This problem is driving me nuts! Coolant was disappearing and oil was milky so I talked to a local mechanic and he told me these engines were famous for bad LIM gaskets so I changed them and the UIM gasket but I also noticed that the UIM itself was rotting away where it meets the throttle body but only on the lower part where the holes ( I don't know what they're called I'm just a shadetree mechanic if that) are but since I didn't have any more money and I figured what the hell only air should be passing through the TB anyway ( I'm used to working on much older carburated cars ) I put it back together and after fixing some leaky plastic elbows (get this they leaked and they are new WTH?) I am still loosing coolant somewhere but its not mixing with the oil or actually leaking anywhere anymore. Its just disappearing! No smoke out exhaust but there is a strong coolant burning smell coming from engine somewhere. It's been doing this for several months but it runs great especially for having 187K on it. Any help would be greatly appreciated. I hate taking cars to the shop. I'd rather do it myself but I'm at my witts end.

 

I'm assuming you're talking about the coolant elbows on the passenger side, that connect between the LIM and alternator bracket?
If so, when you removed the old ones, did you happen to completely clean out the holes that the elbows go into? They are notorious for breaking off the very tip of the elbow when the old ones are removed, and thus causing leaks since the new elbows won't fully seat.

 

The UIM has two small holes that if you follow them allow coolant to pass from the LIM, to the UIM, and through the throttle body. The under part of the throttle body has a passage that lets coolant in to help "warm" air coming into the car. Some people believe DEX Cool causes the break down of the nylon UIM/LIM gaskets. If coolant can promote the break down of the nylon, in theory, perhaps it damages the UIM as well. If those ports are not "sealing" that is possibly your entire coolant problem at this point and you need to replace the UIM.

FYI - I don't believe DEX cool is 100% to blame for damaging nylon gaskets, as I have had brand new nylon gaskets on my '94 Grand Am with a 3100 v6 fail running pure green coolant, non-DEX, after almost 100K on the gaskets.

Also, Biggriggs has a great point. Those plastic elbows are easy to change, but you have to make sure to get the little pieces out of the LIM and the bracket they connect with. I can usually gently use a pick and pop it out, or a small flat blade screw driver (pop on end of the piece to spin it from a vertical position to a horizontal position and pull it ou).

 

Thanks for replying and yeah they did exactly what biggriggs said the plastic elbows both broke off one inside the LIM and the other inside the water pump but I cleaned it all out and the new ones just didn't seat for some reason so I rtv siliconed em shut. I discovered something else thats wierd after the car has been running for a long time I can take off the radiator cap without getting a face full of coolant and the collant inside the radiator isn't hot. I don't think the coolant is circulating through the engine anymore but the car isn't overheating its underheating and I replaced the thermostat about a year ago? Do you guys think my water pump is out or maybe the radiator is plugged full of contaminants from the oil mixing with the coolant for so long? Any suggestions?

 

Possible, id get a coolant flush to make sure... the little holes in the intake manifold are (from what im taught) notirious for breakingor getting a hairline crack in them thus causing coolant loss... have you made sure to bleed all of the air bubbles out of the coolant system? Also it wouldn't hurt to check the t stat and make sure it isn't stuck open.

 

Hey guys thanks for all the advice. I'm going to keep pluggin away at it and hopefully come up with a fix without having to take it to the shop and I'll post what I find out.