4.0 OHV Upper intake gaskets | Ford Explorer Forums - Serious Explorations

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4.0 OHV Upper intake gaskets

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April 1, 2007
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City, State
Halifax, Nova Scotia (Posted to Edmonton, AB for now)
Year, Model & Trim Level
1997 Explorer XLT
I was going through the numerous pictures I took of the engine change I did in the Spring after blowing the original motor in my 1997 XLT 4.0L OHV 5sp Manual, 4X4, and finally figured out which motor had what intake mainfold gasket (upper). The motor I replaced it with was out of a Ranger XLT.

The question I have is, what is the difference with the upper intake gaskets? The original motor had a thick (~1/4") plastic style gasket and the Ranger motor came with a thin paper one. I asked the folks at Ford and they didn't know the answer. The only big difference between the motors is that the Ranger was an Automatic.

I can see a larger intake chamber with the thicker gasket, however he didn't seem to think this had any effect. Nevertheless, I installed the thin paper one and everything seems to be working fine - got rid of the those 171/174 codes.

Just curious - Any ideas what made the difference - or is there any?

Thanks to everyone on the forum that helped me learn a new trade - Explorer mechanics.

Cheers, Roger :salute:
 



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is the paper one a ford original?
 






Yes, they both were/are.

I ordered some felpros (or a similar brand) from crappy tire (Canadian Tire) but they kept giving me the wrong gaskets, so I went directly to the Ford dealer.

Cheers, Roger :salute:
 






they probably redesigned it between 97 and 01 and determined that there would be no significant difference between the two so they are using the paper one
 






they probably redesigned it between 97 and 01 and determined that there would be no significant difference between the two so they are using the paper one

That could be, but they still hold P/N's for both gaskets.

I thought it may be that the Ex was a manual and the Ranger was automatic, but I don't know if that is the case. Maybe those with 1997 4.0L OHV manual/auto trannies could check to see what they have - I'm still curious.

What caught my attention was that the intake (plenum) studs were different lengths when I was swapping some of the parts around...

Cheers, Roger :salute:
 






That could be, but they still hold P/N's for both gaskets.

I thought it may be that the Ex was a manual and the Ranger was automatic, but I don't know if that is the case. Maybe those with 1997 4.0L OHV manual/auto trannies could check to see what they have - I'm still curious.

What caught my attention was that the intake (plenum) studs were different lengths when I was swapping some of the parts around...

Cheers, Roger :salute:

I have a 2000 sport and i had those codes before but i changed the Mass air flow and the codes have not come back but i always have some kind of miss or something running wrong with the truck that i thought maybe i should change them out. how much did the dealer charge you for the gaskets and was it easy to do. Sorry i cant answer your question but i saw your post and thought i ask mine.

thanks
 






we are talking 97 intake to 97 intake correct?

I am wondering if the Ranger and Ex have the exact same upper plenum in 97, I dont know.

Could be the plastic intakes use the thick gasket and the metal uses the thinner? I dunno.......

both gaskets are the same size and shape correct? meaning they fit the same lower intake?

my guess would be metal intake = thinner gasket, plastic intake = shorter bolts and thicker gasket?
I dont know why two 97's would have different parts, but Ford has been known to do silly things
 






Price of gaskets

... how much did the dealer charge you for the gaskets and was it easy to do...

I believe the gasket (paper - with rtv around the ports) was around $15.00Cdn and the plenum gaskets (more like odd shaped O-rings) were about $6.00 each. I purchased some other O-rings (oil filter bracket for 3), a Y-pipe to Cat converter gasket and a few nuts and bolts for the exhaust - all totalled, I spent $52.00Cdn for everything.

As far as the installation, it really isn't that difficult if you have the proper tools and an afternoon off. You will need a special torx socket (e6, I think - I can confirm this if you need) for the Plenum/Fuel rail studs. Just remember what vacuum lines you removed and the rest of the accessories so you put them back in the right spot. The only other thing I will pass on is a reminder of the fuel supply/return lines - there is a procedure for de-pressurizing them prior to just spinning them off. All I did was wait about a 1/2hr and wrap a rag around the fitting and opened it very slowly. The amount of times I have taken the fuel rail off I haven't had any problems doing it this way - just be aware that there is an amount of fuel in the lines and that it is under pressure.

There are some good tips within some of the forums to help you along. If you need any other help, just pm me, and I'll see what I can do to help.

