Took off the upper intake - 94 4.0L

[Brandons]

Hey everyone, just took off my upper intake last night (replacing valve cover gaskets) and noticed theres a fine coat of oil on the inside of every port, except the 2nd last one, which is completely dry and somewhat rusty looking. Ive noticed a loss in power and also the odd time it will start up really rough and sputter when its running. Thinking possibly a bad injector, or burnt valve, but i have no idea otherwise.

I'll have to post pics later.

thanks for any help

 

[410Fortune]

its possible somethng is wrong with that cylinder
I would suspect a code for a spark error if it was a coil/wire/plug issue (mis fire)

You may want to replace your injectors now or at least service them if you have high miles

The change in color from port to port is kind of common on the OHV engines, the rear two cylinders do not get oiled as well as the front 4 in my experience, but if the change is drastic only over one port you are correct to assume a problem

It may have also been an air leak in the intake manifold gasket.
The pattern of oil/film iside the manifold is also effected greatly by the location of the vacuum ports, IAC valve, EGR valve, PCV and throttle body

What I am getting at is you may have an issue and you may not. The older metal intake manifolds I have seen off of OHV engines are not coated with oil/carbon/ film uniformly, the rear two cylinder ports are typically not as dark as the others if I remember correctly or vise versa

regardless now is your chance to check your valves, re-seal and replace the injectors, check the plugs and wires and all teh gaskets and re-seal the top of your engine properly.

Higher mileage OHV's with metal intakes develop alot of leaks in time in the lower and upper intakes, re-sealing them is a great way to get some power back and I consider it to be routine if you have over 150K miles

 

[Brandons]

Yeah i can see what your saying, but this port doesnt have a SINGLE trace of any oil in it at all. All the rest are evenly coated.

 

[Brandons]

oops - internet problem when i tried posting.. :thumbdwn:

 

[Brandons]

Quick picture of the upper intake, its all oily and gunky on the inside, yet the one port is dry as a bone. You can see it in the pic were the dry one stands out well.

 

[Brandons]

I think ill pick up the lower intake gaskets today or tomorrow then.

I dont know how to check the valves, probably requires me to pull the heads doesn't it? I wasn't planning on removing the heads at all, but if the gaskets arent too pricey i might.

I'll also note, im not great with engines, so im a bit afraid to dive into this.

 

[410Fortune]

dont be afraid, its very straight forward

When I say check the valves I mean under the valve covers you will get a good idea if anything is jacked up just by cleaning it up and looking

 

[Brandons]

Oh, everything looks pretty normal to me there then, to my untrained eye, ill take a better look and some pictures though eventually. Tomorrow i plan to do the majority of the work, i have the two gaskets so far for the upper intake and fuel rail.

I was going to use high temperature RTV silicone for the valve covers rather then spending $50 per gasket and seeing if that works, but the more i think about it the more it seems too cheap to actually work..

There is also alot of bad wiring from a previous natural gas system, they did a hack job on it. So I will be soldering and running new cables tomorrow or when i get home from work tonight.

Thanks alot for the help! Im hoping this goes smoothly lol.

 

[Brandons]

Alright, lower intake is off! That was a hell of a lot easier then i expected!

Going to get the other parts soon, thats the hard part..


Next - Clean upper intake, fix wiring (solder and heat shrink), re-assemble, fix mafs housing to have smaller port.

 

[mawrazen]

Check your vacuum lines for ATF. When had to remove the intake manifold to fix a leaking gasket on my 94 Ex. I had ATF fluid in the throttle body. I got the tranny modulator changed and the truck ran like new!

You probably need a new Tranny modulator Valve!

 

[Brandons]

Hmm i totally forgot about that!! there is some oil coming out of the vacume line to the brakes. Ill check the rest, I installed this tranny not too long ago, but i also have a new modulator in my old tranny i can use (if thats the issue).

Thanks!!!

 

[410Fortune]

replace your PCV valve while you are at it, oil in the brake booster line points to a bad PCV I believe as does excessive oil in the intake

 

[pope_face]

This is probably somewhere in this section of the forums, but when you're cleaning the valves, what do you use? Can you use a spray-on carb cleaner or something of the like, or is there an actual way to do this?

Also, $50 each for valve cover gaskets sounds a bit steep... I went to Lordco this past weekend and I was quoted about $35 for a set... unless you're referring to composite/metal/high-end gaskets as opposed to the cardboard ones.

I'm going to have to do this pretty soon myself... I really need to check my valves. Did you have a hard time removing the intake, or was it pretty straight-forward?

 

[Maniak]

Just a heads up.. if you haven't gotten your lower intake gasket, get the ford ones. The part # is F5TZ-9439-A.

The ford one is metal/rubber..

The felpro one is paper.

~Mark

 

[Brandons]

PCV was just replaced a couple weeks ago

DAMN you were too late mark I just got back and got the felpro crap. the original one was paper or plastic or something... this one is better then the original id have to say.

Using high temp silicone for the valve covers instead of gaskets.

 

[Maniak]

The ford valve cover gaskets are also metal.. but the ford gaskets aren't cheap.. I think I paid $80 or so for the 3 gaskets (lower intake and valve cover) and that was through Torrie

~Mark

 

[Brandons]

Ouch, ill probably end up tearing it down again next year for something so i'm not extreme concerned.. so far everythings going together nicely, but i still have loads of wiring to do.

 

[Brandons]

Well this is were im at now, i just have to tape back up the wiring harness (fixed some broken wires) and then i can get that back together.

Since i have a spare mass air housing off the parts explorer, im thinking of grinding down the one end and using the filter on that. Its about the same diameter as the current one (if i shave the metal off of course) so well see, just for testing to see if the housing makes any difference for me.

I have a feeling most of the ports were leaking at the gasket in the lower intake as almost every port (except the furthest back and 2nd furthest from the front) had traces of burnt-on oil were the gasket would mate.

Thanks again guys, and cheers!

P.S - Deep Green was the only colour i had left.

 

[Brandons]

Well its all back together, and ive found the main problem ive been having, the fuel pressure regulator.

If i unplug the vacume line to it it makes no difference idling (when its running rough). Im told this is a problem so i have the spare one ready to go on when im not lazy.

 

[pope_face]

Replacing the FPR is pretty easy... you could probably do it in about 15 minutes... But it's 15 minutes that will likely make a huge difference in performance. I just replaced my FPR and it seems to be running better than it was when I bought it 9 months ago...