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PostPosted: Sat Mar 21, 2009 12:37 am 
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Well I got new NGK plugs and Beldin wires today at NAPA but didn't have any time to install them until 10pm. With my daughter's help holding a flashlight I got them installed in about an hour... but what I found was not good and I think the lower intake gasket must be leaking and causing the bucking in OD that I'm seeing at speeds around 50-60mph going up hills, which I new was most likely from a misfire... I just didn't expect to find this. I though a set of plugs and wires was the cure :sad:

I didn't get a picture of the plugs yet but this is basically what they look like. Although there isn't much of any deposits between the Insulator nose and electrode on mine, most of it is on the insulator nose and there's not really much on the electrode at all. I am starting to notice a hard start/extended cranking situation sometimes. This is what plugs 3 and 4 look like -the center two on the block. I also looked at the coolant reservoir and noticed it's down about an inch since I purchased the car. It has been driven about 1,000 miles so far.
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Last edited by Whitecrystal1 on Tue Mar 31, 2009 7:32 pm, edited 2 times in total.

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PostPosted: Sat Mar 21, 2009 3:33 am 
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You are taking in coolant in some manner... But you may have some other issues..

It may be a good precaution to do the lower gaskets and replace the upper to lower gasket as well.. Both together should be less than $40... at the same time you could do a little lower intake smoothing and slight porting..

94-95 3800 TPI engines also had some valve stem seal issues... Usually if they had this issues the tended to burn some oil off...

I would say coil issues as well but 3 and 4 are on different coils...

My thought is to do the above first and see what you get..


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PostPosted: Sat Mar 21, 2009 9:15 am 
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That engine has other issues besides a vacuum leak. That plug doesn't look oil-fouled to me, it looks like aluminum deposits from detonation-in other words, melted piston.

If it IS a vacuum leak, it's a serious one-the mixture is lean enough to cause damage to the pistons. It's really no wonder it's running crappy.

I wouldn't drive it until I diagnosed and fixed the problem. It appears a hole in a piston crown is not far away. This is N/A, right? Because that plug looks like a supercharged engine that's running way lean.

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PostPosted: Sat Mar 21, 2009 10:07 am 
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Updated original post to add actual pictures of the plugs.

What would the plugs look like if burning coolant? I did swap out the coils and ICM since I had a spare.

To add; the car just passed emissions (dyno) if that matters.

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2002 Buick Lesabre Custom L36 Titanium Blue Metallic/Medium Gray Cloth
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2015 SS Roof, Spare & 6M 6.2L LS3 415HP/415TQ SLIHRM/Jet Black Leather-Red Stitching
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2013 Enclave Premium AWD 3.6L LLT White Diamond Tricoat/Cocoa Leather
2001 Wellcraft Martinique 2400 Merc 5.7L BIII 327hrs


1995 Bonneville SSE L36 Dark Polo Green Metallic **R.I.P. 4/28/10 236,400 miles**


Last edited by Whitecrystal1 on Sat Mar 21, 2009 10:20 am, edited 2 times in total.

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PostPosted: Sat Mar 21, 2009 2:47 pm 
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Whitecrystal1 wrote:
What would the plugs look like if burning coolant?


I have some pics of plugs somewhere from our '98 SE (N/A) that was definitely "burning" coolant before I did the new UIM and LIM gasket. I will find the pics later in the day and try to edit back into this post. Different engine, but effect should be the same.

The thing I remember for sure is that the plugs gapped out at over 100 thousandths (hard to even measure). They were really "eaten", (but amazingly the car was still running fine--that's the sneaky thing about UIM/LIM problems).

(edited)

Ok, here's my coolant damaged plug pics. Really weird, huh? There's actually siginificant build-up of something on the ground electrode strap.

There were no known other issues with the engine, except maybe a misfire code on one of the cylinders. That could account for the plug that's a little darker than the rest.




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(second edit)

Just remembered that I had DexCool in my coolant system, and you would have something earlier (greenish fluid color rather than pink).

DexCool is reported to have serious detrimental effects on LIM/UIM parts, but I don't know if that extends to spark plugs.

