Ben, as an "old mechanic" myself, Yes there is validity to the mention about the spark plug "cleaning." And, I'll not go into all the details here. (actually, you can kind of think of it as a crude form of "steam cleaning.") There are usually other variables involved too, so that "reading" by itself may not be very pertinent to your exact situation. -another thought, depending the hardness of the deposits on the spark plugs, "steam cleaning" will not remove them.

"Back in the old days",,,,,sorry,,,, when there was sometimes some oil residue and certainly some "soft carbon" in the combustion chambers (spark plugs included) then the "steam cleaning" could be VERY APPARENT. With today'* engines running so clean, things can be somewhat different. There is almost NEVER any soft carbon in the chambers.

I would be more inclined to think that if coolant was passing through one cylinder, and not the others, then I would expect to see a noticeably different color on that one plug, as compared to all the rest. -AND, you would have to "read" all the plugs to be sure.

ANYWAY, keep us posted !! -and good luck.

This is all good stuff to know, so I'm glad I'm getting the experience of dealing with it. Like I said my mechanic doesn't see any telltale signs of coolant being burned in the cylinder, but it'* also a very small amount of coolant being lost, so maybe it'* not burning enough to "clean" the combustion chamber and plug. The car was misfiring again today though, so SOMETHING is going on! My plan for this weekend is to take a chance and drive the thing home, then hopefully tear into it when I get there tomorrow night.

One more round of questions for you guys. Can I get the lower intake gasket changed in a weekend? I know it depends on experience, but on the average is it a realistic expectation? Also, what else will I need to replace when doing this job? Will I have to get new upper intake elements as well? I'm sure Chilton'* tells most of this, but I also want a real world opinion.

I'll have access to my buddy'* Digimoto while I'm home. Are there any parameters I can observe that may give clues to the root of this problem?

Again, my humble thanks. Your input has been a relief and a good starting place for investigation.

IMO, you can get this done over a weekend. The actual tear down and reassembly isn't the time taker...it'* the cleaning!! Everything needs to be throughly cleaned when apart, and before assembly. The lower intake can take some time to clean in all the ports. Since you're already into the intakes it would be a good time to clean the throttle body too. My way of cleaning them is to remove ALL sensors and soak it in a coffee can of gasoline. Then, lightly scrub the carbon deposits with a toothbrush (or sorts).

As for other things to change... The only other thing I changed was the coolant bypass elbow that goes between the lower intake and belt tensioner. They have a history of cracking with higher miles and age. The dealers keep them in stock and are only $7.

I found this particular thread/documentation of particular help:

http://www.bonnevilleclub.com/forum/...595&highlight=

That thread, combined with a Chiltons...you'll have enough time over a weekend!

BTW...once you get it done, drive on the new intake and lower seals for 25-50 miles then change the oil. Any traces of coolant in the oil will get removed from the crankcase.

Good luck!

Got another morsel of info here... and another question. First the question: if I go after the intake job over the weekend what'* everything I need to replace and/or clean? Do I need to redo the whole upper as well? How much money am I looking at spending?

Secondly, the morsel of info. Through this whole process I've been completely forgetting about this awful burning smell that comes through the vents into the cabin every now and then, mainly because it had stopped happening for a while. Well, it'* back now. I had attributed it to power steering before, but could it be related to these other symptoms? The smell is very foul and thick, quite similar to burning rubber. It most often occurred under low speed turning conditions where there seemed to be more strain on the power steering pump. However, it has now happened twice when simply driving down the street. Does this smell fit in with any of the causes that have been suggested? Or is it simply a coincidental power steering issue? Could it be the smell of a gasket being fried?

As you probably understand, I don't want to get into this intake if signs point to something else. As it stands, I probably will end up doing the lower gaskets, but please let me know if this points to anything else. This burning smell is obviously not normal, and neither is misfiring and very slow coolant loss. I'll entertain any other possibilities. Thanks!

