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RonRepair, Auto Mechanic/Tech
Category: Car
Satisfied Customers: 76
Experience:  40 years of experience on all makes, 15 yrs. ASE Master Tech, 5 yrs. Certified Toyota Tech
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Chevy 3100 engine intake manifold repair

Resolved Question:

I just bought a 1996 Chevy Lumina which I knew has a Coolant leak into the engine.   I suspected a blown head gasket but in tearing down the engine I found the ever so popular blown lower intake manifold gasket.   The engine is throwing a code so I suspect the EGR passage to the throttle body is blocked, which more than likely is what caused the gasket to go.    What really need to know is, I don't feel comfortable that just replacing the gasket and cleaning the passage is a the best repair proceedure to stop this from ever happening again.   I have heard about a Toyota proceedure reading in the blogs using a F.I.P.G. material to replace the gasket.   I can not find the closly guarded proceedure online, can you provide me with this proceedure.   I s this a viable repair soloution? Is there a better repair method?
Submitted: 11 years ago.
Category: Car
Expert:  RonRepair replied 11 years ago.
Hi thanks for your question.

F.I.P.G. is Toyota's designation for their silicone sealer.

The gaskets in these are fairly thick, so it would take a thick bead of silicone to seal it. Any excess silicone would be squeezed into the port area, which could cause performance (flow) problems. It would be hard to line up the manifold too. You should also not use sealer on these gaskets.

So I would just use a quality gasket. I happen to prefer Fel Pro, O.E.M. are good too. Do clean all threads, follow the torque spec. and sequence, and use thread locker on the bolts. Although these gaskets are problematic, I don't think there is a better way.
Customer: replied 11 years ago.
Reply to RonRepair's Post: HI,
Thank you for your reply, my son is in school at UTI in PA for auto tech. He said that Toyota throws away the OEM gasket and uses FIPG(Form in place gasket) without the OEM gasket and this solves the problem for the life of the engine. (GM can't tell you to do this as they would be admitting to a design flaw in the engine, so they have to stick with the faulty hardened carrier design) My question is, what is the proceedure for applying the FIPG gasket material (Bead size), and how long do I let it cure before tigthening the intake manifold down. Placement of the lower intake manifold will not be an issue as I will be placing 4 wooden dowels in the four center screw holes of the manifold to make ceratin as I drop it on to the block it is centered corretly and does not disturb the silicone gasket material.I also need to know what the torque spec. is, if different, and what the tightening pattern is if different when using this FIPG material. Unfortunately UTI won't let myu son print or e-mail the TSB to me from all data and his typing skills are not the greatest so I can't rely on him typing what he remembers into an e-mail because it will probably be incorrect.
Expert:  RonRepair replied 11 years ago.
I was actually hoping I could dissuade you from attempting this. Aside from the reasons I have already mentioned, without a solid backing the manifold could bend or break in areas where your dowels are not acting as torque limiters. To overcome this you would need two dowels per bolt hole (one on each side horizontally, vertically, or diagonally) or spacers on each bolt hole, that the bolt could pass through.

If you can resolve that issue. First finger tighten all bolts, then torque to 115 inch lbs. (5 Nm). Start at a center bolt then move vertically, then diagonally, working from the center to both ends.

Silicone sealer uses moisture as a catalyst. So drying time is dependent on humidity. It can take days to fully cure. As far bead size it needs to be slightly thicker then the gap.

I mentioned using thread locker. I should have been more specific. Use the white (if you can find it) or blue. Do not use red.
Customer: replied 11 years ago.
Reply to RonRepair's Post: Well the dowels are only to locate the intake manifold onto the block, once the intake is placed dowels will be removed immediately and replaced with loose bolts. The new torque proceedure with the original OEM gasket is as follows: tighten from center bolts 67 In/lb. then outside bolts 67 Then retighten to 115 in/lbs in same pattern. Problem is I'm not using the OEM gasket, only the F.I.P.G.   So what I need to know is what is the recomended cure time on the F.I.P.G. before I begin to torque the bolts and with this FI.P.G. material as the new gasket is torque proceedure the same as with the OEM gasket? I have a Hanes manual with allof the other info you have been giving me, Medium loctite is what yopu meant to say and the bolt holes need to be chased with a thread cutting bit to clean them out, I also know that you have to put plumbers sealant ion the threads as well. This I all know, what I don't know is what the Toyota TSB says about the proceedure with in referance to bead size of the F.I.P.G., curing time,torque spec. and tightening pattern. I know what the Chevy TSB on this says and the two step proceedure for torquing the bolts is part of that Chevy TSB with the new redesigned OEM gasket. I am wondering if with all of your experience as a auto tech. why you were not aware of the new bolt tightening proceedure? My main problem is that as an Engineer and a do-it-yourselfer auto tech. I don't have any faith in the repair using a redesigned OEM gasket.   The design is flawed with to two dissimular metals which expand and contract at different rates, from what my experience tells me this is not a real fix that solves the problem, its only band-aid and the leak is only going to happen again.   In my opinion the Toyota repair is the best chance to once and for all solve the problem. The FIPG is a more forgiving material and will tend to allow the two surfaces to move at different rates and not tear the gasket apart over the next 25k to 80k miles.   What everyone fails to tell the consumer is that if you run you vehicle with coolant in the oil for too long it ruins your main bearings and the engine will eventually fail.
Expert:  RonRepair replied 11 years ago.
I am aware of how well F.I.P.G. works. I do agree that it would provide a permanent bond.

I am unable to find a Toyota TSB that refers to this procedure. If you have a specific year, model and engine I would be happy to recheck. When I looked up the torque specs., I did not find a TSB for revised specs. so I assumed the information was updated. I was aware that it was supplied with the gaskets. I apologize for the misinformation.

I would use the thickness of the frame on the original gasket to determine your bead size. I would take this dimension and add about .040 inch. I would also leave the spacers in until the bead becomes firm, and also start the bolts to keep things lined up. Remove them and apply the loctite when you are ready to tighten them. You will not need to use sealer in addition to the loctite, as it will also seal the bolts. I was referring to light or medium loctite.

The cure does depend on humidity, so what I would do is lay down a bead that you can check to see if it has cured. The bead will compress as you tighten the bolts, so the torque specs. will not be useful. I would tighten them to achieve dimension equal to the stock gasket thickness.

Have you considered using the gaskets, and cutting out the seals. Then putting them in place on the heads. You would have to find a way to hold the loose pieces in place. Replace the seals with the F.I.P.G. Then you would be able to use the torque specs. and sequence.
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