Upper Intake Failure Information - Page 4 - GM Forum - Buick, Cadillac, Chev, Olds, GMC & Pontiac chat


1992-1999 Series I L27 (1992-1994 SE,SLE, SSE) & Series II L36 (1995-1999 SE, SSE, SLE) and common problems for the Series I and II L67 (all supercharged models 92-99) Including Olds 88's, Olds LSS's and Buick Lesabres Please use General Chat for non-mechanical issues, and Performance and Brainstorming for improvements.

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Old 05-04-2004, 07:37 PM   #31
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Question: Why are so many people so set on changing to the 180 degree thermostat??
(--please understand, actual factual true racing applications excluded--)

I guess here are my main points for leaving it at 195:

1. The cooling system pressure will not be any less, that being determined by the pressure cap.
2. The whole darn computerized system (-actually multiple systems-) is designed for use with the 195. That is what the system is expecting to see, and I'd darn sure be very careful about messing with anything that is likely to aggravate the computer.
3. Running a 180 absolutely WILL NOT make your engine run cooler in a hot climate, or on a hot day. Remember, once the thermostatic controlled temperature is reached, and the 'stat is open, then it is "out of the picture." The max engine temperature attained then is dependent on many other cooling system factors, most of them related to the ability to dissipate heat. NOT THE STAT.
4. The hotter you run an internal combustion engine - w i t h i n r e a * o n- the more efficient it is overall. And this includes engine internal cleanliness, especially crankcase.

Okay, I agree that most of the above factors will not play too heavily with only the difference between a 180, and the 195. (however, my bet is that anyone who attempts to run a 160 on the street on a long term basis will be in for some disappointments in the long run,,)

Mostly I see it as one of those things "that isn't broken, so why are we trying to fix it " Okay, okay, I know, "designer spark plugs" bright neon wires, and chrome plated dipsticks also make your engine run so much better, faster, better fuel economy,,,,

If the truth were known, we would probaly all be better off running an engine temp of well over 200, and full synthetic oil, etc. A couple of years ago, I did a lot of studying on cooling system engineering, design, and application. (-another whole story). I remember a person by the name of Steve Jacks, -I think his company was Concept One Pulleys,,, that had a lot of good info on the internet. Also, some other study to really give you something to think about is the "Evans Cool" information. (-a non-aqueous coolant. -ie:no water,,) I never was quite brave enough to go that far,,,,,

Enjoy !!
Harry
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Old 05-04-2004, 10:06 PM   #32
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I'm currently running stant 195'*.
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Old 05-07-2004, 09:32 AM   #33
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I just ordered the stove pipe sleeve kit from Gagnon'* Auto & RV Sales at 800-498-3350. Cost of the kit is $80 delivered to my door step.

Here'* the link to see the kit:
http://www.ken-co.com/manifold/default.htm

When talking with the sales person at Gagnon he indicated that the Dorman replacement upper intake is not the answer to fixing the notorius Series II issues. He said that the Dorman part is made in Korea and the grade of plastic falls way below the specs that GM uses. Even though the wall thickness may be greater, failure with the Dorman is still inevitable. He said the best solution is to go with the GM replacement upper intake and the sleeve kit that he sells. Now, I don't know if he was just trying to be cleaver salesperson, or if there was some truth in it.

Food for thought, but it does make some sense....
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Old 05-07-2004, 03:59 PM   #34
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In reply to the above response by vital49:

My personal experience from having installed the Korean plastic plenum, is that I was most certainly NOT impressed with the overall quality appearance of the part. -and who knows how good or bad the composition of the plastic is.

If I had to do it again, (-and I probably will, as I'm certain that there will be more SeriesII 3800'* in my future) I would do these two things: (1) Try to find a good used original GM plenum, or even better, try to purchase the part made by Delphi. (-which I think is the genuine GM part.) (2) DEFINITELY install the Ken Co Ind. kit.

I am of the very clear opinion that no matter what plenum a person uses, the kit is an absolute "no brainer" as to how to properly fix the EGR tube design weakness. It is totally clear to me that the only correct, long term fix, is to get the heat away from the plastic.

I'll say it this way, I'd be willing to bet that if GM had figured out the "double tube" idea in the first place, we very definately would not be having this discussion.

