The car: 2001 SLE, 124k miles.

Symptoms:
SES light comes on with the P0404, sometimes P1404. I have a scanner. I can clear the code but it will come back after driving for a while, sometimes 5 minutes or sometimes 45.

Small amount of coolant in the little recess just to the left of the thermostat housing. All the other recesses are dry, front and back. I change the thermostat (180 to 195, or vice versa) and thought it might have been from that procedure, but I cleaned it up after the last time and the coolant has reappeared in that one recess.

For the first time today I noticed about 10 tiny drops of something on the inside of the oil cap. Reading this forum taught me to look there. Being the pessimist about this kind of thing, I'm assuming it'* coolant. I should have checked, will tomorrow.

A week or two ago, the car has started to stumble some at low throttle, like parking lot speeds, or after letting it warm up for 5 minutes in the morning (damn cold here lately, single didgts some mornings!).

Nothing else comes to mind, but I'm guessing UIM gasket. Or would the coolant under the oil cap mean LIM gasket? I'm not "afraid" of replacing the UIM gasket, but the LIM kinda freaks me out for some reason. I read the procedure here in the how-to tech section, looks simple enough, but going that deep into the motor... I may have to find a real mecahnic if the LIM gasket is shot.

Thoughts? Anything else I should look for? Anything besides the gaskets that may be the problem?

First, your LIM gasket is shot, I've found threw testing on my own engine, they only last about a year. Unless you go with the aluminum gaskets. Chances are your UIM gasket is leaking and causing the stumble. The UIM I'm sure is also going out. Just did a Lumina LIM and UIM gaskets. A few days later the UIM failed and she was hydrolocked. So off it game again. This time I sealed the coolant passages. Changing the LIM gaskets is really not that hard. If you can do the UIM, you can do the LIM gaskets.

That'* what I figured. Damn.

Thanks for the reply, and I believe the how-to on changing them was done by you, no? Very nice job, I'll probably print it out and keep it close by.

Not that I want to let it go, but how unsafe is this for the engine? Aside from the occassional low speed stumble, the car seems to be running great.

So, aluminum LIM gasket if I recall, any special rec'* for the upper?

There is a chance of total UIM failure. This is what happened to the car I was working on today. It stumbled real bad, she shut if off, then tried to start it again later and no crank. It'* possible then during start if you have a hydrolock it will snap a rod, and then it'* lights out for the engine.

Alrighty, been doing some looking at the parts. I found the GM part numbers listed on this site in a few threads (89017554 and 89017816). On Rockauto they have the same part numbers for AC Delco gaskets, and Intense Racing has "Genuine GM" parts but not the part numbers listed, and they are more expensive.

Aside from the GM (assuming AC Delco is the same), any other brands acceptable for either upper or lower gaskets? Seems I can get Dorman, Felpro or VIctor Reinz if I walk into a local store or two around here. Are those all crap? Many of the threads on this topic I've read are a few years old now, just want to make sure nothing has changed with regards to quality of what'* available.

Discovered after reading I'll probably be needing a few coolant elbows, too.

Thanks again for the assist.

Here'* what a UIM failure will do.




And here'* what I did.




And what I didn't get a picture of is put a think layer of RTV over the plugs. I then went to the UIM and removed the rubber seals from the coolant passages on the gasket. A nickel fits perfectly in to the opening. A bit of red RTV in the UIM, put the nickels in to the openings, a bit more red RTV smoothed over. Let it dry. Then seal it up. You will never again have a coolant problem due to your UIM. Total fix, a few buck, + 10 cents.

Maybe I research too much. This is the Felpro Perma Dry Plus gasket design available through most any local parts store.

http://www.aftermarketnews.com/Item/...us_design.aspx

Does this compare well to the GM gaskets at all?



Trying to balance cost/time/risk here....

Dorman makes a good gasket, so does fel pro. As long as the fit it good, it will be fine. No real difference in performance. The biggest issue is the coolant passages, and capping them removes that issue. There'* really no reason for the coolant to go threw there. It simply goes up one side, goes in to the throttle body about a half inch, then right back down.

You are a huge help, not sure what I'd be doign without you and this board.

Quesiton, what are the odds the intake itself is damaged? I ask because buying a new one from Dorman (comes with gaskets, apparently) is only about $25 more than the gasket kit itself. Prices found on amazon. I'm not one to toss away $25, but if it would be wise to replace the whole unit instead of just the gaskets, I'd rather do it than not. Looks like the LIM gasket kit and Dorman UIM come to $132 delivered. Compared to other online and local stores, that seems pretty reasonable to me.

I'll study capping off those passages, too. I got rid of the dexcool last year and replaced witih universal green, so if universal coolant doesn't pose a threat, I may just leave the passages stock.

BIg help, thanks!

If your going to change your gaskets, I suggest you either replace the UIM, or cap the pasages, the choice is yours. But I really don't suggest reusing the UIM as it is. It only takes a small crack to fill your LIM with coolant.