Cheers, Roger :salute:
 






Plenum styles

we are talking 97 intake to 97 intake correct?

I am wondering if the Ranger and Ex have the exact same upper plenum in 97, I dont know.

Could be the plastic intakes use the thick gasket and the metal uses the thinner? I dunno.......

both gaskets are the same size and shape correct? meaning they fit the same lower intake?

my guess would be metal intake = thinner gasket, plastic intake = shorter bolts and thicker gasket?
I dont know why two 97's would have different parts, but Ford has been known to do silly things


410Fortune, The plenums are identical - and both plastic. The thick gasket was from the original engine on the Ex and the thin one was on the Ranger. I've interchanged the fuel rails and both have worked.

The only other subtle difference was that of the fuel injectors - though I can't be sure which ones came from what engine as I went a little wrench crazy taking parts off both engines at the same time (I was pushed for time). One set of injectors have a plastic gnurled cap on the end of the injector and the others have a smooth hard plastic end (this is where the o-ring slips over on the injector).

The shorter studs are for the paper gasket and the longer ones for the thick plastic style gasket.

Oh well, will keep on guessing - maybe the motor in my Ex wasn't the original???? hmmmmm

Cheers, Roger :salute:
 






I did not know that, I assumed all the Ex 4.0 OHV upper manifolds were aluminum. I knew the Rangers were plastic, but not the Ex's. Does anyone know what year they switched from aluminum to plastic?

Does the plastic upper intake manifold have o-rings where the manifold meets the gasket?
 






Plastic/metal plenums?

I did not know that, I assumed all the Ex 4.0 OHV upper manifolds were aluminum. I knew the Rangers were plastic, but not the Ex's. Does anyone know what year they switched from aluminum to plastic?

Does the plastic upper intake manifold have o-rings where the manifold meets the gasket?

I think it was 1995/96, but I'm probably wrong. Anyway, there's likely a more experienced person on the forum that can answer that.

When you talk about the upper intake manifold I am assuming you are talking about the plenum. Yes, there is a set of rubber/neoprene (square-ish) o-rings that are inset into the groove on the bootom of the plenum. These are the only seal between the plenum and the aluminum fuel rail, which suggests a problem with heat and expansion between the two very different compositions.

The paper gasket I am speaking about goes between the fuel rail (on its bottom) and the top of the intake manifold (lower). I hope this clarifies a few things.

I haven't (yet) changed any gaskets on the lower intake, I think I'll need a little more time than just an afternoon to do that....I do believe there is an o-ring that has something to do with the cam sensor though.

There is a very good post (with pics) that show the upper intake (plenum) and how to change the gaskets.

Cheers, Roger :salute:
 






Two countries separated by a common language. Pic below.

On the 91 OHVs the upper intake manifold is aluminum. On the Rangers in the pics I've seen it is plastic.
As I understand you are saying the original upper intake you had was plastic like the one you recently installed on the Ranger drop in.

Not shown in the pic is the gasket that goes under the fuel rail on top of the lower manifold.
Now I understand that is the one you are talking about. On the felpro kit I got both the upper and lower manifold to fuel rail gaskets were the same siliconized cardboard.

Thanks for the clarification.
 

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Hey Shamaal, Is that pic a '91 or a '97 exploded view? It doesn't look like the plenum & fuel rails changed all that much ...

The gasket that is in the diagram is very, very similar to the thick plastic-style that I mentioned earlier, only it is under the fuel rail, not on top (I have pictures showing it under the fuel rail). Could it be that the old motor was worked on before and the (maybe wrong) gasket(s) replaced in the wrong position?

In the felpro kit, how thick are the gaskets? I'm not sure because when I initially ordered the felpro kit it only had one gasket and it was the wrong one anyway...

Cheers, Roger :salute:
 






I think it's out of Haynes and it matches my 91. The gasket shown sits between the aluminum upper intake and the rail. An identical one is underneath the rail between the rail and the lower manifold. The felpro gaskets are maybe an eighth inch thick made out of a shiny cardboard with a silicone bead around the inlets. I no longer recall what the OEM's were.

As to whether your configuration is wrong or right, I'm of no help. I wasn't aware that the upper manifolds changed from aluminum to plastic. Now I understand people complaining about the manifold o'rings (squarish) leaking on their OHV, I always assumed they were confusing the OHV with the SOHC or the ranger.
 






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