3100 SFI intake manifold failure - fix it or let it die? (PICS ADDED)

Turn2Stone · Poncho Master!

3100 SFI intake manifold failure - fix it or let it die? (PICS ADDED)

427carl · A Poncho Legend!

3100 SFI intake manifold failure - fix it or let it die?

68post · Poncho Master!

What he said, a common problem with these.

Turn2Stone · Poncho Master!

I really dont know the history. I suppose there is only one way to find out if it will last, but there are so many horror stories about the head gasket going soon after, or the problem never going away even with gasket changes. I'll give it a try as the parts cost is low. I just thought that if this engine is going to be a royal pain forever, I might be better off replacing it before sinking time and money into it. Peace of mind has big cash value to me. Thanks for the experienced thoughts!

66 Beau · Poncho Master!

My Venture van needed the gasket at 120,000 km. the original gaskets were sh:t. I've been told the replacement gaskets fix the problem and you should not expect another failure. I'm hoping that's true.

Could the plugged rad be a Dexcool problem? I've heard that adding regular glycol to the original Dexcool would create a real mess. Another great idea by the General.

68post · Poncho Master!

66 Beau wrote:
My Venture van needed the gasket at 120,000 km. the original gaskets were sh:t. I've been told the replacement gaskets fix the problem and you should not expect another failure. I'm hoping that's true.

Could the plugged rad be a Dexcool problem? I've heard that adding regular glycol to the original Dexcool would create a real mess. Another great idea by the General.

Yes, that's true, Dex-Cool ( Extended Life Coolant) and regular Glycol are not compatible.

ashmore · Guru

Watch out for head gasket leaking as well.The rear head leaks near the front cover and runs down the block.I repair at least 3 per month.

67Poncho · Uber Guru

As an edit to my post here, Ashmore posted his before me even though I had mine in the works for over an hour now.... I just don't want it to look like I am repeating him!!!

Actually, I am doing head gaskets in an '02 Rendezvous right now and yes, intake gaskets are an issue. Also, this one had a misfire on #1 and this is the most common area to inspect for coolant leaks on the outside of the engine. (Back of engine towards the passenger wheel)

The firing ring on the gasket was like an egg instead of being round and as well as leaking outside, she was burning coolant too! The piston, valves and chamber were nice and clean. But I have done many of these so I know what to look for. So, inspect the right rear of the engine underneath for coolant seepage/leakage. But since you are that far in, think about doing them if you are going to keep the car!

As for coolant, watch out for some of these extended coolants as some of them are a clear/yellow colour instead of the green and dex-cool orange.

And, I would like to add that if you mix green coolant and dex-coolant, it will not be the end of the world.

**DEX-COOL(TM) IS AN ETHYLENE GYLCOL BASED PRODUCT, THEREFORE, BOIL AND FREEZE PROTECTION ARE MEASURED IN THE SAME FASHION AS CONVENTIONAL COOLANTS.**

**TO FULLY REALIZE ITS MANY ADVANTAGES, DEX-COOL(TM) MUST NEVER BE MIXED WITH CONVENTIONAL COOLANTS**.

IT IS PARTICULARLY IMPORTANT TO TOP-OFF NEW VEHICLES WITH DEX-COOL(TM). DEX-COOL(TM) FORMS A PROTECTIVE FILM ON ALUMINUM SURFACES, HOWEVER, IF A VEHICLE WITH LESS THAN 3,000 MILES IS TOPPED-OFF WITH CONVENTIONAL COOLANT, ALUMINUM CORROSION MAY OCCUR.

**DEX-COOL(TM) CAN BECOME CONTAMINATED BY INADVERTENTLY TOPPING-OFF WITH CONVENTIONAL COOLANT, ADDING CONVENTIONAL COOLANT TO THE RADIATOR, OR EVEN IF FILL/DRAIN CONTAINERS ARE SHARED BETWEEN COOLANTS.**

IF CONTAMINATION OCCURS ON A NEW VEHICLE (I.E. DURING VEHICLE PREP), THE COOLING SYSTEM MUST BE IMMEDIATELY DRAINED AND REFILLED WITH DEX-COOL(TM). IF CONTAMINATION WITH CONVENTIONAL COOLANT OCCURS AFTER THE VEHICLE HAS BEEN DRIVEN FOR AT LEAST 3,000 MILES, NO SHORT-TERM PROBLEMS WILL OCCUR; HOWEVER, THE SERVICE CHANGE INTERVAL WILL BE REDUCED FROM 5 YEARS/100,000 MILES TO 2 YEARS/30,000 MILES.

