Replacing Lower Intake Manifold Gasket

[sjjones]

Well, my No. 5 spark plug on my 94 4.0L OHV has been showing up oily for several years now. Retorquing the lower manifold bolts have no effect.

The X generally starts and runs great with no lack of power; except, at highway speed it will ping going uphill. I've been through most all the suggestions for pinging on this board except replacing the lower manifold gasket and looking into the No. 5 plug oily problem.

Anyway, I've got an after Chilton Ford Truck manual. Although I don't particular like the generalization of the manual, it does go into the process somewhat. My question goes out to anyone who has actually successfully completed the gasket replacement process *How difficult is the procedure for a first timer with a Chilton manual? What parts should I have on hand prior to getting into it (other than of course a new Ford brand lower manifold intake gasket). I've got plenty of regular tools include several torque wrenches.

My goal would be to start and complete the process within one weekend during the summer while I can ride my motorcycle to work just in case things take a little longer. Many thanks in advance. Private e-mail welcome at seamansjones@hotmail.com

 

[lifeguard379]

i have changed mine. the only prob i ran into was smaking the cps with the manifold and haveing to take it all apart agen to fix it. :fire: get some o rings for your injectors to. good luck.

 

[shamaal]

Is this a lower manifold intake problem? I'd be more inclined to believe it's a driver's side cylinder head or gasket problem. Compression test would help diagnose - do search.

I used the Haynes manual - no problem. Chilton's can't be too bad. For lower manifold removal, common handtools are fine, 10 mm is most common, use a deep dish socket for the valve cover stud. If you're going to disassemble the fuel rail and replace the injector o-rings (good idea as long as you're there) you'll need a Torx socket (T-28) to remove the studs. Lube the new rings with motor oil. This is an easy weekend job.

If it's a head or gasket problem, removing the exhaust manifold was my biggest headache. Other than that you'll need a Torx bit (T-55) and new head bolts. Inspect head for cracks after removal. Give serious thought to bringing to machine shop for cleaning and rebuild.

Read/search the forum and ask questions. Everyone's friendly.

 

[EMG7895]

I'll be doing mine, and the injector o -rings and valve cover gaskets in the next few weeks and I'll do a writeup then.

 

[sjjones]

Thanks to everyone for their responses - many thanks.

Shamall,

I've read many times on this board that a No. 5 oily spark plug, plus my continual pinging, plug the slow but gradual loss of antifreeze are signs of a lower intake manifold gasket leak - or just improper torquiing. I've retorqued them with no help.

I may end up doing more to the engine other than just replace the gasket if folks recommend it while I'm there, and I don't know whether or not I have a cracked head or not. At this stage, I'm most interested in getting some feel from folks how have actually done the gasket replacement on a 4.0L V6 OHV. There are always some parts and steps that can be taken to make the job go easier and successful. I'm cruising for wisdom - and really appreciate it.

 

[shamaal]

I changed my heads last month, removal of the lower manifold gasket is the last step before removing the heads. Both Haynes and the gasket kit recommended a thin film of silicone sealant around the water jacket ports, the sealing surface and the corners before installing the lower manfold gasket, I don't know if that's in Chiltons. The job goes really smooth. Cleaning the lower manifold was the biggest chore.

 

[hogmeat]

bump. just been told by my mechanic that i have an oily #5 plug (what is with that?!), and that most likely a leak. If anyone has pics or a walkthrough....i'd be your friend forever....

 

[sjjones]

Don't have pictures, but its real easy to determine yourself. Plug No. 5 is the middle plug on the "drivers" side of the engine. It happens to be one of the easiest plugs to remove on my 94 - so absolutely no problem checking it yourself. In fact, I can see that the plug is oily without even removing it. On the other hand, I've had an oily No. 5 for about 4 or 5 years and the vehicle runs great except for a minor ping that irrates me - but I've lived with for a long time. I do have a very slow antifreeze leak, but have had it for 100K miles. Still - I really like my X and will probably check out the head gasket and heads. Haven't done it yet - so can't be of any help.

BTW - an Oily No. 5 plug is a common sign that there is a manifold gasket leak; however, it coud always be something else. I understand that some folks have corrected the problem by retorquing the bolts - but it needs to be done correctly and not just tugging on them all - but in order and specs.

 

[shamaal]

I wish I had taken a pic when I had mine apart, in the meantime I've attached a pic from Haynes, and highlighted in red the area that requires RTV. It's around the water port and the ridge that runs between them. Other than that the repair is pretty simple. The lower manifold gasket kit should have everything else you need.
If you need a torque diagram I can add that but that should be in your Chilton's. In the meantime I've seen a real good set of pics elsewhere.