You do seem to have quite a bit more build-up of schtuff on your plugs. And my plugs had been in there quite some time--probably well over the recommended change limit.

(third edit)

I was just going through the dealer repair info on our '94SLE (which was my daughter's in another state at the time). It had pretty severe coolant problems for an L27 engine. Dealer reported that the LIM was leaking both oil and coolant. I assume that they meant externally. I really don't know for sure, but my money would be on internal leakage as well.

When the car became ours, I changed plugs. No pics, but the plugs looked like normal used plugs. Not corroded up much.

You certainly want to watch your coolant reservoir for loss very carefully (if in fact you decide to drive it, which Bob says not), but I would take very seriously what our experts Bob and Don are saying about other issues. Good luck!


Last edited by slug on Sat Mar 21, 2009 5:53 pm, edited 5 times in total.

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PostPosted: Tue Mar 31, 2009 7:16 pm 
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Jrs3800 wrote:
You are taking in coolant in some manner... But you may have some other issues..

It may be a good precaution to do the lower gaskets and replace the upper to lower gasket as well.. Both together should be less than $40... at the same time you could do a little lower intake smoothing and slight porting..

94-95 3800 TPI engines also had some valve stem seal issues... Usually if they had this issues the tended to burn some oil off...

My thought is to do the above first and see what you get..


Coolant now has been maintaining the same level for about 1500 miles since it dropped :???: but I am noticing is that it's consuming a quart of oil every 1K miles driven (I've added 2 quarts in 2K miles so far). How can I confirm if this is a valve issue or not? Goggling a spark plug chart, it looks like this is oil related... maybe the valve stem seals as you noted.. #3 and #4 cylinder?

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2002 Buick Lesabre Custom L36 Titanium Blue Metallic/Medium Gray Cloth
2004 Buick Lesabre Custom L36 White/Graphite Gray Cloth
2015 SS Roof, Spare & 6M 6.2L LS3 415HP/415TQ SLIHRM/Jet Black Leather-Red Stitching
2010 Silverado LTZ Crew 4x4 6.2L L9H 417HP/403TQ NHT Black Granite Metallic/Ebony Leather
2013 Enclave Premium AWD 3.6L LLT White Diamond Tricoat/Cocoa Leather
2001 Wellcraft Martinique 2400 Merc 5.7L BIII 327hrs


1995 Bonneville SSE L36 Dark Polo Green Metallic **R.I.P. 4/28/10 236,400 miles**


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PostPosted: Tue Mar 31, 2009 9:17 pm 
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Hard to say... But it may just be the valve stem seals... For some reason the 94-95 L27's had issues in that department.. It wasn't all of them tho... My 95 L27 doesn't use a drop..

Sandrock used to have a 94 SSE, and we noticed that it used oil as well.. Not as bad as yours but it was close... And every now and again we would notice a puff of smoke on start up like a chevy 350 would do once it had some good miles on it..

Sandrocks didn't burn enough to be a problem, so we left it alone... It had 140k on it I believe and we figgured it would make it to 200k...

He sold it a good while back and the other owner is still driving it..


Not sure what to tell you to do at this point..


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PostPosted: Tue Mar 31, 2009 9:33 pm 
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I'm going on vacation this saturday, when I get back I'm gonna check the compression on it and see how each cylinder compares. I'll post up the results after I get a chance to do it the following week... I'm not really sure what else to check at this point.

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2002 Buick Lesabre Custom L36 Titanium Blue Metallic/Medium Gray Cloth
2004 Buick Lesabre Custom L36 White/Graphite Gray Cloth
2015 SS Roof, Spare & 6M 6.2L LS3 415HP/415TQ SLIHRM/Jet Black Leather-Red Stitching
2010 Silverado LTZ Crew 4x4 6.2L L9H 417HP/403TQ NHT Black Granite Metallic/Ebony Leather
2013 Enclave Premium AWD 3.6L LLT White Diamond Tricoat/Cocoa Leather
2001 Wellcraft Martinique 2400 Merc 5.7L BIII 327hrs


1995 Bonneville SSE L36 Dark Polo Green Metallic **R.I.P. 4/28/10 236,400 miles**


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