@farmerjg -You could have a LIM gasket, UIM Gasket, or even the UIM itself fail. Pressure testing would help. If you pressure test and find coolant bubbling where the head and LIM meet up, you have bad LIM gaskets. If the coolant comes from the meeting of the UIM and the LIM (probably close to the throttle body), then it could be a UIM gasket or even the UIM itself. There is a EGR "stove pipe" that goes up the UIM between two coolant passages. Over time, the UIM breaks down (like the gaskets) and it fails. Normally when that happens, it sprays coolant in with your air (small amounts give you steam out the exhaust, lots of coolant hydrolock the engine).

Odds are, it's probably LIM gaskets. Get Felpro aluminum LIM gaskets, and I think Dorman might be the only ones to make a UIM gasket (sadly, still nylon, but I solved the big problem with mine, I don't have coolant going through my UIM anymore).

 

hey l67ss do you think bleeding my coolant will help my heat issue in my monte??? and how do I bleed it???

 

Well, I had a similar issue, sans heat. My heat goes away when the engine drops to 160 (I took my T-stat out and never bothered to put it back in), but idling it goes up to 210. It used to go to 230, and even close to 260 sometimes before it would drop back again. Anyways, one time I cut the car off as soon as it hit 260, and I had the same boiling thing in between the valve cover area and UIM. Anyways, my point is that more than likely it's going to be the LIM, because it if was a head gasket, your oil would be milky and you would have an engine with a cylinder or 2 that's not running right. The idle would be very choppy. Granted that's not always the sign of a failing HG but the general consensus with people in experience with the 3800 is that once you take the LIM off, you're already more than halfway there to get to the head gasket, so you might as well change it for precaution.

I would recommend what was told to me... pressure test the rad, see if you can see or hear the water squirting from the top or the bottom of the engine and go from there. More than likely it's the LIM OR the overlooked heater elbows that go near the tensioner assembly. I know those are really known for going and no one can spot it until they get to the details, or take the heater assembly off. When/If you do a pressure test, look for leaks near the hoses that go to the tensioner pulley assembly and around the assembly itself. That may very well explain your no heat problem and maybe the coolant smell.

BTW if you wanna do the head gasket as well, Felpro sells a kit that regaskets your whole engine. It sells for $200 but it has every single gasket the engine has and it's made of metal. It's not that plastic bs that GM used when they made these engines.

 

What engine do you have?

 

Jason, thanks for all your help. Did you replace coolant elbows at the same time? Metal, plastic, do I have a choice? I noticed on one of your other posts you had highlighted a replacement UIM kit, did you opt for that route or did you put your old UIM back on?

I've done a bit of searching for step-by-step and the below seems to be one of the most thorough.

Change Upper Intake Manifold & Lower Intake Manifold gaskets : Engine

Does anybody have any others they'd recommend?

I've seen a few people say they do valve cover gaskets at the same time. It doesn't seem absolutely necessary, unless I just want to do it, right?

So, for parts (assuming the leak test shows LIM gasket);
LIM Replacement


UIM Replacement

GM Intake Manifold Kit
or

Although, it appears if I only do UIM gaskets and not the replacement kit then I still need to procure fuel injector o-rings?

 

I did in fact change the elbows (at the time only plastic ones were out). I had the Dorman ones blow out the following spring, still no metal ones, so I went with genuine GM elbows (about $30 for the pair from the dealer). The castings are different on them then the Dorman (allegedly, Dorman put the wrong O-ring on them causing that problem). Many members here have switched to the aluminum ones and have been happy with them.

I did not change the UIM when I tore my car apart. I was actually changing the gaskets as part of some performance upgrades (I port matched a LIM and plugged the coolant ports that feed the throttle body). Here's a link to the LIM I messed with:
'04 Monte Carlo SS - Port Matched LIM

As for the UIM I've recommended, I have not used it, but it comes with the UIM and all gaskets and o-rings needed to do the UIM job. That APN UIM is highly recommended by the Bonneville guys (some of them claim they had input into improvements that one has, such as a steel bushing around the EGR stove pipe). If the problem is coolant leaking from the UIM, you can end that by plugging the holes like I did in the LIM.

As for your injector o-rings, the Fel-Pro LIM kit I believe includes it (and the pic of the kit looks like they are with it). As for the UIM gasket kit, if you get the Dorman UIM gasket kit, it's more complete (as it includes a throttle body gasket as well, which is not a bad idea to change during this time). But if you opt for the APN UIM kit, you just need the APN UIM kit and the Felpro LIM kit.

 

So, this question probably doesn't invoke the most amount of confidence I'm prepared to change gaskets.

I got the pressure tester home. My car has a threaded radiator cap. The adaptor on the pressure tester is a 'two tab' style radiator cap where you press on and maybe only turn a quarter to half turn.

There's no threaded adaptor piece. What am I missing?

 

Absent the pressure tester, I opted to run the car for about 10 minutes and just sat there and watched. I suppose my last hope was that it was maybe just coolant elbows. After watching, there was no leakage out of the elbows. Granted, I didn't see it come out of the LIM, but the oil wasn't milky (not a head gasket) and the elbows weren't leaking (so not cracked), so it seems logical (to me at least) that it's the LIM. There was still a decent amount of coolant in the recess between the valve cover and the UIM so.

Anyway, absent any reason to think my UIM is damaged, I think I'm probably just going to get the UIM gasket kit.

Jason, is this what you were referencing in the "more complete" comment?

Chevrolet Monte Carlo Upper Dorman Engine Intake Manifold Gasket Set 615-207 at Auto Parts Network

So if I can find that, get the FelPro metal LIM gaskets, and new elbows I should be good to go, right?

 

Sounds like the rad tester you have is missing an adapter. The one I use has the two tabs and is meant to go on an older style radiator (that has a metal cap). I actually bought my own adapter to have around (it threads to the radiator and then gives the correct flange for the tester to connect with).

Anycase, that is the Dorman kit I mentioned for the UIM. Notice it has all kinds of goodies (it's what I have on my Monte).

Dorman UIM kit, Felpro metal LIM kit, new elbows, and I think just fluids, that it's. Make sure after your done, change the oil (as you will drop coolant down the engine).

When you have the UIM off, you can do an easy test to see if it's got a problem. Locate the two coolant passages that run parallel to the opening for the EGR stove pipe. Put you finger over one end, run compressed air in the other, if anything sprays out that is not at an opening (such as in the area for the EGR stove pipe) then the UIM is damaged. You can either replace the UIM or plug the coolant holes in the LIM (I vote plug the holes, you'll never notice any issues from it).

 

Jason, did you use the t-stat that came with the Dorman UIM gasket kit? I trust it's the right temperature? And that's the new stovepipe in the kit also, right?

I really appreciate all the help. The UIM gasket kit shipped today and I believe the LIM gaskets/elbows are shipping Monday. I'm going to try to tear down Monday night so everything is ready Wednesday when it gets here.