-- Edited by 67Poncho on Monday 22nd of August 2011 05:14:30 PM

Elroy · Poncho Master!

ive been through this all with the manufacturer of all these products. GM makes it sound way worse than it is. If you mix, the special additives in the Dex get screwed up but really its not a huge problem exc for warranty claims. Do not panic, I add Diesel extended life to all my systems and anything going for a complete replacement. Thats on trucks cars aluminum you name it. I don't think most of us will live long enough to see the aluminum coolant ports rot out

MorePower · Poncho Master!

one word for you....HYDROLOCK....ok two more words....tow truck
Just did lower gasket and upper plenum on my car.....Yes it will puke, just a matter of time. Todd, Tiny and I all worked together at GM.
Fix it. I got all my parts for $400 incl complete tune up, oil change etc.
If its worth maintaining, do it. If not get CAA
Mine is a 3800 but the 3100 has same issue

eeluddy · Uber Guru

If the car was cheap enough, spend the money and do the top end gaskets including the head gaskets. Sh*tty gaskets from GM are not a good choice. I know a lot of non car (and car) people who will never buy GM again because of that problem.
Those Buicks are decent cars once that is fixed.

67Poncho · Uber Guru

MorePower wrote:
one word for you....HYDROLOCK....ok two more words....tow truck
Just did lower gasket and upper plenum on my car.....Yes it will puke, just a matter of time. Todd, Tiny and I all worked together at GM.
Fix it. I got all my parts for $400 incl complete tune up, oil change etc.
If its worth maintaining, do it. If not get CAA
Mine is a 3800 but the 3100 has same issue

I have never seen the 3100 and 3400 engines hydro like the 3800 because the upper plenum is aluminum instead of plastic composite. As we know, the EGR internal routing in the 3800 upper plenum is too close to the throttle body coolant access passages. Over time with EGR heat, the plastic becomes mush, fails and then under pressure coolant fills the upper plenum and then is sucked into the combustion chamber.

The failure of the head gasket in the 31 and 3400 is generally slow and over time but that doesn't mean it can't fail all at once and hydrolock!

Guess the "gaskets" are in your court!! wink

-- Edited by 67Poncho on Monday 22nd of August 2011 10:27:29 PM

Turn2Stone · Poncho Master!

Thanks for the input. I'm going to try to replace the gaskets myself. I suppose I should get a manual. I have found the torque specs online for these bolts in multiple places, but they differ, so I cant trust any of them. Can anyone recommend a good manual that covers the 3100? I've read that Chiltons and Haynes sux. I think I've tackled almost every other car job, but have avoided engines. Time to get dirty. I'm going to try to get the dexcool out of there, mainly because I have a cache of regular coolant.

-- Edited by Turn2Stone on Tuesday 23rd of August 2011 06:31:17 AM

Turn2Stone · Poncho Master!

Thanks again for taking the time to share your knowledge.....much appreciated. Here are some pics of the Buick. Nothing to get excited about, except maybe the price. There was a very poor turnout at my local auction. It was mostly flippers and dealers who generally wont even look at a car older than 5 years or so. A/C works great, and the 'concert sound' system is quite good. It looks as clean in person as it does in the pics, so you can see why I think its worth fixing.

-- Edited by Turn2Stone on Tuesday 23rd of August 2011 09:12:01 AM

-- Edited by Turn2Stone on Tuesday 23rd of August 2011 09:12:33 AM

68post · Poncho Master!

RE: 3100 SFI intake manifold failure - fix it or let it die? (PICS ADDED)

Turn2Stone · Poncho Master!

Barry,....Yes it was Jardines. I paid $1300. It has a book value of $4300-$5900 for whatever that is worth, insurance maybe. I was bidding based on condition and sound as it rolled up. I had never seen it before, and took a gamble. My last car from there, the 07 Crown Vic was $1700, and is the absolute 'best ride' for least money I ever bought, and I dont like F0rds. I've put nothing in it but a carpet and gas and drive it everyday. Its solid, comfy and has ice cold air. The Buick is saftied and on the road, I'm being quite picky about it. My whole philosophy about auction cars was that you dont have to fix em....just buy another one, as some repairs cost more, and most time you get years out of them, but it is a gamble. I've paid more for a set of tires than I did for this car. It seems the older I get....the more broken things bother me. Now this car comes along, and it just seems right to me to fix it.