4.9 refresh questions.

Reply Subscribe

Thread Tools

Search this Thread

Oct 5, 2022 | 07:48 AM

b00mhower

Thread Starter

Trailering

Joined: Mar 2016

Posts: 18

Likes: 3

4.9 refresh questions.

Currently in the process of removing a busted spark plug in my 91 F-150, 4.9L 4x2 automagic. Decided to take the intake plenum off for a little more elbow room and set to wondering what else I should check on or replace while I'm digging into it. Already have a distributor, plugs, and wires going in but wasn't sure if I should go ahead and dig deeper to save myself a return trip down the line. Insights, comments, concerns, anything you got is appreciated.
Thanks in advance

Oct 5, 2022 | 08:34 AM

AuroraGirl

Lead Driver

Joined: Jun 2021

Posts: 5,217

Likes: 803

Quote:

Originally Posted by b00mhower

chase all spark plug threads and probably wise to clean up cylinder 6 if you are willing to pull the head(all of them, but 6 prob looks the worst)

Oct 5, 2022 | 10:45 AM

b00mhower

Thread Starter

Trailering

Joined: Mar 2016

Posts: 18

Likes: 3

Quote:

Originally Posted by AuroraGirl

chase all spark plug threads and probably wise to clean up cylinder 6 if you are willing to pull the head(all of them, but 6 prob looks the worst)

I was hoping to not pull the head unless I had to but I'm not opposed to it. Why cylinder 6 specifically?

Oct 5, 2022 | 11:06 AM

cannothinkofaname

Mountain Pass

Joined: Jul 2022

Posts: 130

Likes: 16

vacuum lines might be easier with the intake plenum off. especially the ones which go behind the motor. You could clean the injectors. https://www.ford-trucks.com/forums/1...to-thread.html
clean the IAC valve, inspect the air charge sensor. clean the EGR. The injector kit comes with the gaskets to remove most of the intake.

Oct 5, 2022 | 11:40 AM

AuroraGirl

Lead Driver

Joined: Jun 2021

Posts: 5,217

Likes: 803

Quote:

Originally Posted by b00mhower

I was hoping to not pull the head unless I had to but I'm not opposed to it. Why cylinder 6 specifically?

if you dont want to pull the head, skip it, I said that for mechanical reasons, 6 tends to get leanest hottest or maybe it was carbon build up. what can said about vacuum lines 100% do those that run behind. also pcv and grommets for pcv + breather

Oct 5, 2022 | 11:41 AM

b00mhower

Thread Starter

Trailering

Joined: Mar 2016

Posts: 18

Likes: 3

Quote:

Originally Posted by cannothinkofaname

beautiful, all of that just made the checklist thank you

Oct 5, 2022 | 10:30 PM

Moongypsy

Mountain Pass

Joined: Nov 2021

Posts: 227

Likes: 75

Have you done a compression check? After purchasing my truck last year I replaced the plugs and had a hell-of-a-time removing #5 spark plug. The only large job I thought was needed was an exhaust manifold gasket, but after a compression check found two hairline cracks in the head for valves 3 and 5 and a pinhole in the block at cylinder 5. The previous owner filled the engine with stop leak instead of fixing the issue early. Now we're putting in a reconditioned motor...