Upper Intake Manifold

315 Views 13 Replies 4 Participants Last post by JeebaJeebas, 8 d ago

JeebaJeebas

Discussion Starter · 14 d ago

98 F250 5.4L 120k miles

Hey all,

Mediocre mechanic, mostly YouTube and watching/talking/helping with friends' car repairs/maintenance.

In working through a misfire problem I noticed there was liquid around cylinder #1. Turns out the bottom of the thermostat housing's gasket is leaking. Also, it appears that the bottom part of the housing is moulded to the top of the intake manifold, in which I have to take that entire top piece off to operate/replace gaskets. Researching this leak it appears it was quite common for a few years around 96-98. There's a plastic internal gasket holder I guess that fails. 99 and on they released a fixed version of the manifold.

I watched a detailed video about this exact engine gasket replacement, and it doesn't seem too intimidating since I recently learned how to remove throttle housing (broke EGR bolt trying to replace that 😶 and had to remove a lot to get it drilled out). Only a few more steps and I was at the manifold removal part. It seems relatively straight forward now, but curious if any traps to watch out for.

Also, videos state that if the gasket holder is broken, in the part of the upper manifold, I'll have two options to deal with it. Option 1 is to buy a new upper assembly. Researching this I haven't been able to find the unit. There are similar versions for the f250 4.6, but I don't know if it'll work. I emailed a few aftermarket suppliers to see what they know and am waiting for word. Option 2 is to JB Weld any portion of the retainer that may be missing. The video stated in 10 or so repairs doing this, only one came back failed. Obviously I would rather buy the new assembly than risk redoing this project. But all assemblies now are plastic and that worries me, if I can even find one. Can anyone give advice on either of these options, or know how to track down this OEM part (F75Z-9424-DA)? Any help is extremely appreciated and thanks in advance!

Matt

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Bajarider

· #2 · 13 d ago

Hello Matt:
"Similar" helps, but not much. Which engine do you have and what year is your truck? (Looking at the part number it appears to be a '97 F 250??) To R&R the intake manifold is not complicated, BUT you must be clean and methodical. If you have not done this before, take a lot of photos before disassembly. You mentioned that you broke a throttle body bolt. A torque wrench (probably 3/8 drive) is an essential tool for this job. OEM parts are still available for that part number.

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JeebaJeebas

Discussion Starter · #3 · 13 d ago

Hi Baja thanks for your reply. My truck is a 98 F250 with the 5.4L Triton.

The part # I listed was obtained from calling the closest Ford dealership. They said that OEM part was obsolete and thus discontinued. I'd prefer an aluminum replacement instead of the plastic aftermarket ones, but I'll take what I can get. I'm going to remove the manifold sometime over the next few days and look at the underside of the therm housing to see if I'm worrying for nothing. If the plastic gasket holder is intact, can I reinforce it with JB Weld or something similar? Thanks again!

Matt

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YooperDave

· #4 · 13 d ago

You can try it, but all you'd be doing is kicking the can down the road.
Given the amount of work and time involved, you're better off with a new manifold if the old one is busted,
which it most likely is, cause they usually squirt the coolant out through where it cracked...DAHIK.

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JeebaJeebas

Discussion Starter · #5 · 13 d ago

Ya I don't want to redo this, it's just that a compatible manifold is nearly impossible to find for this year/model. I finally received word from a Ford parts department. He asked for my VIN to help track an option down. To see what I'm working with I'm going to remove the manifold and investigate 😶. I'll update what I find. One guy I read on here said he had a lot of success in creating his own 'gasket'. He fills the channel up with an appropriate epoxy and leaves a little room at top to finish with RTV (more detailed than that but it's the gist). It's scary, I know, but I'm just researching worst case scenario if I can't find a replacement (and I'm not going to listen to o'reilly dudes saying I need a new engine, at least until it's the only option cause everything else failed, truck was extremely solid before this). Shootin the ish, I appreciate your warnings ✊.

Matt

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YooperDave

· #6 · 13 d ago

Might have to go with aftermarket if no OEs are available.
Anyone who says you need a new engine because of a manifold needs their head examined.
Maybe a new coil and injector where the coolant was spraying, but new engine? Not likely.

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JeebaJeebas

Discussion Starter · #7 · 13 d ago

Any suggestions for further parts to replace while I'm in there would be appreciated. Not looking to throw money around at all, but learning the importance of preventative measures I can learn how to do myself.