Bump

:( hmmmm,,, Ben, I don't have any idea how the occasional burning smell could be connected to the upper manifold, and lower gaskets failing. However, burnt coolant does have a very strong distinctive smell,,,

The only * T R E T C H of the imagination that I can come up with, is that you have a poor or damaged rubber seal between the hood and the cowl vent air intake area at the bottom edge of the windshield. -allowing engine compartment odors to get into the car.

One time I had an Olds 88 that would occasionally have a gasoline odor inside the car. That one turned out to be a missing piece of seal at the bottom edge of the windshield. -Oh, and the gasoline odor was caused by and external leak on one of the fuel injectors.

Alright, I've got some pics for you guys... and I think we've found some problems. Is there supposed to be oil pooled up in the lower intake? You'll see what I mean in these pics. We also found a ton of gunk (possibly carbon buildup? or goo from an already-melting UIM?) that I'm gonna clean with a bunch of carb cleaner and whatever else I can get my hands on. Didn't get pics of the lower intake gasket, but I can if it would help. The holes for the water ports looked a cracked possibly a little leaky, but nothing showed evidence of coolant making its way to any of the intake ports. So I really don't know what to think. Please shed some light on this if you guys have any ideas!





Let me know if you need more pics.

Well, the project is going well so far... we hit a snag that could be a pretty big deal, but I'll explain that later. We cleaned up the lower, the TB and the upper, and modified the upper a little bit, as you can see in the pics. I took a keyhole saw to the vertical piece at the mouth of the upper and got rid of it. Here'* a before & after of it (yeah yeah, the "before" shot is a reenactment).



Now the snag I mentioned... When we were bolting the upper to the lower (and torquing everything per the Chiltons) the last bolt right under the PCV housing decided to be a jerk. Right as the torque wrench was clicking, the corner of the lower broke right off. Can you believe that? We were so bummed, but we decided to continue assembly. Here'* the pic:


Everything other than that went perfectly. As I said in my previous post, it didn't appear that there was coolant that had leaked anywhere in the upper or lower intakes. But we're still wondering if that pooled oil in the lower was normal. I'd appreciate some feedback based on these pics and descriptions.

Anther thing: are the new gaskets in the upper and lower reuseable? If and when I replace the lower manifold (which may be sometime soon, depending on whether or not it leaks) I don't want to buy new gaskets again. But I will if I have to. Please give me feedback and let me know what else I may want to check out. We're gonna run Seafoam through it right now, then change the oil again and give it new Autolite coppers. Hope this solves my woes; if it turns out to be a head gasket problem I will be bummed!

Anybody care to give me some feedback about the oil in that lower intake? We've conjectured that it was probably due to the straw that attaches to the PCV inside the upper. We found it was crushed and split open at the 90 degree bend. Also, what do you guys think about that upper intake mod?

We have the thing reassembled and running well. We let 5 quarts of cheap oil flow through the system before starting it, then filled it up with more cheap oil and a new filter. Took it for a spin, seemed to drive well, but I still think I'm missing some power somewhere. Can anyone confirm/deny my theory about having a junk dogbone? To get a rough estimate of performance we're going to race the Bonnie against my parents' 95' Olds 88 next weekend and see how it stacks up. How'* that for a dyno?

Anyway, no misfiring or SES light so far. We even ran some Seafoam through it to make sure we had all the deposits out of there. It smoked a fair bit, then we took it for an aggressive run on some back roads. Brought it home and did a final oil change to Valvoline, also swapped the Bosch Platinum +2s for Autolite copper plugs. I actually don't have the car in Ames right now; it'* spending the week in Muscatine with my parents. Next weekend I'll do the "dyno race" and post the results.

Please give me any feedback pertaining to this whole process and anything I've posted. Let me know what any of you think of the lower intake problem, the upper intake mod, and my theory about the dogbone being junk.

Wait what is he doing exactly just cleaning things up or looking for a problem? I will be doing all this tomorrow to replace some gaskets and sort of to determine where my coolant leak is. Its going to suck if the coolant has mixed with the oil because we just changed the oil and my dad will be a bit upset to have to buy more oil, but I guess its better than buying another engine.