Ford used to do that. The older modulars had metal backed timing guides and tensioner assemblies but at some point they switched to all plastic.

 

didn't know that, bet those older motors are bulletproof.

and to help with those questions you had before, not sure on the navigators, since mine is still running well, but you may get away with dropping the diff and dropping the oil pan and pop the 6th cylinder to redo the rings if necessary. but gotta be careful putting it back in so the rod don't touch the crank journal. did that on a 4.6 on a mountaineer with nothin but a tarp over my as LOL, i had before the nav without pulling the entire thing aside from the heads. on my 06 nav the differential can come apart in two pieces, pretty sure it can be done unless you are planning to rebuild the whole motor

 

My issue is that occasionally ill get a slight ticking sound that sounds like its coming from the drivers side bottom end, could be a crank or rod bearing, im not sure, but the weird part is that its intermittent, and its not loud. Some of thr other.modulars that ive torn down due to bad bearings could be heard down the block clacking away.

I am fortunate that my navigator is only 2wd. I picked it up a few weeks ago and had some buyers remorse wishing that i had bought a 4x4, but the price was great, and if i need a 4x4 ill drive my 05 f350, so now im kind of glad.

A trick i learned a while back when you are going to insert a piston into a mod motor, i get 2 pieces of 5/16s or 3/8s vacuum hose about 4 inches long each and stick one over each of studs sticking out of the bottom of the connecting rod. When you push the piston down most of the time the pieces of hose will straddle the crank and center the rod right onto the crank, and even if they dont, the pieces of hose prevent metal to metal contact. Once the rod is against the crank, just pull the pieces of hose off, bolt the cap on and your golden.

Andy

 

The older modar motors were great, just dont overheat em. My favorite trick is to find a non-pi modular, say a 97 mustang, or a pre 99 f150, yank the heads off and stick a set of pi heads and a pi intake onto the non pi engine. You get a signifigant boost in compression from the dang near flat top pistons of the non pi motor, and the small combustion chamber of the pi heads. With a proper tune they run like a r8ped ape.

 

Yeah! i've heard about that LOL, I was looking into that a few months ago, though, the pi heads and pi intake are pricey as hell. it would definitely be worth it for a drag project or a towing rig

 

Check your local wrecking yards. A few weeks ago i picked up a complete engine. Pan to manifold for 450. It was from an 02 f150. Just check the specs before u buy 1. The mustangs, f150s, expeditions, crown vics, and all the other platforms that used modulars got the pi upgrades at different years. Same with the 4.6 vs 5.4. If i recall, the 5.4s in the expedition and f150 were the last to get the pi upgrade, except for the lincoln town car, i think it waited all the way until 03 to get it even though it was a 4.6

 

Interesting I have the same 5 sec startup clatter, and also a similar occasional "knock", my "knock" only occurs when the engine is warm... never when hot, never when cold, but for maybe 30 sec on warm startup (warm startup = engine was hot, then turned off for ~20min, then restarted).

It performs fine in normal driving and towing, and after the initial startup is probably the smoothest/quietest engine I've ever had. I have just elected to not worry about the odd/occasional noises since they don't seem to affect anything now and any repairs would be time consuming and/or expensive.

Love this write-up overall though. Great to see someone putting some work into a Navi, they are really great vehicles!

 

Yup, it only does the knocking once its warm and not all the time. Funny thing is that the knocking sound almost exactly.coincides with the thumping i can feel from the mis fire. Im almost positive that the rattling in getting on startup is a bad chain tensioner. On the older.modulars ford used tensioners that were made from iron. These iron tensioners has a small ratchet built into them. Basicially what it would do it expand out as far as it could and put tension on the guides. Once expanded, the ratchet would not retract, so when your engine was initially started, the ratchets would keep tension on the timing guide until there was enough oil pressure to pressureize the pistons inside the tensioner units. It was a great design. When ford went to the newer style tensioners which are made of plastic, they eliminates the ratchets and replaced them with a spring that was supossed to do the same thing as the ratchets, but these tensioners were never as good. Im 99 percent positive the clattering i hear on startup is the chains smacking around until the tensioner piston pumps up and takes out the slack. This is due to a failed or failing tensioner.

the engine knocking has me a bit perplexed. Everything i know about engines tells me that if a bearing is damaged enough to knock, that it will continue to knock until it fails, not knock sometimes and not others. The only thing that could cause this behavior in my mind is that, its knocking because that cylinder is not being loaded up by the force of the combustion and this is being dragged around, but when it does decide to light and the bearings get loaded, it quiets down.

i still plan on yanking it and going thru it completely.

also, heres a video of my knocking sound, im curious to see if it sounds like yours.

https://youtu.be/gaONcprlwgs

Andy