@%#! Freaking Intake Problems!

[Roadbastard]

Getting the motor back together. Everything going smooth with a big smile on my face like as I day dream about driving my car down the highway and then... I put my intake on after getting the valves nice and adjusted. You know I got me some of those good ol' FelPro metal gaskets. Line em up nicely and lay the the bead down. I felt an eaze of comfort as I knew I was a step closer to getting everything done. Yep... then I go to torque down the intake. Still nice and smooth then I get to the rear bolt and there seems to be a tiny gap between the intake and the head on the side of the lifter and spring area. I keep thinking why is this little gap here it should be sealed shut. I look and check the gaskets and everything is lined up, and sealed except for this one spot. So I go to re-torque the bolt.

Thinking it must not be tight enough.. the gaps starts to close slightly but so much pressure and then... it happens.. the threads loosen... they're stripped. now I have to helicoil fix it but the real problem is the gap. I'm baffled as I've never seen that happen on any gasket. Everything is lined up perfectly. Took my flashlight and checked the other spaces for gaps and everything is sealed but this one section where the top of the lower intake manifold meets with the head. It's like the rubber mold didn't form right in that area.

Now I'm at a crossroad. I guess. On one hand I can take the intake off and get a new gasket set to see if that fix the problem or I can leave it as is and helicoil the busted bolt threads and stick some RTV in between the little gap on the side. I can't think of a single reason why there's a small gap there other than QC.

[caffeine]

Seems to me there's an alignment tab in that corner. Are you sure it was seated properly in the head?

[Roadbastard]

Seems to me there's an alignment tab in that corner. Are you sure it was seated properly in the head?

Yeah, I'm pretty meticulous when assembling engine pieces. I must have checked that tab about 4 times before I put the intake on and once again right before I bolted it down. It's lined up and in place below everything. I'm going to take it off again but I'm quite sure once I do my full metal gaskets are ruined. It's better to do that that then jeopardize a a fresh bottom end for the same reason I had to rebuild it in the first place (coolant leak). Just strange this motor and it's intake design. Just about every other GM motor has intake bolts galore to secure the manifold over the ports but the 3100 doesn't get the same level of security. I'm not surprised coolant mixing in the oil via the intake gasket is a common problem on this engine. It's truly an Achilles heel to what's otherwise an excellent motor.

[fat rabbit]

When ever I change out lower intake gaskets and I'm to the point of re installing the lower intake I always do a dry test fit to make sure the lower intake lines up with the head bolt holes, having to clean up and re apply RTV around the cam valley is no fun lol

I've always had problems with Fel-Pro problem solver gaskets being slightly warped out of the box and they don't usually like to stay in all the alignment holes, my guess is with Caffeine on this one. Honestly I don't like nor recommend Fel-Pro problem solver gaskets, OEM gaskets are cheaper and don't have the problems that the Fel-Pro gaskets create.

[Roadbastard]

They're the FELPRO 98004. This is my second set after changing out the factory defects. I never had a fitment issue with the first set. It was made much better than the OEM's plastic vs metal and nice thick rubber. Just seems to be with the fitment of this set. You're right about the alignment holes they like to pop out. I had to keep pushing them in frequently.

I actually dislike GM's OEM gaskets. Nearly every GM vehicle I've owned has had a coolant leak or issue of some sort because of a GM gasket. They don't make their gaskets out of the best materials mostly the cheapest but efficient designs so they save in production costs. Then later on after a few thousand people complain they issue a "Re-design" for the gasket or what's really just a better produced gasket that should have been in there from the start.

On a side note though I'm surprised there was never a lawsuit against GM for the 3.1 Intake Gasket leaks. I never heard of a 3.1 that didn't have the leak or have the gaskets changed preventively.

[fat rabbit]

Fel-Pro Problem Solver lower intake gaskets have a problem with the rubber separating from the rubber frame as apposed to GM boxing in the rubber seal, I normally see them separate at the cylinder #3 intake seal and on 2 different cars at the coolant port seal. Another problem that was stated earlier is there just about always warped coming out of the box new, getting them to stay flat and in the alignment holes can be difficult. Then there more pricey then OEM lower intake gaskets, because of the problems I just can't justify spending more money on the fel-Pro's when there only going last just as the OEM set.

I'm most likely starting a debate with this but the problem with the lower intake leaking isn't because of the gaskets, its because of the design of the engine. The cooling system was poorly designed on the 3100, 3400, and 3500. It wasn't until they introduced the 3500 vvt and 3900 vvt that they ditched pumping coolant through the lower intake and instead pump it through the side of the head and make the filler neck the tallest point in the system. Then its also an open deck block and I've them all go through lower intake gaskets from the 3800 engines to 350 small block Chevy engines, I've never seen the problem with a closed deck engine and most likely because there isn't any lower intake gaskets.

