Gaskets AND Seals on intake manifold?


3rd Gear Poster
Oct 5, 2023
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My 96 Bird intake was leaking coolant into my spark plug holes. I took it off yesterday only to find that not only are there intake manifold gaskets but there also were seals around all the ports on the manifold itself. Is this normal? In all my years of engineering, I've never seen a gasket with silicone seals used in conjunction with a mating piece that also has seals.

I would think that the seals alone on the manifold were designed to do the job and that adding another level of gasket where silicone meets silicone would be asking for a leak? Please educate me... I'm very confused...

That sounds like a previous repair changed the intake to a Dorman replacement (with the integrated seals) but also purchased a new set of gaskets for a standard Ford intake which (doesn’t have integrated gaskets) and put them together anyway. Yeah that’s not right!
So the Doorman replacement has seals around the ports and the OEM Ford does not? I'll take some pics of the intake tonight when I get home and post them for review. Are there replacement seals available for the Doorman? I'm certainly going to need them. They ones on the manifold were mangled and some even pulled out where they stuck to the silicone on the gaskets. Hmmm....

Edit: A quick search shows that it appears replacement seals for the Doorman replacement are available...
Correct, the Ford intake is like traditional intakes requiring a separate gasket to seal, Dormans use integrated gaskets like some more modern intakes so you don’t need the separate gaskets.
Well I would imagine that's probably why the coolant was leaking and I always had a suspicion of a vacuum leak. I've already cleaned up the mounting platform, just have to wipe it with some solvent to remove any oil, grease or coolant. I just ordered some seals from a local parts store. I won't be able to reinstall tonight and I'm busy this weekend. I guess it's another 2 week wait. :-(
I figured I'd better do a bit of cleaning on the intake before I install it. The green corrosion around the temperature sending unit is suspect. I probably have another used unit laying around. I'm wondering if I should even remove it. Also, I'm wondering about removing the injectors before I wash the intake. I don't think I have the "Ford" replacement O-rings but I have a LARGE assortment of Buna-N rings (quality ones, not Harbor Freight) and I might have the particular sizes. If not I could order them, they are dirt cheap buying in bulk. I have no idea how much a parts store wants for the O-rings but I'm sure it ain't cheap. What do y'all think, leave the injectors in place or remove them before cleaning the manifold? I was going to use water and detergent and a stiff brush. Oh, and thermostats USED to be cheap... I suppose I should replace it while I have the waterneck out? This coolant is some of the worst I've ever seen. A flush will be in order once I get the intake back on...


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That is definitely a Dorman intake. You can even see Dorman's logo cast into the bottom of the manifold. You can get a new set of the Dorman seals on Rockauto. As for the rest, I would leave the injectors in place, and I would definitely replace that thermostat!
That is definitely a Dorman intake. You can even see Dorman's logo cast into the bottom of the manifold. You can get a new set of the Dorman seals on Rockauto. As for the rest, I would leave the injectors in place, and I would definitely replace that thermostat!
Thank you for the information! I picked up a new set of seals... $60 at Advance Auto. I'm concerned about the Temp. Sending unit and all the corrosion... I think I'll have to replace that. I may have a new thermostat...have to check.
The color of the connector is critical.
There are 2 sensors, one for the gauge and one for the computer. They work on different resistances. From the factory, the different sensors have different colors that correspond to the connector color so the guy on the assembly line doesn’t have to think. Aftermarket sensors sometimes have the correct color and sometimes don’t, but the connectors themselves are actually different (the position of the locating tab is different) so as long as it plugs in, it should be fine.
Well, because of your warning, I put the green one back in. I cleaned up all the green copper corrosion on the brass sensor. I used PTFE sealant on the threads. The sensor may have been leaking from the threaded condition or it may have been leaking through the top of the connector. Since I cleaned it up, I should be able to tell if it's through the connector. The threads will not leak with the sealant.
After resealing and properly installing the aftermarket Doorman intake, she runs as she should. I think it still idles a bit high, 800 in park and 600 in drive according to the OBD scanner. I'm getting much closer to getting it on the road!

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