Noahfreak

Hi Guys,

I just got this 1988 F150 with the 4.9L 6 in it and about 140k mi. on it, and am already stumped with a problem it's having. The other day I was driving it up a mild incline in second gear, felt a violent jolt, and the engine cut out at the same time. I cranked the engine and it would not start again. Checked spark, no spark, so I did some troubleshooting and found that it needed a new PIP sensor and changed the whole distributor as this part is a PITA to get out and wanted to do a new ignition module to make it all new. Changed the coil too because the old one had arcing pits on the terminal because the previous owner had never changed the wires or plugs/cap/rotor.
I marked the position of the old distributor, so I'm pretty sure I got it clocked right when I put the new one in. But when I start it up, it makes an awful clatter. Sounds like a diesel but definitely not right. Just to drive the point home, it is LOUD, almost as loud as a rod or wrist-pin knock would be, but not as solid. I tried adjusting the timing, but it doesn't stop making noise at any position of the distributor.
My theory is: the timing chain jumped time. My thinking is that the violent lurch it had when the spark cut out caused the old chain to jump a tooth. I've never had this happen though, so I don't know if these symptoms match. Has anyone ever experienced this problem before? If so, was it the timing chain or do I just have the distributor in wrong?

Noahfreak

Cranked it over again to move it and realized no oil pressure, so didn't run it long. Sat there cursing my luck when I realized the new distributor didn't have an oil pump shaft on it, and I forgot to switch the old one to it. Put that back in and it made a LOT of lifter noise for a while, even after the oil pressure came up. No lifter noise or knock after about 3 minutes of running, but now it has an intermittent miss at idle. Not sure how much damage I did, but this looks like it's going to be an expensive mistake.

This is my first inline six engine. I've always run 302w and 351m motors, and even had some sbc v8s in different vehicles. Any of those motors would have seized in about 15 seconds with no oil pressure. I'd say with the several startups I did after I put in the new distributor, the engine had 3-5 minutes running with no oil pressure, and all I've got with this one is a little miss at idle. Simply put, I am amazed.

RocketMedic

Noah, I actually think our 4.9s have timing gears, not chains. Have you checked your injectors?

summertop511

I would do a compression check it couldn't hurt and you would kno if your block is ok and has enough compression.

On a side note my friend had a 4.9 in his bronco. I never seen a vehicle beat so bad and survive for years. Finally one day out in the woods the front wheel fell off and destroyed the front end. Still ran going to the junkyard on a flat bed. They are beastly engines. Way better than any jap could make.

SUPERLOOP

I work at a Ford dealership (parts) and I remember back when we had the "cash for clunkers" program. After you got the paper from the government to destroy the motor, you would drain all the oil out and put a quart of liquid glass mixture in the crankcase. You would then start it up and let it idle before it seized. We had a 94 F-150 with the 4.9L (had only 40,000 miles to destroy). We let it idle for over 30 minutes and it still never seized. We finally had to rev it and it still didn't want to die, but you could hear every main bearing howling on the crank. After 45 minutes it finally seized. They were the toughest motors to destroy. For the record, this easiest one was a Dodge Caravan with the V-6. Hit the key and it quickly went CLUNK! LOL

Jmfalcon1

I had a '93 Chevy with a 5.7 that I ran dry (11,000 mi between oil changes and had a bad rear seal I didn't know about). Don't know how long I drove it dry before noticing that I had no oil pressure, but I had to drive 5 minutes to the nearest gas station to put oil in it. I put three quarts in and drove to the nearest Jiffy Lube. When they drained it, only 2 quarts came out. That truck was a champ! I hit three fuxking poles with it. Only things I ever replace on it were a starter, a thermostat, a power steering pump, and two tie rods (broke them hitting the second pole). The power steering pump got thrashed by the tow truck driver when the starter went out. I don't blame the manufacturer.

Jmfalcon1

I guess the manifold gasket did go bad too, but that was because the truck was barely driven for five years before I got it (maybe a hundred miles in that time). When we replaced it, we removed the distributor, marking it first. Put it back on, and we got the same diesel clatter you got. Just needed the timing adjusted, but we couldn't seem to get it at all. Had to have a shop do it. Had to rev the engine at red lights or it would stall.

TommySD

My old 99 Powerstroke. Drove it 12 miles with the turbo not spooling. No long term damage at all. Hit a total of 6 deer in the 2 years I had it. Backing out of a parking spot, I caught a festiva that quickly parked as I was backing out. I flipped it over and all it did was scratch the paint on my truck. Beast of a truck for sure!

Noahfreak

Took the truck and had it smogged yesterday. Passed with flying colors. Once again, I'm amazed. After sitting all night, cold start, not so much as a lifter tick on startup.
Jmfalcon1, I didn't have the same experience with the earlier small block chevy 350. I think yours was a different generation. My cousin parked his van in some overgrown weeds and he rusted the oil pan through from the moisture that collected over the several months it was sitting. When he started it up, it cut right out after 2 or 3 seconds. He called me over to look at it for him and I noticed that there was no oil in it and towed it to the shop to have a look. It was bone dry, and couldn't have run more than 20 seconds before the battery died from cranking. I changed the oil pan, filled it with oil, and it knocked like crazy. He drove it anyway and it was chewing through 2 quarts a day, and finally siezed after about two weeks. It had spun the bearings inside the block, so we ended up having to scrap the block. Moral of the story, small block v8's don't hold up quite as well as this one has when you accidentally run them without oil. I guess yours had some oil in it too, so maybe that's why. I have similar stories of sbf engines as well, they don't like being run without oil either.
RocketMedic, I just put new injectors in before the mishap, so they're good to go
Summertop511, that's a good plan. I'm assuming it's okay though since the smog check passed. I can't imagine it would pass the test with bad compression, but it's worth a check.
Superloop, that's a pretty amazing story. I was always skeptical when people told me similar ones, but I realize that they're probably all true. Guess I made the right choice picking the 300. I wish they had just put overhead cams on this and called it a day instead of going to the old v6. The newest variable timed 6's are pretty good, but we have yet to see how those things perform with 200k on them in the real world. We shall see.