Here's what I've done within last year (and I put less than average miles on it - bought in '15 with 73k miles, 120k now - put new MAF and IAC in '16 and remained purring until recently):

Plugs, Coils, Injectors, EGR, PCV, all vacuum lines I could find (hose that connects from PCV into back of Intake housing, the elbow itself, had a GIANT hole in the underside of it (saw that while throttle/upper plenum was removed trying to drill busted EGR bolt out), and Fuel Filter. I just put on a new Mevotech front end kit for adventurous wood collecting this summer. Pretty much stock truck otherwise.

I'm going to replace thermostat. Hoping water pump/fan clutch isn't necessary yet. I don't mind redoing -some- work later on. Timing system seems to be ok, but I don't know how to diagnose that. Thanks again.

Matt

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YooperDave

· #8 · 12 d ago

Two things are accessible when the manifold is off (that I recall): a metal coolant tube that goes to the back of the water pump, and the knock sensor.
If the tube has any kind of rust on it, consider replacing it, or cleaning and repainting it if it isn't blistering with rust along with new O rings.
To remove, take out any bolts holding it in place, and pull towards the back of the engine, then make sure to remove the old O rings. Pretty simple.
As for the knock sensor, your call. I didn't do it on mine 'cause I didn't know about it until I had it apart and decided not to bother (it's just my work beater/winter sacrificial truck).
Not really a major issue unless you do a lot of hauling or trailer towing...or hill climbing.

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JeebaJeebas

Discussion Starter · #9 · 12 d ago

Cheers thanks Yoooop! I appreciate a friendly answer instead of deriding my lack of knowledge. I take it with a grain of salt online but still it amazes me at times. Like making fun of a fat person at the gym 😳.

I found the knock sensor, looks easy. Would my screenshot be the tube you mention?

Many thanks again,

Matt

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YooperDave

· #10 · 12 d ago

It is the one I mentioned.
Most here try to help without bashing.
Those who go on the attack typically get moderated out in short order.

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bismic

· #11 · 11 d ago

Could you post the link to the video you watched?

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JeebaJeebas

Discussion Starter · #12 · 11 d ago

Hey bismic, didn't see you posted here 🙂

Here's the link to the video of the upper assembly gasket replacement. Seems straight forward based on my throttle/upper plenum(?) surgery recently (to drill press broken bolt from EGR housing?.

Here's the link to the guy about JB Welding a retaining structure with more detail about the failing inner retainer. He doesn't show how of course, just that he's 9/10 on average. It's scary, but worst case scenario I may be able to take my time with appropriate JB and Epoxies to create the new gasket channel (kinda like making a form and pouring concrete? Which I haven't done either ha).

Apparently there are no aftermarket uppers for my model. I've found car-part.com that have versions of my manifold. Scary getting one shipped that may already have same problem, or close to it. Since I never overheated, just the small leak, I'm hoping it's just the gasket and not the inner plastic. Tomorrow my plan is to disassemble everything and investigate after work. I'll update. Any thoughts on self-repair would be appreciated.

Matt

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bismic

· #13 · 11 d ago

Thanks for the links.

This is where a company like CarParts.com fits in well, but as you said - it can be a bit of a risk. I am not an aftermarket fan on MANY things, but sometimes it is our only choice as we deal with vanishing parts inventory.

I do think you are reasonable in your estimation of it being a gasket issue.

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JeebaJeebas

Discussion Starter · #14 · 8 d ago

Hey all,

1st part of surgery went well. Got everything disconnected and removed the upper manifold assembly. Turns out it was still an all-aluminum housing; the water crossover pipe was completely integrated with the housing. I could see on the old gasket where it was beat up and was in fact right under the thermostat housing and leaking into only cylinder 1. I don't need a new assembly and don't have to deal with the plastic retainer b.s.!!! The valve covers we're pretty dirty around edges, and the seam where the heads are looked pretty clean. I'm going to do valve gaskets and grommets this next weekend as well, plus clean all ports on upper assembly I can get to while it's off.

Thanks all for helping troubleshoot this!! I've learned a lot from reading these forums and then watching videos on the toob (the effort and detailedness y'all give is a godsend!). Never thought I could do this kind of surgery. I'll update once reinstalled and everything clears

.

Matt

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Upper Intake Manifold

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