I don't know why when GM redesigned the lower intake gaskets that they didn't go to a metal frame, they changed over to a metal frame design with the lower intake gaskets on the 3800 series 2 and 3 engines as with just about every gasket being metal now on the 3500 vvt and 3900 vvt.

There was a lawsuit against GM over the problem and GM lost, it was the Dex-Cool lawsuit. They claimed that Dex-cool ate away at the gaskets, though its honestly because of the design flaws of the engine. The only harm I've seen Dex-Cool do is when its not flushed out when recommended(like any type of coolant) it has a chemical reaction with aluminum and and causes it to pit, it also sludge up when mixed with coolant but that shouldn't happen and if so it seems to lead back to the design flaw of the engine.

These are just the conclusions I've come up with from what I've heard from others, seen with my own eyes and researched. I more then welcome being educated as I feel that when you think you know everything you have learned nothing.

[caffeine]

I also have seen two sets of felpro metal gaskets with the rubber separating with very low mileage. I say why bother with the more expensive gaskets if they're just going to leak anyway.

[Roadbastard]

That's funny to hear about the lawsuit. I always hated Dex cool and the red gunk. My Century has the greenstuff in it and it still had the leak. I went and pulled the lower intake off. The gaskets were in place but the rear lower intake manifold bolt wasn't holding too tight. They both seem to need some thread action now. Much better to address the problem in the garage than on the side of the road .


I did notice on my old FelPro gaskets the one that was in the motor before the rebuild that the Rubber seals split around the ports and kind of separated from the metal but for me that came from taking them out the engine. They were really fitted to the heads nicely and when I pulled to get them out they ripped.

[Roadbastard]

Welp. Took the intake off, helicoiled the bolts test fitted everything again and now it's highly obvious somethings wrong with the gaskets. They're too thick all that rubber and it's not letting the intake seat properly. Damn shame and waste of good money.

[Roadbastard]

And another update. After Helicoiling the rear bolts and torquing down everything in sequence it fit snugly into place finally. I had to do tighten the center bolts on one side of the LIM to get it to seat one rear bolt, then undo then and then tighten them on the other side to get it to seat the other rear bolt. Once I had the two rear bolts in place I tighten down the center bolts in sequence and then I did the front and rear bolts as usual. The Felpro metal gaskets were so thick I had to install them in that weird manner. When it was in it was IN!

[caffeine]

I don't think the Fel pros are any thicker than OEM. Usually the side bolts won't line up properly until the centre bolts are snugged even with OEM gaskets. You can easily start cross-threading the side bolts if you try threading them in without the centre bolts snugged

[Roadbastard]

I don't think the Fel pros are any thicker than OEM. Usually the side bolts won't line up properly until the centre bolts are snugged even with OEM gaskets. You can easily start cross-threading the side bolts if you try threading them in without the centre bolts snugged

The metal portion of it is thinner I think but it's the rubber molding that's thicker in certain areas. Atleast that's what I noticed when I had compared it to the old set before sending it back and going with the metal ones. Since they're the "Felpro problem Savers" they adjusted the design over the factory copies. With the OEM set the gaskets lining the ports gets compressed in to the plastic when you torque everything down. With the problem savers the gasket doesn't compress inward and seal when you torque the intake. It's a firmer rubber that the intake indents into the body of the port instead of just pressing against the port seal to make a tight seal around the ports. It does have a raised area for the ports though.

I remember the OEM gaskets going on smoothly and fitting comfortably while you torqued everything in. Never had to put much pressure on the intake at all. With the Metal Problem Savers you have have to be a bit firmer getting the intake on. I guess what they were thinking is if they used a harder rubber and a lager surface area that didn't compress into the gasket like the OEM's they could get a better leak proof seal.

What I did notice looking at my set I took off is that the metal can separate from the gasket or tear the gasket from the torque pressure. Since there's no relief for it and all that pressure is place on the firm rubber it just pushes right into the metal. With the OEM gasket once the you torque the intake down the gaskets gets compressed into the plastic but then the plastics takes the pressure from the torque. With the Metal FelPro's in some areas the rubber separated from the metal. Mostly around the top of the ports where both the metal and the rubber seal are thinnest.

Now that I think about it I like the OEM design better but haven't used the Problem savers long enough to tell if they can stand the test of time. Maybe 5-6 years from now there will be guys on here with 300K 3.1's complaining about the metal intake gaskets