Harry
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Old 05-07-2004, 11:05 PM   #35
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The original plenum on my 96 SE is a Rochester products part.
The 2001 used plenum I bought is a Delphi part.
This may explain when the upgrade to the higher heat resistant material was made.
Also improved to resist backfire explosion.
I bought the new upper gasket and plan to install this sometime this summer as a preventative measure.
I noticed that the 96 Plenum has a larger fin around the bolt area that the Delphi part does not have.
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Old 05-08-2004, 01:24 AM   #36
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This is the first I heard about substandard material in the dorman manifold.I will say that the Dorman I installed looked identical to the original on my 98 Regal.I could see Zero difference except for heavier wall thickness between the stovepipe hole and the throttle body coolant passages.Otherwise they could have come from the same mold.So compared to the original (any material differences aside) the quality looked fine.The gaskets supplied looked nice also.However when i checked out a few at different stores prior to purchase, I found one that had a slightly warped "runner" in the runner insert that snaps inside the manifold shell,which probably wouldn't have mated properly with the gasket for that particular cylinder.If your gonna buy one of these plastic manifolds check it out closely if possible.I got mine at Pep Boys (who wanted 199) for 144 after price matching it against Advance Auto'* price of 144.I probably could have saved a few bucks shopping online but I wanted it now and wanted to see it first.Ah, the plastic manifold saga continues.
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Old 05-08-2004, 01:52 AM   #37
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Just an afterthought.When I replaced my upper intake (didn't do the lower gaskets) I checked the bolt torque on the lower manifold and found the two "hidden " bolts in the corners were looser than the rest.Actually below torque spec so tightened them up again.Also,at 43,000 miles,the original plastic upper showed no signs of heat degradation from the stovepipe .It'* the gasket longevity that bothers me more.
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Old 05-11-2004, 11:09 AM   #38
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Hey guys...

Not trying to beat a dead horse here, but I'm going to start on my upper intake real soon. Is there anything else that I should change in addition to the following list?

New GM upper intake
New upper intake gasket
New throttle body gasket
Clean the throttle body
EGR sleeve (mentioned in this thread)
New lower intake gasket
180 degree thermostat
Stant spring loaded radiator cap

Am I missing anything?? Trans cooler is the only addition, but that will be a seperate project!
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Old 05-11-2004, 11:37 AM   #39
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Quote:
Originally Posted by vital49
When talking with the sales person at Gagnon he indicated that the Dorman replacement upper intake is not the answer to fixing the notorius Series II issues. He said that the Dorman part is made in Korea and the grade of plastic falls way below the specs that GM uses. Even though the wall thickness may be greater, failure with the Dorman is still inevitable. He said the best solution is to go with the GM replacement upper intake and the sleeve kit that he sells. Now, I don't know if he was just trying to be cleaver salesperson, or if there was some truth in it.

Food for thought, but it does make some sense....
It is food for thought, but seeing as he doesn't sell the Dorman I'm not so sure that I would trust his comments.

When I checked out the quality of the Dorman, it appeared to be identical to OEM. The shop I used has put in about 20-30 Dormans so far without a complaint from anyone.
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Old 05-11-2004, 11:51 AM   #40
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Vital49, looks like you've got your parts list together. I found that it was really not too bad of a job to do. About the only difficulty I had was getting everything coordinated with that dumb little 90 degree coolant elbow on the passenger side (-front?) of the engine when replacing the lower intake. (-in fact, I forgot it at first, and notice my mistake when starting to torque down the bolts.)

Say, be sure to let us know the condition of the lower intake-to-heads gaskets. Mine were in ABSOLUTELY HORRIBLY BAD condition. -like totally wasted. I feel for sure that on my particular failure, that is how all the coolant got into the oil. And I'm talking about all within about 60 to 90 seconds of failure,,,,, bad news,, -and I even wound up replacing the connecting rod bearings too, just for good insurance. -they definitely had some discoloration on the back of each insert, as well as some "wiping" on the front surface along with some hard deposits.

YOU ARE SO LUCKY to be doing this as a good preventive measure, instead of waiting for the inevitable to happen.

This Bonneville Club Forum is GREAT !!
Thanks to everyone who makes this possible. You are providing a great service.

Harry
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