmly do with one hand.
Any tighter and you will deform the rubber washer and create worse sealing, not better.
IMO damned GM shoulda made this a self-torquing 'clicky-cap' like fuel tank caps.

Hope this helps.
-Rick

PS:
Emergency procedure, when stuck halfway-past nowhere and there's a minor but non-repairable leak in the cooling system:
* Drive slowly and easily, so as little as possible engine heat is generated.
* Remove the pressure cap, to eliminate internal pressure and thus reduce leakage at hole. With so little pressure, even ducttape can 'seal' a pinhole in a radiator hose.
* The waterpump will still circulate coolant properly to cool the engine.
* Stop every mile or so and top-off the coolant that has evaporated.
Essentially, the evaporation is less than the leak would be, and you can limp home for as long as you have water for topping-off.

[Refuse Winst]

Very helpful information, thank you. I just have one question, though...

If the pressure cap is loose, would it not also, besides evaporating, actually cause the level of the coolant to boil over, and overflow through the cap and the tank's overflow? Just like if you overfill it past the "Full Cold" line, the excess will boil over once the fluid is heated and expands... and will pour out of the overflow onto the groud. I think I read on here somewhere (might have even been one of your posts, actually) that a loss of pressure can cause a boil over at around 210*? In normal atmospheric conditions, without pressure, it's said that the boiling point of water is around 212*... so it would make sense, I would think, that once the car reached that temp, the coolant would boil over.

This was more what I assumed may have happened... that since there was no pressure in the system, the coolant actually boiled over... once it cooled down, it settled back down in the engine, and that's why the surge tank was empty after I filled it the first time, with no leakage on the ground or anything... and the leak I found on the LIM was actually something that had been happening over time, but was not related to the coolant loss then. Yesterday I drove the car much longer than I did that day, and (I checked the weather reports) it was the exact same temperature both days. The car also reached the same "normal" running temperature (around 200-210*) as it did on Tuesday just before this happened, and I had no problems.

I would have a much better idea of what had happened had I not stupidly drove it 1/4 mile when the "Low Coolant" light came on... I have no idea why I didn't just pop the hood right then and take a look at it before leaving the parking space I was in. If I had, I may have been able to see where it was losing coolant from, or at least if there was a puddle underneath the car.

Edit; This thread confirms what I was talking about... lack of pressure causing boil-over :P http://gaownersclub.com/forum/showthread.php?s=&threadid=57201&perpage=20&highlight=took%20off%20cap%20flush&pagenumber=1

[rixGAphx]

Originally posted by Refuse Winst
....If the pressure cap is loose, ......it would make sense, I would think, that once the car reached that temp, the coolant would boil over.
Edit; This thread confirms what I was talking about... lack of pressure causing boil-over :P http://gaownersclub.com/forum/showthread.php?s=&threadid=57201&perpage=20&highlight=took%20off%20cap%20flush&pagenumber=1
Yes, you are probably right, especially if the driving and weather conditions were hot.

Water's boiling point is 212*F at 'standard temperature and pressure', which for the US was basically established as Long Beach CA on a spring or fall afternoon (sea level, ~78*F, ~29.xx barometric pressure).
The atmospheric pressure drops about 3 psi per 1000 ft. of elevation, so water boils at 209*F in Phoenix (1000 ft.) and 197*F in Denver ("mile high" = ~5,000'; therefore 15*F less).

After an engine has reached 'operating temperature, in a water-type cooling system there are basically 3 different water temperatures occurring at any given time:
1. The water temp as it leaves the engine (governed by the t-stat), so this is about 195*F for the GA [*assuming* ideal operating and cooling conditions].
2. The water temp after it has been cooled by the radiator and it's re-entering the engine at the waterpump; assuming 40*F temperature drop, this water is at ~155*F.
Note that under these ideal conditions, and ignoring the 'boilover protection' that antifreeze provides, nothing is in danger of 'boiling' even in Denver's high altitude.
But, there's one more factor: How does the water get heated by the engine's metal?
It's not a smooth and even process, and since the water flows from the passenger side (waterpump) to the driver side (t-stat and upper radiator hose outlet), it varies across the engine.
The water flows into the block and picks-up some heat from the cylinder walls, then flows thru passages into the head.
As it travels across the head, and enters passages into the LIM, something slightly bizarre happens:
3. Right at the combustion chamber roof (and the exhaust runners) the cast aluminum is always VERY hot because the combustion has just occurred less than 1/4" the other side of the metal. Tiny steam bubbles are always being generated at this metal-to-water interface, just like at the hot spots on the bottom of a pan of water simmering on the stove. Not 'air', but steam which is pure water in gaseous form.
As long as the water keeps traveling across the metal, the tiny bubbles dissipate as they cool (lose their heat to the adjacent liquid water).
So the water at the 'interface' can be much higher thatn the 195*F of the water leaving engine at the t-stat.

This is where the pressure cap is important: Without it, the water will always turn to steam bubbles. Under 14 psi pressure, the bubbles don't form, so the water remains a liquid.
Who cares??
Steam is kinda like air, and it's an insulator. If tiny bubbles form and move along, then everything is basically OK.
But if they don't move, 'cuz the waterpump is stopped, then they form insulating pockets right on top of the combustion chamber and in little crevices of the casting. BAD NEWS, since the heat really builds quickly.

The net result is that when the engine has been running hot (say, 205*F, theoretically below 'boiling' in Phoenix) and you shut the engine off, the pressure cap is necessary to prevent the water next to the combustion chambers and exhaust runners from flashing into steam. When it does flash, it takes up a lot of volume, and 'pushes' the water away from it; toward the driver side/t'stat/radiator and toward the passenger side/waterpump/lower radiator hose.
The only physical place this volume of water can go is into the reservoir.
And depending upon the pressure and volume of steam being generated, the volume displaced into the reservoir CAN quickly 'boil-over' (even though that water itself maybe less than 175*F).

So, yeah, that may have been your situation.

Ain't theoretical physics fun when it meets the real world of GM engineering?? :D :D :banghead:

Definitely get a new cap, ~$12.
As you probably have learned, a LIM gasket failure needs to be fixed, but you can often limp-along for months as long as
1) You keep the coolant level high by checking often, even twice daily; and,
2) You are willing to gamble against another 'catastrophic' coolant loss and possible head failure.

Hope this helps,
-Rick

[Refuse Winst]

Wow, thanks again... I always learn a lot from your posts :D

The LIM will get fixed soon... I'm not someone that likes to procrastinate when it comes to my car, because when you do, it gets more expensive as other things go bad. I actually take care of my car better than I take care of myself in most respects :P. At the very least, this will be fixed before winter, but most likely within the next month.

[TorquePower]

I did it myself...$90 for the Fel Pro upgrade for me. :)!!

I went ahead and bought new F/I o rings, and a few other things. But I did it myself within 10 hours of total work.

[daman]

Yup it's not hard, ,just take your time :)