Hey all---new member here looking for some insight---

I have a 1999 LeSabre that on thanksgiving lost heat. the temp was not elevated, but it only blew cold air. After adding some coolant, the heater worked fine again. I inspected the engine for any leaks, and found none, and have never seen a puddle under the car ever. The next day, my girl takes the car to get coffee and it raps really loud. 1/4 mile later she returns home and tells me. I start the car, and its making a horrible rapping sound in the "top end" of the motor. I noticed billowing white smoke from the exhaust and shut it off. It wouldn't turn over again. I removed all 6 plugs, and the front passengers side 2 cylinders had antifreeze in them.

i have read the woes of the intake manifold and the leaking problems. But, what I am unsure of is whether or not I have blown head gaskets? Can the leaking intake cause coolant to appear in the cylinders? It is possible thet the car has overheated, I don't drive it often, but the primary driver never noticed The car always seemed to run just perfect, then the heater was blowing cold air.....
I am brave enough to change the upper intake, and the upper and lower intake gaskets, but pulling off the heads in Maine in lete november may be too much for me.

I tried to do a compression test on the front 3 cylinders. From left to right---140lbs, 190lbs, 80lbs. I had a hard time getting the compression tester to thread into the spark plugs holes, and am not sure I did it right----- It seemed to take 15-20 turns of the motor before the gauge "pumped up" to it'* final reading.


Help me Obi Wan LeSabre----your my only hope.

Your readings will be off on compression unless you open the TB and have all 6 plugs out when you do it. Not sure from the quick reading if you did that. Worth giving it another try.

Typically these motors can take a serious overheating and not have a head gasket issue. The most common issue is the UIM itself, not the gasket, but the UIM popping a leak in the hole where the EGR tube passes through it.

If you still have back compression, I'd pull the valve cover and check the springs, rockers and pushrods. After that, it'* possible the piston chipped/cracked but that would lead you to less compression that you are seeing typically.

thanks for the insight Bill---I did NOT have the throttle body 100% open, but did remove all 6 spark plugs. I will try again tonite and repost the results. Is it ok to just check the pistons with coolant in them, or do I have to hire a contortionist to get the compression tester into the rear 3 cylinders??? I will also remove the oil plug and drain to see if there is coolant in the oil. the dipstick shows no sign.


But the question remains----can the leaking upper intake manifold/gaskets introduce coolant in to the cylinders?? is it even possible?

thanks--

As Bill said, the UIM leaks arond the EGR, and that lets coolant right in to the intake. So yes, the cylinders can fill up. When you pulled the plugs, did you notice and fowling on the plugs?

Two of the plugs were soaked with coolant (looking from the front they were the passengers side and middle front 2 cylinders) , and the other 4 were wet with fuel, but seemed to be relatively clean.

another thought---i am going to fix this, but there are many aftermarket upper intakes out there. some people are saying buy the "APN" kit, which I thinkk is made by Delphi. Others swear by the Dorman---any thoughts???

If you can find a aluminum intake, sorry, can't remember which one that is. Bill should know. Take care of the leaking intake, change the plugs and clear the cylinders and you should be fine. I looked on Ebay and only found stock type. Looks like the Dorman is reinforced over stock and is the best bet.

I'm not sure if the actual intakes are reinforced. The whole purpose of the "redesigned" upper intake is that it comes with a different EGR stovepipe. The stock pipe fits right against the UIM plastic, heats it up, makes it brittle, and eventually causes it to crack. All of the revised upper intakes come with a different stovepipe that has a much smaller diameter exit which does not sit right against the UIM plastic, and therefore significantly reduces this problem.

The aluminum intakes I believe are from the Series 3 N/A engines, though I'm not sure if the throttle body will bolt right up without an adapter plate. Don't quote me on that though.

I have done this job twice and used the Dorman intakes both times. I believe GM has a redesigned one as well. I'd go with whichever is cheaper.

If you're going to replace that intake, I would very highly recommend you take the extra 10 or so bolts off of the lower intake manifold and replace the 1 or 2 coolant elbows toward the passenger side (which are prone to failure), and the lower intake manifold gaskets with the also redesigned aluminum framed ones, available by FelPro and ACDelco. You'll hate yourself later if you don't do it an they start leaking, which they always do. The factory gaskets are plastic framed and leak easily. The aftermarket aluminum framed gaskets last the life of the engine from what I've seen. I haven't yet seen one fail.

I've found after club discount Rockauto has the Dorman intake for ~$85 shipped. Tough to beat at that price. Being that you had all 6 out ...forget the TB, but try the compression test again. That 130# seems a bit low.

If you'd like to keep this from happening again, find a couple headless 1/4" npt pipe plugs. When the LIM is off, drill and tap the two coolant holes and plug them. The amount of area that the coolant goes into the TB is insignificant to be nice about it. By plugging those holes you'll ensure this issue never happens to you again.

The aluminum intake is a S3 NA item that would require further modding and a TB adapter, then adapted air box etc etc to make it work.

Thanks so much!! So great to have all this help----

Is there a step by step illustrated procedure for replacing the UIM and the LIM gaskets? also, where are the coolant elbows and what size are they? i probably will find them when disassembling, but want to know what to look for---

thanks again---